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  • 51.
    König, Malin A. E.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Lehtila, Kari
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Among-Population Variation in Tolerance to Larval Herbivory by Anthocharis cardamines in the Polyploid Herb Cardamine pratensis2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 6, p. e99333-Article in journal (Refereed)
    Abstract [en]

    Plants have two principal defense mechanisms to decrease fitness losses to herbivory: tolerance, the ability to compensate fitness after damage, and resistance, the ability to avoid damage. Variation in intensity of herbivory among populations should result in variation in plant defense levels if tolerance and resistance are associated with costs. Yet little is known about how levels of tolerance are related to resistance and attack intensity in the field, and about the costs of tolerance. In this study, we used information about tolerance and resistance against larval herbivory by the butterfly Anthocharis cardamines under controlled conditions together with information about damage in the field for a large set of populations of the perennial plant Cardamine pratensis. Plant tolerance was estimated in a common garden experiment where plants were subjected to a combination of larval herbivory and clipping. We found no evidence of that the proportion of damage that was caused by larval feeding vs. clipping influenced plant responses. Damage treatments had a negative effect on the three measured fitness components and also resulted in an earlier flowering in the year after the attack. Tolerance was related to attack intensity in the population of origin, i.e. plants from populations with higher attack intensity were more likely to flower in the year following damage. However, we found no evidence of a relationship between tolerance and resistance. These results indicate that herbivory drives the evolution for increased tolerance, and that changes in tolerance are not linked to changes in resistance. We suggest that the simultaneous study of tolerance, attack intensity in the field and resistance constitutes a powerful tool to understand how plant strategies to avoid negative effects of herbivore damage evolve.

  • 52.
    König, Malin A. E.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Butterfly oviposition preference is not related to larval performance on a polyploid herb2016In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 6, no 9, p. 2781-2789Article in journal (Refereed)
    Abstract [en]

    The preference-performance hypothesis predicts that female insects maximize their fitness by utilizing host plants which are associated with high larval performance. Still, studies with several insect species have failed to find a positive correlation between oviposition preference and larval performance. In the present study, we experimentally investigated the relationship between oviposition preferences and larval performance in the butterfly Anthocharis cardamines. Preferences were assessed using both cage experiments and field data on the proportion of host plant individuals utilized in natural populations. Larval performance was experimentally investigated using larvae descending from 419 oviposition events by 21 females on plants from 51 populations of two ploidy types of the perennial herb Cardamine pratensis. Neither ploidy type nor population identity influenced egg survival or larval development, but increased plant inflorescence size resulted in a larger final larval size. There was no correlation between female oviposition preference and egg survival or larval development under controlled conditions. Moreover, variation in larval performance among populations under controlled conditions was not correlated with the proportion of host plants utilized in the field. Lastly, first instar larvae added to plants rejected for oviposition by butterfly females during the preference experiment performed equally well as larvae growing on plants chosen for oviposition. The lack of a correlation between larval performance and oviposition preference for A. cardamines under both experimental and natural settings suggests that female host choice does not maximize the fitness of the individual offspring.

  • 53.
    König, Malin A. E.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Context-dependent resistance against butterfly herbivory in a polyploid herb2014In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 174, no 4, p. 1265-1272Article in journal (Refereed)
    Abstract [en]

    Spatial variation in biotic interactions and natural selection are fundamental parts of natural systems, and can be driven by differences in both trait distributions and the local environmental context of the interaction. Most studies of plant–animal interactions have been performed only in natural settings, making it difficult to disentangle the effects of traits and context. To assess the relative importance of trait differences and environmental context for among-population variation in plant resistance to herbivory, we compared oviposition by the butterfly Anthocharis cardamines on two ploidy types of the herb Cardamine pratensis under experimentally controlled conditions with oviposition in natural populations. Under controlled conditions, plants from octoploid populations were significantly more preferred than plants from tetraploid populations. This difference was largely mediated by differences in flower size. Among natural populations, there was no difference in oviposition rates between the two ploidy types. Our results suggest that differences in oviposition rates among populations of the two cytotypes in the field are caused mainly by differences in environmental context, and that the higher attractiveness of octoploids to herbivores observed under common environmental conditions is balanced by the fact that they occur in habitats which harbor lower densities of butterflies. This illustrates that spatial variation in biotic interactions is the net result of differences in trait distributions of the interacting organisms and differences in environmental context, and that variation in both traits and context are important in understanding species interactions.

  • 54.
    König, Malin A. E.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Timing of flowering and intensity of attack by a butterfly herbivore in a polyploid herb2015In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 5, no 9, p. 1863-1872Article in journal (Refereed)
    Abstract [en]

    Timing of plant development both determines the abiotic conditions that the plant experiences and strongly influences the intensity of interactions with other organisms. Plants and herbivores differ in their response to environmental cues, and spatial and temporal variation in environmental conditions might influence the synchrony between host plants and herbivores, and the intensity of their interactions. We investigated whether differences in first day of flowering among and within 21 populations of the polyploid herb Cardamine pratensis influenced the frequency of oviposition by the butterfly Anthocharis cardamines during four study years. The proportion of plants that became oviposited upon differed among populations, but these differences were not related to mean flowering phenology within the population in any of the four study years. Attack rates in the field were also not correlated with resistance to oviposition estimated under controlled conditions. Within populations, the frequency of butterfly attack was higher in early-flowering individuals in two of the four study years, while there was no significant relationship in the other 2years. Larger plants were more likely to become oviposited upon in all 4years. The effects of first flowering day and size on the frequency of butterfly attack did not differ among populations. The results suggest that differences in attack intensities among populations are driven mainly by differences in the environmental context of populations while mean differences in plant traits play a minor role. The fact that within populations timing of flowering influenced the frequency of herbivore attack only in some years and suggests that herbivore-mediated selection on plant phenology differs among years, possibly because plants and herbivores respond differently to environmental cues.

  • 55.
    König, Malin
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Lehtilä, Kari
    Södertörn University.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Among-population variation in tolerance to larval herbivory by Anthocharis cardamines in the polyploid herb Cardamine pratensisManuscript (preprint) (Other academic)
  • 56.
    König, Malin
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Among-population variation in butterfly oviposition preference and larval performance on a polyploid herbManuscript (preprint) (Other academic)
  • 57.
    König, Malin
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Timing of flowering influence intensity of attack by a butterfly herbivore in a polyploid herbManuscript (preprint) (Other academic)
  • 58.
    Larsdotter Mellström, Helena
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Friberg, Magne
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Borg-Karlson, Anna-Karin
    KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry.
    Murtazina, Rushana
    KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry.
    Palm, Mikael
    KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Seasonal polyphenism in life history traits: Time costs of direct development in a butterfly2010In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 64, p. 1377-1383Article in journal (Refereed)
    Abstract [en]

    Insects with two or more generations per year will generally experience different selection regimes depending on the season, and accordingly show seasonal polyphenisms. In butterflies, seasonal polyphenism has been shown with respect to morphology, life history characteristics and behaviour. In temperate bivoltine species, the directly developing generation is more time-constrained than the diapause generation and this may affect various life history traits, such as mating propensity (time from eclosion to mating). Here we test whether mating propensity differs between generations in Pieris napi, along with several physiological parameters, for males sex pheromone synthesis, and for females ovigeny index and fecundity.

    As predicted, individuals of the directly developing generation – who have shorter time for pupal development - are more immature at eclosion; males take longer to synthesize the male sex pheromone after eclosion and also take longer to mate than diapause generation males. Females show the same physiological pattern, the directly developing females lay fewer eggs than diapausing females during the first days of their life. Nevertheless, the directly developing females mate faster after eclosion than diapausing females, indicating substantial adult time stress in this generation and possibly an adaptive value of shortening the pre-reproductive period.

    Our study highlights how time-stress can be predictably different between generations, affecting both life history and behaviour. By analyzing several life history traits simultaneously we adopt a multi-trait approach to examining how adaptations and developmental constraints likely interplay to shape these seasonal polyphenisms.

  • 59.
    Larsdotter Mellström, Helena
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Murtazina, Rushana
    KTH - Royal Institute of Technology, School of Chemical Science.
    Borg-Karlson, Anna-Karin
    KTH - Royal Institute of Technology, School of Chemical Science.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Timing of Male Sex Pheromone Biosynthesis in a Butterfly –  Different Dynamics under Direct or Diapause Development2012In: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 38, no 5, p. 584-591Article in journal (Refereed)
    Abstract [en]

    The life history traits and behavior of the butterfly are well-known, as the species is often used as a model organism for evolutionary and ecological studies. The species has two or more generations per year in the major part of its temperate distribution, and as different selection pressures affect the different generations, both behavioral and physiological seasonal polyphenisms have been shown previously. Here, we explored the dynamics of male sex pheromone production. The two generations are shown to have significantly different scent compositions early in life; the direct developers-who have shorter time for pupal development-need the first 24 hr of adult life after eclosion to synthesize the sex pheromone citral (geranial and neral 1:1)-whereas the diapausing individuals who have spent several months in the pupal stage eclose with adult scent composition. Resource allocation and biosynthesis also were studied in greater detail by feeding butterflies C-13 labeled glucose either in the larval or adult stage, and recording incorporation into geranial, neral, and other volatiles produced. Results demonstrate that the pheromone synthesized by newly eclosed adult males is based on materials ingested in the larval stage, and that adult butterflies are able to synthesize the pheromone components geranial and neral and the related alcohols also from adult intake of glucose. In summary, our study shows that time-stress changes the timing in biosynthesis of the complete pheromone between generations, and underpins the importance of understanding resource allocation and the physiological basis of life history traits.

  • 60.
    Larsdotter Mellström, Helena
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Different mating expenditure in response to sperm competition risk between generations in the bivoltine butterfly Pieris napi2015In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 69, no 7, p. 1067-1074Article in journal (Refereed)
    Abstract [en]

    Examining how the response to sperm competition risk varies in a population is essential in order to understand variation in reproductive success and mating system. In polyandrous butterflies, males transfer a large spermatophore at mating that delays female remating and confers an advantage in sperm competition. However, as large ejaculates are costly to produce—male expenditure on ejaculate size should be selected to vary with risk of sperm competition, as previously shown in the butterfly Pieris napi. In P. napi, adults can either emerge after winter diapause, or they can emerge as a directly developing generation later in the summer. Post-diapause adults have fewer developmental constraints because direct developers have to grow, develop, emerge, mate, and reproduce during a more limited seasonal timeframe, and as a result are more time-stressed. The two generations show polyphenisms in a variety of traits including polyandry, pheromone production, mating propensity, and sexual maturity at eclosion. Using these within-species, between generation differences in ecology, we generated three important findings: (1) that both generations respond to an immediate risk of elevated sperm competition and significantly raise ejaculate investment, (2) that the diapausing generation raises this investment by a far greater 65 % increase compared with the direct generation males’ 28 %, and (3) that males show a graded response relative to sperm competition risk and increase their ejaculate investment in relation to the actual level of mate competition. The difference in male mating allocation between generations may help explain life history evolution and geographic differences in mating patterns.

  • 61.
    Larsdotter Mellström, Helena
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Males use sex pheromone assessment to tailor ejaculates to risk of sperm competition in a butterfly2009In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 20, no 5, p. 1147-1151Article in journal (Refereed)
    Abstract [en]

    In polyandrous butterflies males transfer a large, nutritious ejaculate at mating. Larger ejaculates delay female remating and confer an advantage in sperm competition. However, large ejaculates are costly, potentially selecting for male adjustment of ejaculate size to the risk of sperm competition. Here, we test if male ejaculate size in the butterfly Pieris napi varies with male density, and whether males assess sperm competition risk using the male sex pheromone citral as a cue. The results conform to sperm competition theory and showed that male P. napi tailored their reproductive investment in response to the risk of sperm competition; ejaculates transferred by males in the high male density treatments were on average 23% larger than ejaculates transferred at low male densities. The results also show for the first time, that the sex pheromone citral was used by males to assess male density; ejaculates transferred by males in presence of added male sex-pheromone were 19% larger than ejaculates transferred in the control. In conclusion, the study shows how the sex pheromone not only facilitates female acceptance when dispensed by courting males, but also allows males to assess the degree of male competition for matings.

  • 62.
    Larsdotter Mellström, Helena
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    What affects mating rate?: Polyandry is higher in the directly developing generation of the butterfly Pieris napi2010In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 80, p. 413-418Article in journal (Refereed)
    Abstract [en]

    Polyandry is common among insects and female insects in general gain directly from mating multiply in terms of increased lifetime reproductive success. Nevertheless, polyandry is not rampant, suggesting that realized polyandry is the outcome of costs and benefits associated with multiple matings. In the bivoltine green-veined white butterfly Pieris napi, females gain from mating multiply as males transfer a substantial nuptial gift along with the sperm at mating. Nonetheless, lifetime number of matings varies between 1 and 6 and 12 % of females mate only once. Here, we explore the reason for this variation and test (1) whether female polyandry is contingent on environmental conditions, specifically whether females can compensate for adverse conditions by mating more often, and (2) whether the level of polyandry differs between the diapausing generation that flies after pupal hibernation, and the directly developing generation, specifically whether females in the more time-constrained summer generation are more polyandrous, possibly as a result of selection for early high mating propensity and thereby shorter pre-reproductive period. Results showed that (1) females do not compensate for adverse conditions by mating more often, and (2) the level of polyandry was higher in the directly developing generation than in the diapause generation. Hence, we argue that differences in time stress and mating propensity between generations interplay in shaping mating frequency, and that the difference in polyandry between generations highlights the importance of integrating developmental pathway and life history.

  • 63.
    Larsdotter-Mellström, Helena
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. The University of Western Australia, Australia.
    Eriksson, Kerstin
    Liblikas, Ilme
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Borg-Karlsson, Anna K.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Janz, Niklas
    Stockholm University, Faculty of Science, Department of Zoology.
    Carlsson, Mikael A.
    Stockholm University, Faculty of Science, Department of Zoology.
    It's All in the Mix: Blend-Specific Behavioral Response to a Sexual Pheromone in a Butterfly2016In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 7, article id 68Article in journal (Refereed)
    Abstract [en]

    Among insects, sexual pheromones are typically mixtures of two to several components, all of which are generally required to elicit a behavioural response. Here we show for the first time that a complete blend of sexual pheromone components is needed to elicit a response also in a butterfly. Males of the Green-veined White, Pieris napi, emit an aphrodisiac pheromone, citral, from wing glands. This pheromone is requisite for females to accept mating with a courting male. Citral is a mixture of the two geometric isomers geranial (E-isomer) and neral (Z-isomer) in an approximate 1:1 ratio. We found that both these compounds are required to elicit acceptance behaviour, which indicates synergistic interaction between processing of the isomers. Using functional Ca2+ imaging we found that geranial and neral evoke significantly different but overlapping glomerular activity patterns in the antennal lobe, which suggests receptors with different affinity for the two isomers. However, these glomeruli were intermingled with glomeruli responding to ,for example, plant-related compounds, i.e. no distinct subpopulation of pheromone-responding glomeruli as in moths and other insects. In addition, these glomeruli showed lower specificity than pheromone-activated glomeruli in moths. We could, however, not detect any mixture interactions among four identified glomeruli, indicating that the synergistic effect may be generated at a higher processing level. Furthermore, correlations between glomerular activity patterns evoked by the single isomers and the blend did not change over time.

  • 64. Leal, Luis
    et al.
    Talla, Venkat
    Källman, Thomas
    Friberg, Magne
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Dincă, Vlad
    Vila, Roger
    Backström, Niclas
    Gene expression profiling across ontogenetic stages in the wood white (Leptidea sinapis) reveals pathways linked to butterfly diapause regulation2018In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 27, no 4, p. 935-948Article in journal (Refereed)
    Abstract [en]

    In temperate latitudes, many insects enter diapause (dormancy) during the cold season, a period during which developmental processes come to a standstill. The wood white (Leptidea sinapis) is a butterfly species distributed across western Eurasia that shows photoperiod-induced diapause with variation in critical day-length across populations at different latitudes. We assembled transcriptomes and estimated gene expression levels at different developmental stages in experimentally induced directly developing and diapausing cohorts of a single Swedish population of L. sinapis to investigate the regulatory mechanisms underpinning diapause initiation. Different day lengths resulted in expression changes of developmental genes and affected the rate of accumulation of signal molecules, suggesting that diapause induction might be controlled by increased activity of monoamine neurotransmitters in larvae reared under short-day light conditions. Expression differences between light treatment groups of two monoamine regulator genes (DDC and ST) were observed already in instar III larvae. Once developmental pathways were irreversibly set at instar V, a handful of genes related to dopamine production were differentially expressed leading to a significant decrease in expression of global metabolic genes and increase in expression of genes related to fatty acid synthesis and sequestration. This is in line with a time-dependent (hour-glass) model of diapause regulation where a gradual shift in the concentration of monoamine neurotransmitters and their metabolites during development of larvae under short-day conditions leads to increased storage of fat, decreased energy expenditures, and ultimately developmental stasis at the pupal stage.

  • 65.
    Lehmann, Philipp
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Pruisscher, Peter
    Stockholm University, Faculty of Science, Department of Zoology.
    Kostal, Vladimir
    Moos, Martin
    Simek, Petr
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Agren, Rasmus
    Varemo, Leif
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Wheat, Christopher W.
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Metabolome dynamics of diapause in the butterfly Pieris napi: distinguishing maintenance, termination and post-diapause phases2018In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 221, no 2, article id UNSP jeb169508Article in journal (Refereed)
    Abstract [en]

    Diapause is a deep resting stage facilitating temporal avoidance of unfavourable environmental conditions, and is used by many insects to adapt their life cycle to seasonal variation. Although considerable work has been invested in trying to understand each of the major diapause stages (induction, maintenance and termination), we know very little about the transitions between stages, especially diapause termination. Understanding diapause termination is crucial for modelling and predicting spring emergence and winter physiology of insects, including many pest insects. In order to gain these insights, we investigated metabolome dynamics across diapause development in pupae of the butterfly Pieris napi, which exhibits adaptive latitudinal variation in the length of endogenous diapause that is uniquely well characterized. By employing a time-series experiment, we show that the whole-body metabolome is highly dynamic throughout diapause and differs between pupae kept at a diapause-terminating (low) temperature and those kept at a diapause-maintaining (high) temperature. We showmajor physiological transitions through diapause, separate temperature-dependent from temperature-independent processes and identify significant patterns of metabolite accumulation and degradation. Together, the data show that although the general diapause phenotype (suppressed metabolism, increased cold tolerance) is established in a temperature-independent fashion, diapause termination is temperature dependent and requires a cold signal. This revealed several metabolites that are only accumulated under diapause-terminating conditions and degraded in a temperature-unrelated fashion during diapause termination. In conclusion, our findings indicate that some metabolites, in addition to functioning as cryoprotectants, for example, are candidates for having regulatory roles as metabolic clocks or time-keepers during diapause.

  • 66.
    Lehmann, Philipp
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Pruisscher, Peter
    Stockholm University, Faculty of Science, Department of Zoology.
    Posledovich, Diana
    Stockholm University, Faculty of Science, Department of Zoology.
    Carlsson, Mikael
    Stockholm University, Faculty of Science, Department of Zoology.
    Käkelä, Reijo
    Tang, Patrik
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Wheat, Christopher W.
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Energy and lipid metabolism during direct and diapause development in a pierid butterfly2016In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 219, no 19, p. 3049-3060Article in journal (Refereed)
    Abstract [en]

    Diapause is a fundamental component of the life-cycle in the majority of insects living in environments characterized by strong seasonality. The present study addresses poorly understood associations and trade-offs between endogenous diapause duration, thermal sensitivity of development, energetic cost of development and cold tolerance. Diapause intensity, metabolic rate trajectories and lipid profiles of directly developing and diapausing animals were studied using pupae and adults of Pieris napi butterflies from a population for which endogenous diapause is well studied. Endogenous diapause was terminated after 3 months and termination required chilling. Metabolic and postdiapause development rates increased with diapause duration, while the metabolic cost of postdiapause development decreased, indicating that once diapause is terminated development proceeds at a low rate even at low temperature. Diapausing pupae had larger lipid stores than the directly developing pupae and lipids constituted the primary energy source during diapause. However, during diapause lipid stores did not decrease. Thus, despite lipid catabolism meeting the low energy costs of the diapausing pupae, primary lipid store utilization did not occur until the onset of growth and metamorphosis in spring. In line with this finding, diapausing pupae contained low amounts of mitochondria-derived cardiolipins, which suggests a low capacity for fatty acid β-oxidation. While ontogenic development had a large effect on lipid and fatty acid profiles, only small changes in these were seen during diapause. The data therefore indicate that the diapause lipidomic phenotype is built early, when pupae are still at high temperature, and retained until diapause post-diapause development.

  • 67.
    Leimar, Olof
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Norberg, Ulf
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Habitat preference and habitat exploration in two species of satyrine butterflies2003In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 26, p. 474-480Article in journal (Refereed)
  • 68. Lukhtanov, Vladimir A.
    et al.
    Dinca, Vlad
    Friberg, Magne
    Sichova, Jindra
    Olofsson, Martin
    Stockholm University, Faculty of Science, Department of Zoology.
    Vila, Roger
    Marec, Frantisek
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Versatility of multivalent orientation, inverted meiosis, and rescued fitness in holocentric chromosomal hybrids2018In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 115, no 41, p. E9610-E9619Article in journal (Refereed)
    Abstract [en]

    Chromosomal rearrangements (e.g., fusions/fissions) have the potential to drive speciation. However, their accumulation in a population is generally viewed as unlikely, because chromosomal heterozygosity should lead to meiotic problems and aneuploid gametes. Canonical meiosis involves segregation of homologous chromosomes in meiosis I and sister chromatid segregation during meiosis II. In organisms with holocentric chromosomes, which are characterized by kinetic activity distributed along almost the entire chromosome length, this order may be inverted depending on their metaphase I orientation. Here we analyzed the evolutionary role of this intrinsic versatility of holocentric chromosomes, which is not available to monocentric ones, by studying F-1 to F-4 hybrids between two chromosomal races of the Wood White butterfly (Leptidea sinapis), separated by at least 24 chromosomal fusions/fissions. We found that these chromosomal rearrangements resulted in multiple meiotic multivalents, and, contrary to the theoretical prediction, the hybrids displayed relatively high reproductive fitness (42% of that of the control lines) and regular behavior of meiotic chromosomes. In the hybrids, we also discovered inverted meiosis, in which the first and critical stage of chromosome number reduction was replaced by the less risky stage of sister chromatid separation. We hypothesize that the ability to invert the order of the main meiotic events facilitates proper chromosome segregation and hence rescues fertility and viability in chromosomal hybrids, potentially promoting dynamic karyotype evolution and chromosomal speciation.

  • 69.
    Mozuraitis, Raimondas
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Murtazina, Rushana
    Zurita, Javier
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Pei, Yuxin
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Borg-Karlson, Anna Karin
    Anti-aphrodisiac pheromone, a renewable signal in adult butterfliesManuscript (preprint) (Other academic)
  • 70.
    Navarro-Cano, Jose A.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Karlsson, Bengt
    Stockholm University, Faculty of Science, Department of Zoology.
    Posledovich, Diana
    Stockholm University, Faculty of Science, Department of Zoology.
    Toftegaard, Tenna
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Climate change, phenology, and butterfly host plant utilization2015In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 44, no S!, p. S78-S88Article in journal (Refereed)
    Abstract [en]

    Knowledge of how species interactions are influenced by climate warming is paramount to understand current biodiversity changes. We review phenological changes of Swedish butterflies during the latest decades and explore potential climate effects on butterfly-host plant interactions using the Orange tip butterfly Anthocharis cardamines and its host plants as a model system. This butterfly has advanced its appearance dates substantially, and its mean flight date shows a positive correlation with latitude. We show that there is a large latitudinal variation in host use and that butterfly populations select plant individuals based on their flowering phenology. We conclude that A. cardamines is a phenological specialist but a host species generalist. This implies that thermal plasticity for spring development influences host utilization of the butterfly through effects on the phenological matching with its host plants. However, the host utilization strategy of A. cardamines appears to render it resilient to relatively large variation in climate.

  • 71.
    Olofsson, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Dimitrova, Marina
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    The white 'comma' as a distractive mark on the wings of comma butterflies2013In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 86, no 6, p. 1325-1331Article in journal (Refereed)
    Abstract [en]

    Distractive marks have been suggested to prevent predator detection or recognition of a prey, by drawing the attention away from recognizable traits of the bearer. The white 'comma' on the wings of comma butterflies, Polygonia c-album, has been suggested to represent such a distractive mark. In a laboratory experiment using blue tits, Cyanistes caeruleus, as predators, we show that the comma increased survival, since the blue tits attacked butterflies with overpainted commas more often than sham-painted butterflies with intact commas. In a field experiment we placed hibernating, similarly manipulated, comma butterflies on tree trunks of two different species and noted their survival. Although survival was higher on birch trees than on oak trees, there was no effect of treatment, probably because the butterflies were preyed on by both diurnal and nocturnal predators and the latter are unlikely to attend to small conspicuous markings.

  • 72.
    Olofsson, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Dimitrova, Marina
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    The white “comma” as a distractive mark on the wings of comma butterflies – experimental tests in the lab and in the field: Distractive mark in a butterflyManuscript (preprint) (Other academic)
    Abstract [en]

    Distractive marks have been suggested to prevent predator detection or recognition of a prey, by drawing the attention away from recognizable traits of the bearer. The white “comma” on the wings of comma butterflies (Polygonia c-album) has been suggested to represent such a distractive mark. In a laboratory experiment using blue tits as predators, we show that the comma on female butterflies effect their survival, since the blue tits attacked butterflies with over-painted commas more often than sham-painted butterflies with intact commas. There was no such effect with respect to male butterflies. Interestingly, the comma contrasts more against the uniformly brown ventral wing surface on females, than on the more variegated coloration of males. Hence, the comma can function as a distractive marking, at least when perceived against a uniformly coloured wing. In a field experiment we placed hibernating, similarly manipulated, comma butterflies on tree trunks of two different species and noted their survival. Although survival was higher on birch than on oak trees, there was no effect of our treatment, likely as a result of butterflies being preyed on by both diurnal and nocturnal predators, the latter of whom are unlikely to pay attention to distractive marks.

  • 73.
    Olofsson, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Eriksson, Stephan
    Stockholm University, Faculty of Science, Department of Zoology.
    Jakobsson, Sven
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Deimatic Display in the European Swallowtail Butterfly as a Secondary Defence against Attacks from Great Tits2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 10, p. e47092-Article in journal (Refereed)
    Abstract [en]

    Background: Many animals reduce the risk of being attacked by a predator through crypsis, masquerade or, alternatively, by advertising unprofitability by means of aposematic signalling. Behavioural attributes in prey employed after discovery, however, signify the importance of also having an effective secondary defence if a predator uncovers, or is immune to, the prey's primary defence. In butterflies, as in most animals, secondary defence generally consists of escape flights. However, some butterfly species have evolved other means of secondary defence such as deimatic displays/startle displays. The European swallowtail, Papilio machaon, employs what appears to be a startle display by exposing its brightly coloured dorsal wing surface upon disturbance and, if the disturbance continues, by intermittently protracting and relaxing its wing muscles generating a jerky motion of the wings. This display appears directed towards predators but whether it is effective in intimidating predators so that they refrain from attacks has never been tested experimentally. Methodology/Principal Findings: In this study we staged encounters between a passerine predator, the great tit, Parus major, and live and dead swallowtail butterflies in a two-choice experiment. Results showed that the dead butterfly was virtually always attacked before the live butterfly, and that it took four times longer before a bird attacked the live butterfly. When the live butterfly was approached by a bird this generally elicited the butterfly's startle display, which usually caused the approaching bird to flee. We also performed a palatability test of the butterflies and results show that the great tits seemed to find them palatable. Conclusions/Significance: We conclude that the swallowtail's startle display of conspicuous coloration and jerky movements is an efficient secondary defence against small passerines. We also discuss under what conditions predator-prey systems are likely to aid the evolution of deimatic behaviours in harmless and palatable prey.

  • 74.
    Olofsson, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Jakobsson, Sven
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Auditory defence in the peacock butterfly (Inachis io) against mice (Apodemus flavicollis and A. sylvaticus)2012In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 66, no 2, p. 209-215Article in journal (Refereed)
    Abstract [en]

    Morphological and behavioural traits can serve as anti-predator defence either by reducing detection or recognition risks, or by thwarting initiated attacks. The latter defence is secondary and often involves a 'startle display' comprising a sudden release of signals targeting more than one sensory modality. A suggested candidate for employing a multimodal defence is the peacock butterfly, Inachis io, which, by wing-flicking suddenly, produces sonic and ultrasonic sounds and displays four large eyespots when attacked. The eyespots make small birds retreat, but whether the sounds produced thwart predator attacks is largely unknown. Peacocks hibernate as adults in dark wintering sites and employ their secondary defence upon encounter with small rodent predators during this period. In this study, we staged predator-prey encounters in complete darkness in the laboratory between wild mice, Apodemus flavicollis and Apodemus sylvaticus, and peacocks which had their sound production intact or disabled. Results show that mice were more likely to flee from sound-producing butterflies than from butterflies which had their sound production disabled. Our study presents experimental evidence that the peacock butterfly truly employs a multimodal defence with different traits targeting different predator groups; the eyespots target birds and the sound production targets small rodent predators.

  • 75.
    Olofsson, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Jakobsson, Sven
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Bird attacks on a butterfly with marginal eyespots and the role of prey concealment against the background2013In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 109, no 2, p. 290-297Article in journal (Refereed)
    Abstract [en]

    Small eyespots on butterflies have long been thought to deflect attacks, and birds are the presumptive drivers selecting for these patterns; however, evidence of this function is still ambiguous. Marginal eyespots typically consist of a UV-reflective white pupil, surrounded by one black and one yellowish ring. We have recently shown that Cyanistes caeruleus (blue tits) attack such eyespots, but only under low light intensities with accentuated UV levels: the increased salience of the eyespots relative to the rest of the butterfly probably explains this result. Possibly the background against which the butterfly is concealed may deceive birds to make similar errors. We therefore presented speckled wood butterflies decorated with eyespots (or controls without eyespots) to C.caeruleus against two backgrounds: oak and birch bark. Our results show that: (1) eyespots, independent of background, were effective in deflecting attacks; (2) the time elapsed between a bird landing and the attack was interactively dependent on the background and whether the butterfly bore an eyespot; and (3) the speed at which a butterfly was attacked predicted the outcome, with faster birds being more prone to errors than slower birds. This underscores a speedaccuracy trade-off in the predators, and that background plays a role in the defensive qualities of marginal eyespots.(c) 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 290297.

  • 76.
    Olofsson, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Løvlie, Hanne
    Stockholm University, Faculty of Science, Department of Zoology.
    Tibblin, Jessika
    Stockholm University, Faculty of Science, Department of Zoology.
    Jakobsson, Sven
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Eyespot display in the peacock butterfly triggers antipredator behaviors in naive adult fowl2013In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 24, no 1, p. 305-310Article in journal (Refereed)
    Abstract [en]

    Large conspicuous eyespots have evolved in multiple taxa and presumably function to thwart predator attacks. Traditionally, large eyespots were thought to discourage predator attacks because they mimicked eyes of the predators' own predators. However, this idea is controversial and the intimidating properties of eyespots have recently been suggested to Amply be a consequence of their conspicuousness. Some lepidopteran species include large eyespots in their antipredation repertoire. In the peacock butterfly, Mathis io, eyespots are typically hidden during rest and suddenly exposed by the butterfly when disturbed. Previous experiments have shown that small wild passerines are intimidated by this display. Here, we test whether eyespots also intimidate a considerably larger bird, domestic fowl, Gallus gallus domesticus, by staging interactions between birds and peacock butterflies that were sham-painted or had their eyespots painted oven Our results show that birds typically fled when peacock butterflies performed their display regardless of whether eyespots were visible or painted over. However, birds confronting butterflies with visible eyespots delayed their return to the butterfly, were more vigilant, and more likely to utter alarm calls associated with detection of ground-based predators, compared with birds confronting butterflies with eyespots painted over. Because production of alarm calls and increased vigilance are antipredation behaviors in the fowl, their reaction suggests that eyespots may elicit fear rather than just an aversion to conspicuous patterns. Our results, therefore, suggest that predators perceive large lepidopteran eyespots as belonging to the eyes of a potential predator.

  • 77.
    Olofsson, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Sven, Jakobsson
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Bird attacks on a butterfly with marginal eyespots and the role of prey concealment against the background: Marginal eyespots can deflect bird attacksManuscript (preprint) (Other academic)
    Abstract [en]

    Small eyespots on butterflies have long been thought to deflect attacks and birds are presumptive drivers selecting for these patterns. However, evidence of this function is still ambiguous. Marginal eyespots typically consist of a UV-reflective white pupil, surrounded by one black and one yellowish ring. We have recently shown that blue tits attack such eyespots, but only under low light intensities with accentuated UV-levels. An increased salience of the eyespots relative to the rest of the butterfly probably explains this result. Possibly, a background against which the butterfly is concealed may deceive birds to making similar errors. We therefore presented speckled wood butterflies provided with eyespots (or controls without eyespots) to blue tits against two backgrounds, oak- and birch bark. Results show that (i) eyespots, independent of background, were effective in deflecting attacks, (ii) the time elapsed between a bird’s landing and attack was interactively dependent on background and whether the butterfly bore an eyespot and (iii) the speed at which a butterfly was attacked predicted the outcome, with faster birds being more prone to errors than slower birds. This underscores a speed-accuracy tradeoff in the predators and that background plays a role in the defensive qualities of marginal eyespots.

  • 78.
    Olofsson, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Vallin, Adrian
    Stockholm University, Faculty of Science, Department of Zoology.
    Jakobsson, Sven
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Marginal eyespots on butterfly wings deflect bird attacks under low light intensities with UV wavelengths2010In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 5, no 5, p. e10798-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Predators preferentially attack vital body parts to avoid prey escape. Consequently, prey adaptations that make predators attack less crucial body parts are expected to evolve. Marginal eyespots on butterfly wings have long been thought to have this deflective, but hitherto undemonstrated function. METHODOLOGY/PRINCIPAL FINDINGS: Here we report that a butterfly, Lopinga achine, with broad-spectrum reflective white scales in its marginal eyespot pupils deceives a generalist avian predator, the blue tit, to attack the marginal eyespots, but only under particular conditions-in our experiments, low light intensities with a prominent UV component. Under high light intensity conditions with a similar UV component, and at low light intensities without UV, blue tits directed attacks towards the butterfly head. CONCLUSIONS/SIGNIFICANCE: In nature, birds typically forage intensively at early dawn, when the light environment shifts to shorter wavelengths, and the contrast between the eyespot pupils and the background increases. Among butterflies, deflecting attacks is likely to be particularly important at dawn when low ambient temperatures make escape by flight impossible, and when insectivorous birds typically initiate another day's search for food. Our finding that the deflective function of eyespots is highly dependent on the ambient light environment helps explain why previous attempts have provided little support for the deflective role of marginal eyespots, and we hypothesize that the mechanism that we have discovered in our experiments in a laboratory setting may function also in nature when birds forage on resting butterflies under low light intensities.

  • 79.
    Olofsson, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Vallin, Adrian
    Stockholm University, Faculty of Science, Department of Zoology.
    Jakobsson, Sven
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Winter predation on two species of hibernating butterflies: monitoring rodent attacks with infrared cameras2011In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 81, no 3, p. 529-534Article in journal (Refereed)
    Abstract [en]

    Documentation of predator attacks in nature is important for understanding how specific antipredator defences have evolved, but previous accounts have been mostly anecdotal. Therefore, we monitored predation on two closely related butterfly species, Aglais urticae and Inachis io, during winter hibernation. Butterflies were placed singly close to the floor on walls in dark, seminatural hibernation sites (e.g. unheated outhouses). We used motion-initiated infrared-sensitive cameras to record predator attacks on the butterflies. The antipredator attributes of the two species have two characteristics: during rest the butterflies reduce predators’ attention by mimicking leaves but they can suddenly change their guise by repeatedly flicking their wings. The wing flicking also produces hissing sounds and ultrasonic clicks and, furthermore, I. io, but not A. urticae, have large eyespots on the dorsal wing surface. The two butterfly species suffer from mouse predation during the winter and mice have been suggested as potential targets for the butterflies’ sound production. Results showed that (1) mice (Apodemus spp.) were important predators on butterflies, (2) I. io often survived attacks by wing-flicking behaviour, and (3) both species moved to less accessible positions after interactions with mice and other small mammalian predators, but I. io more often so. The successful predator evasion in darkness by I. io suggests a multimodal defence; in addition to the large eyespots, which intimidate birds, we suggest that the hissing and/or click sounds produced during wing flicking may have evolved as defence against rodent attacks

  • 80.
    Olofsson, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Indian Institute of Science Education and Research Thiruvananthapuram, India.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Favati, Anna
    Stockholm University, Faculty of Science, Department of Zoology.
    On the deterring effect of a butterfly's eyespot in juvenile and sub-adult chickens2015In: Current Zoology, ISSN 1674-5507, Vol. 61, no 4, p. 749-757Article in journal (Refereed)
    Abstract [en]

    Circular patterns, or eyespots, are common anti-predator features in a variety of animals. Two defensive functions have been documented: large eyespots may intimidate predators, whereas smaller marginal eyespots may divert attacks. However, a given eyespot potentially serves both functions, possibly depending on the predator's size and/or experience. Naive predators are potentially more likely to misdirect their attacks towards eyespots; alternatively, their typically smaller size would make them more intimidated by the same eyespots. Here we test how juvenile and sub-adult naive chickens respond to a single eyespot on a butterfly's wing. We presented the birds with dead wall brown butterflies, Lasiommata megera, that had their apical eyespot visible or painted over. We assessed the birds' responses' by (i) scoring their intimidation reaction, (ii) whether they uttered alarm calls and, (iii) if they attacked the butterfly and where they targeted their attacks. Results show that both age categories received higher intimidation scores when offered a butterfly with a visible eyespot. Juveniles were more intimidated by the butterfly than the sub-adults: they received higher intimidation scores and were more prone to utter alarm calls. Moreover, only sub-adults attacked and did so by preferentially attacking the butterfly's anterior. We demonstrate an intimidating effect of the type of eyespot that has previously been shown only to divert attacks. We suggest that one and the same eyespot may serve two functions relative to different predators; however, further experiments are needed to disentangle the role of predator identity and its link to size, ontogeny and experience.

  • 81.
    Posledovich, Diana
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Toftegaard, Tenna
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Navarro-Cano, Jose A.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Latitudinal variation in thermal reaction norms of post-winter pupal development in two butterflies differing in phenological specialization2014In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 113, no 4, p. 981-991Article in journal (Refereed)
    Abstract [en]

    Latitudinal clines in thermal reaction norms of development are a common phenomenon in temperate insects. Populations from higher latitudes often develop faster throughout the range of relevant temperatures (i.e countergradient variation) because they must be able to complete their life cycle within a shorter seasonal time window compared to populations at lower latitudes. In the present study, we experimentally demonstrate that two species of butterflies Anthocharis cardamines (L.) and Pieris napi (L.) instead show a cogradient variation in thermal reaction norms of post-winter pupal development so that lower latitude populations develop faster than higher latitude populations. The two species share host plants but differ in the degree of phenological specialization, as well as in the patterns of voltinism. We suggest that the pattern in A. cardamines, a univoltine phenological specialist feeding exclusively on flowers and seedpods, is the result of selection for matching to the phenological pattern of its local host plants. The other species, P. napi, is a phenological generalist feeding on the leaves of the hosts and it shows a latitudinal cline in voltinism. Because the latitudinal pattern in P. napi was an effect of slow development in a fraction of the pupae from the most northern population, we hypothesize that this population may include both bivoltine and univoltine genotypes. Consequently, although the two species both showed cogradient patterns in thermal reaction norms, it appears likely that this was for different reasons.

  • 82.
    Posledovich, Diana
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Toftegaard, Tenna
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Latitudinal variation in diapause duration and post-winter development in two pierid butterflies in relation to phenological specialization2015In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 177, no 1, p. 181-190Article in journal (Refereed)
    Abstract [en]

    Diapause plays a central role in insect life cycles by allowing survival during adverse seasonal conditions as well as synchronizing life cycles with the period of mate and food availability. Seasonal timing is expected to be particularly important for species that are dependent on resources available during a short time window-so-called phenological specialists-and latitudinal clines in seasonality are expected to favor local adaptation in phenological timing. However, to what degree latitudinal variation in diapause dynamics and post-winter development due to such local adaptation is influenced by the degree of phenological specialization is not well known. We experimentally studied two pierid butterfly species and found that the phenological specialist Anthocharis cardamines had shorter diapause duration than the phenological generalist Pieris napi along a latitudinal gradient in Sweden. Moreover, diapause duration increased with latitude in P. napi but not in A. cardamines. Sensitivity of the two species to winter thermal conditions also differed; additional cold temperature during the winter period shortened diapause duration for P. napi pupae but not for A. cardamines pupae. In both species, post-winter pupal development was faster after longer periods of cold conditions, and more southern populations developed faster than northern populations. Post-winter development was also invariably faster at higher temperatures in both species. We argue that the observed differences in diapause dynamics between the two species might be explained by the difference in phenological specialization that influences the costs of breaking diapause too early in the season.

  • 83.
    Posledovich, Diana
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Toftegaard, Tenna
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Phenological synchrony between a butterfly and its host plants: Experimental test of effects of spring temperature2018In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 87, no 1, p. 150-161Article in journal (Refereed)
    Abstract [en]

    1. Climate-driven changes in the relative phenologies of interacting species may potentially alter the outcome of species interactions. 2. Phenotypic plasticity is expected to be important for short-term response to new climate conditions, and differences between species in plasticity are likely to influence their temporal overlap and interaction patterns. As reaction norms of interacting species may be locally adapted, any such climate-induced change in interaction patterns may vary among localities. However, consequences of spatial variation in plastic responses for species interactions are understudied. 3. We experimentally explored how temperature affected synchrony between spring emergence of a butterfly, Anthocharis cardamines, and onset of flowering of five of its host plant species across a latitudinal gradient. We also studied potential effects on synchrony if climate-driven northward expansions would be faster in the butterflies than in host plants. Lastly, to assess how changes in synchrony influence host use we carried out an experiment to examine the importance of the developmental stage of plant reproductive structures for butterfly oviposition preference. 4. In southern locations, the butterflies were well-synchronized with the majority of their local host plant species across temperatures, suggesting that thermal plasticity in butterfly development matches oviposition to host plant development and that thermal reaction norms of insects and plants result in similar advancement of spring phenology in response to warming. In the most northern region, however, relative phenology between the butterfly and two of its host plant species changed with increased temperature. We also show that the developmental stage of plants was important for egg-laying, and conclude that temperature-induced changes in synchrony in the northernmost region are likely to lead to shifts in host use in A.cardamines if spring temperatures become warmer. Northern expansion of butterfly populations might possibly have a positive effect on keeping up with host plant phenology with more northern host plant populations. 5. Considering that the majority of insect herbivores exploit multiple plant species differing in their phenological response to spring temperatures, temperature-induced changes in synchrony might lead to shifts in host use and changes in species interactions in many temperate communities.

  • 84.
    Posledovich, Diana
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Toftegaard, Tenna
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    The developmental race between maturing host plants and their butterfly herbivore – the influence of phenological matching and temperature2015In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 84, no 6, p. 1690-1699Article in journal (Refereed)
    Abstract [en]

    Interactions between herbivorous insects and their host plants that are limited in time are widespread. Therefore, many insect-plant interactions result in a developmental race, where herbivores need to complete their development before plants become unsuitable, while plants strive to minimize damage from herbivores by outgrowing them. When spring phenologies of interacting species change asymmetrically in response to climate warming, there will be a change in the developmental state of host plants at the time of insect herbivore emergence. In combination with altered temperatures during the subsequent developmental period, this is likely to affect interaction strength as well as fitness of interacting species. Here, we experimentally explore whether the combined effect of phenological matching and thermal conditions influence the outcome of an insect-host interaction. We manipulated both developmental stages of the host plants at the start of the interaction and temperature during the subsequent developmental period in a model system of a herbivorous butterfly, Anthocharis cardamines, and five of its Brassicaceae host plant species. Larval performance characteristics were favoured by earlier stages of host plants at oviposition as well as by higher developmental temperatures on most of the host species. The probability of a larva needing a second host plant covered the full range from no influence of either phenological matching or temperature to strong effects of both factors, and complex interactions between them. The probability of a plant outgrowing a larva was dependent only on the species identity. This study demonstrates that climatic variation can influence the outcome of consumer-resource interactions in multiple ways and that its effects differ among host plant species. Therefore, climate warming is likely to change the temporal match between larval and plant development in some plant species, but not in the others. This is likely to have important implications for host plant use and possibly influence competitive relationships.

  • 85.
    Posledovich, Diana
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Toftegaard, Tenna
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Weak effect of spring temperatures on phenological synchrony between herbivore emergence and host plant suitabilityManuscript (preprint) (Other academic)
    Abstract [en]

    Many species interactions are maintained by precise timing of life-cycle events across seasonal variation. Ecological implications of changes in phenologies, associated with climate change, with respect to species interactions are to a large extent unexplored. Changes in phenological distance between herbivores and their host plant species under new environmental conditions may potentially lead to shifts in host use patterns, with some plant species becoming more or less available at the time of a herbivore’s emergence. In addition, latitudinal variation in the timing of phenological events can lead to different patterns in host use shifts among populations of a given herbivore. Here we explored latitudinal variation in the effects of temperature on the degree of phenological synchrony between emergence of a butterfly, A. cardamines, and five of its herbaceous host plant species in a set of laboratory experiments to investigate the possibility that there will be shifts in the butterfly’ host utilization due to changes in thermal environment. The results suggest a similar temperature-mediated phenological plasticity between the butterflies and their host plants in three latitudinally divergent populations. In general, butterflies appeared to be well-synchronized with the majority of their host plant species across temperatures. In the most northern region, however, phenological distance between the butterfly and two out of four plant species was affected by temperature and decreased in warmer treatments. We relate this to a lower diversity of plant species and shorter period of host availability in the northern region. This creates a stronger selection pressure on the northern butterflies for a closer matching of their emergence to the plant flowering period. As the butterflies discriminated against non-flowering hosts with respect to oviposition, we conclude that a shift in host use in A. cardamines appears to be a possible scenario under spring warming, especially in the northern region.

  • 86.
    Schäpers, Alexander
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Petrén, Hampus
    Wheat, Christopher W.
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Friberg, Magne
    Female fecundity variation affects reproducibility of experiments on host plant preference and acceptance in a phytophagous insect2017In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 284, no 1849, article id 20162643Article in journal (Refereed)
    Abstract [en]

    Reproducibility is a scientific cornerstone. Many recent studies, however, describe a reproducibility crisis and call for assessments of reproducibility across scientific domains. Here, we explore the reproducibility of a classic ecological experiment—that of assessing female host plant preference and acceptance in phytophagous insects, a group in which host specialization is a key driver of diversification. We exposed multiple cohorts of Pieris napi butterflies from the same population to traditional host acceptance and preference tests on three Brassicaceae host species. Whereas the host plant rank order was highly reproducible, the propensity to oviposit on low-ranked hosts varied significantly even among cohorts exposed to similar conditions. Much variation could be attributed to among-cohort variation in female fecundity, a trait strongly correlated both to female size and to the size of the nuptial gift a female receives during mating. Small males provide small spermatophores, and in our experiment small females that mated with small males had a disproportionally low propensity to oviposit on low-ranked hosts. Hence, our results provide empirical support to the theoretical prediction that female host utilization is strongly affected by non-genetic, environmental variation, and that such variation can affect the reproducibility of ecological experiments even under seemingly identical conditions.

  • 87.
    Stålhandske, Sandra
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Olofsson, Martin
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Leimar, Olof
    Stockholm University, Faculty of Science, Department of Zoology.
    Phenological matching rather than genetic variation in host preference underlies geographical variation in host plants used by the orange tip butterflies2016In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 119, no 4, p. 1060-1067Article in journal (Refereed)
    Abstract [en]

    An insect species that shows variation in host species association across its geographical range may do so either because of local adaptation in host plant preference of the insect, or through environmentally or genetically induced differences in the plants, causing variation in host plant suitability between regions. Here we experimentally investigate host plant preference of Anthocharis cardamines (orange tip butterfly) of two populations from UK and two from Sweden. Previous reports indicate that A. cardamines larvae are found on different host plant species in different regions of the United Kingdom, and some variation has been reported in Sweden. Host plant choice trials showed that females prefer to oviposit on plants in an earlier phenological stage, as well as on larger plants. When controlling for plant phenological stage and size, the host species had no statistically significant effect on the choice of the females. Moreover, there were no differences in host plant species preference among the four butterfly populations. Based on our experiment, the oviposition choice by A. cardamines mainly depends on the phenological stage and the size of the host plant. This finding supports the idea that the geographical patterns of host-plant association of A. cardamines in the UK and Sweden are consequences of the phenology and availability of local hosts, rather than regional genetic differences in host species preference of the butterfly.

  • 88. Talla, Venkat
    et al.
    Johansson, Anna
    Dincă, Vlad
    Vila, Roger
    Friberg, Magne
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Backström, Niclas
    Lack of gene flow: Narrow and dispersed differentiation islands in a triplet of Leptidea butterfly species2019In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 28, no 16, p. 3756-3770Article in journal (Refereed)
    Abstract [en]

    Genome scans in recently separated species can inform on molecular mechanisms and evolutionary processes driving divergence. Large-scale polymorphism data from multiple species pairs are also key to investigate the repeatability of divergence-whether radiations tend to show parallel responses to similar selection pressures and/or underlying molecular forces. Here, we used whole-genome resequencing data from six wood white (Leptidea sp.) butterfly populations, representing three closely related species with karyomorph variation, to infer the species' demographic history and characterize patterns of genomic diversity and differentiation. The analyses supported previously established species relationships, and there was no evidence for postdivergence gene flow. We identified significant intraspecific genetic structure, in particular between karyomorph extremes in the wood white (L. sinapis)-a species with a remarkable chromosome number cline across the distribution range. The genomic landscapes of differentiation were erratic, and outlier regions were narrow and dispersed. Highly differentiated (F-ST) regions generally had low genetic diversity (theta(pi)), but increased absolute divergence (D-XY) and excess of rare frequency variants (low Tajima's D). A minority of differentiation peaks were shared across species and population comparisons. However, highly differentiated regions contained genes with overrepresented functions related to metabolism, response to stimulus and cellular processes, indicating recurrent directional selection on a specific set of traits in all comparisons. In contrast to the majority of genome scans in recently diverged lineages, our data suggest that divergence landscapes in Leptidea have been shaped by directional selection and genetic drift rather than stable recombination landscapes and/or introgression.

  • 89. Talla, Venkat
    et al.
    Suh, Alexander
    Kalsoom, Faheema
    Dincă, Vlad
    Vila, Roger
    Friberg, Magne
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Backström, Niclas
    Rapid Increase in Genome Size as a Consequence of Transposable Element Hyperactivity in Wood-White (Leptidea) Butterflies2017In: Genome Biology and Evolution, ISSN 1759-6653, E-ISSN 1759-6653, Vol. 9, no 10, p. 2491-2505Article in journal (Refereed)
    Abstract [en]

    Characterizing and quantifying genome size variation among organisms and understanding if genome size evolves as a consequence of adaptive or stochastic processes have been long-standing goals in evolutionary biology. Here, we investigate genome size variation and association with transposable elements (TEs) across lepidopteran lineages using a novel genome assembly of the common wood-white (Leptidea sinapis) and population re-sequencing data from both L. sinapis and the closely related L. reali and L. juvernica together with 12 previously available lepidopteran genome assemblies. A phylogenetic analysis confirms established relationships among species, but identifies previously unknown intraspecific structure within Leptidea lineages. The genome assembly of L. sinapis is one of the largest of any lepidopteran taxon so far (643Mb) and genome size is correlated with abundance of TEs, both in Lepidoptera in general and within Leptidea where L. juvernica from Kazakhstan has considerably larger genome size than any other Leptidea population. Specific TE subclasses have been active in different Lepidoptera lineages with a pronounced expansion of predominantly LINEs, DNA elements, and unclassified TEs in the Leptidea lineage after the split from other Pieridae. The rate of genome expansion in Leptidea in general has been in the range of four Mb/Million year (My), with an increase in a particular L. juvernica population to 72Mb/My. The considerable differences in accumulation rates of specific TE classes in different lineages indicate that TE activity plays a major role in genome size evolution in butterflies and moths.

  • 90.
    Toftegaard, Tenna
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Posledovich, Diana
    Stockholm University, Faculty of Science, Department of Zoology.
    König, Malin A. E.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Linking small-scale temperature variations to plant phenology and plant-herbivore interactionsManuscript (preprint) (Other academic)
  • 91.
    Toftegaard, Tenna
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Posledovich, Diana
    Stockholm University, Faculty of Science, Department of Zoology.
    Navarro-Cano, José A.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Desertification Research Centre (CSIC‐UV‐GV), Spain.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Butterfly-host plant synchrony determines patterns of host use across years and regions2019In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 128, no 4, p. 493-502Article in journal (Refereed)
    Abstract [en]

    Variation in the degree of synchrony among host plants and herbivores can disrupt or intensify species interactions, alter the strength of natural selection on traits associated with phenological timing, and drive novel host plant associations. We used field observations from three regions during four seasons to examine how timing of the butterfly herbivore Anthocharis cardamines relative to six host plant species (Arabis hirsuta, Cardamine pratensis, Arabis glabra, Arabidopsis thaliana, Thlaspi caerulescens and Capsella bursa-pastoris) influenced host species use and the choice of host plant individuals within populations. Butterflies laid a larger fraction of their eggs on species that were closer to the butterfly's preferred stage of development than on other host species. Within host plant populations, butterflies showed a stronger preference for individuals with a late phenology when plants within the population were on average more developed at the time of butterfly flight. Our results suggest that changes in synchrony between herbivores and their host plants are associated with changes in both host species use and the choice of host plant individuals differing in phenology within populations. This is likely to be an important mechanism generating variation in interaction intensities and trait selection in the wild, and therefore also relevant for understanding how anthropogenic induced changes, such as global warming, will influence natural communities.

  • 92.
    Toftegaard, Tenna
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Posledovich, Diana
    Stockholm University, Faculty of Science, Department of Zoology.
    Navarro-Cano, José A.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Desertification Research Centre (CSIC-UV-GV), Spain.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Variation in plant thermal reaction norms along a latitudinal gradient - more than adaptation to season length2016In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 125, no 5, p. 622-628Article in journal (Refereed)
    Abstract [en]

    Little is known about the extent to which observed phenological responses to changes in climate are the result of phenotypic plasticity or genetic changes. We also know little about how plasticity, in terms of thermal reaction norms, vary spatially. We investigated if the thermal reaction norms for flower development of five crucifer species (Brassicaceae) differed among three regions along a south-north latitudinal gradient in replicated experiments. The mean response (elevation) of thermal reaction norms of flowering differed among regions in all study species, while sensitivity of flower development to temperature (slope) differed in only one of the species. Differences in mean responses corresponded to cogradient patterns in some species, but countergradient patterns in other. This suggests that differences among regions were not solely the result of adaptation to differences in the length of the growing season, but that other factors, such as herbivory, play an important role. Differences in development rate within species were mainly explained by variation in early phases of bud formation in some species but by variation in later phases of bud formation in other species. The differences in latitudinal patterns of thermal reaction norms among species observed in this study are important, both to identify agents of selection and to predict short- and long-term responses to a warming climate.

  • 93.
    Toftegaard, Tenna
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Posledovich, Diana
    Stockholm University, Faculty of Science, Department of Zoology.
    Navarro-Cano, José Antonio
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Effect of spring temperature on flower development differs among closely related plantsManuscript (preprint) (Other academic)
  • 94.
    Toftegaard, Tenna
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Posledovich, Diana
    Stockholm University, Faculty of Science, Department of Zoology.
    Navarro-Cano, José Antonio
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Timing of a butterfly influences host plant species use and the relationship between plant phenology and butterfly attackManuscript (preprint) (Other academic)
  • 95.
    Vallin, Adrian
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Jakobsson, Sven
    Lind, Johan
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution. Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Crypsis versus intimidation - anti-predation defence in three closely related butterflies2006In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, Vol. 59, no 3, p. 455-459Article in journal (Refereed)
  • 96.
    Vallin, Adrian
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Jakobsson, Sven
    Lind, Johan
    Wiklund, Christer
    Prey survival by predator intimidation: an experimental study of peacock butterfly defence against blue tits2005In: Proceedings of the Royal Society B: Biological Sciences, ISSN 0962-8452, Vol. 272, no 1569, p. 1203-1207Article in journal (Refereed)
  • 97.
    Vallin, Adrian
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Jakobsson, Sven
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    An eye for an eye – on the generality of the intimidating quality of eyespots in a butterfly and a hawkmoth2007In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 61, no 9, p. 1419-1424Article in journal (Refereed)
    Abstract [en]

    Large eyespots on the wings of butterflies and moths have been ascribed generally intimidating qualities by creating a frightening image of a bird or mammal much larger than the insect bearing the eyespots. However, evidence for this anti-predator adaptation has been largely anecdotal and only recently were peacock butterflies, Inachis io, shown to effectively thwart attacks from blue tits, Parus caeruleus. Here we test whether large eyespots on lepidopterans are generally effective in preventing attacks from small passerines, and whether the size of insect or bird can influence the outcome of interactions. We staged experiments between the larger eyed hawkmoths, Smerinthus ocellatus, and the smaller peacock butterflies, I. io, and the larger great tits, Parus major, and the smaller blue tits, P. caeruleus. Survival differed substantially between the insect species with 21 of 24 peacocks, but only 6 of 27 eyed hawkmoths, surviving attacks from the birds. Thus, surprisingly, the smaller prey survived to a higher extent, suggesting that other factors than insect size may be important. However, great tits were less easily intimidated by the insects’ eyespots and deimatic behaviour and consumed 16 of 26, but the blue tits only 8 of 25 of the butterflies and hawkmoths. Our results demonstrate that eyespots per se do not guarantee survival, and that these two insects bearing equally large eyespots are not equally well protected against predation.

  • 98.
    Vallin, Adrian
    et al.
    Stockholm University.
    Jakobsson, Sven
    Stockholm University.
    Wiklund, Christer
    Stockholm University.
    Constant eyespot display as a primary defense – survival of male and female emperor moths when attacked by blue tits2010In: The Journal of Research on the Lepidoptera, ISSN 0022-4324 (prINt) 2156-5457 (oNlINe), Vol. 43, p. 9-17Article in journal (Refereed)
    Abstract [en]

    Large conspicuous eyespots, commonly found on the wings of butterflies and moths, have been shown to thwart attacks from predators. Previous experiments have focused on lepidopteran species that expose eyespots only when harassed by a predator. In contrast, we investigate the potential efficiency of the constantly exposed eyespots of emperor moths thus constituting a primary defense. We staged experiments between blue tits and moths having either intact or painted over eyespots. Moths with eyespots were killed as often as moths without eyespots and were, additionally, approached earlier by the birds suggesting that birds were not intimidated by their eyespots. Female moths weighed three times more than males and were less often eaten, suggesting that their large size intimidated the birds. We suggest that the constant eyespot display of the emperor moth may be associated with a cost, because potential predators seem to be attracted rather than intimidated by the display.

  • 99.
    Vallin, Adrian
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Jakobsson, Sven
    Wiklund, Christer
    Size does matter – differences in intimidation efficiency in male and female small emperor moths (Saturnia pavonia) against blue tits (Parus caeruleus)Article in journal (Refereed)
  • 100. Wedell, Nina
    et al.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Bergström, Jonas
    Stockholm University, Faculty of Science, Department of Zoology.
    Coevolution of non-fertile sperm and female receptivity in a butterfly.2009In: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 5, no 5, p. 678-81Article in journal (Refereed)
    Abstract [en]

    Sexual conflict can promote rapid evolution of male and female reproductive traits. Males of many polyandrous butterflies transfer nutrients at mating that enhances female fecundity, but generates sexual conflict over female remating due to sperm competition. Butterflies produce both normal fertilizing sperm and large numbers of non-fertile sperm. In the green-veined white butterfly, Pieris napi, non-fertile sperm fill the females' sperm storage organ, switching off receptivity and thereby reducing female remating. There is genetic variation in the number of non-fertile sperm stored, which directly relates to the female's refractory period. There is also genetic variation in males' sperm production. Here, we show that females' refractory period and males' sperm production are genetically correlated using quantitative genetic and selection experiments. Thus selection on male manipulation may increase the frequency of susceptible females to such manipulations as a correlated response and vice versa.

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