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  • 1.
    Audusseau, Hélène
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Paris-Est Créteil University, France.
    Le Vaillant, Maryline
    Stockholm University, Faculty of Science, Department of Zoology.
    Janz, Niklas
    Stockholm University, Faculty of Science, Department of Zoology.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Karlsson, Bengt
    Stockholm University, Faculty of Science, Department of Zoology.
    Schmucki, Reto
    Species range expansion constrains the ecological niches of resident butterflies2017In: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 44, no 1, p. 28-38Article in journal (Refereed)
    Abstract [en]

    Aim: Changes in community composition resulting from environmental changes modify biotic interactions and affect the distribution and density of local populations. Such changes are currently occurring in nettle-feeding butterflies in Sweden where Araschnia levana has recently expanded its range northward and is now likely to interact with resident species (Aglais urticae and Aglais io). Butterfly occurrence data collected over years and across regions enabled us to investigate how a recent range expansion of A. levana may have affected the environmental niche of resident species.

    Location: We focused on two regions of Sweden (Skane and Norrstrom) where A. levana has and has not established and two time periods (2001-2006 and 2009-2012) during its establishment in Skane.

    Methods: We performed two distinct analyses in each region using the PCA-env and the framework described in Broennimann etal. (2012). First, we described the main sources of variation in the environment. Second, in each time period and region, we characterized the realized niches of our focal species across topographic and land use gradients. Third, we quantified overlaps and differences in realized niches between and within species over time.

    Results: In Skane, A. levana has stabilized its distribution over time, while the distribution of the native species has shifted. These shifts depicted a consistent pattern of avoiding overlap between the native species and the environmental space occupied by A. levana, and it was stronger for A. urticae than for A. io. In both regions, we also found evidence of niche partitioning between native species.

    Main conclusions: Interspecific interactions are likely to affect local species distributions. It appears that the ongoing establishment of A. levana has modified local biotic interactions and induced shifts in resident species distributions. Among the mechanisms that can explain such patterns of niche partitioning, parasitoid-driven apparent competition may play an important role in this community.

  • 2.
    Berger, David
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Uppsala University, Sweden.
    Olofsson, Martin
    Stockholm University, Faculty of Science, Department of Zoology.
    Friberg, Magne
    Stockholm University, Faculty of Science, Department of Zoology. University of California Santa Cruz, USA.
    Karlsson, Bengt
    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.
    Intraspecific variation in body size and the rate of reproduction in female insects- adaptive allometry or biophysical constraint?2012In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 81, no 6, p. 1244-1258Article in journal (Refereed)
    Abstract [en]

    1. A high rate of reproduction may be costly if ecological factors limit immediate reproductive output as a fast metabolism compromises own future survival. Individuals with more reserves need more time and opportunity to realize their reproductive potential. Theory therefore predicts that the reproductive rate, defined as the investment in early reproduction in proportion to total potential, should decrease with body size within species. 2. However, metabolic constraints on body size- and temperature-dependent biological rates may impede biophysical adaptation. Furthermore, the sequential manner resources that are allocated to somatic vs. reproductive tissue during ontogeny may, when juveniles develop in unpredictable environments, further contribute to non-adaptive variation in adult reproductive rates. 3. With a model on female egg laying in insects, we demonstrate how variation in body reserves is predicted to affect reproductive rate under different ecological scenarios. Small females always have higher reproductive rates but shorter lifespans. However, incorporation of female host selectivity leads to more similar reproductive rates among female size classes, and oviposition behaviour is predicted to co-evolve with reproductive rate, resulting in small females being more selective in their choice and gaining relatively more from it. 4. We fed simulations with data on the butterfly Pararge aegeria to compare model predictions with reproductive rates of wild butterflies. However, simulated reproductive allometry was a poor predictor of that observed. Instead, reproductive rates were better explained as a product of metabolic constraints on rates of egg maturation, and an empirically derived positive allometry between reproductive potential and size. However, fitness is insensitive to moderate deviations in reproductive rate when oviposition behaviour is allowed to co-evolve in the simulations, suggesting that behavioural compensation may mitigate putative metabolic and developmental constraints. 5. More work is needed to understand how physiology and development together with compensatory behaviours interact in shaping reproductive allometry. Empirical studies should evaluate adaptive hypotheses against proper null hypotheses, including prediction from metabolic theory, preferentially by studying reproductive physiology in combination with behaviour. Conversely, inferences of constraint explanations on reproductive rates must take into consideration that adaptive scenarios may predict similar allometric exponents.

  • 3.
    Friberg, Magne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Karlsson, Bengt
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Life-history polyphenism in the Map butterfly (Araschnia levana): developmental constraints versus season-specific adaptations2010In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 12, p. 603-615Article in journal (Refereed)
    Abstract [en]

    Hypothesis: Different generations of a seasonally polyphenic butterfly allocate their resources differently between dispersal ability and reproduction to fit the environmental circumstances specific to the seasonal environment of each generation.

    Organism: Map butterfly (Araschnia levana).

    Site of experiments: The Department of Zoology/Tovetorp Research Station, Stockholm University.

    Methods: We estimated fecundity by assessing the amount of the limiting resource nitrogen that individuals of each generation allocated to their abdomens. We studied dispersal ability by assessing thorax nitrogen content, and by studying flight ability of both generations in a suite of temperatures.

    Results: Individuals of the summer generation performed longer sustained flights than individuals of the spring generation in all temperatures except the warmest treatment. In males, abdomen nitrogen content was poorly correlated with thorax nitrogen content. Thus males do not need to trade off nitrogen between the tissues. However, female thorax and abdomen nitrogen contents were strongly positively correlated, and although summer females were better flyers than spring females, they still allocated disproportionately more nitrogen to the reproductive tissue in the abdomen. We conclude that the divergent allocation patterns between different Map butterfly generations are better understood in terms of developmental constraints acting on spring butterflies, rather than by season-specific adaptations.

  • 4.
    Friberg, Magne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Olofsson, Martin
    Stockholm University, Faculty of Science, Department of Zoology.
    Berger, David
    Stockholm University, Faculty of Science, Department of Zoology.
    Karlsson, Bengt
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology. Zoologisk ekologi.
    Habitat choice precedes host plant choice - niche separation in a species pair of a generalist and a specialist butterfly2008In: Oikos, Vol. 117, no 9, p. 1337-1344Article in journal (Refereed)
    Abstract [en]

    The sister species Leptidea reali and L. sinapis have partitioned their niches differently in different parts of their sympatric distribution. In Spain and France L. sinapis is a widespread generalist whereas L. reali is specialized on high altitude open areas. Interestingly, the reverse is true in Ireland and the Czech Republic where L. reali is widespread and L. sinapis specialized on meadows. In Sweden, L. reali is a habitat specialist confined to meadows, whereas L. sinapis is a habitat generalist also inhabiting forests. Ultimately, the geographic mosaic of niche separation is the result of local processes in each contact zone or a secondary effect of the host plant distribution, if L. sinapis and L. reali prefer different legume host plants. Hence, in Sweden L. sinapis might utilize the forest habitat either due to a wider habitat preference or due to a wider host plant preference than L. reali. Studies of wild butterflies showed that L. sinapis laid 26% of their eggs on forest-associated legumes compared to 6% in L. reali, although laboratory experiments showed that both species had virtually identical host plant preferences strongly preferring the meadow-associated legume Lathyrus pratensis. Furthermore, flight duration tests in a variety of temperatures demonstrated a between-species difference; L. sinapis females reached their flight optimum at a lower temperature than L. reali females. The lower L. sinapis flight temperature optimum is most probably a secondary effect due to habitat-specific selection, and therefore a consequence rather than the cause of the habitat partitioning. The finding that habitat choice precedes host plant choice suggests that the European geographic mosaic of niche separation, with L. sinapis and L. reali shifting habitat specialist/generalist roles, is not caused by rigid between-species differences in a related niche parameter, but instead is a result of local processes within each secondary contact zone.

  • 5.
    Gibbs, Melanie
    et al.
    Centre for Ecology and Hydrology, Oxon, UK.
    Van Dyck, Hans
    Behavioural ecology and conservation group, Université catholique de Louvain, Belgium.
    Karlsson, bengt
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Reproductive placticity, ovarian dynamics and maternal effects in response to temperature and flight in Pararge aegeria2010In: Journal of insect physiology, ISSN 0022-1910, E-ISSN 1879-1611, Vol. 56, no 9, p. 1275-1283Article in journal (Refereed)
    Abstract [en]

    In nature, ovipositing females may be subjected to multiple extrinsic and intrinsic environmental factors simultaneously. To adequately assess a species response to environmental conditions during oviposition it may therefore be necessary to consider the interaction between multiple intrinsic and extrinsic factors simultaneously. Using the butterfly, Pararge aegeria, this study examined the combined effects of extrinsic (temperature and flight) and intrinsic (body mass and age) factors on ovarian dynamics, egg provisioning and reproductive output, and explored how these effects subsequently influenced offspring fitness when egg-stage development occurred in a low humidity environment. Both temperature- and flight- mediated plasticity in female reproductive output was observed, and there were strong temperature by flight interaction effects for the traits oocyte size and egg mass. As females aged, mean daily fecundity differed across temperature treatments, but not across flight treatments. Overall, temperature had more pronounced effects on ovarian dynamics than flight. Flight mainly influenced egg mass via changes in relative water content. A mismatch between the physiological response of females to high temperature and the requirements of their offspring had a negative impact on offspring fitness via effects on egg hatching success.

  • 6.
    Karlsson, Bengt
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Extended season for northern butterflies2014In: International journal of biometeorology, ISSN 0020-7128, E-ISSN 1432-1254, Vol. 58, no 5, p. 691-701Article in journal (Refereed)
    Abstract [en]

    Butterflies are like all insects temperature sensitive and a changing climate with higher temperatures might affect their phenology. Several studies have found support for earlier flight dates among the investigated species. A comparative study including 66 species of Swedish butterflies in Sweden was undertaken and the result confirms that most butterfly species will now fly earlier during the season. This is especially evident for butterflies overwintering as adults or as pupae. However, the advancement in phenology is correlated with flight date and some late season species show no advancement or have even postponed their flight dates and are now flying later in the season. The result also showed that latitude had a strong effect on the adult flight date, and the majority of the investigated species showed significantly later flights towards the north. Species flying early in the season were more affected by temperature than species flying later in the season and species overwintering in their late stages (as pupae or adults) were more influenced by temperature compared to species overwintering in their early stages (as larvae or eggs). In essence, a climate with earlier springs and longer growing seasons seems not to change the appearance patterns in a one way direction. We now see butterflies on the wings both earlier and later in the season and some consequences of these understudied and complex patterns are discussed. So far, studies have concentrated mostly on early season butterfly – plant interactions but also late season studies are needed for a better understanding of long term population consequences.

  • 7.
    Karlsson, Bengt
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Stockholm University, Faculty of Science, Department of Zoology. ekologi.
    Johansson, Anna
    Stockholm University, Faculty of Science, Department of Zoology. Stockholm University, Faculty of Science, Department of Zoology. ekologi.
    Seasonal polyphenism and developmental trade-offs between flight ability and egg laying in a pierid butterfly2008In: Proceedings of the royal society: Biological sciences, ISSN 0962-8452, Vol. 275, no 1647, p. 2131-2136Article in journal (Refereed)
    Abstract [en]

    Butterflies have competing demands for flight ability depending on e.g. mating system, predation pressure, localization of host plants and dispersal needs. The flight apparatus, however, are costly to manufacture and therefore trade-offs are expected since resources are limited and must be allocated between flight ability and other functions, such as reproduction. Trade-offs between flight and reproduction may be difficult to reveal since they interact with other factors and be confounded by differences in resource consumption. Previous studies have shown that adults of the summer generation of Pieris napi have relatively larger thoraxes compared to the spring generation. To study whether difference in thorax size results in a trade-off between flight ability and reproduction among the two generations we conducted a split-brood experiment under common garden conditions. Our results show, that summer generation adults have a higher dispersal capacity, measured as flight duration in five different temperatures. Reproductive output differed between the two developmental pathways; spring generation females laid a significantly higher output of eggs compared to summer generation females. We suggest that this is a consequence of a resource allocation trade-off made during pupal development implemented by different demands for flight between the spring and summer generations. The significance of this finding is discussed in relation to reproduction and mobility in butterflies.

  • 8.
    Karlsson, Bengt
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Prasai, Keshav
    Stockholm University, Faculty of Science, Department of Zoology.
    Variation in immune defence in relation to developmental pathway in the green veined white butterfly, Pieris napi2011In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 13, no 3, p. 295-305Article in journal (Refereed)
    Abstract [en]

    Question: Is immune defence affected by developmental pathway in a bivoltine butterfly?

    Hypotheses: Individuals of the pierid butterfly, Pieris napi, undergoing direct development (development without diapause) are time and nutrient stressed compared with overwintering individuals. If this is the case, direct developers will have a diminished immune defence system.

    Organism: Green-veined white butterfly, Pieris napi .

    Methods: In a laboratory experiment, we examined phenoloxidase activity in larvae of P. napi and their adult encapsulation ability in response to artificial parasites made of nylon monofilaments. We reared larvae on two different food plants, Alliaria petiolata and Armoracia rusticana.

    Results: The developmental pathway (direct or diapause) can have a strong impact on the defence system in Pieris napi. Individuals of the direct-developing summer generation had lower phenoloxidase activity and lower encapsulation ability than individuals of the overwintering generation. Larvae reared on the two different food plants showed no difference regarding phenoloxidase activity, but encapsulation ability was higher for individuals reared on Armoracia rusticana. Males had higher phenoloxidase activity but lower encapsulation ability than females.

  • 9.
    Karlsson, Bengt
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Stjernholm, Fredrik
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Test of a developmental trade-off in a polyphenic butterfly: direct development favours reproductive output2008In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 22, no 1, p. 121-126Article in journal (Refereed)
    Abstract [en]

    1.Evolutionary theory predicts that resource allocation decisions taken during development are adjusted to an organism's life-history. These decisions may have irreversible effects on body design and strong fitness consequences. Holometabolous insects that have a long expected life span typically postpone reproduction, and so are expected to allocate resources for somatic maintenance prior to investing in reproduction. In contrast, insects that have a short expected life span are expected to allocate relatively less to soma and more to reproduction. In support of this theory, an earlier investigation of resources allocated to soma vs. reproductive reserves in the comma butterfly, Polygonia c-album, revealed that short-lived females indeed allocate more resources to reproductive reserves as compared to longer lived females that hibernate before reproduction suggesting that short-lived females should have higher fecundity.

    2. Here we test this prediction, using the comma butterfly as our study organism. Depending on daylength and temperature this butterfly produces one of two morphs: (i) a light summer morph that reproduces directly after adult eclosion and has a short expected life span of a couple of weeks; or (ii) a darker winter morph that normally lives for 8–9 months before the onset of reproduction. Our test is based on experimental manipulation that allowed us to induce reproduction without prior hibernation in winter morph comma butterflies, and comparing lifetime fecundity among three groups: (i) directly reproducing summer morph commas; (ii) directly reproducing winter morph commas; and (iii) winter morph commas reproducing after overwintering. This protocol allowed us to tease apart trade-offs during development and the hibernation period.

    3. The results showed that the short-lived summer morph had a substantially higher fecundity (total number of eggs = 586 ± 19, mean ± SE) than the winter morph females manipulated to reproduce without hibernation (total number of eggs = 334 ± 42). We argue that this is a consequence of a resource allocation trade-off during early development observed in this species; females with a short expected life as adults allocate relatively more of their resources to reproductive parts and thereby reach a higher reproductive output compared to females predisposed for a long adult life.

    4. There was no significant difference in lifetime fecundity between winter morph females that did, or did not, hibernate before reproduction. This suggests that the cost of hibernation per se is small and hence corroborates our conclusion that the life-history implemented trade-off made during early development underlies the lower reproductive output of the winter morph butterflies.

  • 10.
    Karlsson, Bengt
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Van Dyck, Hans
    Université catholique de Louvain, Behavioural ecology and conservation group.
    Evolutionary ecology of butterfly fecundity2009In: Ecology of butterflies in Europe / [ed] Settele, J., Shreeve, T. Konvicka, M. & Van Dyck, H., Cambridge: Cambridge University Press, 2009, 1, p. 189-197Chapter in book (Refereed)
  • 11.
    Karlsson, Åsa
    Stockholm University, Faculty of Social Sciences, Department of Sociology.
    Familjetyp och förväntad utbildningsnivå: En kvantitativ undersökning om sambandet mellan familjetyp och utbildningsförväntningar2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Sammanfattning

    Tidigare studier visar att familjetyp påverkar utbildning på olika sätt. Elever som bor med ensamstående föräldrar tenderar generellt att ha lägre betyg och testresultat, samt uppnår och förväntas uppnå lägre utbildningsnivå än elever som bor med två föräldrar. Studier visar även att uppnådd utbildningsnivå påverkas av diverse andra variabler, så som demografiska bakgrundsvariabler, socioekonomisk status samt testresultat och attityd till skola. Tidigare studier visar även att den effekt som socioekonomisk status påverkar skolval och uppnådd utbildningsnivå till stor del är primära. Det innebär att anledningen till att elever med låg socioekonomisk status uppnår lägre utbildningsnivå är för att de generellt presterar sämre i skolan. Sekundära effekter innebär den effekt som inte kan förklaras av skolprestation.

    Undersökningen syftar till att studera om det finns samband mellan familjetyp och om femtonåriga elever tror att de kommer studera på universitet eller högskola eller ej. Vidare syftar undersökningen till att studera om samband beror på demografiska bakgrundsvariabler, föräldrars utbildning och yrkesstatus, testresultat och/eller attityd till skola. Med familjetyp menas om eleven bor med ensamstående mamma, ensamstående pappa, i familj med annan struktur eller i familj med både mamma och pappa.

    Resultatet visar att elever som inte bor i familj med två föräldrar generellt har lägre utbildningsförväntningar än elever som bor med två föräldrar. En stor del av effekten som familjetyp påverkar utbildningsförväntningar kan förklaras av föräldrars utbildningsnivå och yrkesstatus, etnicitet och testresultat. Resterande effekt kan förklaras av elevers attityd till skola.

    Undersökningens slutsats är att effekten som familjetyp påverkar utbildningsförväntningar främst är primär. Sa

  • 12.
    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.

  • 13.
    Prasai, Keshav
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Karlsson, Bengt
    Stockholm University, Faculty of Science, Department of Zoology.
    Variation in immune defence in relation to age in the green-veined white butterfly (Pieris napi L.)2012In: Journal of Invertebrate Pathology, ISSN 0022-2011, E-ISSN 1096-0805, Vol. 111, no 3, p. 252-254Article in journal (Refereed)
    Abstract [en]

    We investigate how encapsulation ability varies with adult age in overwintering and in direct-developing animals (development without diapause) of the green-veined white butterfly, Pieris napi. Encapsulation is a resource costly trait coupled to the immune system and encapsulation ability is predicted to decrease with age, since the resource pool of important nutrients generally decreases with age in nectar feeding butterflies. The results support this prediction and both sexes showed an age dependent decrease in their encapsulation ability. There were no significant differences between the sexes but direct-developing males tended to have a steeper decrease than females and we hypothesize that this could be the result of low available resources, since this generation is time and nutrient stressed.

  • 14.
    Stjernholm, Fredrik
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Stockholm University, Faculty of Science, Department of Zoology. ekologi.
    Karlsson, Bengt
    Stockholm University, Faculty of Science, Department of Zoology. Stockholm University, Faculty of Science, Department of Zoology. ekologi.
    Flight muscle breakdown in the green-veined white butterfly, Pieris napi (Lepidoptera : Pieridae)2008In: EUROPEAN JOURNAL OF ENTOMOLOGY, ISSN 1210-5759, Vol. 105, no 1Article in journal (Refereed)
    Abstract [en]

    Flight is important for insects but also incurs costs in terms of reduced reproductive reserves. Recent studies on butterflies have shown that thorax mass and nitrogen content decrease over the adult lifespan, suggesting that flight muscle breakdown may also occur in butterflies. However, unlike other insects known to resorb flight muscles, butterflies will continue to fly throughout the reproductive period. Nonetheless, use of nutrients from flight muscles for reproduction has the potential to improve the reproductive output considerably. In this study we have tested to what extent female Pieris napi L. (Pieridae) butterflies actually do breakdown flight muscles. By comparing muscle mass in recently emerged and older free-flying females we show that mass and nitrogen content of the two most important groups of flight muscles each decrease by more than 50% over the adult lifespan. The significance of this finding is discussed in relation to reproduction and flight in butterflies.

  • 15.
    Åhman, Mikael
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Karlsson, Bengt
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Flight endurance in relation to adult age in the green-veined white butterfly Pieris napi2009In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 34, p. 783-787Article in journal (Refereed)
    Abstract [en]

    Abstract. 1. The flight apparatus in butterflies as well as in other insects is costly to manufacture. Since most animals live in a world where resources are limited, trade-offs are expected and available resources must thus be allocated between flight and other functions such as reproduction.

    2. To mitigate this trade-off, previous studies have shown that butterflies can break down flight muscles in the thorax as they age in order to use muscle nutrients for reproduction.

    3. Although breakdown of flight muscles is expected to reduce flight ability, relative flight muscle ratio (thorax mass/body mass) in many butterfly species does not decrease with age.  Our aim in this study was to test the relationship between flight endurance and adult age in the green-veined white butterfly Pieris napi (L.). The tests were performed in the laboratory under five different temperatures.

    4. The results showed that age has a significant influence on butterfly flight endurance; older butterflies showed reduced flight endurance. Male butterflies fly for a longer time than females and flight endurance increase with temperature in both sexes.

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