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  • 1.
    Aalberg Haugen, Inger M.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Berger, David
    Stockholm University, Faculty of Science, Department of Zoology. Uppsala University, Sweden.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    The evolution of alternative developmental pathways: footprints of selection on life-history traits in a butterfly2012In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 25, no 7, p. 1377-1388Article in journal (Refereed)
    Abstract [en]

    Developmental pathways may evolve to optimize alternative phenotypes across environments. However, the maintenance of such adaptive plasticity under relaxed selection has received little study. We compare the expression of life-history traits across two developmental pathways in two populations of the butterfly Pararge aegeria where both populations express a diapause pathway but one never expresses direct development in nature. In the population with ongoing selection on both pathways, the difference between pathways in development time and growth rate was larger, whereas the difference in body size was smaller compared with the population experiencing relaxed selection on one pathway. This indicates that relaxed selection on the direct pathway has allowed life-history traits to drift towards values associated with lower fitness when following this pathway. Relaxed selection on direct development was also associated with a higher degree of genetic variation for protandry expressed as within-family sexual dimorphism in growth rate. Genetic correlations for larval growth rate across sexes and pathways were generally positive, with the notable exception of correlation estimates that involved directly developing males of the population that experienced relaxed selection on this pathway. We conclude that relaxed selection on one developmental pathway appears to have partly disrupted the developmental regulation of life-history trait expression. This in turn suggests that ongoing selection may be responsible for maintaining adaptive developmental regulation along alternative developmental pathways in these populations.

  • 2. Abrahamczyk, S.
    et al.
    Kessler, M.
    Hanley, D.
    Karger, D. N.
    Mueller, M. P. J.
    Knauer, A. C.
    Keller, F.
    Schwerdtfeger, M.
    Humphreys, Aelys M.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Imperial College London, UK.
    Pollinator adaptation and the evolution of floral nectar sugar composition2017In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 30, no 1, p. 112-127Article in journal (Refereed)
    Abstract [en]

    A long-standing debate concerns whether nectar sugar composition evolves as an adaptation to pollinator dietary requirements or whether it is 'phylogenetically constrained'. Here, we use a modelling approach to evaluate the hypothesis that nectar sucrose proportion (NSP) is an adaptation to pollinators. We analyse similar to 2100 species of asterids, spanning several plant families and pollinator groups (PGs), and show that the hypothesis of adaptation cannot be rejected: NSP evolves towards two optimal values, high NSP for specialist-pollinated and low NSP for generalist-pollinated plants. However, the inferred adaptive process is weak, suggesting that adaptation to PG only provides a partial explanation for how nectar evolves. Additional factors are therefore needed to fully explain nectar evolution, and we suggest that future studies might incorporate floral shape and size and the abiotic environment into the analytical framework. Further, we show that NSP and PG evolution are correlated - in a manner dictated by pollinator behaviour. This contrasts with the view that a plant necessarily has to adapt its nectar composition to ensure pollination but rather suggests that pollinators adapt their foraging behaviour or dietary requirements to the nectar sugar composition presented by the plants. Finally, we document unexpectedly sucrose-poor nectar in some specialized nectarivorous bird-pollinated plants from the Old World, which might represent an overlooked form of pollinator deception. Thus, our broad study provides several new insights into how nectar evolves and we conclude by discussing why maintaining the conceptual dichotomy between adaptation and constraint might be unhelpful for advancing this field.

  • 3.
    Amcoff, Mirjam
    et al.
    Uppsala universitet, Zooekologi.
    Gonzalez-Voyer, A.
    Kolm, Niclas
    Uppsala universitet, Zooekologi.
    Evolution of egg dummies in Tanganyikan cichlid fishes: the roles of parental care and sexual selection2013In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 26, no 11, p. 2369-2382Article, review/survey (Refereed)
    Abstract [en]

    Sexual selection has been suggested to be an important driver of speciation in cichlid fishes of the Great Lakes of Africa, and the presence of male egg dummies is proposed to have played a key role. Here, we investigate how mouthbrooding and egg dummies have evolved in Tanganyikan cichlids, the lineage which seeded the other African radiations, with a special emphasis on the egg dummies. Using modern phylogenetic comparative analyses and a phylogeny including 86% of the 200 described species, we provide formal evidence demonstrating correlated evolution between mouthbrooding and egg dummies in Tanganyikan cichlids. These results concur with existing evidence, suggesting that egg dummies have evolved through sensory exploitation. We also demonstrate that there is a strong evolutionary correlation between the presence of egg dummies and both pre- and post-copulatory sexual selection. Moreover, egg dummy evolution was contingent on the intensity of pre- and post-copulatory sexual selection in Tanganyikan cichlids. In sum, our results provide evidence supporting the hypothesis of egg dummies evolving through sensory exploitation and highlight the role of sexual selection in favouring the evolution and maintenance of this trait.

  • 4.
    Arnqvist, Göran
    et al.
    Uppsala universitet, Zooekologi.
    Kolm, Niclas
    Uppsala universitet, Zooekologi.
    Population differentiation in the swordtail characin (Corynopoma riisei): a role for sensory drive?2010In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 23, no 9, p. 1907-1918Article, review/survey (Refereed)
    Abstract [en]

    Sensory drive, where the efficacy of a sexual signal depends on the environment in which it is employed, is a potential mechanism behind divergent evolution of secondary sexual traits. Male swordtail characins are equipped with a narrow and transparent extension of the gill cover with a flag-like structure at its tip. This opercular flag mimics a prey item and is employed by males as a 'lure' to attract the attention of females during mating attempts. We conducted a study of genetic and morphological differentiation across swordtail characin populations throughout their native range in Trinidad. The morphology of the opercular flag varied across populations and several aspects of this variation match the predicted hallmarks of sensory drive. First, morphological differentiation of the flag across populations was unrelated to genetic similarity at neutral genetic markers. Second, the shape of the flag covaried with those aspects of body shape that should reflect adaptation to different feeding regimes. Third, and most importantly, the shape of the flag covaried across populations with those environmental characteristics that should most closely reflect differences in local prey abundance. Overall, our results are consistent with a scenario where the evolution of this male sexual signal tracks food-related shifts in female sensory biases across populations, thus providing at least provisional support for a role for sensory drive in population differentiation.

  • 5.
    Devigili, Alessandro
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. University of Padova, Italy.
    Fitzpatrick, John L.
    Stockholm University, Faculty of Science, Department of Zoology. University of Western Australia, Australia.
    Gasparini, C.
    Ramnarine, I. W.
    Pilastro, A.
    Evans, J. P.
    Possible glimpses into early speciation: the effect of ovarian fluid on sperm velocity accords with post-copulatory isolation between two guppy populations2018In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 31, no 1, p. 66-74Article in journal (Refereed)
    Abstract [en]

    Identifying mechanisms of reproductive isolation is key to understanding speciation. Among the putative mechanisms underlying reproductive isolation, sperm-female interactions (post-mating-prezygotic barriers) are arguably the hardest to identify, not least because these are likely to operate at the cellular or molecular level. Yet sperm-female interactions offer great potential to prevent the transfer of genetic information between different populations at the initial stages of speciation. Here, we provide a preliminary test for the presence of a putative post-mating-prezygotic barrier operating between three populations of Trinidadian guppies (Poecilia reticulata), an internally fertilizing fish that inhabits streams with different levels of connectivity across Trinidad. We experimentally evaluate the effect of female ovarian fluid on sperm velocity (a predictor of competitive fertilization success) according to whether males and females were from the same (native) or different (foreign) populations. Our results reveal the potential for ovarian fluid to act as a post-mating-prezygotic barrier between two populations from different drainages, but also that the strength of this barrier is different among populations. This result may explain the previous finding that, in some populations, sperm from native males have precedence over foreign sperm, which could eventually lead to reproductive isolation between these populations.

  • 6.
    Dinca, Vlad
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Lukhtanov, V. A.
    Kodandaramaiah, U.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Dapporto, L.
    Wahlberg, N.
    Vila, R.
    Friberg, Mange
    Stockholm University, Faculty of Science, Department of Zoology.
    Reproductive isolation and patterns of genetic differentiation in a cryptic butterfly species complex2013In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 26, no 10, p. 2095-2106Article in journal (Refereed)
    Abstract [en]

    Molecular studies of natural populations are often designed to detect and categorize hidden layers of cryptic diversity, and an emerging pattern suggests that cryptic species are more common and more widely distributed than previously thought. However, these studies are often decoupled from ecological and behavioural studies of species divergence. Thus, the mechanisms by which the cryptic diversity is distributed and maintained across large spatial scales are often unknown. In 1988, it was discovered that the common Eurasian Wood White butterfly consisted of two species (Leptidea sinapis and Leptidea reali), and the pair became an emerging model for the study of speciation and chromosomal evolution. In 2011, the existence of a third cryptic species (Leptidea juvernica) was proposed. This unexpected discovery raises questions about the mechanisms preventing gene flow and about the potential existence of additional species hidden in the complex. Here, we compare patterns of genetic divergence across western Eurasia in an extensive data set of mitochondrial and nuclear DNA sequences with behavioural data on inter- and intraspecific reproductive isolation in courtship experiments. We show that three species exist in accordance with both the phylogenetic and biological species concepts and that additional hidden diversity is unlikely to occur in Europe. The Leptidea species are now the best studied cryptic complex of butterflies in Europe and a promising model system for understanding the formation of cryptic species and the roles of local processes, colonization patterns and heterospecific interactions for ecological and evolutionary divergence.

  • 7.
    Espeland, Marianne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Systematic Zoology.
    Johanson, Kjell Arne
    Swedish Museum of Natural History, Entomology department.
    The diversity and radiation of the largest monophyletic animal group on New Caledonia (Trichoptera: Ecnomidae: Agmina)2010In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 23, no 10, p. 2112-2122Article in journal (Refereed)
    Abstract [en]

    In area, New Caledonia is the smallest of the world's 25 official biodiversity hotspots, but in many taxonomic groups, the island has the highest concentration of species on earth, particularly so in the freshwater insect order Trichoptera. This study aims at applying molecular data and morphology for estimating the real species diversity of the genus Agmina on New Caledonia and investigating potential effects of ultramafic rock substrate on diversification. A dated molecular phylogeny was applied to study diversity and diversification related to geological substrate using the dispersal-extinction-cladogenesis model, diva and Bayesian ancestral character reconstruction. More than 47 species (> 63%) were unknown to science. Initial radiation occurred on ultramafic substrate followed by several independent dispersal events to nonultramafic substrate. The rate of shift from ultramafic to nonultramafic substrate was significantly higher than the rate of shift in the opposite direction, indicating a possible cost associated with living on ultramafic substrate.

  • 8. Fitzpatrick, J. L.
    et al.
    Almbro, M.
    Gonzalez-Voyer, A.
    Hamada, S.
    Pennington, C.
    Scanlan, J.
    Kolm, Niclas
    Uppsala universitet, Zooekologi.
    Sexual selection uncouples the evolution of brain and body size in pinnipeds2012In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 25, no 7, p. 1321-1330Article in journal (Refereed)
    Abstract [en]

    The size of the vertebrate brain is shaped by a variety of selective forces. Although larger brains (correcting for body size) are thought to confer fitness advantages, energetic limitations of this costly organ may lead to trade-offs, for example as recently suggested between sexual traits and neural tissue. Here, we examine the patterns of selection on male and female brain size in pinnipeds, a group where the strength of sexual selection differs markedly among species and between the sexes. Relative brain size was negatively associated with the intensity of sexual selection in males but not females. However, analyses of the rates of body and brain size evolution showed that this apparent trade-off between sexual selection and brain mass is driven by selection for increasing body mass rather than by an actual reduction in male brain size. Our results suggest that sexual selection has important effects on the allometric relationships of neural development.

  • 9.
    Fitzpatrick, John L.
    et al.
    University of Manchester, UK; University of Western Australia, Australia.
    Evans, J. P.
    Postcopulatory inbreeding avoidance in guppies2014In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 27, no 12, p. 2585-2594Article in journal (Refereed)
    Abstract [en]

    In many species, the negative fitness effects of inbreeding have facilitated the evolution of a wide range of inbreeding avoidance mechanisms. Although avoidance mechanisms operating prior to mating are well documented, evidence for postcopulatory mechanisms of inbreeding avoidance remain scarce. Here, we examine the potential for paternity biases to favour unrelated males when their sperm compete for fertilizations though postcopulatory inbreeding avoidance mechanisms in the guppy, Poecilia reticulata. To test this possibility, we used a series of artificial inseminations to deliver an equal number of sperm from a related (either full sibling or half sibling) and unrelated male to a female while statistically controlling for differences in sperm quality between rival ejaculates. In this way, we were able to focus exclusively on postcopulatory mechanisms of inbreeding avoidance and account for differences in sperm competitiveness between rival males. Under these carefully controlled conditions, we report a significant bias in paternity towards unrelated males, although this effect was only apparent when the related male was a full sibling. We also show that sperm competition generally favours males with highly viable sperm and thus that some variance in sperm competitiveness can be attributed to difference in sperm quality. Our findings for postcopulatory inbreeding avoidance are consistent with prior work on guppies, revealing that sperm competition success declines linearly with the level of relatedness, but also that such effects are only apparent at relatedness levels of full siblings or higher. These findings reveal that postcopulatory processes alone can facilitate inbreeding avoidance.

  • 10.
    Friberg, Magne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Uppsala universitet.
    Leimar, Olof
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Heterospecific courtship, minority effects and niche separation between cryptic butterfly species2013In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 26, no 5, p. 971-979Article in journal (Refereed)
    Abstract [en]

    Species interacting in varied ecological conditions often evolve in different directions in different local populations. The butterflies of the cryptic Leptidea complex are sympatrically distributed in different combinations across their Eurasian range. Interestingly, the same species is a habitat generalist in some regions and a habitat specialist in others, where a sibling species has the habitat generalist role. Previous studies suggest that this geographically variable niche divergence is generated by local processes in different contact zones. By varying the absolute and relative densities of Leptidea sinapis and Leptidea juvernica in large outdoor cages, we show that female mating success is unaffected by conspecific density, but strongly negatively affected by the density of the other species. Whereas 80% of the females mated when a conspecific couple was alone in a cage, less than 10% mated when the single couple shared the cage with five pairs of the other species. The heterospecific courtships can thus affect the population fitness, and for the species in the local minority, the suitability of a habitat is likely to depend on the presence or absence of the locally interacting species. If the local relative abundance of the different species depends on the colonization order, priority effects might determine the ecological roles of interacting species in this system.

  • 11.
    Gonzalez-Voyer, Alejandro
    et al.
    Uppsala universitet, Zooekologi.
    Kolm, Niclas
    Uppsala universitet, Zooekologi.
    Rates of phenotypic evolution of ecological characters and sexual traits during the Tanganyikan cichlid adaptive radiation2011In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 24, no 11, p. 2378-2388Article in journal (Refereed)
    Abstract [en]

    Theory suggests that sexual traits evolve faster than ecological characters. However, characteristics of a species niche may also influence evolution of sexual traits. Hence, a pending question is whether ecological characters and sexual traits present similar tempo and mode of evolution during periods of rapid ecological divergence, such as adaptive radiation. Here, we use recently developed phylogenetic comparative methods to analyse the temporal dynamics of evolution for ecological and sexual traits in Tanganyikan cichlids. Our results indicate that whereas disparity in ecological characters was concentrated early in the radiation, disparity in sexual traits remained high throughout the radiation. Thus, closely related Tanganyikan cichlids presented higher disparity in sexual traits than ecological characters. Sexual traits were also under stronger selection than ecological characters. In sum, our results suggest that ecological characters and sexual traits present distinct evolutionary patterns, and that sexual traits can evolve faster than ecological characters, even during adaptive radiation.

  • 12.
    Gotthard, Karl
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Berger, David
    Stockholm University, Faculty of Science, Department of Zoology.
    The diapause decision as a cascade switch for adaptive developmental plasticity in body mass in a butterfly.2010In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 23, no 6, p. 1129-37Article in journal (Refereed)
    Abstract [en]

    Switch-induced developmental plasticity, such as the diapause decision in insects, is a major form of adaptation to variable environments. As individuals that follow alternative developmental pathways will experience different selective environments the diapause decision may evolve to a cascade switch that induces additional adaptive developmental differences downstream of the diapause decision. Here, we show that individuals following alternative developmental pathways in a Swedish population of the butterfly, Pararge aegeria, display differential optimization of adult body mass as a likely response to predictable differences in thermal conditions during reproduction. In a more northern population where this type of selection is absent no similar difference in adult mass among pathways was found. We conclude that the diapause decision in the southern population appears to act as a cascade switch, coordinating development downstream of the diapause decision, to produce adult phenotypes adapted to the typical thermal conditions of their expected reproductive period

  • 13. Hayward, A.
    et al.
    Tsuboi, M.
    Owusu, C.
    Kotrschal, Alexander
    Stockholm University, Faculty of Science, Department of Zoology.
    Buechel, Severine D.
    Stockholm University, Faculty of Science, Department of Zoology.
    Zidar, J.
    Cornwallis, C. K.
    Lovlie, H.
    Kolm, Niclas
    Stockholm University, Faculty of Science, Department of Zoology.
    Evolutionary associations between host traits and parasite load: insights from Lake Tanganyika cichlids2017In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 30, no 6, p. 1056-1067Article in journal (Refereed)
    Abstract [en]

    Parasite diversity and abundance (parasite load) vary greatly among host species. However, the influence of host traits on variation in parasitism remains poorly understood. Comparative studies of parasite load have largely examined measures of parasite species richness and are predominantly based on records obtained from published data. Consequently, little is known about the relationships between host traits and other aspects of parasite load, such as parasite abundance, prevalence and aggregation. Meanwhile, understanding of parasite species richness may be clouded by limitations associated with data collation from multiple independent sources. We conducted a field study of Lake Tanganyika cichlid fishes and their helminth parasites. Using a Bayesian phylogenetic comparative framework, we tested evolutionary associations between five key host traits (body size, gut length, diet breadth, habitat complexity and number of sympatric hosts) predicted to influence parasitism, together with multiple measures of parasite load. We find that the number of host species that a particular host may encounter due to its habitat preferences emerges as a factor of general importance for parasite diversity, abundance and prevalence, but not parasite aggregation. In contrast, body size and gut size are positively related to aspects of parasite load within, but not between species. The influence of host phylogeny varies considerably among measures of parasite load, with the greatest influence exerted on parasite diversity. These results reveal that both host morphology and biotic interactions are key determinants of host-parasite associations and that consideration of multiple aspects of parasite load is required to fully understand patterns in parasitism.

  • 14. Katvala, Mari
    et al.
    Liljestrand Rönn, Johanna
    Uppsala universitet.
    Arnqvist, Göran
    Correlated evolution between male ejacualte allocation and female remating behaviour in seed beetles (Bruchidae)2008In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 21, no 2, p. 471-479Article in journal (Refereed)
    Abstract [en]

    The pattern with which males allocate their ejaculate resources is at the heart of postmating sexual selection, and theory suggests that female remating rate is key in determining the selective regime under which male ejaculate traits evolve. Intraspecific studies have shown that males are able to adaptively allocate ejaculates according to the intensity of sperm competition, but observational data does not allow explicitly comparative tests of theory in this field. Using a group of seed beetles as a model system, we analyzed experimental quantifications of a suite of relevant male and female traits and behaviors in a phylogenetic comparative framework. We found a strongly and positively correlated evolution between the weight of males’ first ejaculate and the rate at which ejaculate weight decreases over successive matings. Sperm competition theory predicts that increased female remating should result in the evolution of larger male testes but smaller ejaculates, and both of these predictions were upheld in seed beetles. Theory also predicts that increased female remating should lead to the evolution of more prudent allocation of ejaculate resources over successive matings. In contrast to this prediction, we found that elevated female remating was associated with a less prudent ejaculate allocation. We suggest that this pattern of correlated evolution, apparently incongruent with classic sperm competition theory, is the result either of trade-offs between ejaculate expenditure and other competing demands or of evolution in total resource acquisition rather than in the evolution of resource allocation.

  • 15.
    Kodandaramaiah, Ullasa
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Wahlberg, Niklas
    Stockholm University, Faculty of Science, Department of Zoology.
    Out-of-Africa origin and dispersal mediated diversification of the butterfly genus Junonia (Nymphalidae: Nymphalinae)2007In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 20, no 6, p. 2181-2191Article in journal (Refereed)
    Abstract [en]

    The relative importance of dispersal and vicariance in the diversification of taxa has been much debated. Within butterflies, a few studies published so far have demonstrated vicariant patterns at the global level. We studied the historical biogeography of the genus Junonia (Nymphalidae: Nymphalinae) at the intercontinental level based on a molecular phylogeny. The genus is distributed over all major biogeographical regions of the world except the Palaearctic. We found dispersal to be the dominant process in the diversification of the genus. The genus originated and started diversifying in Africa about 20 Ma and soon after dispersed into Asia possibly through the Arabian Peninsula. From Asia, there were dispersals into Africa and Australasia, all around 5 Ma. The origin of the New World species is ambiguous; the ancestral may have dispersed from Asia via the Beringian Strait or from Africa over the Atlantic, about 3 Ma. We found no evidence for vicariance at the intercontinental scale. We argue that dispersal is as important as vicariance, if not more, in the global diversification of butterflies.

  • 16.
    Kodandaramaiah, Ullasa
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Weingartner, Elisabet
    Stockholm University, Faculty of Science, Department of Zoology.
    Janz, Niklas
    Stockholm University, Faculty of Science, Department of Zoology.
    Dalén, L.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Population structure in relation to host-plant ecology and Wolbachia infestation in the comma butterfly2011In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 24, no 10, p. 2173-2185Article in journal (Refereed)
    Abstract [en]

    Experimental work on Polygonia c-album, a temperate polyphagous butterfly species, has shown that Swedish, Belgian, Norwegian and Estonian females are generalists with respect to host-plant preference, whereas females from UK and Spain are specialized on Urticaceae. Female preference is known to have a strong genetic component. We test whether the specialist and generalist populations form respective genetic clusters using data from mitochondrial sequences and 10 microsatellite loci. Results do not support this hypothesis, suggesting that the specialist and generalist traits have evolved more than once independently. Mitochondrial DNA variation suggests a rapid expansion scenario, with a single widespread haplotype occurring in high frequency, whereas microsatellite data indicate strong differentiation of the Moroccan population. Based on a comparison of polymorphism in the mitochondrial data and sequences from a nuclear gene, we show that the diversity in the former is significantly less than that expected under neutral evolution. Furthermore, we found that almost all butterfly samples were infected with a single strain of Wolbachia, a maternally inherited bacterium. We reason that indirect selection on the mitochondrial genome mediated by a recent sweep of Wolbachia infection has depleted variability in the mitochondrial sequences. We also surmise that P. c-album could have expanded out of a single glacial refugium and colonized Morocco recently.

  • 17.
    Kolm, Niclas
    et al.
    Uppsala universitet, Zooekologi.
    Gonzalez-Voyer, Alejandro
    Uppsala universitet, Zooekologi.
    Brelin, Daniel
    Uppsala universitet, Fysiologi.
    Winberg, Svante
    Uppsala universitet, Fysiologi.
    Evidence for small scale variation in the vertebrate brain: mating strategy and sex affect brain size and structure in wild brown trout (Salmo trutta)2009In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 22, no 12, p. 2524-2531Article in journal (Refereed)
    Abstract [en]

    The basis for our knowledge of brain evolution in vertebrates rests heavily on empirical evidence from comparative studies at the species level. However, little is still known about the natural levels of variation and the evolutionary causes of differences in brain size and brain structure within-species, even though selection at this level is an important initial generator of macroevolutionary patterns across species. Here, we examine how early life-history decisions and sex are related to brain size and brain structure in wild populations using the existing natural variation in mating strategies among wild brown trout (Salmo trutta). By comparing the brains of precocious fish that remain in the river and sexually mature at a small size with those of migratory fish that migrate to the sea and sexually mature at a much larger size, we show, for the first time in any vertebrate, strong differences in relative brain size and brain structure across mating strategies. Precocious fish have larger brain size (when controlling for body size) but migratory fish have a larger cerebellum, the structure in charge of motor coordination. Moreover, we demonstrate sex-specific differences in brain structure as female precocious fish have a larger brain than male precocious fish while males of both strategies have a larger telencephalon, the cognitive control centre, than females. The differences in brain size and structure across mating strategies and sexes thus suggest the possibility for fine scale adaptive evolution of the vertebrate brain in relation to different life histories.

  • 18.
    Kolm, Niclas
    et al.
    Uppsala universitet, Zooekologi.
    Stein, R.W
    Mooers, A.
    Verspoor, J.J.
    Cunningham, J.A.
    Can sexual selection drive female life histories?: A comparative study on Galliform birds2007In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 20, no 2, p. 627-638Article in journal (Refereed)
    Abstract [en]

    Sexual selection has been identified as a major evolutionary force shaping male life history traits but its impact on female life history evolution is less clear. Here we examine the impact of sexual selection on three key female traits (body size, egg size and clutch size) in Galliform birds. Using comparative independent contrast analyses and directionaldiscreteanalyses, based on published data and a new genera-level supertree phylogeny of Galliform birds, we investigated how sexual selection [quantified as sexual size dimorphism (SSD) and social mating system (MS)] affects these three important female traits. We found that female body mass was strongly and positively correlated with egg size but not with clutch size, and that clutch size decreased as egg size increased. We established that SSD was related to MS, and then used SSD as a proxy of the strength of sexual selection. We found both a positive relationship between SSD and female body mass and egg size and that increases in female body mass and egg size tend to occur following increases in SSD in this bird order. This pattern of female body mass increases lagging behind changes in SSD, established using our directionaldiscreteanalysis, suggests that female body mass increases as a response to increases in the level of sexual selection and not simply through a strong genetic relationship with male body mass. This suggests that sexual selection is linked to changes in female life history traits in Galliformes and we discuss how this link may shape patterns of life history variation among species.

  • 19.
    Kotrschal, Alexander
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Uppsala University, Sweden.
    Corral-Lopez, Alberto
    Stockholm University, Faculty of Science, Department of Zoology.
    Zajitschek, S.
    Immler, S.
    Maklakov, A. A.
    Kolm, Niclas
    Stockholm University, Faculty of Science, Department of Zoology.
    Positive genetic correlation between brain size and sexual traits in male guppies artificially selected for brain size2015In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 28, no 4, p. 841-850Article in journal (Refereed)
    Abstract [en]

    Brain size is an energetically costly trait to develop and maintain. Investments into other costly aspects of an organism's biology may therefore place important constraints on brain size evolution. Sexual traits are often costly and could therefore be traded off against neural investment. However, brain size may itself be under sexual selection through mate choice on cognitive ability. Here, we use guppy (Poecilia reticulata) lines selected for large and small brain size relative to body size to investigate the relationship between brain size, a large suite of male primary and secondary sexual traits, and body condition index. We found no evidence for trade-offs between brain size and sexual traits. Instead, larger-brained males had higher expression of several primary and precopulatory sexual traits - they had longer genitalia, were more colourful and developed longer tails than smaller-brained males. Larger-brained males were also in better body condition when housed in single-sex groups. There was no difference in post-copulatory sexual traits between males from the large- and small-brained lines. Our data do not support the hypothesis that investment into sexual traits is an important limiting factor to brain size evolution, but instead suggest that brain size and several sexual traits are positively genetically correlated.

  • 20.
    Liljestrand Rönn, Johanna
    et al.
    Uppsala universitet.
    Katvala, Mari
    Arnqvist, Göran
    Interspecific variation in ejaculate allocation and associated effects on female fitness in seed beetles2008In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 21, no 2, p. 461-470Article in journal (Refereed)
    Abstract [en]

    When ejaculates are costly to produce, males are expected to allocate their ejaculate resources over successive matings in a manner that optimises their reproductive success. Theory predicts that two factors should affect optimal ejaculate allocation: the sperm competition regime and variation in female fecundity. In seed beetles (Bruchidae), ejaculates vary in size across species from weighing a few, up to as much as twelve percent, of male body weight. Ejaculates in this group contain not only sperm but also a range of additional substances and it has been proposed that females gain benefits from receiving large ejaculates. Male ejaculate allocation may thus affect female fitness and, indirectly, his own reproductive output. Here, we first measured how males allocate ejaculates over successive matings in seven seed beetle species. We then assessed how this allocation affected female fitness. We found that ejaculate weight drops dramatically over successive matings in some species but not in others. This interspecific variation in ejaculate allocation pattern was matched with extensive variation in the effects of ejaculate allocation on female fitness. Species varied both in terms of the size of the effect of male mating history on female fitness and in terms of which female fitness components were affected. In summary, despite the fact that the species included in this study are closely related, interspecific variation in ejaculate allocation patterns and their effects on female fitness was remarkably large. We discuss the possible causes of this variation and its implications for male-female coevolution.

  • 21.
    Lindenfors, Patrik
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Sexually antagonistic selection on primate size2002In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 15, p. 595-607Article in journal (Refereed)
    Abstract [en]

    Male intrasexual selection in haplorhine primates has previously been shown to increase male size and to a lesser degree also female size. I address the following questions: (1) why does female size increase when the selection is on males, and (2) why does female size not increase to the same extent as that of males. The potential for correlational selection on females through increased resource competition was analysed with independent contrasts analyses. No such effect was found, nor did matched pairs comparisons reveal females to increase in size because of selection to bear larger male offspring. Instead further matched pairs analyses revealed higher female postpartum investment, as indicated by a longer lactation period, in more sexually selected species, also after correcting for body weight. Concerning the second question, independent contrast analyses showed that large size has had negative effects on female reproductive rate across the primate order. Matched-pairs analyses on haplorhines revealed that females of species in more polygynous clades have lower reproductive rates than females of species in less polygynous clades. This is also true after the effects of body weight are removed. These results, both when correcting for body weight and when not, suggest that sexual selection has shifted female size from one favouring female lifetime fecundity to one favouring male success in competition. This depicts antagonistic selection pressures on female size and a trade-off for females between the ecologically optimal size of their foremothers and the larger size that made their forefathers successful

  • 22.
    Lindenfors, Patrik
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology. Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution.
    Revell, Liam J
    National Evolutionary Synthesis Center, Durham, NC, USA.
    Nunn, Charles L
    Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA.
    Sexual dimorphism in primate aerobic capacity: a phylogenetic test2010In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 23, no 6, p. 1183-1194Article in journal (Refereed)
    Abstract [en]

    Male intrasexual competition should favour increased male physical prowess.This should in turn result in greater aerobic capacity in males than in females(i.e. sexual dimorphism) and a correlation between sexual dimorphism inaerobic capacity and the strength of sexual selection among species. However,physiological scaling laws predict that aerobic capacity should be lower perunit body mass in larger than in smaller animals, potentially reducing orreversing the sex difference and its association with measures of sexualselection. We used measures of haematocrit and red blood cell (RBC) countsfrom 45 species of primates to test four predictions related to sexual selectionand body mass: (i) on average, males should have higher aerobic capacity thanfemales, (ii) aerobic capacity should be higher in adult than juvenile males,(iii) aerobic capacity should increase with increasing sexual selection, but alsothat (iv) measures of aerobic capacity should co-vary negatively with bodymass. For the first two predictions, we used a phylogenetic paired t-testdeveloped for this study. We found support for predictions (i) and (ii). For prediction (iii), however, we found a negative correlation between the degreeof sexual selection and aerobic capacity, which was opposite to our prediction.Prediction (iv) was generally supported. We also investigated whethersubstrate use, basal metabolic rate and agility influenced physiologicalmeasures of oxygen transport, but we found only weak evidence for acorrelation between RBC count and agility.

  • 23.
    Lindenfors, Patrik
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Székely, Tamás
    Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, UK.
    Reynolds, John
    Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich, UK.
    Directional changes in sexual size dimorphism in shorebirds, gulls and alcids2003In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 16, p. 930-938Article in journal (Refereed)
    Abstract [en]

    The Charadrii (shorebirds, gulls and alcids) are one of the most diverse avian groups from the point of view of sexual size dimorphism, exhibiting extremes in both male-biased and female-biased dimorphism, as well as monomorphism. In this study we use phylogenetic comparative analyses to investigate how size dimorphism has changed over evolutionary time, distinguishing between changes that have occurred in females and in males. Independent contrasts analyses show that both body mass and wing length have been more variable in males than in females. Directional analyses show that male-biased dimorphism has increased after inferred transitions towards more polygynous mating systems. There have been analogous increases in female-biased dimorphism after transitions towards more socially polyandrous mating systems. Changes in dimorphism in both directions are attributable to male body size changing more than female body size. We suggest that this might be because females are under stronger natural selection constraints related to fecundity. Taken together, our results suggest that the observed variation in dimorphism of Charadrii can be best explained by male body size responding more sensitively to variable sexual selection than female body size

  • 24.
    Lindenfors, Patrik
    et al.
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution. Stockholm University, Faculty of Science, Department of Zoology.
    Tullberg, Birgitta
    Stockholm University, Faculty of Science, Department of Zoology.
    Lowering sample size in comparative analyses can indicate a correlation where there is none: example from Rensch’s rule in primates2006In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 19, p. 1346-1351Article in journal (Refereed)
    Abstract [en]

    The fact that characters may co-vary in organism groups because of shared ancestry and not always because of functional correlations was the initial rationale for developing phylogenetic comparative methods. Here we point out a case where similarity due to shared ancestry can produce an undesired effect when conducting an independent contrasts analysis. Under special circumstances, using a low sample size will produce results indicating an evolutionary correlation between characters where an analysis of the same pattern utilizing a larger sample size will show that this correlation does not exist. This is the opposite effect of increased sample size to that expected; normally an increased sample size increases the chance of finding a correlation. The situation where the problem occurs is when co-variation between the two continuous characters analysed is clumped in clades; e.g. when some phylogenetically conservative factors affect both characters simultaneously. In such a case, the correlation between the two characters becomes contingent on the number of clades sharing this conservative factor that are included in the analysis, in relation to the number of species contained within these clades. Removing species scattered evenly over the phylogeny will in this case remove the exact variation that diffuses the evolutionary correlation between the two characters – the variation contained within the clades sharing the conservative factor. We exemplify this problem by discussing a parallel in nature where the described problem may be of importance. This concerns the question of the presence or absence of Rensch’s rule in primates.

  • 25.
    Löwenborg, Kristin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Shine, R.
    Hagman, Mattias
    Stockholm University, Faculty of Science, Department of Zoology.
    Fitness disadvantages to disrupted embryogenesis impose selection against suboptimal nest-site choice by female grass snakes, Natrix natrix (Colubridae)2011In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 24, no 1, p. 177-183Article in journal (Refereed)
    Abstract [en]

    Phenotypic traits of hatchling reptiles are strongly influenced by incubation regimes (e.g. of temperature and moisture), suggesting that maternal choice of suitable nest-sites should be under intense selection. Our laboratory incubation of 209 eggs (17 clutches) from wild-caught Swedish grass snakes (Natrix natrix) showed that scale abnormalities (half-scales on one side of the body, often reflecting lateral asymmetry in the number of ribs) occurred more frequently if eggs were incubated under cooler conditions. Especially at low incubation temperatures, individuals with scale asymmetries took longer to hatch than did symmetric conspecifics, were smaller in body length at hatching and were slower in trials of locomotor speed. Anti-predator tactics also covaried with scale asymmetry. These patterns suggest that individuals with asymmetric scales should have lower fitness and hence should rarely survive to adulthood in the wild. We tested this prediction by examining 201 field-collected snakes from museum collections. As predicted, scale asymmetries were seen primarily in small snakes, and rarely in larger animals. We interpret these data to suggest that scale asymmetries in this species offer an index of developmental instability and that fitness disadvantages to disrupted embryogenesis impose selection against suboptimal nest-site choice by females.

  • 26. Morandin, C.
    et al.
    Dhaygude, K.
    Paviala, J.
    Trontti, K.
    Wheat, Christopher
    Stockholm University, Faculty of Science, Department of Zoology.
    Helanterä, H.
    Caste-biases in gene expression are specific to developmental stage in the ant Formica exsecta2015In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 28, no 9, p. 1705-1718Article in journal (Refereed)
    Abstract [en]

    Understanding how a single genome creates and maintains distinct phenotypes is a central goal in evolutionary biology. Social insects are a striking example of co-opted genetic backgrounds giving rise to dramatically different phenotypes, such as queen and worker castes. A conserved set of molecular pathways, previously envisioned as a set of 'toolkit' genes, has been hypothesized to underlie queen and worker phenotypes in independently evolved social insect lineages. Here, we investigated the toolkit from a developmental point of view, using RNA-Seq to compare caste-biased gene expression patterns across three life stages (pupae, emerging adult and old adult) and two female castes (queens and workers) in the ant Formica exsecta. We found that the number of genes with caste-biased expression increases dramatically from pupal to old adult stages. This result suggests that phenotypic differences between queens and workers at the pupal stage may derive from a relatively low number of caste-biased genes, compared to higher number of genes required to maintain caste differences at the adult stage. Gene expression patterns were more similar among castes within developmental stages than within castes despite the extensive phenotypic differences between queens and workers. Caste-biased expression was highly variable among life stages at the level of single genes, but more consistent when gene functions (gene ontology terms) were investigated. Finally, we found that a large part of putative toolkit genes were caste-biased at least in some life stages in F. exsecta, and the caste-biases, but not their direction, were more often shared between F. exsecta and other ant species than between F. exsecta and bees. Our results indicate that gene expression should be examined across several developmental stages to fully reveal the genetic basis of polyphenisms.

  • 27. Ord, Terry
    et al.
    Klomp, Danielle
    Garcia-Porta, Joan
    Hagman, Mattias
    University of New South Wales, Kensington, Australia.
    Repeated evolution of exaggerated dewlaps and other throat morphology in lizards.2015In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 28, p. 1948-1964Article in journal (Refereed)
    Abstract [en]

    The existence of elaborate ornamental structures in males is often assumed to reflect the outcome of female mate choice for showy males. However, female mate choice appears weak in many iguanian lizards, but males still exhibit an array of ornament-like structures around the throat. We performed a phylogenetic comparative study to assess whether these structures have originated in response to male–male competition or the need for improved signal efficiency in visually difficult environments. We found little evidence for the influence of male–male competition. Instead, forest species were more likely to exhibit colourful throat appendages than species living in open habitats, suggesting selection for signal efficiency. On at least three independent occasions, throat ornamentation has become further elaborated into a large, conspicuously coloured moving dewlap. Although the function of the dewlap is convergent, the underlying hyoid apparatus has evolved very differently, revealing the same adaptive outcome has been achieved through multiple evolutionary trajectories. More generally, our findings highlight that extravagant, ornament-like morphology can evolve in males without the direct influence of female mate choice and that failure to consider alternative hypotheses for the evolution of these structures can obscure the true origins of signal diversity among closely related taxa.

  • 28. Paccard, Antoine
    et al.
    Wasserman, Ben A.
    Hanson, Dieta
    Astorg, Louis
    Durston, Dan
    Kurland, Sara
    Stockholm University, Faculty of Science, Department of Zoology.
    Apgar, Travis M.
    El-Sabaawi, Rana W.
    Palkovacs, Eric P.
    Hendry, Andrew P.
    Barrett, Rowan D. H.
    Adaptation in temporally variable environments: stickleback armor in periodically breaching bar-built estuaries2018In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 31, no 5, p. 735-752Article in journal (Refereed)
    Abstract [en]

    The evolutionary consequences of temporal variation in selection remain hotly debated. We explored these consequences by studying threespine stickleback in a set of bar-built estuaries along the central California coast. In most years, heavy rains induce water flow strong enough to break through isolating sand bars, connecting streams to the ocean. New sand bars typically re-form within a few weeks or months, thereby re-isolating populations within the estuaries. These breaching events cause severe and often extremely rapid changes in abiotic and biotic conditions, including shifts in predator abundance. We investigated whether this strong temporal environmental variation can maintain within-population variation while eroding adaptive divergence among populations that would be caused by spatial variation in selection. We used neutral genetic markers to explore population structure and then analysed how stickleback armor traits, the associated genes Eda and Pitx1 and elemental composition (%P) varies within and among populations. Despite strong gene flow, we detected evidence for divergence in stickleback defensive traits and Eda genotypes associated with predation regime. However, this among-population variation was lower than that observed among other stickleback populations exposed to divergent predator regimes. In addition, within-population variation was very high as compared to populations from environmentally stable locations. Elemental composition was strongly associated with armor traits, Eda genotype and the presence of predators, thus suggesting that spatiotemporal variation in armor traits generates corresponding variation in elemental phenotypes. We conclude that gene flow, and especially temporal environmental variation, can maintain high levels of within-population variation while reducing, but not eliminating, among-population variation driven by spatial environmental variation.

  • 29. Pereyra, R. T.
    et al.
    Huenchunir, C.
    Johansson, D.
    Forslund, Helena
    Stockholm University, Faculty of Science, Department of Botany.
    Kautsky, Lena
    Stockholm University, Faculty of Science, Department of Botany.
    Jonsson, P. R.
    Johannesson, K.
    Parallel speciation or long-distance dispersal?: Lessons from seaweeds (Fucus) in the Baltic Sea2013In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 26, no 8, p. 1727-1737Article in journal (Refereed)
    Abstract [en]

    Parallel evolution has been invoked as a forceful mechanism of ecotype and species formation in many animal taxa. However, parallelism may be difficult to separate from recently monophyletically diverged species that are likely to show complex genetic relationships as a result of considerable shared ancestral variation and secondary hybridization in local areas. Thus, species' degrees of reproductive isolation, barriers to dispersal and, in particular, limited capacities for long-distance dispersal will affect demographical structures underlying mechanisms of divergent evolution. Here, we used nine microsatellite DNA markers to study intra- and interspecific genetic diversity of two recently diverged species of brown macroalgae, Fucus radicans (L. Bergstrom & L. Kautsky) and F.vesiculosus (Linnaeus), in the Baltic Sea. We further performed biophysical modelling to identify likely connectivity patterns influencing the species' genetic structures. For each species, we found intraspecific contrasting patterns of clonality incidence and population structure. In addition, strong genetic differentiation between the two species within each locality supported the existence of two distinct evolutionary lineages (F-ST=0.15-0.41). However, overall genetic clustering analyses across both species' populations revealed that all populations from one region (Estonia) were more genetically similar to each other than to their own taxon from the other two regions (Sweden and Finland). Our data support a hypothesis of parallel speciation. Alternatively, Estonia may be the ancestral source of both species, but is presently isolated by oceanographic barriers to dispersal. Thus, a limited gene flow in combination with genetic drift could have shaped the seemingly parallel structure.

  • 30. Reber, A
    et al.
    Purcell, J
    Buechel, S D
    Buri, P
    Chapuisat, M
    The expression and impact of antifungal grooming in ants.2011In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 24, no 5, p. 954-64Article in journal (Refereed)
    Abstract [en]

    Parasites can cause extensive damage to animal societies in which many related individuals frequently interact. In response, social animals have evolved diverse individual and collective defences. Here, we measured the expression and efficiency of self-grooming and allo-grooming when workers of the ant Formica selysi were contaminated with spores of the fungal entomopathogen Metarhizium anisopliae. The amount of self-grooming increased in the presence of fungal spores, which shows that the ants are able to detect the risk of infection. In contrast, the amount of allo-grooming did not depend on fungal contamination. Workers groomed all nestmate workers that were re-introduced into their groups. The amount of allo-grooming towards noncontaminated individuals was higher when the group had been previously exposed to the pathogen. Allo-grooming decreased the number of fungal spores on the surface of contaminated workers, but did not prevent infection in the conditions tested (high dose of spores and late allo-grooming). The rate of disease transmission to groomers and other nestmates was extremely low. The systematic allo-grooming of all individuals returning to the colony, be they contaminated or not, is probably a simple but robust prophylactic defence preventing the spread of fungal diseases in insect societies.

  • 31. Ridley, J.
    et al.
    Kolm, Niclas
    Uppsala universitet, Institutionen för ekologi och evolution.
    Freckleton, R.P.
    Gage, M.J.
    An unexpected influence of widely used significance thresholds on the distribution of reported P-values2007In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 20, no 3, p. 1082-1089Article in journal (Refereed)
    Abstract [en]

    We consider the problematic relationship between publication success and statistical significance in the light of analyses in which we examine the distribution of published probability (P) values across the statistical `significance' range, below the 5% probability threshold. P-values are often judged according to whether they lie beneath traditionally accepted thresholds (< 0.05, < 0.01, < 0.001, < 0.0001); we examine how these thresholds influence the distribution of reported absolute P-values in published scientific papers, the majority in biological sciences. We collected published P-values from three leading journals, and summarized their distribution using the frequencies falling across and within these four threshold values between 0.05 and 0. These published frequencies were then fitted to three complementary null models which allowed us to predict the expected proportions of P-values in the top and bottom half of each inter-threshold interval (i.e. those lying below, as opposed to above, each P-value threshold). Statistical comparison of these predicted proportions, against those actually observed, provides the first empirical evidence for a remarkable excess of probability values being cited on, or just below, each threshold relative to the smoothed theoretical distributions. The pattern is consistent across thresholds and journals, and for whichever theoretical approach used to generate our expected proportions. We discuss this novel finding and its implications for solving the problems of publication bias and selective reporting in evolutionary biology.

  • 32.
    Stålhandske, Sandra
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Posledovich, Diana
    Stockholm University, Faculty of Science, Department of Zoology.
    Leimar, Olof
    Stockholm University, Faculty of Science, Department of Zoology.
    Variation in two phases of post-winter development of a butterfly2014In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 27, no 12, p. 2644-2653Article in journal (Refereed)
    Abstract [en]

    The temporal aspects of life cycle characteristics, such as diapause development, are under strong selection in seasonal environments. Fine-tuning of the life cycle may be particularly important to match the phenology of potential mates and resources as well as for optimizing abiotic conditions at eclosion. Here, we experimentally study the spring phenology of the orange tip butterfly, Anthocharis cardamines, by analysing post-winter pupal development in three populations along a latitudinal cline in each of Sweden and the United Kingdom. These countries differ substantially in their seasonal temperature profile. By repeatedly recording pupal weights, we established that post-winter development has two separate phases, with a more rapid weight loss in the second phase than in the first, likely corresponding to a ramping up of the rate of development. Variation in the duration of the first phase contributed more strongly than the second phase to the differences in phenology between the localities and sexes. We found that insects from Sweden had a faster overall rate of development than those from the United Kingdom, which is consistent with countergradient variation, as Sweden is colder during the spring than the United Kingdom. Similar trends were not observed at the within-country scale, however. A cogradient pattern was found within Sweden, with populations from the north developing more slowly, and there was no clear latitudinal trend within the United Kingdom. In all localities, males developed faster than females. Our results point to the importance of variation in the progression of post-winter development for spring phenology.

  • 33. Tsuboi, M.
    et al.
    Lim, A. C. O.
    Ooi, B. L.
    Yip, M. Y.
    Chong, V. C.
    Ahnesjö, I.
    Kolm, Niclas
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Brain size evolution in pipefishes and seahorses: the role of feeding ecology, life history and sexual selection2017In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 30, no 1, p. 150-160Article in journal (Refereed)
    Abstract [en]

    Brain size varies greatly at all taxonomic levels. Feeding ecology, life history and sexual selection have been proposed as key components in generating contemporary diversity in brain size across vertebrates. Analyses of brain size evolution have, however, been limited to lineages where males predominantly compete for mating and females choose mates. Here, we present the first original data set of brain sizes in pipefishes and seahorses (Syngnathidae) a group in which intense female mating competition occurs in many species. After controlling for the effect of shared ancestry and overall body size, brain size was positively correlated with relative snout length. Moreover, we found that females, on average, had 4.3% heavier brains than males and that polyandrous species demonstrated more pronounced (11.7%) female-biased brain size dimorphism. Our results suggest that adaptations for feeding on mobile prey items and sexual selection in females are important factors in brain size evolution of pipefishes and seahorses. Most importantly, our study supports the idea that sexual selection plays a major role in brain size evolution, regardless of on which sex sexual selection acts stronger.

  • 34.
    Vanhoenacker, Didrik
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Toräng, P.
    Ågren, J.
    Ehrlen, Johan
    Stockholm University, Faculty of Science, Department of Botany.
    Morph-specific selection on floral traits in a polymorphic plant2010In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 23, no 6, p. 1251-1260Article in journal (Refereed)
    Abstract [en]

    Correlations between phenotypic traits are common in many organisms, but the relative importance of nonadaptive mechanisms and selection for the evolution and maintenance of such correlations are poorly understood. In polymorphic species, morphs may evolve quantitative differences in additional characters as a result of morph-specific selection. The perennial rosette herb Primula farinosa is polymorphic for scape length. The short-scaped morph is less damaged by grazers and seed predators but is more strongly pollen limited than the long-scaped morph. We examined whether morph-specific differences in biotic interactions are associated with differences in selection on two other traits affecting floral display (number of flowers and petal size) and on one trait likely to affect pollination efficiency (corolla tube width) in three P. farinosa populations. Differences in selection between morphs were detected in one population. In this population, selection for more flowers and larger petals was stronger in the short-scaped than in the long-scaped morph, and although there was selection for narrower corolla tubes in the short-scaped morph, no statistically significant selection on corolla tube width could be detected in the long-scaped morph. In the study populations, the short-scaped morph produced more and larger flowers and wider corolla tubes. Current morph-specific selection was thus only partly consistent with trait differences between morphs. The results provide evidence of morph-specific selection on traits associated with floral display and pollination efficiency, respectively.

  • 35.
    Woronik, Alyssa
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Wheat, Christopher W.
    Stockholm University, Faculty of Science, Department of Zoology.
    Advances in finding Alba: the locus affecting life history and color polymorphism in a Colias butterfly2017In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 30, no 1, p. 26-39Article in journal (Refereed)
    Abstract [en]

    Although alternative life-history strategies exist within many populations, very little is known about their genetic basis and mechanistic insight into these traits could greatly advance the understanding of eco-evolutionary dynamics. Many species of butterfly within the genus Colias exhibit a sex-limited wing colour polymorphism, called Alba, which is correlated with an alternative life-history strategy. Here, we have taken the first steps in localizing the region carrying Alba in Colias croceus, a species with no genomic resources, by generating whole genome sequence of a single Alba mother and two sequencing pools, one for her Alba and another for her orange, offspring. These data were used in a bulk-segregant analysis wherein SNPs fulfilling the Mendelian inheritance expectations of Alba were identified. Then, using the conserved synteny in Lepidoptera, the Alba locus was assigned to chromosome 15 in Bombyx mori. We then identified candidate regions within the chromosome by investigating the distribution of Alba SNPs along the chromosome and the difference in nucleotide diversity in exons between the two pools. A region spanning similar to 5.7 Mbp at the 50 end of the chromosome was identified as likely to contain the Alba locus. These insights set the stage for more detailed genomic scans and mapping of the Alba phenotype, and demonstrate an efficient use of genomic resources in a novel species.

1 - 35 of 35
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