| 1. |
- Abbott, Jessica, et al.
(författare)
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Ontogeny of sexual dimorphism and phenotypic integration in heritable morphs
- 2008
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; 22:1, s. 103-121
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Tidskriftsartikel (refereegranskat)abstract
- In this study we investigated the developmental basis of adult phenotypes in a non-model organism, a polymorphic damselfly (Ischnura elegans) with three female colour morphs. This polymorphic species presents an ideal opportunity to study intraspecific variation in growth trajectories, morphological variation in size and shape during the course of ontogeny, and to relate these juvenile differences to the phenotypic differences of the discrete adult phenotypes; the two sexes and the three female morphs. We raised larvae of different families in individual enclosures in the laboratory, and traced morphological changes during the course of ontogeny. We used principal components analysis to examine the effects of Sex, Maternal morph, and Own morph on body size and body shape. We also investigated the larval fitness consequences of variation in size and shape by relating these factors to emergence success. Females grew faster than males and were larger as adults, and there was sexual dimorphism in body shape in both larval and adult stages. There were also significant effects of both maternal morph and own morph on growth rate and body shape in the larval stage. There were significant differences in body shape, but not body size, between the adult female morphs, indicating phenotypic integration between colour, melanin patterning, and body shape. Individuals that emerged successfully grew faster and had different body shape in the larval stage, indicating internal (non-ecological) selection on larval morphology. Overall, morphological differences between individuals at the larval stage carried over to the adult stage. Thus, selection in the larval stage can potentially result in correlated responses in adult phenotypes and vice versa.
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| 2. |
- Arct, Aneta, et al.
(författare)
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Heterozygosity-fitness correlations in blue tit nestlings (Cyanistis caeruleus) under contrasting rearing conditions
- 2017
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Ingår i: Evolutionary Ecology. - : SPRINGER. - 0269-7653 .- 1573-8477. ; 31:5, s. 803-814
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the relation between genetic variation and fitness remains a key question in evolutionary biology. Although heterozygosity has been reported to correlate with many fitness-related traits, the strength of the heterozygosity-fitness correlations (HFCs) is usually weak and it is still difficult to assess the generality of these associations in natural populations. It has been suggested that HFCs may become meaningful only under particular environmental conditions. Moreover, existing evidence suggests that HFCs may also differ between sexes. The aim of this study was to investigate correlations between heterozygosity in neutral markers (microsatellites) and fitness-related traits in a natural population of blue tits (Cyanistes caeruleus). Additionally, we tested whether sex and environmental conditions may influence the magnitude and direction of HFCs. We found a positive relationship between heterozygosity and body mass of 14 days post-hatching nestlings, but only among females. Our results suggest that the correlation between heterozygosity and nestling body mass observed among female offspring could be attributed to within-brood effects. We failed to find any evidence that environmental conditions as simulated by brood size manipulation affect HFCs.
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| 3. |
- Berdan, Emma L, 1983, et al.
(författare)
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Inversion frequencies and phenotypic effects are modulated by the environment: insights from a reciprocal transplant study in Coelopa frigida
- 2018
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 32:6, s. 683-698
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Tidskriftsartikel (refereegranskat)abstract
- Understanding how environmental variation drives phenotypic diversification within species is a major objective in evolutionary biology. The seaweed fly Coelopa frigida provides an excellent model for the study of genetically driven phenotypes because it carries an / inversion polymorphism that affects body size. Coelopa frigida inhabits highly variable beds of decomposing seaweed on the coast in Scandinavia thus providing a suitable test ground to investigate the genetic effects of substrate on both the frequency of the inversion (directional selection) and on the phenotype (genotypexenvironment effects). Here we use a reciprocal transplant experiment to test the effect of the / inversion on body size traits and development time across four suitable natural breeding substrates from the clinal distribution. We show that while development time is unaffected by GxE effects, both the frequency of the inversion and the relative phenotypic effects of the inversion on body size differ between populationxsubstrate combinations. This indicates that the environment modulates the fitness as well as the phenotypic effects of the inversion karyotypes. It further suggests that the inversion may have accumulated qualitatively different mutations in different populations that interact with the environment. Together our results are consistent with the idea that the inversion in C. frigida likely evolves via a combination of local mutation, GxE effects, and differential fitness of inversion karyotypes in heterogeneous environments.
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| 4. |
- Berger, David, et al.
(författare)
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What keeps insects small? - Size dependent predation on two species of butterfly larvae
- 2006
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 20:6, s. 575-589
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Tidskriftsartikel (refereegranskat)abstract
- Insect size usually increases greatly in the latter stages of development, while reproductive value increases strongly with adult size. Mechanisms that can balance the benefits associated with increased growth are poorly understood, raising the question: what keeps insects from becoming larger? If predation risk was to increase with juvenile size, it would make an extension of development very risky, favouring smaller final sizes. But field measures of juvenile mortality seldom show any general patterns of size dependence. We here therefore try to estimate a mechanistic relationship between juvenile size and predation risk by exposing the larvae of two closely related butterflies to a generalist invertebrate predator in a laboratory experiment. Predation risk increased with larval size but was not affected by the species-specific growth rate differences. These results indicate that predation risk may increase with the size of the juvenile even when predators are relatively small. By basing a model simulation on our data we also show that size dependent predation of the kind found in this study has potential to stabilise selection on body size in these species. Thus, these findings suggest that more detailed studies of the size dependence of predation risk on juvenile instars will increase the understanding of what it is that keeps insects small.
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| 5. |
- Berglund, Anders
(författare)
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To change or not to change sex : A comparison between two Ophryotrocha species (Polychaeta)
- 1991
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Ingår i: Evolutionary Ecology. - 0269-7653 .- 1573-8477. ; 5:2, s. 128-135
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Tidskriftsartikel (refereegranskat)abstract
- The polychaete Ophryotrocha puerilis is a male-to-female sex-changer, whereas O. labronica has separate sexes throughout life. In other respects the two species are remarkably similar: they occur in the same habitat, they look the same, they eat the same things, and in some O. labronica populations sex-changers can actually be found. The size-advantage hypothesis predicts that in O. puerilis males should not benefit reproductively from a size increase as much as males in O. labronica: hence O. puerilis but not O. labronica males should change to the female sex at a certain size. I experimentally compared reproductive success at different body sizes between the two species. In isolated male-female pairs reproductive rate increased significantly with female body size but not with male body size, and this pattern was the same in both species. Hence male fecundity per se cannot account for the difference in reproductive type between the two species. In other experiments I investigated if larger males gained access to more females because they were superior competitors for mates or were preferred by females, compared to small males. In O. puerilis the combined effect of these two factors conferred no size advantage to the males, whereas in O. labronica larger males acquired more females than did smaller males. Hence interactions among males and females, in accordance with the size-advantage hypothesis, can explain why sex change is maintained in O. puerilis, and why separate sexes are maintained in O. labronica.
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| 6. |
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| 7. |
- Boalt, Elin, et al.
(författare)
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The association among herbivory tolerance, ploidy level, and herbivory pressure in cardamine pratensis
- 2010
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 24:5, s. 1101-1113
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Tidskriftsartikel (refereegranskat)abstract
- We tested whether differences in ploidy level and previous exposure to herbivory can affect plant tolerance to herbivory. We conducted a common garden experiment with 12 populations of two ploidy levels of the perennial herb Cardamine pratensis (five populations of tetraploid ssp. pratensis and seven populations of octoploid ssp. paludosa). Earlier studies have shown that attack rates by the main herbivore, the orange tip butterfly Anthocharis cardamines, are lower in populations of octoploids than in populations of tetraploids, and vary among populations. In the common garden experiment, a combination of natural and artificial damage significantly reduced seed and flower production. We measured tolerance based on four plant-performance metrics: survival, growth, seed production and clonal reproduction. For three of these measurements, tolerance of damage did not differ between ploidy levels. For clonal reproduction, the octoploids had a higher tolerance than the tetraploids, although they experience lower herbivore attack rates in natural populations. Populations from sites with high levels of herbivory had higher tolerance, measured by seed production, than populations with low levels of herbivory. We did not detect any significant costs of tolerance. We conclude that high intensity of herbivory has selected for high tolerance measured by seed production in C. pratensis.
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| 8. |
- Brodin, Anders, et al.
(författare)
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Hybrid zone maintenance by non-adaptive mate choice
- 2009
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; 23:1, s. 17-29
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Tidskriftsartikel (refereegranskat)abstract
- In a spatial simulation we show that formation of a stable, narrow hybrid zone requires no selection, only that individuals can recognize their own population type since this is a prerequisite for assortative mating. The European crow occurs in two species/subspecies that meet in a long hybrid zone, the black carrion crow Corvus corone and the grey and black hooded crow C. cornix. In a previous study (Brodin A, Haas F (2006) Anim Behav 72:139) we mimicked sexual imprinting in nestling crows with artificial neural networks, using a learning process that simulates proximate retina perception. The networks were trained on 700 images to recognize either carrion, hooded or hybrid phenotypes as their own. After training the networks were exposed to 300 new, unfamiliar pictures of crows. The networks that had been trained on pure subspecies then showed strong preference for their own type. Networks trained on hybrid crows showed weaker preference for their own type. Assuming that these preferences will determine mate choice preferences we have combined them with empirical data on dispersal of young crows to investigate what kind of geographical distribution pattern this would create. We then assume that the two subspecies meet and hybridize along a straight border. In only 60 generations a stable, narrow hybrid zone that resembles the real hybrid zone was formed. This zone remained stable over time. With minor adjustments of parameters the results would not only fit the width but also the shapes of the clines in the field.
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| 9. |
- Broggi, Juli, et al.
(författare)
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Idle slow as you grow old: longitudinal age-related metabolic decline in a wild passerine
- 2010
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; 24:1, s. 177-184
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Tidskriftsartikel (refereegranskat)abstract
- Physiological changes due to aging are intensively studied as they have far-reaching implications for the mechanistic and evolutionary theories of senescence. In this respect, metabolic rate has been suggested to play a role for the deterioration and damage of cells and tissues with age, partly due to the generation of reactive oxygen species. To mitigate such damage, individuals can be predicted to reduce basal metabolic rate (BMR) with age. This prediction has been verified in humans and some laboratory animals but never in wild animal populations. We analyzed the change in BMR within individuals across years in two wild populations of great tit (Parus major) differing in BMR. Great tits, living under stressful conditions towards the northern limit of their distribution, decreased their BMR as they aged whereas no such decrease was found in a southern population. Thus, we found a clear decline only in the population with the highest BMR levels. This study provides the first evidence of an age-related decline in BMR for a wild homeotherm.
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| 10. |
- Chakarov, Nayden, et al.
(författare)
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Immune responses link parasite genetic diversity, prevalence and plumage morphs in common buzzards
- 2017
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 31:1, s. 51-62
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Tidskriftsartikel (refereegranskat)abstract
- The evolution and maintenance of conspicuous phenotypic polymorphisms has challenged evolutionary ecologists for centuries. Polymorphisms in pleiotropic cascades or genetic linkage may lead to correlations of life history traits such as immunity, parasite infection levels, pigmentation and lifetime reproductive success. The common buzzard Buteo buteo is a bird of prey occurring in several plumage morphs, which differ in pigmentation and in the prevalence, infection intensity and clone composition of their most common blood parasite, as well as in ectoparasite infestation levels. Buzzard morphs are heritable and exhibit a heterozygote advantage where intermediates have higher lifetime reproductive success (LRS). We explored the hypothesis that the differences in pigmentation also correspond to differences in immunity. We hence compared an inducible adaptive and an innate constitutive immune response between the buzzard plumage morphs. The increase of specific anti-tetanus antibodies after vaccination was explained by the morph of the nestling’s mother and was highest in offspring of intermediate mothers. Additionally, nestlings with higher humoral response were less infected with blood parasites and, if infected, harboured a lower genetic diversity of these parasites. The phytohaemagglutinin-induced skin swelling, a complex of cellular inflammatory responses, was lowest in intermediate nestlings. The higher LRS of intermediate buzzards suggests that the cellular immunity is an inferior fitness determinant compared to humoral immunity. The strength of immune responses was not linear along the melanisation gradient, indicating that there is most likely no simple genetic correlation between immune responses and plumage morphs.
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