| 1. |
- Ceplitis, Helene
(författare)
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Evolutionary dynamics of mitochondrial plasmids in natural populations of Silene vulgaris
- 2002
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Ingår i: Evolution. - : Wiley. - 1558-5646 .- 0014-3820. ; 56:8, s. 1592-1598
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Tidskriftsartikel (refereegranskat)abstract
- Although plasmid-like mitochondrial DNA molecules have been investigated in a number of cultivated plant species, knowledge about their occurrence and behavior in natural plant populations is scarce. In the bladder campion, Silene vulgaris, a common weed of northern Europe, mt-plasmids of three different sizes were detected in a survey of S. vulgaris populations in southern Sweden. Two of the three plasmids usually occurred together within individual plants and showed large variation in frequency between populations. From F-ST-estimates of plasmids, mitochondrial markers, and nuclear markers it was concluded that the plasmids are predominantly maternally inherited in their natural habitat, as observed in greenhouse experiments. The association between mt-plasmids and mitochondrial haplotype was strong, but not complete, in the natural material. These results indicate that the mt-plasmids of S. vulgaris have evolved toward almost strict maternal inheritance.
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| 2. |
- Ceplitis, Helene, et al.
(författare)
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Transmission rates and phenotypic effects of mitochondrial plasmids and cytotypes in Silene vulgaris
- 2002
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Ingår i: Evolution. - : Wiley. - 1558-5646 .- 0014-3820. ; 56:8, s. 1586-1591
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the transmission properties and the phenotypic effects of two mitochondrial plasmids in a population of the bladder campion, Silene vulgaris. In reciprocal crosses between plasmid-free and plasmid-carrying plants, no cases of paternal transmission or loss during maternal transmission were recorded. Neither was any transmission via pollen observed when plasmid-carrying plants of S, vulgaris were used to pollinate plasmid-free plants of the closely related species Silene uniflora. The phenotypic effects of the plasmids were investigated by comparing germination rate, early growth properties, and the gender of plants grown from seeds with and without plasmids. A significant association between plasmid status, on the one hand, and germination propensity and offspring gender, on the other, was found. However, because all plants carrying plasmids in the experiment shared the same cytoplasmic background, the exact contribution of the plasmid to the phenotypic variation could not be determined. Taken together, our experiments show that in S. vulgaris the mt-plasmids are not currently involved in any strong genetic conflict, but that they evolve in close association with their mitochondrial host.
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| 3. |
- Hargeby, Anders, et al.
(författare)
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Habitat-specific pigmentation in a freshwater isopod : Adaptive evolution over a small spatiotemporal scale
- 2004
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 58:1, s. 81-94
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Tidskriftsartikel (refereegranskat)abstract
- Pigmentation in the freshwater isopod Asellus aquaticus (Crustacea) differed between habitats in two Swedish lakes. In both lakes, isopods had lighter pigmentation in stands of submerged vegetation, consisting of stoneworts (Chara spp.), than in nearby stands of reed (Phragmites australis). Experimental crossings of light and dark isopods in a common environment showed that pigmentation had a genetic basis and that genetic variance was additive. Environmental effects of diet or chromatophore adjustment to the background had minor influence on pigmentation, as shown by laboratory rearing of isopods on stonewort or reed substrates, as well as analyses of stable isotope ratios for isopods collected in the field. In both study lakes, the average phenotype became lighter with time (across generations) in recently established stonewort stands. Taken together, these results indicate that altered phenotype pigmentation result from evolutionary responses to local differences in natural selection. Based on the assumption of two generations per year, the evolutionary rate of change in pigmentationwas 0.08 standard deviations per generation (haldanes) over 20 generations in one lake and 0.22 haldanes over two generations in the other lake. This genetic change occurred during an episode of population growth in a novel habitat, a situation known to promote adaptive evolution. In addition, stonewort stands constitute large and persistent patches, characteristics that tend to preserve local adaptations produced by natural selection. Results from studies on selective forces behind the adaptivedivergence suggest that selective predation from visually oriented predators is a possible selective agent. We found no indications of phenotype-specificmovements between habitats. Mating within stonewort stands was random with respect to pigmentation, but on a whole-lake scale it is likely that mating is assortative, as a result of local differences in phenotype distribution.
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| 4. |
- Richardson, David, et al.
(författare)
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Direct benefits and the evolution of female-biased cooperative breeding in Seychelles warblers
- 2002
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Ingår i: Evolution. - : Wiley. - 1558-5646 .- 0014-3820. ; 56:11, s. 2313-2321
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Tidskriftsartikel (refereegranskat)abstract
- Inclusive fitness benefits have been suggested to be a major selective force behind the evolution of cooperative breeding. We investigated the fitness benefits selecting for cooperative breeding in the Seychelles warbler, Acroccphalus sechellensis. A microsatellite-based genotyping method was used to determine the relatedness of subordinates to group offspring in an isolated population of Seychelles warblers. The indirect and direct breeding benefits accruing to individual subordinates were then calculated for every successful breeding event over a three-year period. We show that female subordinates frequently gained parentage and that this, combined with high levels of extragroup paternity, resulted in low levels of relatedness between subordinates and nondescendent offspring within a territory. Direct breeding benefits were found to be significantly higher than indirect kin benefits for both female and male subordinates. As predicted, female subordinates gained significantly more direct breeding opportunities and therefore higher inclusive fitness benefits by being a subordinate within a group than did males. This may explain why most subordinates in the Seychelles warbler are female.
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| 5. |
- Richardson, David, et al.
(författare)
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Inbreeding in the seychelles warbler: Environment-dependent maternal effects
- 2004
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Ingår i: Evolution. - : Wiley. - 1558-5646 .- 0014-3820. ; 58:9, s. 2037-2048
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Tidskriftsartikel (refereegranskat)abstract
- The deleterious effects of inbreeding can be substantial in wild populations and mechanisms to avoid such matings have evolved in many organisms. In situations where social mate choice is restricted, extrapair paternity may be a strategy used by females to avoid inbreeding and increase offspring heterozygosity. In the cooperatively breeding Seychelles warbler, Acrocephalus sechellensis, neither social nor extrapair mate choice was used to avoid inbreeding facultatively, and close inbreeding occurred in approximately 5% of matings. However, a higher frequency of extra-group paternity may be selected for in female subordinates because this did reduce the frequency of mating between close relatives. Inbreeding resulted in reduced individual heterozygosity, which, against expectation, had an almost significant (P = 0.052). positive effect on survival. Conversely, low heterozygosity in the genetic mother was linked to reduced offspring survival, and the magnitude of this intergenerational inbreeding depression effect was environment-dependent. Because we controlled for genetic effects and most environmental effects (through the experimental cross-fostering of nestlings), we conclude that the reduced survival was a result of maternal effects. Our results show that inbreeding can have complicated effects even within a genetic bottlenecked population where the "purging'' of recessive alleles is expected to reduce the effects of inbreeding depression.
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| 6. |
- Bensch, Staffan, et al.
(författare)
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Linkage between nuclear and mitochondrial DNA sequences in avian malaria parasites: Multiple cases of cryptic speciation?
- 2004
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Ingår i: Evolution. - : Wiley. - 1558-5646 .- 0014-3820. ; 58:7, s. 1617-1621
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Tidskriftsartikel (refereegranskat)abstract
- Analyses of mitochondrial cytochrome b diversity among avian blood parasites of the genera Haemoproteus and Plasmodium suggest that there might be as many lineages of parasites as there are species of birds. This is in sharp contrast to the approximately 175 parasite species described by traditional methods based on morphology using light microscopy. Until now it has not been clear to what extent parasite mitochondrial DNA lineage diversity reflects intra- or interspecific variation. We have sequenced part of a fast-evolving nuclear gene, dihydrofolate reductase-thymidylate synthase (DHFR-TS), and demonstrate that most of the parasite mitochondrial DNA lineages are associated with unique gene copies at this locus. Although these parasite lineages sometimes coexist in the same host individual, they apparently do not recombine and could therefore be considered as functionally distinct evolutionary entities, with independent evolutionary potential. Studies examining parasite virulence and host immune systems must consider this remarkable diversity of avian malaria parasites.
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| 7. |
- Forsman, Anders, et al.
(författare)
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Calling is an honest indicator of paternal genetic quality in male poison frogs
- 2006
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 60:10, s. 2148-2157
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Tidskriftsartikel (refereegranskat)abstract
- Several competing hypotheses have been put forward to explain why females of many species mate preferentially with males possessing the most conspicuous signals (e.g., ornaments, displays, or songs). We performed a laboratory experiment using two species of poison frogs, Dendrobates leucomelas and Epipedobates tricolor, to test the hypothesis that male calling performance is an honest indicator of parental quality. Our analyses are based on data from behavioral observations of mating activities of captive-reared individuals (and their offspring) that were housed in terraria for four consecutive breeding seasons. Male mating success increased with male calling rate and chirp duration in both species, suggesting that females preferred males with more elaborate calls. Because calling performance improved with age in D. leucomelas, female poison frogs that prefer males with more elaborate calls in the wild may end up mating with older males that have already proven their ability to survive. Females that mated with good callers obtained higher quality offspring. Eggs fertilized by males with high calling rates and long chirp durations had higher hatching success and produced tadpoles that were more likely to metamorphose into surviving frogs. As a consequence, females that mated with males with high calling performance obtained more surviving offspring per egg, compared to females that mated with poor callers. Collectively, our findings comply with the notion that female poison frogs prefer to mate with good callers because calling performance is a reliable predictor of offspring quality. The possible influence of maternal allocation and reasons for the strong effect size compared to previous studies are discussed.
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| 8. |
- Friberg, Urban, et al.
(författare)
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Assessing the potential for an ongoing arms race within and between the sexes : selection and heritable variation
- 2005
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Ingår i: Evolution. - Lawrence, Kans. : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 59:7, s. 1540-1551
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Tidskriftsartikel (refereegranskat)abstract
- In promiscuous species, sexual selection generates two opposing male traits: offense (acquiring new mates and supplanting stored sperm) and defense (enforcing fidelity on one's mates and preventing sperm displacement when this fails). Coevolution between these traits requires both additive genetic variation and associated natural selection. Previous work with Drosophila melanogaster found autosomal genetic variation for these traits among inbred lines from a mixture of populations, but only nonheritable genetic variation was found within a single outbred population. These results do not support ongoing antagonistic coevolution between offense and defense, nor between either of these male traits and female reproductive characters. Here we use a new method (hemiclonal analysis) to study genomewide genetic variation in a large outbred laboratory population of D. melanogaster. Hemiclonal analysis estimates the additive genetic variation among random, genomewide haplotypes taken from a large, outbred, locally adapted laboratory population and determines the direction of the selection gradient on this variation. In contrast to earlier studies, we found low but biologically significant heritable variation for defensive and offensive offspring production as well as all their components (P1, fidelity, P2, and remating). Genetic correlations between these traits were substantially different from those reported for inbred lines. A positive genetic correlation was found between defense and offense, demonstrating that some shared genes influence both traits. In addition to this common variation, evidence for unique genetic variation for each trait was also found, supporting an ongoing coevolutionary arms race between defense and offense. Reproductive conflict between males can strongly influence female fitness. Correspondingly, we found genetic variation in both defense and offense that affected female fitness. No evidence was found for intersexual conflict in the context of male defense, but we found substantial intersexual conflict in the context of male offensive sperm competitive ability. These results indicate that conflict between competing males also promotes an associated arms race between the sexes.
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| 9. |
- Hagman, Mattias, et al.
(författare)
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Correlated evolution of conspicuous colouration and body size in the poison frog family Dendrobatidae
- 2003
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 57:12, s. 2904-2910
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Tidskriftsartikel (refereegranskat)abstract
- Conspicuous coloration is often used in combination with chemical defenses to deter predators from attacking. Experimental studies have shown that the avoidance inducing effect of conspicuous prey coloration increases with increasing size of pattern elements and with increasing body size. Here we use a comparative approach to test the prediction from these findings, namely that conspicuous coloration will evolve in tandem with body size. In our analysis, we use a previously published mitochondrial DNA-based phylogeny and comparative analysis of independent contrasts to examine if evolutionary shifts in color pattern have been associated with evolutionary changes in body size in aposematic poison frogs (Anura: Dendrobatidae). Information on body size (snout to vent length) and coloration were obtained from the literature. Two different measures of conspicuousness were used, one based on rankings by human observers and the other based on computer analysis of digitized photographs. The results from comparative analyses using either measure of coloration indicated that avoidance inducing coloration and body size have evolved in concert in poison frogs. Results from reconstruction of character change further indicate that the correlated evolution of size and coloration has involved changes in both directions within each of the different clades of the phylogenetic tree. This finding is consistent with the hypothesis that selection imposed by visually guided predators has promoted the evolution of larger body size in species with conspicuous coloration, or enhanced evolution of conspicuous coloration in larger species.
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| 10. |
- Hollander, Johan, 1969, et al.
(författare)
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Evolution of adaptation through allometric shifts in a marine snail
- 2006
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 60:12, s. 2490-2497
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Tidskriftsartikel (refereegranskat)abstract
- Variation in ontogenetic development among individuals may be a major contributor to morphological variation within species. Evolution of different growth trajectories might, for example, evolve as a response to varying ecological contexts of individuals living in different environments, or by life-stage or gender differences. The intertidal periwinkle Littorina saxatilis is strongly polymorphic in shell shape. We compared ontogenetic trajectories between life stages, local populations, and sexes to understand how different morphological end points are reached during ontogeny and what might cause these differences. Applying landmark-based geometric morphometrics, we captured shell shape variation for four Swedish populations of this species. We also derived a method to visualize ontogenetic trajectories described by the relationship of size to the multivariate shape space. We found that growth trajectories differed between individuals living in different habitats, as well as between sexes and maturity stages. Males living on rocky cliffs grew isometrically throughout life, whereas females from the same habitat switched from isometric growth as juveniles to allometric growth as adults. In contrast, males and females living on boulders grew allometrically as juveniles but changed to isometric growth at sexual maturity. Thus, in this species, ontogenetic growth seems influenced by habitat-associated selection as well as by gender and age-specific selection. These differing selection regimes result in ontogenetic shifts in allometry in three of the four groups examined.
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| 11. |
- Lehtilä, Kari
(författare)
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Precision of herbivore tolerance experiments with imposed and natural damage
- 2003
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Ingår i: Evolution. - : Wiley-Blackwell. - 0014-3820 .- 1558-5646. ; 57:3, s. 677-680
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Tidskriftsartikel (refereegranskat)abstract
- Tiffin and Inouye (2000) discussed the use of natural and imposed (controlled) damage in experiments of herbivore tolerance. They constructed a statistical model of the effect of herbivory on plant fitness, including damage level and an environmental factor as the independent factors, in which tolerance is defined as a slope of the regression line when damage level is regressed with plant fitness. They claim that while experiments with imposed damage are more accurate (i.e., they give a more correct estimate of tolerance), experiments with natural damage are more precise under a wide range of parameter values (i.e., tolerance estimates explain a larger part of variation in fitness). I show, however, that experiments with imposed damage are less precise only when an experimenter uses an experimental design that has weaker statistical power than in experiments with natural herbivory. The experimenter can nevertheless control the damage levels to optimize the experimental designs. For instance, when half of the experimental plants are left undamaged and the other half treated with maximal relevant damage level, experiments with imposed damage are almost always much more precise than experiments with natural damage.
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| 12. |
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| 13. |
- Fritz, Robert S., et al.
(författare)
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Fitness and genetic architecture of parent and hybrid willows in common gardens
- 2006
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Ingår i: Evolution. - : Society for the Study of Evolution. - 0014-3820 .- 1558-5646. ; 60:6, s. 1215-1227
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Tidskriftsartikel (refereegranskat)abstract
- Models of hybrid zone dynamics incorporate different patterns of hybrid fitness relative to parental species fitness. An important but understudied source of variation underlying these fitness differences is the environment. We investigated the performance of two willow species and their F1, F2, and backcross hybrids using a common‐garden experiment with six replicated gardens that differed in soil moisture. Aboveground biomass, catkin production, seed production per catkin, and seed germination rate were significantly different among genetic classes. For aboveground biomass and catkin production, hybrids generally had intermediate or inferior performance compared to parent species. Salix eriocephala had the highest performance for all performance measures, but in two gardens F1 plants had superior or equal performance for aboveground biomass and female catkin production. Salix eriocephala and backcrosses to S. eriocephala had the highest numbers of filled seeds per catkin and the highest estimates of total fitness in all gardens. Measures of filled seeds per catkin and germination rate tend to support the model of endogenous hybrid unfitness, and these two measures had major effects on estimates of total seed production per catkin. We also estimated how the two willow species differ genetically in these fitness measures using line cross analysis. We found a complex genetic architecture underlying the fitness differences between species that involved additive, dominance, and epistatic genetic effects for all fitness measures. The environment was important in the expression of these genetic differences, because the type of epistasis differed among the gardens for aboveground biomass and for female catkin production. These findings suggest that fine‐scale environmental variation can have a significant impact on hybrid fitness in hybrid zones where parents and hybrids are widely interspersed.
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| 14. |
- Maklakov, Alexei A, et al.
(författare)
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Within-population variation in cytoplasmic genes affects female life span and aging in Drosophila melanogaster
- 2006
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 60:10, s. 2081-2086
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that mitochondrial DNA (mtDNA) may play an important role in aging. Yet, few empirical studies have tested this hypothesis, partly because the degree of sequence polymorphism in mtDNA is assumed to be low. However, low sequence variation may not necessarily translate into low phenotypic variation. Here, we report an experiment that tests whether there is within-population variation in cytoplasmic genes for female longevity and senescence. To achieve this, we randomly selected 25 "mitochondrial founders" from a single, panmictic population of Drosophila melanogaster and used these founders to generate distinct "mt" lines in which we controlled for the nuclear background by successive backcrossing. Potential confounding effects of cytoplasmically transmitted bacteria were eliminated by tetracycline treatment. The mt lines were then assayed for differences in longevity, Gompertz intercept (frailty), and demographic rate of change in mortality with age (rate-of-senescence) in females. We found significant cytoplasmic effects on all three variables. This provides evidence that genetic variation in cytoplasmic genes, presumably mtDNA, contributes to variation in female mortality and aging.
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| 15. |
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| 16. |
- Albertsen, Elena, et al.
(författare)
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Using ecological context to interpret spatiotemporal variation in natural selection
- 2021
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 75:2, s. 294-309
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Tidskriftsartikel (refereegranskat)abstract
- Spatiotemporal variation in natural selection is expected, but difficult to estimate. Pollinator-mediated selection on floral traits provides a good system for understanding and linking variation in selection to differences in ecological context. We studied pollinator-mediated selection in five populations of Dalechampia scandens (Euphorbiaceae) in Costa Rica and Mexico. Using a nonlinear path-analytical approach, we assessed several functional components of selection, and linked variation in pollinator-mediated selection across time and space to variation in pollinator assemblages. After correcting for estimation error, we detected moderate variation in net selection on two out of four blossom traits. Both the opportunity for selection and the mean strength of selection decreased with increasing reliability of cross-pollination. Selection for pollinator attraction was consistently positive and stronger on advertisement than reward traits. Selection on traits affecting pollen transfer from the pollinator to the stigmas was strong only when cross-pollination was unreliable and there was a mismatch between pollinator and blossom size. These results illustrate how consideration of trait function and ecological context can facilitate both the detection and the causal understanding of spatiotemporal variation in natural selection.
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| 17. |
- Alger, Ingela, et al.
(författare)
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Does evolution lead to maximizing behavior?
- 2015
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Ingår i: Evolution. - : Wiley: 12 months. - 0014-3820. ; 69:7, s. 1858-1873
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Tidskriftsartikel (refereegranskat)abstract
- A long-standing question in biology and economics is whether individual organisms evolve to behave as if they were striving to maximize some goal function. We here formalize this “as if” question in a patch-structured population in which individuals obtain material payoffs from (perhaps very complex multimove) social interactions. These material payoffs determine personal fitness and, ultimately, invasion fitness. We ask whether individuals in uninvadable population states will appear to be maximizing conventional goal functions (with population-structure coefficients exogenous to the individual's behavior), when what is really being maximized is invasion fitness at the genetic level. We reach two broad conclusions. First, no simple and general individual-centered goal function emerges from the analysis. This stems from the fact that invasion fitness is a gene-centered multigenerational measure of evolutionary success. Second, when selection is weak, all multigenerational effects of selection can be summarized in a neutral type-distribution quantifying identity-by-descent between individuals within patches. Individuals then behave as if they were striving to maximize a weighted sum of material payoffs (own and others). At an uninvadable state it is as if individuals would freely choose their actions and play a Nash equilibrium of a game with a goal function that combines self-interest (own material payoff), group interest (group material payoff if everyone does the same), and local rivalry (material payoff differences).
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| 18. |
- Anderson, Bruce, et al.
(författare)
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Evolution and coexistence of pollination ecotypes in an African Gladiolus (Iridaceae)
- 2010
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 64:4, s. 960-972
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Tidskriftsartikel (refereegranskat)abstract
- Pollinator-mediated selection has been suggested as a key driver of speciation in plants. We examined the potential role of hawkmoth pollinators in driving allopatric divergence and maintaining sympatric coexistence of morphotypes in the African iris Gladiolus longicollis. Floral tube length in this species varies from 35 mm to 130 mm across its geographic range and reflects the prevailing tongue lengths of local hawkmoth assemblages. The distribution of floral tube lengths is bimodal with two relatively discrete categories—long (about 90 mm) or short (about 50 mm)—that match the bimodal distribution of hawkmoth tongue lengths in eastern South Africa. At a contact site between these two floral morphs, we found few individuals of intermediate length, suggesting limited gene flow between morphs despite their interfertility. A difference in flowering phenology appears to be the main isolating barrier between morphs at this site. Long- and short-tubed morphs differed markedly in the chemical composition of their floral fragrance, a trait that could be used as a cue for morph-specific foraging by hawkmoths. Positive directional selection on tube length was found to occur in both morphs.
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| 19. |
- Andersson, Malte, 1941
(författare)
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Social polyandry, parental investment, sexual selection, and evolution of reduced female gamete size
- 2004
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Ingår i: Evolution. - 0014-3820. ; 58:1, s. 24-34
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Tidskriftsartikel (refereegranskat)abstract
- Sexual selection in the form of sperm competition is a major explanation for small size of male gametes. Can sexual selection in polyandrous species with reversed sex roles also lead to reduced female gamete size? Comparative studies show that egg size in birds tends to decrease as a lineage evolves social polyandry. Here, a quantitative genetic model predicts that female scrambles over mates lead to evolution of reduced female gamete size. Increased female mating success drives the evolution of smaller eggs, which take less time to produce, until balanced by lowered offspring survival. Mean egg size is usually reduced and polyandry increased by increasing sex ratio (male bias) and maximum possible number of mates. Polyandry also increases with the asynchrony (variance) in female breeding start. Opportunity for sexual selection increases with the maximum number of mates but decreases with increasing sex ratio. It is well known that parental investment can affect sexual selection. The model suggests that the influence is mutual: owing to a coevolutionary feedback loop, sexual selection in females also shapes initial parental investment by reducing egg size. Feedback between sexual selection and parental investment may be common.
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| 20. |
- Antoniazza, Sylvain, et al.
(författare)
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Local adaptation maintains clinal variation in melanin-based coloration of European barn owls (Tyto alba).
- 2010
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 64:7, s. 1944-1954
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Tidskriftsartikel (refereegranskat)abstract
- Ecological parameters vary in space, and the resulting heterogeneity of selective forces can drive adaptive population divergence. Clinal variation represents a classical model to study the interplay of gene flow and selection in the dynamics of this local adaptation process. Although geographic variation in phenotypic traits in discrete populations could be remainders of past adaptation, maintenance of adaptive clinal variation requires recurrent selection. Clinal variation in genetically determined traits is generally attributed to adaptation of different genotypes to local conditions along an environmental gradient, although it can as well arise from neutral processes. Here, we investigated whether selection accounts for the strong clinal variation observed in a highly heritable pheomelanin-based color trait in the European barn owl by comparing spatial differentiation of color and of neutral genes among populations. Barn owl's coloration varies continuously from white in southwestern Europe to reddish-brown in northeastern Europe. A very low differentiation at neutral genetic markers suggests that substantial gene flow occurs among populations. The persistence of pronounced color differentiation despite this strong gene flow is consistent with the hypothesis that selection is the primary force maintaining color variation among European populations. Therefore, the color cline is most likely the result of local adaptation.
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| 21. |
- Archer, C. R., et al.
(författare)
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Sexual selection affects the evolution of lifespan and ageing in the decorated cricket gryllodes sigillatus
- 2012
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 66:10, s. 3088-3100
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Tidskriftsartikel (refereegranskat)abstract
- Recent work suggests that sexual selection can influence the evolution of ageing and lifespan by shaping the optimal timing and relative costliness of reproductive effort in the sexes. We used inbred lines of the decorated cricket, Gryllodes sigillatus, to estimate the genetic (co)variance between age-dependent reproductive effort, lifespan, and ageing within and between the sexes. Sexual selection theory predicts that males should die sooner and age more rapidly than females. However, a reversal of this pattern may be favored if reproductive effort increases with age in males but not in females. We found that male calling effort increased with age, whereas female fecundity decreased, and that males lived longer and aged more slowly than females. These divergent life-history strategies were underpinned by a positive genetic correlation between early-life reproductive effort and ageing rate in both sexes, although this relationship was stronger in females. Despite these sex differences in life-history schedules, age-dependent reproductive effort, lifespan, and ageing exhibited strong positive intersexual genetic correlations. This should, in theory, constrain the independent evolution of these traits in the sexes and may promote intralocus sexual conflict. Our study highlights the importance of sexual selection to the evolution of sex differences in ageing and lifespan in G. sigillatus.
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| 22. |
- Arnqvist, Göran
(författare)
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Assortative mating by fitness and sexually antagonistic genetic variation
- 2011
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 65:7, s. 2111-2116
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Tidskriftsartikel (refereegranskat)abstract
- Recent documentations of sexually antagonistic genetic variation in fitness have spurred an interest in the mechanisms that may act to maintain such variation in natural populations. Using individual-based simulations, I show that positive assortative mating by fitness increases the amount of sexually antagonistic genetic variance in fitness, primarily by elevating the equilibrium frequency of heterozygotes, over most of the range of sex-specific selection and dominance. Further, although the effects of assortative mating by fitness on the protection conditions of polymorphism in sexually antagonistic loci were relatively minor, it widens the protection conditions under most reasonable scenarios (e. g., under heterozygote superiority when fitness is averaged across the sexes) but can also somewhat narrow the protection conditions under other circumstances. The near-ubiquity of assortative mating in nature suggests that it may contribute to upholding standing sexually antagonistic genetic variation in fitness.
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| 23. |
- Arnqvist, Göran, 1961-, et al.
(författare)
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Copulatory behavior, genital morphology, and male fertilization success in water striders
- 1999
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Ingår i: Evolution. - Umea Univ, Dept Anim Ecol, SE-90187 Umea, Sweden. Univ Gothenburg, Dept Zool, SE-40530 Gothenburg, Sweden. : Oxford University Press (OUP). - 0014-3820 .- 1558-5646. ; 53:1, s. 147-156
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Tidskriftsartikel (refereegranskat)
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| 24. |
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| 25. |
- Arnqvist, Göran, et al.
(författare)
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Genetic architecture of metabolic rate : environment specific epistasis between mitochondrial and nuclear genes in an insect
- 2010
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 64:12, s. 3354-3363
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Tidskriftsartikel (refereegranskat)abstract
- The extent to which mitochondrial DNA (mtDNA) variation is involved in adaptive evolutionary change is currently being reevaluated. In particular, emerging evidence suggests that mtDNA genes coevolve with the nuclear genes with which they interact to form the energy producing enzyme complexes in the mitochondria. This suggests that intergenomic epistasis between mitochondrial and nuclear genes may affect whole-organism metabolic phenotypes. Here, we use crossed combinations of mitochondrial and nuclear lineages of the seed beetle Callosobruchus maculatus and assay metabolic rate under two different temperature regimes. Metabolic rate was affected by an interaction between the mitochondrial and nuclear lineages and the temperature regime. Sequence data suggests that mitochondrial genetic variation has a role in determining the outcome of this interaction. Our genetic dissection of metabolic rate reveals a high level of complexity, encompassing genetic interactions over two genomes, and genotype x genotype x environment interactions. The evolutionary implications of these results are twofold. First, because metabolic rate is at the root of life histories, our results provide insights into the complexity of life-history evolution in general, and thermal adaptation in particular. Second, our results suggest a mechanism that could contribute to the maintenance of nonneutral mtDNA polymorphism.
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