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Joel W. McGlothlin 《Evolution; international journal of organic evolution》2010,64(5):1377-1385
Studies measuring natural selection acting via different components of fitness may provide insight into such central questions in evolutionary biology as the evolution of life histories and sexual dimorphism. It is often desirable to combine estimates of selection at different episodes to understand how they interact to produce total lifetime selection. When selective episodes are sequential, total directional selection may be calculated by summing directional selection across episodes. However, it is unclear whether lifetime nonlinear (e.g., stabilizing, disruptive, or correlational) selection may be similarly calculated using estimates of quadratic selection from sequential episodes. Here, I show that lifetime quadratic selection depends not only upon the sum total of quadratic selection across episodes but also upon the pattern of directional selection across episodes. In certain cases, the effects of directional selection across episodes may cancel one another, leading to no net directional selection but strong stabilizing selection. This result suggests that true stabilizing selection may be more common than previously thought, especially when the entire life cycle is considered. The equations derived here are easily applicable to empirical data, as is illustrated both with a simulated dataset and with a reanalysis of a study of quadratic selection in dark‐eyed juncos. 相似文献
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DARRELL J. KEMP 《Biological journal of the Linnean Society. Linnean Society of London》2006,88(4):565-578
The study of sexual selection has recently been enriched by an explicit life history focus. This lifetime perspective has much to offer the field; however, most existing interdisciplinary exchanges have restricted themselves to the context of mate choice and associated phenomena. The present study explores the consequences of an explicit life history view upon the evolution of male–male contest competition. Key to this view is the fact that fighting typically has lifetime consequences, and thus the costs involved with contests are best considered in lifetime currencies such as residual reproductive value. The rate of contemporary contest cost accrual may vary among contestants due to differences between them in what they 'stand to lose', in terms of future reproductive opportunities. It is also suggested that it may be fruitful to partition key life history parameters into components that are either dependent or independent of future choice of mating strategy. Using a simple simulation, it is demonstrated that the optimum pattern of lifetime contest participation may vary depending upon lifetime variation in 'strategy-independent' components of reproductive value (such as the rate of mortality experienced in contexts unrelated to mating behaviour). In line with previous models of age-specific sexual advertisement, increasing lifetime aggression appears as the most favoured strategy; however, young age aggression is predicted if resource holding potential is expected to decline with age irrespective of prior contest participation. The model is discussed, along with key concepts surrounding the life history viewpoint, in light of prior life history/sexual selection models and the existing empirical data regarding lifetime fighting strategies in the wild. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 565–578. 相似文献
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Several factors shape lifetime reproductive success, including genetic background, body condition, environmental conditions and ecological interactions such as parasitism. Adults often show higher reproductive success than their young conspecifics, especially in long-lived bird species, and this may be explained by the cumulative effects of an increase in reproductive experience and the selection of high-quality individuals from one year to the next. To test whether this pattern also exists in short-lived bird species, we used 13 years of monitoring data from two Great Tit Parus major populations. The effects of male and female age on several reproductive parameters were analysed in 419 pairs of Great Tits, while accounting for body condition and infection by haemosporidian parasites. Reproductive success was mainly affected by the age-class of males. Pairs containing a sub-adult male fledged one-third fewer chicks than pairs containing an adult male. The difference was not caused by variation in male fertility but could have been caused by better parental care provided by adult birds. In addition to lower reproductive success, first-year males also had reduced access to mating compared with adult males, suggesting an avoidance of sub-adult males by females. Nestling body condition was positively correlated with parental body condition, and the body condition of male and female members of breeding pairs was positively correlated. Finally, the number of fledged chicks was mainly affected by the infection status of males. These results temper our previously published results showing an effect of infection on Great Tit reproduction regardless of their sex. In our previous study, and as in most cases, the status of the partner was not taken into account and we show here that this is essential because it can lead to a biased interpretation of the results. 相似文献
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JUAN CARRANZA CONCHA MATEOS SUSANA ALARCOS CRISTINA B. SÁNCHEZ-PRIETO JULIANA VALENCIA 《Biological journal of the Linnean Society. Linnean Society of London》2008,93(3):487-497
Worn teeth in herbivore ungulates may be related to lower efficiency in mastication and hence lower performance. However, selection should favour maximal performance in terms of body mass and reproductive capacity during reproductive lifespan, when permanent teeth are already partially worn. We hypothesize that wear rate may respond to a strategy of use of tooth materials (notably dentine), which balances instantaneous wear rate and performance against tooth preservation for future performance and reproduction. In the present study, we investigated 4151 carcasses of Iberian red deer Cervus elaphus hispanicus and show that more worn molars were not related to lower performance throughout age. By comparing between sexes, tooth wear rates were smaller in females than in males, but the relationship between tooth wear and body performance also differed between the sexes: females did not show a significant relationship between tooth wear and performance but males with more worn teeth were in general heavier and had larger antlers until senile age, when more depleted teeth were related to smaller antlers. These results reveal, for the first time, sex-specific lifetime strategies of dentine expenditure: maintenance of performance ability throughout a longer reproductive lifespan in females, compared with maximizing current performance by depleting dentine reserves within a shorter lifespan in males. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 487–497. 相似文献
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Whether environmental effects during juvenile development can alter the ontogeny of adult mating behaviour remains largely unexplored. We evaluated the effect of diet on the early expression of conspecific recognition in spadefoot toads, Spea bombifrons. We found that juvenile toads display phonotaxis behaviour six weeks post-metamorphosis. However, preference for conspecifics versus heterospecifics emerged later and was diet dependent. Thus, the environment can affect the early development of species recognition in a way that might alter adult behaviour. Evaluating such effects is important for understanding variation in hybridization between species and the nature of species boundaries. 相似文献
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Judge KA Ting JJ Gwynne DT 《Evolution; international journal of organic evolution》2008,62(4):868-878
Sexually selected traits are thought to impose survival costs on showy males. Recent empirical work found a negative relationship between male display and survival in a field cricket species (Orthoptera, Gryllidae, Gryllinae) where there is no evidence of a mating bias toward older males. In most species, however, male survival and ornamentation are positively correlated, and older males often have a mating success advantage over younger males. These findings suggest that male quality and survival are positively correlated, but more tests of this hypothesis are needed. We measured the condition dependence of male survival and calling effort in another grylline, Gryllus pennsylvanicus, where older males have previously been shown to have greater mating success. We varied condition by manipulating diet, and measured male life span and calling effort to assess the relative condition dependence of these traits. High- and medium-condition males survived longer than low-condition males, and high-condition males called more than medium- and low-condition males. Differences in calling effort among the condition treatments were not apparent early in life, but emerged as males aged. We discuss possible explanations for the differences between our study and contrasting results such as the previous grylline work. 相似文献
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1. Sexual selection is a powerful evolutionary force that is hypothesised to play an important role in the evolution of lifespan. Here we test for the potential contribution of sexual selection to the rapid evolution of male lifespan in replicated laboratory populations of the seed beetle, Callosobruchus maculatus. 2. For 35 generations, newly hatched virgin male beetles from eight different populations were allowed to mate for 24 h and then discarded. Sexual selection was removed in half of these populations by enforcing random monogamy. 3. Classic theory predicts that because of sexual competition, males from sexually selected lines would have higher age‐specific mortality rates and shorter lifespan than males from monogamous lines. 4. Alternatively, condition‐dependent sexual selection may also favour genes that have positive pleiotropic effects on lifespan and ageing. 5. Males from all eight populations evolved shorter lifespans compared with the source population. However, there was no difference in lifespan between males from populations with or without sexual selection. Thus, sexual selection did not contribute to the evolution of male lifespan despite the fact that such evolution did occur in our study populations. 相似文献
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Allocation of resources into the development of sexual displays is determined by a trade-off between the competing demands of current reproduction and self-maintenance. When reproduction overlaps with acquisition of sexual ornamentation, such as in birds with a yearly post-breeding moult, such a trade-off can be expressed in elaboration of sexual traits used in subsequent matings. In turn, selection for elaboration of sexual ornaments should favour resolution of this trade-off through a modification of the ornaments' development, resulting in variable and life history-dependent development of sexual displays. Here we examined a novel hypothesis that the trade-off between current reproduction and development of sexual ornamentation in the house finch (Carpodacus mexicanus) can be mediated by the shared effects of prolactin - a pituitary hormone that regulates both parental care and moult in this species. We compared developmental variation in sexual ornamentation between breeding, nonbreeding, and juvenile males and examined the relative contribution of residual levels of prolactin and individual condition during moult to the acquisition of sexual ornamentation. Males that invested heavily in parental care entered post-breeding moult in lower condition and later in the season, but their higher plasma prolactin was associated with shorter and more intense moult ultimately resulting in equal or greater elaboration of sexual ornamentation compared with nonparental males. Elaboration of sexual ornamentation of nonparental males that entered moult in greater condition, but with lower prolactin, was produced by longer and earlier moult and by lesser overlap in moult between sexual ornaments. Ornamentation of juvenile males that acquire sexual ornamentation for the first time was closely associated with physiological condition during moult. We discuss the implications of such context-dependent ontogenies of sexual ornamentation and resulting differences in condition-dependence of sexual traits across life history stages on the evolution of female preference for elaborated sexual displays. 相似文献
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Zahida Sultanova Roberto García‐Roa Pau Carazo 《Journal of evolutionary biology》2020,33(8):1086-1096
Disentangling the relationship between age and reproduction is central to understand life‐history evolution, and recent evidence shows that considering condition‐dependent mortality is a crucial piece of this puzzle. For example, nonrandom mortality of ‘low‐condition’ individuals can lead to an increase in average lifespan. However, selective disappearance of such low‐condition individuals may also affect reproductive senescence at the population level due to trade‐offs between physiological functions related to survival/lifespan and the maintenance of reproductive functions. Here, we address the idea that condition‐dependent extrinsic mortality (i.e. simulated predation) may increase the age‐related decline in male reproductive success and with it the potential for sexual conflict, by comparing reproductive ageing in Drosophila melanogaster male/female cohorts exposed (or not) to condition‐dependent simulated predation across time. Although female reproductive senescence was not affected by predation, male reproductive senescence was considerably higher under predation, due mainly to an accelerated decline in offspring viability of ‘surviving’ males with age. This sex‐specific effect suggests that condition‐dependent extrinsic mortality can exacerbate survival‐reproduction trade‐offs in males, which are typically under stronger condition‐dependent selection than females. Interestingly, condition‐dependent extrinsic mortality did not affect mating success, hinting that accelerated reproductive senescence is due to a decrease in male post‐copulatory fitness components. Our results support the recent proposal that male ageing can be an important source of sexual conflict, further suggesting this effect could be exacerbated under more natural conditions. 相似文献
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Craig A. Walling Michael B. Morrissey Katharina Foerster Tim H. Clutton-Brock Josephine M. Pemberton Loeske E. B. Kruuk 《Genetics》2014,198(4):1735-1749
Evolutionary theory predicts that genetic constraints should be widespread, but empirical support for their existence is surprisingly rare. Commonly applied univariate and bivariate approaches to detecting genetic constraints can underestimate their prevalence, with important aspects potentially tractable only within a multivariate framework. However, multivariate genetic analyses of data from natural populations are challenging because of modest sample sizes, incomplete pedigrees, and missing data. Here we present results from a study of a comprehensive set of life history traits (juvenile survival, age at first breeding, annual fecundity, and longevity) for both males and females in a wild, pedigreed, population of red deer (Cervus elaphus). We use factor analytic modeling of the genetic variance–covariance matrix (G) to reduce the dimensionality of the problem and take a multivariate approach to estimating genetic constraints. We consider a range of metrics designed to assess the effect of G on the deflection of a predicted response to selection away from the direction of fastest adaptation and on the evolvability of the traits. We found limited support for genetic constraint through genetic covariances between traits, both within sex and between sexes. We discuss these results with respect to other recent findings and to the problems of estimating these parameters for natural populations. 相似文献
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Directly developing larvae of the butterfly Lycaena hippothoe sumadiensis exhibited two growth strategies with one cohort passing four larval instars at high growth rates, and the other five instars at lower growth rates. The 4‐instar‐cohort displayed decreased development times, in combination with slightly reduced pupal and adult weights. In addition to adjustment of growth rate, omitting a larval instar may comprise a further mechanism to decrease development time when needed. Using the 4‐instar‐cohort, sex‐related differences in reaction norms were investigated over a temperature gradient. At high temperatures, protandrous males showed early emergence at a reduced size, whereas weight of females remained similar throughout. These differences suggest that large size is more important for female than for male fitness. The pattern is similar to that previously reported for alpine L. tityrus, indicating that sex‐specific reaction norms might be widespread in species living under severe time constraints. 相似文献
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The Lygaeidae (sensu lato) are a highly successful family of true bugs found worldwide, yet many aspects of their ecology and evolution remain obscure or unknown. While a few species have attracted considerable attention as model species for the study of insect physiology, it is only relatively recently that biologists have begun to explore aspects of their behavior, life history evolution, and patterns of intra‐ and interspecific ecological interactions across more species. As a result though, a range of new phenotypes and opportunities for addressing current questions in evolutionary ecology has been uncovered. For example, researchers have revealed hitherto unexpectedly rich patterns of bacterial symbiosis, begun to explore the evolutionary function of the family's complex genitalia, and also found evidence of parthenogenesis. Here we review our current understanding of the biology and ecology of the group as a whole, focusing on several of the best‐studied characteristics of the group, including aposematism (i.e., the evolution of warning coloration), chemical communication, sexual selection (especially, postcopulatory sexual selection), sexual conflict, and patterns of host‐endosymbiont coevolution. Importantly, many of these aspects of lygaeid biology are likely to interact, offering new avenues for research, for instance into how the evolution of aposematism influences sexual selection. With the growing availability of genomic tools for previously “non‐model” organisms, combined with the relative ease of keeping many of the polyphagous species in the laboratory, we argue that these bugs offer many opportunities for behavioral and evolutionary ecologists. 相似文献
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Kenyon B. Mobley Hanna Granroth‐Wilding Mikko Ellmn Panu Orell Jaakko Erkinaro Craig R. Primmer 《Molecular ecology》2020,29(6):1173-1184
In species with complex life cycles, life history theory predicts that fitness is affected by conditions encountered in previous life history stages. Here, we use a 4‐year pedigree to investigate if time spent in two distinct life history stages has sex‐specific reproductive fitness consequences in anadromous Atlantic salmon (Salmo salar). We determined the amount of years spent in fresh water as juveniles (freshwater age, FW, measured in years), and years spent in the marine environment as adults (sea age, SW, measured in sea winters) on 264 sexually mature adults collected on a river spawning ground. We then estimated reproductive fitness as the number of offspring (reproductive success) and the number of mates (mating success) using genetic parentage analysis (>5,000 offspring). Sea age is significantly and positively correlated with reproductive and mating success of both sexes whereby older and larger individuals gained the highest reproductive fitness benefits (females: 62.2% increase in offspring/SW and 34.8% increase in mate number/SW; males: 201.9% offspring/SW and 60.3% mates/SW). Younger freshwater age was significantly related to older sea age and thus increased reproductive fitness, but only among females (females: ?33.9% offspring/FW and ?32.4% mates/FW). This result implies that females can obtain higher reproductive fitness by transitioning to the marine environment earlier. In contrast, male mating and reproductive success was unaffected by freshwater age and more males returned at a younger age than females despite the reproductive fitness advantage of later sea age maturation. Our results show that the timing of transitions between juvenile and adult phases has a sex‐specific consequence on female reproductive fitness, demonstrating a life history trade‐off between maturation and reproduction in wild Atlantic salmon. 相似文献
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Parasitic botfly larvae (Philornis ssp., Diptera: Muscidae) are found in nests of several bird taxa, although prevalence and impact on nestling survival vary considerably among species. Here we describe patterns of botfly infestation in blue‐black grassquit Volatinia jacarina nestlings. We identified the most typically affected nestling body parts and assessed parasite prevalence, impact on nestling survival, and changes in nestling body shape. Additionally, we tested whether climatic conditions, nest morphology and habitat characteristics are associated with larvae abundance. Blue‐black grassquits had low breeding success (16% of eggs/nestlings survived to fledged; 19% of the nests fledged at least one), but most failures resulted from predation by vertebrate predators. We estimated that 1% of nestlings died due to botfly infestation, and the number of subcutaneous larvae (range 1–18) in a nestling's body did not predict fledging success. Infected chicks exhibited higher tarsus asymmetry. Thus, we argue that although botflies had a small impact on offspring survival, they may reduce fitness in adulthood. There was no evidence that environmental conditions and nest morphology are linked to the number of larvae on nestlings. Nesting areas with higher food supply had lower infestation rates. Possibly, food‐rich habitats allow parents to invest more time in offspring care (brooding nestlings), thus protecting them from fly attacks. Alternatively, vegetation composition could influence local invertebrate diversity, which could provide a natural trophic buffer against adult Philornis. The present study brings to light new perspectives concerning bird–botfly interaction. 相似文献
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Male investment into sexual ornamentation is a reproductive decision that depends on the context of breeding and life history state. In turn, selection for state- and context-specific expression of sexual ornamentation should favour the evolution of developmental pathways that enable the flexible allocation of resources into sexual ornamentation. We studied lifelong variation in the expression and condition-dependence of a sexual ornament in relation to age and the context of breeding in male house finches (Carpodacus mexicanus)--a species that develops a new sexual ornament once a year after breeding. Throughout males' lifetime, the elaboration of ornamentation and the allocation of resources to the development of sexual ornamentation depended strongly on pairing status in the preceding breeding season--males that were single invested more resources into sexual ornamentation and changed ornamentation more than males that were paired. During the initial (post-juvenile) moult, the expression of ornamentation was closely dependent on individual condition, however the condition-dependence of ornamentation sharply decreased throughout a male's lifetime and in older males expression of sexual ornamentation was largely independent of condition during moult. Selection for early breeding favoured greater ornamentation in males that were single in the preceding seasons and the strength of this selection increased with age. On the contrary, the strength of selection on sexual ornamentation decreased with age in males that were paired in the preceding breeding season. Our results reveal strong context-dependency in investment into sexual ornamentation as well as a high flexibility in the development of sexual ornamentation throughout a male's life. 相似文献
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The evolution of immune function depends not only on variation in genes contributing directly to the immune response, but also on genetic variation in other traits indirectly affecting immunocompetence. In particular, sexual selection is predicted to trade-off with immunocompetence because the extra investment of resources needed to increase sexual competitiveness reduces investment in immune function. Additional possible immunological consequences of intensifying sexual selection include an exaggeration of immunological sexual dimorphism, and the reduction of condition-dependent immunological costs due to selection of 'good genes' (the immunocompetence handicap hypothesis, ICHH). We tested for these evolutionary possibilities by increasing sexual selection in laboratory populations of Drosophila melanogaster for 58 generations by reestablishing a male-biased sex ratio at the start of each generation. Sexually selected flies were larger, took longer to develop, and the males were more sexually competitive than males from control (equal sex ratio) lines. We found support for the trade-off hypothesis: sexually selected males were found to have reduced immune function compared to control males. However, we found no evidence that sexual selection promoted immunological sexual dimorphism because females showed a similar reduction in immune function. We found no evidence of evolutionary changes in the condition-dependent expression of immunocompetence contrary to the expectations of the ICHH. Lastly, we compared males from the unselected base population that were either successful (IS) or unsuccessful (IU) in a competitive mating experiment. IS males showed reduced immune function relative to IU males, suggesting that patterns of phenotypic correlation largely mirror patterns of genetic correlation revealed by the selection experiment. Our results suggest increased disease susceptibility could be an important cost limiting increases in sexual competitiveness in populations experiencing intense sexual selection. Such costs may be particularly important given the high intersex correlation, because this represents an apparent genetic conflict, preventing males from reaching their sexually selected optimum. 相似文献
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Cothran RD Stiff AR Jeyasingh PD Relyea RA 《Evolution; international journal of organic evolution》2012,66(3):708-719
Sexual traits are especially sensitive to low food resources. Other environmental parameters (e.g., predation) should also affect sexual trait expression by favoring investment in viability traits rather than sexual traits. We know surprisingly little about how predators alter investment in sexual traits, or how predator and resource environments interact to affect sexual trait investment. We explored how increasing phosphorous (P) availability, at a level mimicking cultural eutrophication, affects the development of sexual, nonsexual, and viability traits of amphipods in the presence and absence of predators. Sexual traits and growth were hypersensitive to low P compared to nonsexual traits. However, a key sexual trait responded to low P only when predator cues were absent. Furthermore, investment trade-offs between sexual traits and growth only occurred when P was low. The phenotypic changes caused by predator cues and increased P availability resulted in higher male mating success. Thus, eutrophication not only affects sexual trait expression but also masks the trade-off between traits with similar P demand. Sensitivity of sexually selected traits to changes in P, combined with the important roles these traits play in determining fitness and driving speciation, suggests that human-induced environmental change can greatly alter the evolutionary trajectories of populations. 相似文献
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Recent theory predicted that male advertisement will reliably signal investment in paternal care in species where offspring survival requires paternal care and males allocate resources between advertisement and care. However, the predicted relationship between care and advertisement depended on the marginal gains from investment in current reproductive traits. Life history theory suggests that these fitness gains are also subject to a trade‐off between current and future reproduction. Here, we investigate whether male signalling remains a reliable indicator of parental care when males allocate resources between current advertisement, paternal care and survival to future reproduction. We find that advertisement is predicted to remain a reliable signal of male care but that advertisement may cease to reliably indicate male quality because low‐quality males are predicted to invest in current reproduction, whereas higher‐quality males are able to invest in both current reproduction and survival to future reproduction. 相似文献