scholarly journals Natural and sexual selection act on different axes of variation in avian plumage color

2015 ◽  
Vol 1 (2) ◽  
pp. e1400155 ◽  
Author(s):  
Peter O. Dunn ◽  
Jessica K. Armenta ◽  
Linda A. Whittingham
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Habitat Type ◽  
Sexual Differences ◽  
Plumage Color ◽  
Evolutionary Transitions ◽  
Testes Size ◽  
Selection For ◽  
Bird Coloration ◽  
Natural And Sexual Selection

The bright colors of birds are often attributed to sexual selection on males, but in many species both sexes are colorful and it has been long debated whether sexual selection can also explain this variation. We show that most evolutionary transitions in color have been toward similar plumage in both sexes, and the color of both sexes (for example, bright or dull) was associated with indices of natural selection (for example, habitat type), whereas sexual differences in color were primarily associated with indices of sexual selection on males (for example, polygyny and large testes size). Debate about the evolution of bird coloration can be resolved by recognizing that both natural and sexual selection have been influential, but they have generally acted on two different axes: sexual selection on an axis of sexual differences and natural selection on both sexes for the type of color (for example, bright or dull).

scholarly journals Integrating natural and sexual selection across the biphasic life cycle

2021 ◽  
Author(s):  
Craig Purchase ◽  
Jonathan Evans ◽  
Julissa Roncal
Keyword(s):  
Sexual Selection ◽  
Life Cycle ◽  
Natural Selection ◽  
Conceptual Framework ◽  
Life Cycles ◽  
Parental Effect ◽  
Biphasic Life Cycle ◽  
Evolutionary Trajectories ◽  
Taxonomic Groups ◽  
Natural And Sexual Selection

An alternation between diploid and haploid phases is universal among sexual eukaryotes. Across this biphasic cycle, natural selection and sexual selection occur in both phases. Together, these four stages of selection act on the phenotypes of individuals and influence the evolutionary trajectories of populations, but are rarely studied holistically. Here, we provide a conceptual framework that transcends taxonomic groups, and unifies the entire selection landscape within and across the diploid and haploid phases. Our synthesis produces six direct links among four selection stages, and from this we define four types of parental effect. We argue that knowledge of the complex and intertwined opportunities for selection within biphasic life cycles will offer clearer insights into key ecological and evolutionary processes, with benefits to applied science.

A Shape to Die for?

2021 ◽  
pp. 481-510
Author(s):  
Graham Mitchell
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Surface Water ◽  
Alternative Hypothesis ◽  
Natural Habitat ◽  
Large Body ◽  
Male And Female ◽  
Large Size ◽  
Selection For ◽  
Competition For Resources

The product of natural selection over at least 15 million years is the elongated, slender shape of giraffes that fits the natural habitat giraffes now occupy. What selection pressures operated to produce their shape? Their shape is partly the product of gravity and could have been an accidental by-product of selection for a large body mass and the protection from predation that large size brings, but the prevailing explanation is that their shape confers a browsing advantage. Preferred browse is concentrated at a height easily reached by giraffes but not by other browsers and natural selection would have favored those giraffes that could reach it. An alternative hypothesis is that their shape confers thermoregulatory benefits in addition to improved vigilance. Another hypothesis is that a long neck evolved to counter long legs allowing giraffes to drink surface water. An attractive hypothesis is that their shape is a product of ‘runaway’ sexual selection by females for males with long heavy necks, but analysis of this hypothesis has shown that the morphology of male and female giraffe does not differ. Nevertheless, all these possibilities could have contributed. A consequence of selection for their shape is over-specialization: giraffes seem to be inextricably dependent on a narrow diet, a diet that is subject to the vagaries of climate and competition for resources. The greatest threat to their survival is, therefore, their shape.

Natural selection drives the link between male immune function and reproductive potential

2005 ◽  
Vol 83 (7) ◽  
pp. 1012-1014 ◽  
Author(s):  
Kenneth M Fedorka ◽  
Marlene Zuk ◽  
Timothy A Mousseau
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Reproductive Potential ◽  
Nuptial Gift ◽  
Honest Signal ◽  
Male Behavior ◽  
Nuptial Gifts ◽  
The Gift ◽  
Selection For ◽  
Allonemobius Socius

In the ground cricket Allonemobius socius (Scudder 1877), males provide females with a hemolymph-based nuptial gift. The size of the gift depends on when copulation is terminated, which can be controlled by either sex. Here we show that more immunocompetent males provide larger nuptial gifts, increasing their reproductive potential. To address if this pattern was the consequence of sexual selection for an honest signal (i.e., females assess mate immune quality through the hemolymph), we examined which sex controlled gift size. We found that the probability that males initiated the end of copulation increased when gift size was small (stereotypical of less immunocompetent males). Thus, early termination of copulation was the consequence of male behavior, suggesting that the association between immunocompetence and gift size was not due to sexual selection, but to natural selection for male vigor.

scholarly journals Natural and sexual selection on many loci.

Genetics ◽  
1991 ◽  
Vol 127 (1) ◽  
pp. 229-255 ◽  
Author(s):  
N H Barton ◽  
M Turelli
Keyword(s):  
Sexual Selection ◽  
Linkage Disequilibrium ◽  
Natural Selection ◽  
Arbitrary Number ◽  
Indirect Selection ◽  
Weak Selection ◽  
Nonrandom Mating ◽  
Linkage Disequilibria ◽  
Female Preferences ◽  
Natural And Sexual Selection

Abstract A method is developed that describes the effects on an arbitrary number of autosomal loci of selection on haploid and diploid stages, of nonrandom mating between haploid individuals, and of recombination. We provide exact recursions for the dynamics of allele frequencies and linkage disequilibria (nonrandom associations of alleles across loci). When selection is weak relative to recombination, our recursions provide simple approximations for the linkage disequilibria among arbitrary combinations of loci. We show how previous models of sex-independent natural selection on diploids, assortative mating between haploids, and sexual selection on haploids can be analyzed in this framework. Using our weak-selection approximations, we derive new results concerning the coevolution of male traits and female preferences under natural and sexual selection. In particular, we provide general expressions for the intensity of linkage-disequilibrium induced selection experienced by loci that contribute to female preferences for specific male traits. Our general results support the previous observation that these indirect selection forces are so weak that they are unlikely to dominate the evolution of preference-producing loci.

scholarly journals Selection on phenotypic plasticity favors thermal canalization

2020 ◽  
Author(s):  
Erik I. Svensson ◽  
Miguel Gomez-Llano ◽  
John T. Waller
Keyword(s):  
Climate Change ◽  
Sexual Selection ◽  
Heat Stress ◽  
Natural Selection ◽  
Phenotypic Plasticity ◽  
Reaction Norm ◽  
Thermal Reaction ◽  
Ambient Temperatures ◽  
Thermal Plasticity ◽  
Natural And Sexual Selection

AbstractClimate change affects organisms worldwide with profound ecological and evolutionary consequences, often increasing population extinction risk. Climatic factors can increase the strength, variability or direction of natural selection on phenotypic traits, potentially driving adaptive evolution. Phenotypic plasticity in relation to temperature can allow organisms to maintain fitness in response to increasing temperatures, thereby “buying time” for subsequent genetic adaptation and promoting evolutionary rescue. Although many studies have shown that organisms respond plastically to increasing temperatures, it is unclear if such thermal plasticity is adaptive. Moreover, we know little about how natural and sexual selection operate on thermal reaction norms reflecting such plasticity. Here, we investigate how natural and sexual selection shape phenotypic plasticity in two congeneric and phenotypically similar sympatric insect species. We show that the thermal optima for longevity and mating success differ, suggesting temperature-dependent trade-offs between survival and reproduction. Males in these species have similar thermal reaction norm slopes but have diverged in baseline body temperature (intercepts), being higher for the more northern species. Natural selection favoured reduced thermal reaction norm slopes at high ambient temperatures, suggesting that the current level of thermal plasticity is maladaptive in the context of anthropogenic climate change and that selection now promotes thermal canalization and robustness. Our results show that ectothermic animals also at high latitudes can suffer from overheating and challenge the common view of phenotypic plasticity as being beneficial in harsh and novel environments.Significance StatementOrganisms are increasingly challenged by increasing temperatures due to climate change. In insects, body temperatures are strongly affected by ambient temperatures, and insects are therefore expected to suffer increasingly from heat stress, potentially reducing survival and reproductive success leading to elevated extinction risks. We investigated how ambient temperature affected fitness in two insect species in the temperate zone. Male and female survivorship benefitted more from low temperatures than did reproductive success, which increased with higher temperatures, revealing a thermal conflict between fitness components. Male body temperature plasticity reduced survival, and natural and sexual selection operated on such thermal plasticity. Our results reveal the negative consequences of thermal plasticity and show that these insects have limited ability to buffer heat stress.

The Alignment of Natural and Sexual Selection

2021 ◽  
Vol 52 (1) ◽  
Author(s):  
Locke Rowe ◽  
Howard D. Rundle
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Population History ◽  
Annual Review ◽  
Publication Date ◽  
Net Benefit ◽  
Mean Fitness ◽  
The Many ◽  
Natural And Sexual Selection ◽  
Natural Selection Theory

Sexual selection has the potential to decrease mean fitness in a population through an array of costs to nonsexual fitness. These costs may be offset when sexual selection favors individuals with high nonsexual fitness, causing the alignment of sexual and natural selection. We review the many laboratory experiments that have manipulated mating systems aimed at quantifying the net effects of sexual selection on mean fitness. These must be interpreted in light of population history and the diversity of ways manipulations have altered sexual interactions, sexual conflict, and sexual and natural selection. Theory and data suggest a net benefit is more likely when sexually concordant genetic variation is enhanced and that ecological context can mediate the relative importance of these different effects. Comparative studies have independently examined the consequences of sexual selection for population/species persistence. These provide little indication of a benefit, and interpreting these higher-level responses is challenging. Expected final online publication date for the Annual Review of Ecology, Evolution, and Systematics, Volume 52 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Interactions of natural and sexual selection: damselfish prioritize brood defense with male–male competition or courtship

Behaviour ◽  
2010 ◽  
Vol 147 (1) ◽  
pp. 37-52 ◽  
Author(s):  
Joseph Leese ◽  
Jennifer Snekser ◽  
Murray Itzkowitz
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Selection Pressure ◽  
Nest Site ◽  
Sexual Competition ◽  
Selection Pressures ◽  
Multiple Factors ◽  
Stegastes Leucostictus ◽  
Brood Defense ◽  
Natural And Sexual Selection

AbstractNatural and sexual selection often act in opposing directions, forcing individuals to prioritize activities necessary for survival with those required for reproduction. We examined the interaction of natural and sexual selection pressures on the behaviour of beaugregory damselfish, Stegastes leucostictus, by presenting territorial males with an egg predator and either a male or female conspecific, requiring males to prioritize brood defense with either courtship or intra-sexual competition. By measuring the time spent near stimuli, we examined the influence of several factors, including stimuli type, variation in predator number, and the presence of eggs in a nest site. Generally, males spent more time with conspecific stimuli than egg predators, suggesting that the sexual selection pressures of deterring rivals and attracting mates outweigh the natural selection pressure to engage in brood defense. This decision was affected by the sex of the conspecific presented, the presence of eggs in a male's territory, and a number of interactions of these factors, indicating that male damselfish consider multiple factors before investing in certain types and intensities of behaviours. Furthermore, observations of behaviours associated with courtship and intrasexual aggression show that a natural selection pressure impacts intra- and inter-sexually selected behaviours differently in this system.

scholarly journals Visual habitat geometry predicts relative morph abundance in the colour-polymorphic ornate rainbowfish

2013 ◽  
Vol 280 (1752) ◽  
pp. 20122377 ◽  
Author(s):  
Daniel Hancox ◽  
Robbie S. Wilson ◽  
Craig R. White
Keyword(s):  
Sexual Selection ◽  
Signal Transmission ◽  
Aquatic Environments ◽  
Visual Context ◽  
Ambient Light ◽  
Polymorphic Species ◽  
Local Abundance ◽  
Selection For ◽  
Natural And Sexual Selection ◽  
Colour Signal

During colour signalling in aquatic environments, the colour of the ambient light, the background against which signals are viewed and signal transmission through the environment can all have profound impacts on the efficacy of a given signal. In colour-polymorphic species, where alternative morphs persist owing to a balance in the natural and sexual selection for each, changes to the visual context can have large effects on the local success and relative abundance of competing phenotypes. The ornate rainbowfish, Rhadinocentrus ornatus , is composed of populations that vary in the relative frequency of red and blue individuals, and inhabit sites that vary in water transmittance from clear (white) to heavily tannin-stained (red-shifted). Using spectroradiometry, we measured the downwelling and sidewelling irradiance, bank radiance and water transmittance of 10 R. ornatus habitats. We found that the relative local abundance of each morph was predicted not by water transmittance but by chromatic differences between the vertical (downwelling light) and horizontal (bank colour) components of the habitat. This visual habitat geometry should increase contrast between the colour signal and background, with large potential to influence the strength of natural and sexual selection in this system.

scholarly journals Selection on phenotypic plasticity favors thermal canalization

2020 ◽  
Vol 117 (47) ◽  
pp. 29767-29774
Author(s):  
Erik I. Svensson ◽  
Miguel Gomez-Llano ◽  
John T. Waller
Keyword(s):  
Climate Change ◽  
Sexual Selection ◽  
Natural Selection ◽  
Phenotypic Plasticity ◽  
Reaction Norm ◽  
Thermal Reaction ◽  
Phenotypic Traits ◽  
Common View ◽  
Thermal Plasticity ◽  
Natural And Sexual Selection

Climate change affects organisms worldwide with profound ecological and evolutionary consequences, often increasing population extinction risk. Climatic factors can increase the strength, variability, or direction of natural selection on phenotypic traits, potentially driving adaptive evolution. Phenotypic plasticity in relation to temperature can allow organisms to maintain fitness in response to increasing temperatures, thereby “buying time” for subsequent genetic adaptation and promoting evolutionary rescue. Although many studies have shown that organisms respond plastically to increasing temperatures, it is unclear if such thermal plasticity is adaptive. Moreover, we know little about how natural and sexual selection operate on thermal reaction norms, reflecting such plasticity. Here, we investigate how natural and sexual selection shape phenotypic plasticity in two congeneric and phenotypically similar sympatric insect species. We show that the thermal optima for longevity and mating success differ, suggesting temperature-dependent trade-offs between survival and reproduction in both sexes. Males in these species have similar thermal reaction norm slopes but have diverged in baseline body temperature (intercepts), being higher for the more northern species. Natural selection favored reduced thermal reaction norm slopes at high ambient temperatures, suggesting that the current level of thermal plasticity is maladaptive in the context of anthropogenic climate change and that selection now promotes thermal canalization and robustness. Our results show that ectothermic animals also at high latitudes can suffer from overheating and challenge the common view of phenotypic plasticity as being beneficial in harsh and novel environments.

scholarly journals Sexual dichromatism in frogs: natural selection, sexual selection and unexpected diversity

2012 ◽  
Vol 279 (1748) ◽  
pp. 4687-4693 ◽  
Author(s):  
Rayna C. Bell ◽  
Kelly R. Zamudio
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Phylogenetic Signal ◽  
Colour Change ◽  
Sexual Dichromatism ◽  
Evolutionary Mechanisms ◽  
Males And Females ◽  
Colour Dimorphism ◽  
Natural And Sexual Selection ◽  
High Diversity

Sexual dichromatism, a form of sexual dimorphism in which males and females differ in colour, is widespread in animals but has been predominantly studied in birds, fishes and butterflies. Moreover, although there are several proposed evolutionary mechanisms for sexual dichromatism in vertebrates, few studies have examined this phenomenon outside the context of sexual selection. Here, we describe unexpectedly high diversity of sexual dichromatism in frogs and create a comparative framework to guide future analyses of the evolution of these sexual colour differences. We review what is known about evolution of colour dimorphism in frogs, highlight alternative mechanisms that may contribute to the evolution of sexual colour differences, and compare them to mechanisms active in other major groups of vertebrates. In frogs, sexual dichromatism can be dynamic (temporary colour change in males) or ontogenetic (permanent colour change in males or females). The degree and the duration of sexual colour differences vary greatly across lineages, and we do not detect phylogenetic signal in the distribution of this trait, therefore frogs provide an opportunity to investigate the roles of natural and sexual selection across multiple independent derivations of sexual dichromatism.

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