scholarly journals Increased adaptability to rapid environmental change can more than make up for the two-fold cost of males

2018 ◽  
Author(s):  
Caroline M. Holmes ◽  
Ilya Nemenman ◽  
Daniel B. Weissman
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Environmental Change ◽  
Male Fitness ◽  
Rapid Adaptation ◽  
Direct Competition ◽  
The Cost ◽  
Enormous Number ◽  
Rapid Environmental Change ◽  
Cost Of Sex

AbstractThe famous “two-fold cost of sex” is really the cost of anisogamy – why should females mate with males who do not contribute resources to offspring, rather than isogamous partners who contribute equally? In typical anisogamous populations, a single very fit male can have an enormous number of offspring, far larger than is possible for any female or isogamous individual. If the sexual selection on males aligns with the natural selection on females, anisogamy thus allows much more rapid adaptation via super-successful males. We show via simulations that this effect can be sufficient to overcome the two-fold cost and maintain anisogamy against isogamy in populations adapting to environmental change. The key quantity is the variance in male fitness – if this exceeds what is possible in an isogamous population, anisogamous populations can win out in direct competition by adapting faster.

scholarly journals Stronger net selection on males across animals

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Lennart Winkler ◽  
Maria Moiron ◽  
Edward H Morrow ◽  
Tim Janicke
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Natural Selection ◽  
Environmental Change ◽  
Evolutionary Dynamics ◽  
Comparative Approach ◽  
Sex Bias ◽  
Adaptive Potential ◽  
Stressful Environment ◽  
Preliminary Support

Sexual selection is considered the major driver for the evolution of sex differences. However, the eco-evolutionary dynamics of sexual selection and their role for a population’s adaptive potential to respond to environmental change have only recently been explored. Theory predicts that sexual selection promotes adaptation at a low demographic cost only if sexual selection is aligned with natural selection and if net selection is stronger on males compared to females. We used a comparative approach to show that net selection is indeed stronger in males and provide preliminary support that this sex bias is associated with sexual selection. Given that both sexes share the vast majority of their genes, our findings corroborate the notion that the genome is often confronted with a more stressful environment when expressed in males. Collectively, our study supports one of the long-standing key assumptions required for sexual selection to bolster adaptation, and sexual selection may therefore enable some species to track environmental change more efficiently.

scholarly journals Sexual selection for rare beneficial mutations promotes the evolution of sexual reproduction and adaptation

2021 ◽  
Author(s):  
Gilbert Roberts ◽  
Marion Petrie
Keyword(s):  
Sexual Selection ◽  
Sexual Reproduction ◽  
Negative Impact ◽  
Reproductive Rate ◽  
Beneficial Mutations ◽  
Selection For ◽  
The Cost ◽  
Average Fitness ◽  
Cost Of Sex

The evolution and widespread maintenance of sexual reproduction remains a conundrum in biology because asexual reproduction should allow twice the reproductive rate. One hypothesis is that sexual selection lessens the negative impact on fitness of accumulating deleterious mutations. However, for adaptation to occur, there must also be selection for beneficial mutations. Here we show that sexual selection can help explain the evolution and maintenance of sexual reproduction. In our model, females chose males with more beneficial mutations (as opposed to just fewer harmful ones) even when these occurred much more rarely. Sexual selection thereby increased fixation of beneficial mutations which increased the absolute genetic quality of sexual offspring. This increase in fitness relative to asexual offspring adds to the previously postulated effect of reduced mutation load in offsetting the cost of sex. Analysing our simulations reveals that female choice among males raised the fitness of reproducing males above that of females. We found that this effect could overcome the decline in average fitness that occurs when mutation rate increases, allowing an increase in the fixation of beneficial mutations. Sexual selection thereby not only facilitates the evolution of sexual reproduction but maintains sex by leveraging its benefits and driving adaptation.

scholarly journals Sexual selection, phenotypic plasticity and female reproductive output

2019 ◽  
Vol 374 (1768) ◽  
pp. 20180184 ◽  
Author(s):  
Rebecca J. Fox ◽  
Lutz Fromhage ◽  
Michael D. Jennions
Keyword(s):  
Sexual Selection ◽  
Phenotypic Plasticity ◽  
Environmental Change ◽  
Reproductive Output ◽  
Foraging Efficiency ◽  
Phenotypic Variance ◽  
Allocation Of Resources ◽  
Sexually Selected Traits ◽  
Selected Traits ◽  
Rapid Environmental Change

In a rapidly changing environment, does sexual selection on males elevate a population's reproductive output? If so, does phenotypic plasticity enhance or diminish any such effect? We outline two routes by which sexual selection can influence the reproductive output of a population: a genetic correlation between male sexual competitiveness and female lifetime reproductive success; and direct effects of males on females' breeding success. We then discuss how phenotypic plasticity of sexually selected male traits and/or female responses (e.g. plasticity in mate choice), as the environment changes, might influence how sexual selection affects a population's reproductive output. Two key points emerge. First, condition-dependent expression of male sexual traits makes it likely that sexual selection increases female fitness if reproductively successful males disproportionately transfer genes that are under natural selection in both sexes, such as genes for foraging efficiency. Condition-dependence is a form of phenotypic plasticity if some of the variation in net resource acquisition and assimilation is attributable to the environment rather than solely genetic in origin. Second, the optimal allocation of resources into different condition-dependent traits depends on their marginal fitness gains. As male condition improves, this can therefore increase or, though rarely highlighted, actually decrease the expression of sexually selected traits. It is therefore crucial to understand how condition determines male allocation of resources to different sexually selected traits that vary in their immediate effects on female reproductive output (e.g. ornaments versus coercive behaviour). In addition, changes in the distribution of condition among males as the environment shifts could reduce phenotypic variance in certain male traits, thereby reducing the strength of sexual selection imposed by females. Studies of adaptive evolution under rapid environmental change should consider the possibility that phenotypic plasticity of sexually selected male traits, even if it elevates male fitness, could have a negative effect on female reproductive output, thereby increasing the risk of population extinction. This article is part of the theme issue ‘The role of plasticity in phenotypic adaptation to rapid environmental change’.

scholarly journals Evolution by Sexual Selection

2021 ◽  
Vol 9 ◽  
Author(s):  
Marion Petrie
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Charles Darwin ◽  
Female Preference ◽  
Rapid Adaptation ◽  
Theory Of Evolution ◽  
Distinct Process ◽  
Long Time ◽  
Evolution By Natural Selection ◽  
Descent Of Man

Charles Darwin published his second book “Sexual selection and the descent of man” in 1871 150 years ago, to try to explain, amongst other things, the evolution of the peacock’s train, something that he famously thought was problematic for his theory of evolution by natural selection. He proposed that the peacock’s train had evolved because females preferred to mate with males with more elaborate trains. This idea was very controversial at the time and it wasn’t until 1991 that a manuscript testing Darwin’s hypothesis was published. The idea that a character could arise as a result of a female preference is still controversial. Some argue that there is no need to distinguish sexual from natural selection and that natural selection can adequately explain the evolution of extravagant characteristics that are characteristic of sexually selected species. Here, I outline the reasons why I think that this is not the case and that Darwin was right to distinguish sexual selection as a distinct process. I present a simple verbal and mathematical model to expound the view that sexual selection is profoundly different from natural selection because, uniquely, it can simultaneously promote and maintain the genetic variation which fuels evolutionary change. Viewed in this way, sexual selection can help resolve other evolutionary conundrums, such as the evolution of sexual reproduction, that are characterised by having impossibly large costs and no obvious immediate benefits and which have baffled evolutionary biologists for a very long time. If sexual selection does indeed facilitate rapid adaptation to a changing environment as I have outlined, then it is very important that we understand the fundamentals of adaptive mate choice and guard against any disruption to this natural process.

Darwinian Evolutionary Theory

2018 ◽  
Author(s):  
Michael Ruse
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Middle Class ◽  
Evolutionary Theory ◽  
Scientific Community ◽  
Homo Sapiens ◽  
Origin Of Species ◽  
Theory Of Evolution ◽  
Descent Of Man

Charles Robert Darwin, the English naturalist, published On the Origin of Species in 1859 and the follow-up work The Descent of Man in 1871. In these works, he argued for his theory of evolution through natural selection, applying it to all organisms, living and dead, including our own species, Homo sapiens. Although controversial from the start, Darwin’s thinking was deeply embedded in the culture of his day, that of a middle-class Englishman. Evolution as such was an immediate success in scientific circles, but although the mechanism of selection had supporters in the scientific community (especially among those working with fast-breeding organisms), its real success was in the popular domain. Natural selection, and particularly the side mechanism of sexual selection, were known to all and popular themes in fiction and elsewhere.

Sign in / Sign up

Export Citation Format

Share Document