scholarly journals Mate competition and resource competition are inter-related in sexual selection

2014 ◽  
Vol 27 (3) ◽  
pp. 466-477 ◽  
Author(s):  
S. Wacker ◽  
T. Amundsen
Keyword(s):  
Sexual Selection ◽  
Resource Competition ◽  
Mate Competition

scholarly journals The effects of male harm vary with female quality and environmental complexity in Drosophila melanogaster

2018 ◽  
Vol 14 (8) ◽  
pp. 20180443 ◽  
Author(s):  
Alison MacPherson ◽  
Li Yun ◽  
Tania S. Barrera ◽  
Aneil F. Agrawal ◽  
Howard D. Rundle
Keyword(s):  
Drosophila Melanogaster ◽  
Sexual Selection ◽  
Natural Selection ◽  
Sexual Conflict ◽  
Mate Competition ◽  
Environmental Complexity ◽  
High Quality ◽  
Female Quality ◽  
Behavioural Interactions ◽  
Recent Attention

Mate competition provides the opportunity for sexual selection which often acts strongly on males, but also the opportunity for sexual conflict that can alter natural selection on females. Recent attention has focused on the potential of sexual conflict to weaken selection on females if male sexual attention, and hence harm, is disproportionately directed towards high- over low-quality females, thereby reducing the fitness difference between these females. However, sexual conflict could instead strengthen selection on females if low-quality females are more sensitive to male harm than high-quality females, thereby magnifying fitness differences between them. We quantify the effects of male exposure on low- versus high-quality females in Drosophila melanogaster in each of two environments (‘simple’ and ‘complex’) that are known to alter behavioural interactions. We show that the effects of male harm are greater for low- compared to high-quality females in the complex but not the simple environment, consistent with mate competition strengthening selection on females in the former but not in the latter environment.

scholarly journals Male cognitive performance declines in the absence of sexual selection

2014 ◽  
Vol 281 (1781) ◽  
pp. 20132873 ◽  
Author(s):  
Brian Hollis ◽  
Tadeusz J. Kawecki
Keyword(s):  
Drosophila Melanogaster ◽  
Sexual Selection ◽  
Cognitive Ability ◽  
Cognitive Performance ◽  
Cognitive Abilities ◽  
Learning Ability ◽  
Cognitive Tasks ◽  
Mate Competition ◽  
Processing Information ◽  
Male Ornaments

Sexual selection is responsible for the evolution of male ornaments and armaments, but its role in the evolution of cognition—the ability to process, retain and use information—is largely unexplored. Because successful courtship is likely to involve processing information in complex, competitive sexual environments, we hypothesized that sexual selection contributes to the evolution and maintenance of cognitive abilities in males. To test this, we removed mate choice and mate competition from experimental populations of Drosophila melanogaster by enforcing monogamy for over 100 generations. Males evolved under monogamy became less proficient than polygamous control males at relatively complex cognitive tasks. When faced with one receptive and several unreceptive females, polygamous males quickly focused on receptive females, whereas monogamous males continued to direct substantial courtship effort towards unreceptive females. As a result, monogamous males were less successful in this complex setting, despite being as quick to mate as their polygamous counterparts with only one receptive female. This diminished ability to use past information was not limited to the courtship context: monogamous males (but not females) also showed reduced aversive olfactory learning ability. Our results provide direct experimental evidence that the intensity of sexual selection is an important factor in the evolution of male cognitive ability.

scholarly journals Sexual selection's impacts on ecological specialization: an experimental test

2015 ◽  
Vol 282 (1807) ◽  
pp. 20150217 ◽  
Author(s):  
Karin S. Pfennig ◽  
David W. Pfennig ◽  
Cody Porter ◽  
Ryan A. Martin
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Resource Competition ◽  
Population Level ◽  
Disruptive Selection ◽  
Ecological Specialization ◽  
Spadefoot Toad ◽  
Novel Traits ◽  
Experimental Mesocosms ◽  
The Cost

In many species, individuals specialize on different resources, thereby reducing competition. Such ecological specialization can promote the evolution of alternative ecomorphs—distinct phenotypes adapted for particular resources. Elucidating whether and how this process is influenced by sexual selection is crucial for understanding how ecological specialization promotes the evolution of novel traits and, potentially, speciation between ecomorphs. We evaluated the population-level effects of sexual selection (as mediated by mate choice) on ecological specialization in spadefoot toad tadpoles that express alternative ecomorphs. We manipulated whether sexual selection was present or reversed by mating females to their preferred versus non-preferred males, respectively. We then exposed their tadpoles to resource competition in experimental mesocosms. The resulting distribution of ecomorphs was similar between treatments, but sexual selection generated poorer trait integration in, and lower fitness of, the more specialized carnivore morph. Moreover, disruptive and directional natural selection were weaker in the sexual selection present treatment. Nevertheless, this effect on disruptive selection was smaller than previously documented effects of ecological opportunity and competitor density. Thus, sexual selection can inhibit adaptation to resource competition and thereby hinder ecological specialization, particularly when females obtain fitness benefits from mate choice that offset the cost of producing competitively inferior offspring.

scholarly journals Sex ratio elasticity influences the selection of sex ratio strategy

2016 ◽  
Author(s):  
Yaqiang Wang ◽  
Ruiwu Wang ◽  
Yaotang Li ◽  
Zhanshan (Sam) Ma
Keyword(s):  
Sex Ratio ◽  
Resource Competition ◽  
Mate Competition ◽  
Unified Theory ◽  
Local Resource Competition ◽  
Local Mate ◽  
Biased Sex Ratio ◽  
Plausible Mechanism ◽  
The Difference ◽  
Selection Of

There are three sex ratio strategies (SRS) in nature—male-biased sex ratio, female-biased sex ratio and, equal sex ratio depending on the proportion of male offspring being greater than, less than, or equal to ½. The problem was already noted in Darwin’s (1859) “Origin of Species,” and it was R. A. Fisher (1930) who first explained why most species in nature display a sex ratio of ½. Consequent SRS theories such as Hamilton’s (1967) local mate competition (LMC) and Clark’s (1978) local resource competition (LRC) separately explained the observed deviations from the seemingly universal 1:1 ratio. However, to the best of our knowledge, there is not yet a unified theory that accounts for the mechanisms of the three SRS. Here, we introduce the price elasticity theory in economics to define sex ratio elasticity (SRE), and present an analytical model that derives three SRSs based on the following assumption: simultaneously existing competitions for both resources and mates influence the level of SRE in both sexes differently. Consequently, it is the difference (between two sexes) in the level of their sex ratio elasticity that leads to three different SRS. Our analytical results demonstrate that the elasticity-based model not only reveals a highly plausible mechanism that explains the evolution of SRS in nature, but also offers a novel framework for unifying two major classical theories (i.e., LMC & LRC) in the field of SRS research.

scholarly journals Competition for mates and the improvement of nonsexual fitness

2018 ◽  
Vol 115 (26) ◽  
pp. 6762-6767 ◽  
Author(s):  
Li Yun ◽  
Patrick J. Chen ◽  
Kevin E. Kwok ◽  
Christopher S. Angell ◽  
Howard D. Rundle ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Substantial Reduction ◽  
Fruit Fly ◽  
Major Effect ◽  
Mate Competition ◽  
Complex Environments ◽  
Complex Environment ◽  
Secondary Sexual Traits ◽  
Genome Wide ◽  
Sexual Traits

Competition for mates can be a major source of selection, not just on secondary sexual traits but across the genome. Mate competition strengthens selection on males via sexual selection, which typically favors healthy, vigorous individuals and, thus, all genetic variants that increase overall quality. However, recent studies suggest another major effect of mate competition that could influence genome-wide selection: Sexual harassment by males can drastically weaken selection on quality in females. Because of these conflicting effects, the net effect of mate competition is uncertain, although perhaps not entirely unpredictable. We propose that the environment in which mate competition occurs mediates the importance of sexual selection relative to sexual conflict and, hence, the net effect of mate competition on nonsexual fitness. To test this, we performed experimental evolution with 63 fruit fly populations adapting to novel larval conditions where each population was maintained with or without mate competition. In half the populations with mate competition, adults interacted in simple, high-density environments. In the remainder, adults interacted in more spatially complex environments in which male-induced harm is reduced. Populations evolving with mate competition in the complex environment adapted faster to novel larval environments than did populations evolving without mate competition or with mate competition in the simple environment. Moreover, mate competition in the complex environment caused a substantial reduction in inbreeding depression for egg-to-adult viability relative to the other two mating treatments. These results demonstrate that the mating environment has a substantial and predictable effect on nonsexual fitness through adaptation and purging.

scholarly journals Sex ratio elasticity influences the selection of sex ratio strategy

2016 ◽  
Author(s):  
Yaqiang Wang ◽  
Ruiwu Wang ◽  
Yaotang Li ◽  
Zhanshan (Sam) Ma
Keyword(s):  
Sex Ratio ◽  
Resource Competition ◽  
Mate Competition ◽  
Unified Theory ◽  
Local Resource Competition ◽  
Local Mate ◽  
Biased Sex Ratio ◽  
Plausible Mechanism ◽  
The Difference ◽  
Selection Of

There are three sex ratio strategies (SRS) in nature—male-biased sex ratio, female-biased sex ratio and, equal sex ratio depending on the proportion of male offspring being greater than, less than, or equal to ½. The problem was already noted in Darwin’s (1859) “Origin of Species,” and it was R. A. Fisher (1930) who first explained why most species in nature display a sex ratio of ½. Consequent SRS theories such as Hamilton’s (1967) local mate competition (LMC) and Clark’s (1978) local resource competition (LRC) separately explained the observed deviations from the seemingly universal 1:1 ratio. However, to the best of our knowledge, there is not yet a unified theory that accounts for the mechanisms of the three SRS. Here, we introduce the price elasticity theory in economics to define sex ratio elasticity (SRE), and present an analytical model that derives three SRSs based on the following assumption: simultaneously existing competitions for both resources and mates influence the level of SRE in both sexes differently. Consequently, it is the difference (between two sexes) in the level of their sex ratio elasticity that leads to three different SRS. Our analytical results demonstrate that the elasticity-based model not only reveals a highly plausible mechanism that explains the evolution of SRS in nature, but also offers a novel framework for unifying two major classical theories (i.e., LMC & LRC) in the field of SRS research.

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