Preferential Sex Linkage of Sexually Selected Genes: Evidence and a New Explanation

This chapter discusses evidence and theory on sex chromosomal linkage of sexually selected traits that may be the key to a functional separation of sexual and natural selection. It reviews the evidence showing that the X chromosome has a disproportional share concerning the inheritance of sexually selected traits in animals with heterogametic males, and suggests a new explanation that relates this X bias with female choice of heterozygotic males. With numeric simulations, it shows that female choice of heterozygotic males is usually disadvantageous. Because this disadvantage cannot occur when females prefer X-linked male traits, preferential X linkage of sexually selected traits can be expected. As an alternative to fluctuating selection on sex-limited traits, the disadvantage of heterozygotic choice may thus explain the X bias observed for sexually selected traits.

Multimodal weighting differences by bats and their prey: probing natural selection pressures on sexually selected traits

Animal Behaviour ◽

10.1016/j.anbehav.2017.10.011 ◽

2017 ◽

Vol 134 ◽

pp. 99-102 ◽

Cited By ~ 7

Author(s):

D.G.E. Gomes ◽

W. Halfwerk ◽

R.C. Taylor ◽

M.J. Ryan ◽

R.A. Page

Keyword(s):

Natural Selection ◽

Selection Pressures ◽

Sex linkage among genes controlling sexually selected traits

Behavioral Ecology and Sociobiology ◽

10.1007/s002650050508 ◽

1998 ◽

Vol 44 (1) ◽

pp. 1-7 ◽

Cited By ~ 111

Author(s):

Klaus Reinhold

Keyword(s):

Sex Linkage ◽

Developmental costs of male sexual traits in the water strider Rheumatobates rileyi

Canadian Journal of Zoology ◽

10.1139/z99-058 ◽

1999 ◽

Vol 77 (6) ◽

pp. 917-922 ◽

Cited By ~ 12

Author(s):

Kathleen P Westlake ◽

Locke Rowe

Keyword(s):

Natural Selection ◽

Meta Analysis ◽

Development Rate ◽

Fourth Instar ◽

Water Strider ◽

The Third ◽

Intermolt Period ◽

Sexual Traits ◽

Natural selection is thought to impose costs on sexually selected traits and thereby constrain their evolutionary modification. Where sexually selected traits involve increases in size or structural elaboration, development of the traits may be costly. Males of some species in the water strider genus Rheumatobates have dramatically elaborated antennae and legs. In a pair of experiments on Rheumatobates rileyi, we tested the hypothesis that in males, the development rate is decreased and mortality increased relative to unelaborated females during the final instar, when these traits were substantially developed. In the first experiment, we reared individual larvae through to adult that were brought into the laboratory during the third, fourth, and fifth (final) instars. The development rate was reduced and the mortality increased during the final intermolt period in males relative to females. The effect on development rate was highly significant, but the effect on mortality was not. Notably, there was no effect of sex on the duration of the fourth instar, when male modifications are not expressed. In a second experiment, 4 potentially cannibalistic adults were included with fifth-instar larvae. We found no effect of potential cannibals on either development rate or mortality of instars. However, as in the first experiment, the development rate was significantly reduced in males relative to females. Mortality of males was also higher than that of females, although this effect was not significant. Meta-analysis of all our mortality results indicate that mortality of developing fifth-instars was higher in males than in females. Our results are consistent with the hypothesis that development of elaborate sexual traits in male R. rileyi is costly.

FEMALE MATE PREFERENCE IS FOR MALE TOTAL LENGTH, NOT TAIL LENGTH IN FERAL GUPPIES

Behaviour ◽

10.1163/15685390260514735 ◽

2002 ◽

Vol 139 (11-12) ◽

pp. 1491-1508 ◽

Cited By ~ 33

Author(s):

Kenji Karino ◽

Jun Matsunaga

Keyword(s):

Female Choice ◽

Tail Length ◽

Female Preference ◽

Male Mating ◽

Handicap Principle ◽

Total Length ◽

Female Preferences ◽

Trade Offs ◽

AbstractExaggerated male traits can evolve either directly by female choice of males with those traits or indirectly by female preferences for related traits. In this study, we tested whether female choice was based upon male tail length or total length in a feral guppy population in Okinawa, Japan. In this population, about 30% of the males had elongated sword-like tails, and even swordless males had longer tails than females. A series of dichotomous female choice experiments revealed that female guppies chose mates by total length, not by tail length itself. This is inconsistent with the handicap principle. Tail elongation of male guppies may have evolved as a male mating strategy to enhance their attraction to females, mediated by female preference for longer male total length. However, only one-third of the males developed pronounced sword-like tails. This suggests that there are some costs for tail elongation or trade-offs between multiple sexually selected traits. Alternatively, tail elongation may be a deceptive male strategy with frequency-dependent success.

Fluctuating selection strength and intense male competition underlie variation and exaggeration of a water strider’s male weapon

10.1101/430314 ◽

2018 ◽

Author(s):

William Toubiana ◽

Abderrahman Khila

Keyword(s):

Mating Behavior ◽

Phenotypic Variation ◽

Male Competition ◽

Egg Laying ◽

Leg Length ◽

Fluctuating Selection ◽

Selected Traits ◽

Gravid Females ◽

The Impact

AbstractSexually selected traits can reach high degrees of expression and variation under directional selection. A growing number of studies suggest that such selection can vary in space, time and form within and between populations. However, the impact of these fluctuations on sexual trait expression is poorly understood. The water striderMicrovelia longipesdisplays a striking case of exaggeration and phenotypic variation where males display extreme differences in the size of their rear legs. To study the origin and maintenance of this exaggerated trait, we conducted comparative behavioral and morphometric experiments in a sample ofMicroveliaspecies. We uncovered differences both in the mating behavior and the degree of sexual dimorphism across these species. Interestingly,M. longipesevolved a specific mating behavior where males compete for egg-laying sites, consisting of small floating objects, to intercept and copulate with gravid females. Field observations revealed rapid fluctuation inM. longipeshabitat stability and the abundance of egg-laying sites. Through male-male competition assays, we demonstrated that male rear legs are used as weapons to dominate egg-laying sites and that intense competition is associated with the evolution of rear leg length exaggeration. Paternity tests using genetic markers demonstrated that small males could only fertilize about 5% of the eggs when egg-laying sites are limiting, whereas this proportion increased to about 20% when egg-laying sites become abundant. Furthermore, diet manipulation and artificial selection experiments also showed that the exaggerated leg length inM. longipesmales is influenced by both genetic and nutritional factors. Collectively, our results highlight how fluctuation in the strength of directional sexual selection, through changes in the intensity of male competition, can drive the exaggeration and phenotypic variation in this weapon trait.

Natural selection reverses the exaggeration of a male sexually selected trait, which increases female fitness

10.1101/2020.10.15.340562 ◽

2020 ◽

Author(s):

Kensuke Okada ◽

Masako Katsuki ◽

Manmohan D. Sharma ◽

Katsuya Kiyose ◽

Tomokazu Seko ◽

...

Keyword(s):

Natural Selection ◽

Experimental Evolution ◽

Genetic Correlations ◽

Lifetime Reproductive Success ◽

Female Fitness ◽

Male Trait ◽

Flour Beetles ◽

Selected Traits ◽

Male Specific

AbstractTheory shows how sexual selection can exaggerate male traits beyond naturally selected optima and also how natural selection can ultimately halt trait elaboration. Empirical evidence supports this theory, but to date, there have been no experimental evolution studies directly testing this logic, and little examination of possible associated effects on female fitness. Here we used experimental evolution of replicate populations of broad-horned flour-beetles to test for evolutionary effects of sex-specific predation on an exaggerated sexually selected male trait, while also testing for effects on female lifetime reproductive success. We found that populations subjected to male-specific predation evolved smaller sexually selected traits and this indirectly increased female fitness, seemingly through intersexual genetic correlations we documented. Predation solely on females had no effects. Our findings support fundamental theory, but also reveal novel outcomes when natural selection targets sex-limited sexually selected characters.

Female × male and male × male interactions have limited influence on competitive fertilization inDrosophila melanogaster

10.1101/702720 ◽

2019 ◽

Cited By ~ 1

Author(s):

Stefan Lüpold ◽

Jonathan Bradley Reil ◽

Mollie K. Manier ◽

Valérian Zeender ◽

John M. Belote ◽

...

Keyword(s):

Sexual Selection ◽

Sperm Competition ◽

Female Choice ◽

Sperm Storage ◽

Sperm Transfer ◽

Cryptic Female Choice ◽

Complex Interactions ◽

Selected Traits ◽

Reproductive Events

AbstractHow males and females contribute to joint reproductive success has been a long-standing question in sexual selection. Under postcopulatory sexual selection (PSS), paternity success is predicted to derive from complex interactions among females engaging in cryptic female choice and males engaging in sperm competition. Such interactions have been identified as potential sources of genetic variation in sexually selected traits but are also expected to inhibit trait diversification. To date, studies of interactions between females and competing males have focused almost exclusively on genotypes and not phenotypic variation in sexually selected traits. Here, we characterize within- and between-sex interactions inDrosophila melanogasterusing isogenic lines with heritable variation in both male and female traits known to influence competitive fertilization. We found surprisingly few genotypic interaction effects on various stages of PSS such as female remating interval, copulation duration, sperm transfer, or sperm storage. Only the timing of female sperm ejection depended on female × male genotypic interactions. By contrast, several reproductive events, including sperm transfer, female sperm ejection and sperm storage, were explained by two- and three-way interactions among sex-specific phenotypes. We also documented complex interactions between the lengths of competing males’ sperm and the female seminal receptacle, which are known to have experienced rapid female-male co-diversification. Our results highlight the non-independence of sperm competition and cryptic female choice and demonstrate that complex interactions between the sexes do not limit the ability of multivariate systems to respond to directional sexual selection.Significance statementFor species with internal fertilization and female promiscuity, postcopulatory sexual selection (PSS) is believed to depend, in part, on complex interactions between rival males and between the sexes. Although little investigated, clarifying such interactions is critical as they may limit the efficacy of PSS in the diversification of reproductive traits (e.g., ejaculate biochemistry and sperm, genitalia and female reproductive tract morphology). Here, we resolve how sex-specific traits and their interactions contribute to key reproductive events and outcomes related to competitive fertilization success, including traits known to have experienced rapid diversification. Our results provide novel insights into the operation and complexity of PSS and demonstrate that the processes of sperm competition and cryptic female choice are not independent selective forces.