scholarly journals Intraspecific sperm competition genes enforce post-mating species barriers in Drosophila

2014 ◽  
Vol 281 (1797) ◽  
pp. 20142050 ◽  
Author(s):  
Dean M. Castillo ◽  
Leonie C. Moyle
Keyword(s):  
Sexual Selection ◽  
Reproductive Isolation ◽  
Sperm Competition ◽  
Competitive Ability ◽  
Sexual Isolation ◽  
Theoretical Models ◽  
Sexually Selected Traits ◽  
Genetic Mechanisms ◽  
Selected Traits ◽  
Additional Role

Sexual selection and sexual conflict are considered important drivers of speciation, based on both theoretical models and empirical correlations between sexually selected traits and diversification. However, whether reproductive isolation between species evolves directly as a consequence of intrapopulation sexual dynamics remains empirically unresolved, in part because knowledge of the genetic mechanisms (if any) connecting these processes is limited. Here, we provide evidence of a direct mechanistic link between intraspecies sexual selection and reproductive isolation. We examined genes with known roles in intraspecific sperm competition (ISC) in D. melanogaster and assayed their impact on conspecific sperm precedence (CSP). We found that two such genes ( Acp36DE and CG9997 ) contribute to both offensive sperm competition and CSP; null/knockdown lines both had lower competitive ability against D. melanogaster conspecifics and were no longer able to displace heterospecific D. simulans sperm in competitive matings. In comparison, Sex Peptide ( Acp70A )—another locus essential for ISC—does not contribute to CSP. These data indicate that two loci important for sperm competitive interactions have an additional role in similar interactions that enforce post-mating reproductive isolation between species, and show that sexual selection and sexual isolation can act on the same molecular targets in a gene-specific manner.

scholarly journals Conspecific sperm precedence is reinforced but sexual selection weakened in sympatric populations ofDrosophila

2016 ◽  
Author(s):  
Dean M. Castillo ◽  
Leonie C. Moyle
Keyword(s):  
Sexual Selection ◽  
Reproductive Isolation ◽  
Sperm Competition ◽  
Competitive Ability ◽  
Genetic Basis ◽  
Direct Selection ◽  
Sperm Precedence ◽  
Sympatric Populations ◽  
Selection For ◽  
The Cost

SUMMARYSexual selection is well recognized as a driver of reproductive isolation between lineages. However, selection for increased reproductive isolation could reciprocally change the outcomes of sexual selection, when these processes share a genetic basis. Direct selection for reproductive isolation occurs in the context of ‘reinforcement’, where selection acts to increase prezygotic barriers to reduce the cost of heterospecific matings. Many studies of reinforcement focus on premating reproductive barriers, however postmating traits-such as conspecific sperm precedence (CSP)-can also respond to reinforcing selection. We tested whether i) CSP responded to reinforcing selection, and ii) this response in sympatric populations altered intraspecific sperm competition (ISC) and the strength of sexual selection, with the sister speciesDrosophila pseudoobscuraandD. persimilis. We used sperm competition experiments to evaluate differences in CSP and ISC between two sympatric and two allopatric populations ofD. pseudoobscura. Using multiple genotypes for each population allowed us to estimate not only patterns of phenotype divergence, but also the opportunity for sexual selection within each population. Consistent with a pattern of reinforcement, the sympatric populations had higher mean CSP. Moreover, ISC was altered in sympatric populations, where we observed decreased average offensive sperm competitive ability against conspecific males, allowing less opportunity for sexual selection to operate within these populations. These data demonstrate that strong reinforcing selection for reproductive isolation can have consequences for sexual selection and sexual interactions within species, in these important postmating sperm competition traits.

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

2019 ◽  
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 ◽  
Sexually Selected Traits ◽  
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.

scholarly journals Socially flexible female choice differs among populations of the Pacific field cricket: geographical variation in the interaction coefficient psi ( Ψ )

2012 ◽  
Vol 279 (1742) ◽  
pp. 3589-3596 ◽  
Author(s):  
Nathan W. Bailey ◽  
Marlene Zuk
Keyword(s):  
Sexual Selection ◽  
Rapid Change ◽  
Theoretical Models ◽  
Interaction Coefficient ◽  
Field Cricket ◽  
Ancestral Population ◽  
Isolated Populations ◽  
Male Song ◽  
Sexually Selected Traits ◽  
Female Choosiness

Indirect genetic effects (IGEs) occur when genes expressed in one individual affect the phenotype of a conspecific. Theoretical models indicate that the evolutionary consequences of IGEs critically depend on the genetic architecture of interacting traits, and on the strength and direction of phenotypic effects arising from social interactions, which can be quantified by the interaction coefficient Ψ . In the context of sexually selected traits, strong positive Ψ tends to exaggerate evolutionary change, whereas negative Ψ impedes sexual trait elaboration. Despite its theoretical importance, whether and how Ψ varies among geographically distinct populations is unknown. Such information is necessary to evaluate the potential for IGEs to contribute to divergence among isolated or semi-isolated populations. Here, we report substantial variation in Ψ for a behavioural trait involved in sexual selection in the field cricket Teleogryllus oceanicus : female choosiness. Both the strength and direction of Ψ varied among geographically isolated populations. Ψ also changed over time. In a contemporary population of crickets from Kauai, experience of male song increased female choosiness. In contrast, experience of male song decreased choosiness in an ancestral population from the same location. This rapid change corroborates studies examining the evolvability of Ψ and demonstrates how interpopulation variation in the interaction coefficient might influence sexual selection and accelerate divergence of traits influenced by IGEs that contribute to reproductive isolation in nascent species or subspecies.

Urban Sexual Selection

2020 ◽  
pp. 234-252
Author(s):  
Tuul Sepp ◽  
Kevin J. McGraw ◽  
Mathieu Giraudeau
Keyword(s):  
Sexual Selection ◽  
Urban Environments ◽  
Wild Animal ◽  
Selection Pressures ◽  
Sexually Selected Traits ◽  
Chemical Signalling ◽  
Animal Populations ◽  
Challenges And Opportunities ◽  
Microevolutionary Change ◽  
Selected Traits

Human-modified habitats can present both challenges and opportunities for wild animals. Changes in the environment caused by urbanization can affect who survives and reproduces in wild animal populations. Accordingly, we can expect that changes in sexual selection pressures may occur in response to urbanization. Changes in sexually selected traits like bird song and colouration have been one of the main thrusts of urban ecology in recent decades. However, studies to date have focused on describing changes in sexual phenotypes in response to urban environmental change, and knowledge about genetic/microevolutionary change is lacking. Also, while some signalling modalities have been well studied and linked to human activities (e.g., changes in auditory signals in response to anthropogenic noise), others have received comparatively less attention in this context (e.g., effects of air pollution on chemical signalling). In addition, the focus has been mainly on the signal sender, instead of the signal receiver, thereby missing an important side of sexual selection. This chapter reviews the evidence that sexual selection pressures and sexually selected traits have been impacted by urban environments, with attention to the potential for rapid adaptive and plastic shifts in traits of signallers and receivers. It explores the possibilities that urbanization causes evolutionary change and speciation in wild animal populations through sexual selection. Finally, it provides new ideas for future studies to explore these questions and especially the evolution of female preferences in urban environments.

The causes and consequences of ornament variation in a natural population

2019 ◽  
Author(s):  
Annabel Ralph ◽  
Terry Burke ◽  
Shinichi Nakagawa ◽  
Alfredo Sánchez-Tójar ◽  
Julia Schroeder
Keyword(s):  
Sexual Selection ◽  
Evolutionary Biology ◽  
Natural Populations ◽  
Size Variation ◽  
Evolutionary Potential ◽  
House Sparrows ◽  
Sexually Selected Traits ◽  
Evolutionary Response ◽  
Significant Heritability ◽  
Selected Traits

The role of sexual selection in natural populations has long been the subject of debate in evolutionary biology. Ornaments are sexually selected traits, which means they should vary within a population, have a genetic basis, and be associated with fitness. Despite evidence of ornaments meeting these criteria, evolutionary responses to sexual selection are rare in nature. This study focuses on two ornaments in a population of house sparrows; the plumage badge has been well-studied but remains poorly understood and the mask has been largely neglected in the literature. Using quantitative genetic techniques, we estimate the heritability of both traits and test for age-dependency of the heritability estimates. We also estimate the strength and direction of any selection acting upon the traits. We found that both ornaments have low, significant heritability, which does not vary with age. Selection only occurs in a small number of years, although when it does it is positive in both ornaments. We also found that early social environment plays a role in badge size variation. The results of this study suggest that an evolutionary response in the ornaments of this population is unlikely, but we highlight the importance of long-term research to improve our understanding of evolution in natural populations. Studies like these will add to our understanding of sexual selection, the causes of trait variation and the evolutionary potential of traits, which could help us to predict how populations will evolve.

scholarly journals Sex allocation and investment into pre- and post-copulatory traits in simultaneous hermaphrodites: the role of polyandry and local sperm competition

2013 ◽  
Vol 368 (1613) ◽  
pp. 20120052 ◽  
Author(s):  
Lukas Schärer ◽  
Ido Pen
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Sex Allocation ◽  
Optimal Allocation ◽  
Recent Theory ◽  
Detailed Knowledge ◽  
Female Reproduction ◽  
Sexually Selected Traits ◽  
Simultaneous Hermaphrodites

Sex allocation theory predicts the optimal allocation to male and female reproduction in sexual organisms. In animals, most work on sex allocation has focused on species with separate sexes and our understanding of simultaneous hermaphrodites is patchier. Recent theory predicts that sex allocation in simultaneous hermaphrodites should strongly be affected by post-copulatory sexual selection, while the role of pre-copulatory sexual selection is much less clear. Here, we review sex allocation and sexual selection theory for simultaneous hermaphrodites, and identify several strong and potentially unwarranted assumptions. We then present a model that treats allocation to sexually selected traits as components of sex allocation and explore patterns of allocation when some of these assumptions are relaxed. For example, when investment into a male sexually selected trait leads to skews in sperm competition, causing local sperm competition, this is expected to lead to a reduced allocation to sperm production. We conclude that understanding the evolution of sex allocation in simultaneous hermaphrodites requires detailed knowledge of the different sexual selection processes and their relative importance. However, little is currently known quantitatively about sexual selection in simultaneous hermaphrodites, about what the underlying traits are, and about what drives and constrains their evolution. Future work should therefore aim at quantifying sexual selection and identifying the underlying traits along the pre- to post-copulatory axis.

scholarly journals Sexually selected skin colour is heritable and related to fecundity in a non-human primate

2014 ◽  
Vol 281 (1794) ◽  
pp. 20141602 ◽  
Author(s):  
Constance Dubuc ◽  
Sandra Winters ◽  
William L. Allen ◽  
Lauren J. N. Brent ◽  
Julie Cascio ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Individual Variation ◽  
Balancing Selection ◽  
Rhesus Macaques ◽  
Reproductive Rate ◽  
Condition Dependence ◽  
Selection Gradients ◽  
Sexually Selected Traits ◽  
Skin Redness ◽  
Selected Traits

Sexual selection promotes the prevalence of heritable traits that increase an individual's reproductive rate. Despite theoretically strong directional selection, sexually selected traits can show inter-individual variation. Here, we investigate whether red skin ornamentation, a rare example of a male mammalian trait involved in mate attraction, influences fecundity and is heritable in rhesus macaques ( Macaca mulatta ), and explore the mechanisms that are involved in maintaining trait variation. Interestingly, the trait is expressed by and is attractive to both sexes. We collected facial images of 266 free-ranging individuals and modelled skin redness and darkness to rhesus macaque vision. We used 20 years of genetic parentage data to calculate selection gradients on the trait and perform heritability analyses. Results show that males who were both darkly coloured and high-ranking enjoyed higher fecundity. Female skin redness was positively linked to fecundity, although it remains unclear whether this influences male selectiveness. Heritability explained 10–15% of the variation in redness and darkness, and up to 30% for skin darkness when sexes are considered separately, suggesting sex-influenced inheritance. Our results suggest that inter-individual variation is maintained through condition-dependence, with an added effect of balancing selection on male skin darkness, providing rare evidence for a mammalian trait selected through inter-sexual selection.

Symmetrical and asymmetrical sexual isolation among laboratory strains of Drosophila ananassae

1985 ◽  
Vol 27 (4) ◽  
pp. 405-409 ◽  
Author(s):  
Bashisth N. Singh ◽  
Sujata Chatterjee
Keyword(s):  
Sexual Selection ◽  
Reproductive Isolation ◽  
Assortative Mating ◽  
Sexual Isolation ◽  
Drosophila Ananassae ◽  
Isofemale Lines ◽  
Male Choice ◽  
Positive Assortative Mating ◽  
Different Strains ◽  
Assortive Mating

Male-choice experiments using five isofemale lines of Drosophila ananassae originating from different localities were performed to study sexual isolation within the species. In most of the crosses homogamic matings outnumber heterogamic ones, and deviation from randomness is statistically significant in 11 of 20 crosses. This provides evidence for positive assortative mating within D. ananassae. Isolation indices range from −0.057 to 0.555. Eleven positive isolation indices are significantly greater than zero. Both types of sexual isolation, symmetrical and asymmetrical, have been observed among different strains. Thus the present results clearly indicate that the laboratory strains of D. ananassae have developed behavioural reproductive isolation as a result of genetic divergence.Key words: Drosophila, assortive mating, sexual selection, behaviour.

scholarly journals Rapid courtship evolution in grouse (Tetraonidae): contrasting patterns of acceleration between the Eurasian and North American polygynous clades

2007 ◽  
Vol 274 (1613) ◽  
pp. 1079-1086 ◽  
Author(s):  
Allen Spaulding
Keyword(s):  
Sexual Selection ◽  
Mating Success ◽  
Male Mating ◽  
Sexually Dimorphic ◽  
Sexually Selected Traits ◽  
Species Pairs ◽  
Rapid Divergence ◽  
Nucleotide Divergence ◽  
Selected Traits ◽  
Dimorphic Species

Sexual selection is thought to be a powerful diversifying force, based on large ornamental differences between sexually dimorphic species. This assumes that unornamented phenotypes represent evolution without sexual selection. If sexual selection is more powerful than other forms of selection, then two effects would be: rapid divergence of sexually selected traits and a correlation between these divergence rates and variance in mating success in the ornamented sex. I tested for these effects in grouse (Tetraonidae). For three species pairs, within and among polygynous clades, male courtship characters had significantly greater divergence than other characters. This was most pronounced for two species in Tympanuchus . In the Eurasian polygynous clade, relative courtship divergence gradually increased with nucleotide divergence, suggesting a less dramatic acceleration. Increase in relative courtship divergence was associated with mating systems having higher variance in male mating success. These results suggest that sexual selection has accelerated courtship evolution among grouse, although the microevolutionary details appear to vary among clades.

scholarly journals Female preference for multi-modal courtship: multiple signals are important for male mating success in peacock spiders

2015 ◽  
Vol 282 (1820) ◽  
pp. 20152222 ◽  
Author(s):  
Madeline B. Girard ◽  
Damian O. Elias ◽  
Michael M. Kasumovic
Keyword(s):  
Sexual Selection ◽  
Mating Success ◽  
Female Preference ◽  
Male Mating ◽  
Sexually Dimorphic ◽  
Complex Signals ◽  
Sexually Selected Traits ◽  
Redundant Signal ◽  
Multiple Messages ◽  
Selected Traits

A long-standing goal for biologists has been to understand how female preferences operate in systems where males have evolved numerous sexually selected traits. Jumping spiders of the Maratus genus are exceptionally sexually dimorphic in appearance and signalling behaviour. Presumably, strong sexual selection by females has played an important role in the evolution of complex signals displayed by males of this group; however, this has not yet been demonstrated. In fact, despite apparent widespread examples of sexual selection in nature, empirical evidence is relatively sparse, especially for species employing multiple modalities for intersexual communication. In order to elucidate whether female preference can explain the evolution of multi-modal signalling traits, we ran a series of mating trials using Maratus volans . We used video recordings and laser vibrometry to characterize, quantify and examine which male courtship traits predict various metrics of mating success. We found evidence for strong sexual selection on males in this system, with success contingent upon a combination of visual and vibratory displays. Additionally, independently produced, yet correlated suites of multi-modal male signals are linked to other aspects of female peacock spider behaviour. Lastly, our data provide some support for both the redundant signal and multiple messages hypotheses for the evolution of multi-modal signalling.

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