Polyandry as a mediator of sexual selection before and after mating

The Darwin–Bateman paradigm recognizes competition among males for access to multiple mates as the main driver of sexual selection. Increasingly, however, females are also being found to benefit from multiple mating so that polyandry can generate competition among females for access to multiple males, and impose sexual selection on female traits that influence their mating success. Polyandry can reduce a male's ability to monopolize females, and thus weaken male focused sexual selection. Perhaps the most important effect of polyandry on males arises because of sperm competition and cryptic female choice. Polyandry favours increased male ejaculate expenditure that can affect sexual selection on males by reducing their potential reproductive rate. Moreover, sexual selection after mating can ameliorate or exaggerate sexual selection before mating. Currently, estimates of sexual selection intensity rely heavily on measures of male mating success, but polyandry now raises serious questions over the validity of such approaches. Future work must take into account both pre- and post-copulatory episodes of selection. A change in focus from the products of sexual selection expected in males, to less obvious traits in females, such as sensory perception, is likely to reveal a greater role of sexual selection in female evolution.

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Epicuticular Compounds of Protopiophila litigata (Diptera: Piophilidae): Identification and Sexual Selection Across Two Years in the Wild

Annals of the Entomological Society of America ◽

10.1093/aesa/saz056 ◽

2019 ◽

Vol 113 (1) ◽

pp. 40-49

Author(s):

Christopher S Angell ◽

Sharon Curtis ◽

Anaïs Ryckenbusch ◽

Howard D Rundle

Keyword(s):

Sexual Selection ◽

Mate Choice ◽

Mating Success ◽

Natural Populations ◽

Male Mating ◽

Cross Sectional ◽

Or Groups ◽

In The Wild ◽

Males And Females

Abstract The epicuticular compounds (ECs) of insects serve both to waterproof the cuticle and, in many taxa, as pheromones that are important for various social interactions, including mate choice within populations. However, ECs have not been individually identified in many species and most studies of their role in mate choice have been performed in a laboratory setting. Here we newly identify and quantify the ECs of the antler fly, Protopiophila litigata Bonduriansky, and use a cross-sectional selection analysis to quantify their association with male mating success in the wild across two years (2013 and 2017). The ECs of antler flies include straight-chain and methylated alkanes, alkenes, and a family of branched wax esters. We find all ECs to be shared between males and females but also demonstrate sexual dimorphism in the abundance of several. Male EC relative abundances were significantly associated with mating success in both years, although the multivariate direction of selection differed significantly between the years. Surprisingly, only two of the 18 compounds (or groups of compounds) we identified were similarly associated with mating success across the sampling years. In 2017, we further partitioned sexual selection into intra- and intersexual components, revealing selection on ECs to be significant via female choice but not male–male competition. Our study is one of few to investigate the potential role of ECs in mating success in the wild and adds to a growing body of evidence demonstrating significant temporal variability in selection in natural populations.

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Epicuticular compounds of Protopiophila litigata (Diptera: Piophilidae): identification and sexual selection across two years in the wild

10.32942/osf.io/cm5sa ◽

2020 ◽

Author(s):

Christopher Angell ◽

Sharon Curtis ◽

Anaïs Ryckenbusch ◽

Howard Rundle

Keyword(s):

Sexual Selection ◽

Mate Choice ◽

Mating Success ◽

Natural Populations ◽

Male Mating ◽

Cross Sectional ◽

Or Groups ◽

In The Wild ◽

Males And Females

The epicuticular compounds (ECs) of insects serve both to waterproof the cuticle and, in many taxa, as pheromones that are important for various social interactions including mate choice within populations. However, ECs have not been individually identified in many species and most studies of their role in mate choice have been performed in a laboratory setting. Here we newly identify and quantify the ECs of the antler fly, Protopiophila litigata Bonduriansky, and use a cross-sectional selection analysis to quantify their association with male mating success in the wild across two years (2013 and 2017). The ECs of antler flies include straight-chain and methylated alkanes, alkenes, and a family of branched wax esters. We find all ECs to be shared between males and females but also demonstrate sexual dimorphism in the abundance of several. Male EC relative abundances were significantly associated with mating success in both years, although the multivariate direction of selection differed significantly between the years. Surprisingly, only two of the 18 compounds (or groups of compounds) we identified were similarly associated with mating success across the sampling years. In 2017, we further partitioned sexual selection into intra- and intersexual components, revealing selection on ECs to be significant via female choice but not male-male competition. Our study is one of few to investigate the potential role of ECs in mating success in the wild and adds to a growing body of evidence demonstrating significant temporal variability in selection in natural populations.

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Plumage iridescence is associated with distinct feather microbiota in a tropical passerine

Scientific Reports ◽

10.1038/s41598-019-49220-y ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Veronika Gvoždíková Javůrková ◽

Erik D. Enbody ◽

Jakub Kreisinger ◽

Kryštof Chmel ◽

Jakub Mrázek ◽

...

Keyword(s):

Sexual Selection ◽

Community Structure ◽

Microbial Communities ◽

Plumage Coloration ◽

Microbial Load ◽

Sexual Dichromatism ◽

Physiological Processes ◽

Fitness Consequences ◽

Future Work

Abstract Birds present a stunning diversity of plumage colors that have long fascinated evolutionary ecologists. Although plumage coloration is often linked to sexual selection, it may impact a number of physiological processes, including microbial resistance. At present, the degree to which differences between pigment-based vs. structural plumage coloration may affect the feather microbiota remains unanswered. Using quantitative PCR and DGGE profiling, we investigated feather microbial load, diversity and community structure among two allopatric subspecies of White-shouldered Fairywren, Malurus alboscapulatus that vary in expression of melanin-based vs. structural plumage coloration. We found that microbial load tended to be lower and feather microbial diversity was significantly higher in the plumage of black iridescent males, compared to black matte females and brown individuals. Moreover, black iridescent males had distinct feather microbial communities compared to black matte females and brown individuals. We suggest that distinctive nanostructure properties of iridescent male feathers or different investment in preening influence feather microbiota community composition and load. This study is the first to point to structural plumage coloration as a factor that may significantly regulate feather microbiota. Future work might explore fitness consequences and the role of microorganisms in the evolution of avian sexual dichromatism, with particular reference to iridescence.

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Influence of density and major histocompatibility genotype on sexual selection in a salmonid alternative mating strategy

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f2012-007 ◽

2012 ◽

Vol 69 (4) ◽

pp. 670-680 ◽

Cited By ~ 5

Author(s):

Laura K. Weir ◽

Jeffrey A. Hutchings ◽

Daniel D. Heath

Keyword(s):

Sexual Selection ◽

Salmo Salar ◽

Fertilization Success ◽

Mating Strategy ◽

Male Mating ◽

Salmonid Fishes ◽

Major Histocompatibility ◽

Main Determinant ◽

Alternative Mating Strategy

Various mechanisms of sexual selection can occur at both the whole organism and gamete levels. Fertilization success in salmonid fishes is largely determined by behavioural competition within and between “fighter” and “sneaker” male strategies, but is also influenced by interactions among gametes. We investigated the influence of density, fighter male presence, and major histocompatibility (MH) genotype on patterns of fertilization success in sneaker Atlantic salmon ( Salmo salar ). At low density and in the absence of fighter males, monopolization by single sneaker males occurred, suggesting that male–male competition was the main determinant of fertilization success. By contrast, at high density and (or) in the presence of fighter males, several sneakers succeeded in fertilizing eggs. Our study, the first to investigate the role of MH-mediated fertilization for a genetically based alternative male mating strategy, suggests that a larger proportion of eggs were fertilized by sneakers whose MH genotypes were more similar to those of the female than expected by chance. These findings highlight the importance of examining sexual selection under different competitive conditions.

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Territory size as a main driver of male-mating success in an Amazonian nurse frog (Allobates paleovarzensis, Dendrobatoidea)

acta ethologica ◽

10.1007/s10211-017-0280-5 ◽

2017 ◽

Vol 21 (1) ◽

pp. 51-57 ◽

Cited By ~ 5

Author(s):

Sulamita Marques Correia da Rocha ◽

Albertina Pimentel Lima ◽

Igor Luis Kaefer

Keyword(s):

Mating Success ◽

Territory Size ◽

Male Mating ◽

Male Mating Success ◽

Main Driver

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Structure of sexual networks determines the operation of sexual selection

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1710450115 ◽

2017 ◽

Vol 115 (1) ◽

pp. E53-E61 ◽

Cited By ~ 21

Author(s):

Grant C. McDonald ◽

Tommaso Pizzari

Keyword(s):

Sexual Selection ◽

Mating Success ◽

Empirical Studies ◽

Evolutionary Process ◽

Population Level ◽

Network Size ◽

Male Mating ◽

Male Mating Success ◽

Sexual Network ◽

Bateman Gradient

Sexual selection is a fundamental evolutionary process but remains debated, particularly in the complexity of polyandrous populations where females mate with multiple males. This lack of resolution is partly because studies have largely ignored the structure of the sexual network, that is, the pattern of mate sharing. Here, we quantify what we call mating assortment with network analysis to specify explicitly the indirect as well as direct relationships between partners. We first review empirical studies, showing that mating assortment varies considerably in nature, due largely to basic properties of the sexual network (size and density) and partly to nonrandom patterns of mate sharing. We then use simulations to show how variation in mating assortment interacts with population-level polyandry to determine the strength of sexual selection on males. Controlling for average polyandry, positive mating assortment, arising when more polygynous males tend to mate with more polyandrous females, drastically decreases the intensity of precopulatory sexual selection on male mating success (Bateman gradient) and the covariance between male mating success and postcopulatory paternity share. Average polyandry independently weakened some measures of sexual selection and crucially also impacted sexual selection indirectly by constraining mating assortment through the saturation of the mating network. Mating assortment therefore represents a key—albeit overlooked—modulator of the strength of sexual selection. Our results show that jointly considering sexual network structure and average polyandry more precisely describes the strength of sexual selection.

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