scholarly journals Experimental evidence that female ornamentation increases the acquisition of sperm and signals fecundity

2006 ◽  
Vol 274 (1609) ◽  
pp. 583-590 ◽  
Author(s):  
Charlie K Cornwallis ◽  
Tim R Birkhead

Mate choice can lead to the evolution of sexual ornamentation. This idea rests on the assumption that individuals with more elaborate ornaments than competitors have higher reproductive success due to gaining greater control over mating decisions and resources provided by partners. Nevertheless, how the resources and quality of sexual partners that individuals gain access to are influenced by the ornamentation of rival individuals remains unclear. By experimentally concealing and subsequently revealing female ornaments to males, we confirm in the fowl, Gallus gallus , that female ornamentation influences male mating decisions. We further show, by manipulating the relative ornament size of females, that when females had larger ornaments than competitors they were more often preferred by males and obtained more sperm, especially from higher quality males, as measured by social status. Males may benefit by investing more sperm in females with larger ornaments as they were in better condition and produced heavier eggs. Female ornament size also decreased during incubation, providing a cue for males to avoid sexually unreceptive females. This study reveals how inter-sexual selection can lead to the evolution of female ornaments and highlights how the reproductive benefits gained from mate choice and bearing ornaments can be dependent upon social context.

Author(s):  
Ingo Schlupp

In this final chapter I want to briefly recap what I presented in the previous chapters and provide a few ideas on what might be done in the future to move the field forward. All three factors I discussed as relevant in male mate choice—male investment in reproduction, sex ratios, and variability in partner quality—are still emerging fields in sexual selection research and need more theoretical and empirical work. I suggest that variability in female quality is more important and more complex than currently known. The same is true for sex ratios. On the other hand, I suggest that sheer investment in gametes may be a little less important than currently assumed. Most importantly we need to explore the interactions of these three pathways to male mate choice. Female competition and also female ornamentation are still somewhat enigmatic and both topics are likely to grow in importance for our understanding of sexual selection. I think considering male and female choice together, as well as female and male competition will ultimately provide a more complete picture of Darwinian sexual selection.


Author(s):  
Ingo Schlupp

When Darwin first proposed sexual selection theory he suggested two mechanisms: competition among males and choice by females. There is no doubt that these mechanisms are immensely important, but their mirror images have been largely underappreciated so far. In fact, males choose as well and females compete. Males choose based on female quality, often selecting mating partners that are more fecund. But male choice is also associated with changes in the sex ratio of a population and males can be choosy when they are rare. Furthermore, males sometimes invest heavily into reproduction and that too can be associated with male choice. That females compete with another, although less often with open aggression, is another understudied phenomenon. Finally, we now know that females are often ornamented, but are these ornaments under sexual selection by males? This book tries to review what we know and point to what we don’t know while pointing out the connections between male mate choice and female competition for a more complete view of sexual selection.


2006 ◽  
Vol 361 (1466) ◽  
pp. 319-334 ◽  
Author(s):  
Hanna Kokko ◽  
Daniel J Rankin

Two very basic ideas in sexual selection are heavily influenced by numbers of potential mates: the evolution of anisogamy, leading to sex role differentiation, and the frequency dependence of reproductive success that tends to equalize primary sex ratios. However, being explicit about the numbers of potential mates is not typical to most evolutionary theory of sexual selection. Here, we argue that this may prevent us from finding the appropriate ecological equilibria that determine the evolutionary endpoints of selection. We review both theoretical and empirical advances on how population density may influence aspects of mating systems such as intrasexual competition, female choice or resistance, and parental care. Density can have strong effects on selective pressures, whether or not there is phenotypic plasticity in individual strategies with respect to density. Mating skew may either increase or decrease with density, which may be aided or counteracted by changes in female behaviour. Switchpoints between alternative mating strategies can be density dependent, and mate encounter rates may influence mate choice (including mutual mate choice), multiple mating, female resistance to male mating attempts, mate searching, mate guarding, parental care, and the probability of divorce. Considering density-dependent selection may be essential for understanding how populations can persist at all despite sexual conflict, but simple models seem to fail to predict the diversity of observed responses in nature. This highlights the importance of considering the interaction between mating systems and population dynamics, and we strongly encourage further work in this area.


2015 ◽  
Vol 11 (10) ◽  
pp. 20150599 ◽  
Author(s):  
Juhani Hopkins ◽  
Gautier Baudry ◽  
Ulrika Candolin ◽  
Arja Kaitala

In many species, males rely on sexual ornaments to attract females. Females, by contrast, rarely produce ornaments. The glow-worm ( Lampyris noctiluca ) is an exception where wingless females glow to attract males that fly in search of females. However, little is known about the factors that promote the evolution of female ornaments in a sexual selection context. Here, we investigated if the female ornament of the glow-worm is a signal of fecundity used in male mate choice. In support of this, we found brightness to correlate with female fecundity, and males to prefer brighter dummy females. Thus, the glow emitted by females is a reliable sexual signal of female fecundity. It is likely that male preference for the fecundity-indicating ornament has evolved because of large variation among females in fecundity, and because nocturnal males cannot directly assess female size and fecundity. These results indicate that female ornamentation may evolve in capital breeders (i.e. those in which stored resources are invested in reproduction) when females vary significantly in fecundity and this variation cannot be assessed directly by males.


2009 ◽  
Vol 6 (2) ◽  
pp. 225-228 ◽  
Author(s):  
Aleksi Lehikoinen ◽  
Kim Jaatinen ◽  
Markus Öst

The fitness consequences of female ornamentation remain little studied and the results are often contradictory. Female ornamentation may be an artefact of a genetic correlation with male ornamentation, but this possibility can be disregarded if the ornament only occurs in females. Female-specific white wing bars in eiders ( Somateria mollissima ) have been suggested to indicate individual quality, and we studied size variation in this trait in relation to key fitness components and quality attributes. We found that clutch size, body condition, female age, hatching date and success were unrelated to female ornament size; ornament size was explained by its size in the previous year. In contrast, good body condition was associated with hatching success. These results suggest that the breadth of the white wing bars does not indicate individual quality in our study population.


2019 ◽  
Vol 113 (1) ◽  
pp. 40-49
Author(s):  
Christopher S Angell ◽  
Sharon Curtis ◽  
Anaïs Ryckenbusch ◽  
Howard D Rundle

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.


2020 ◽  
Author(s):  
Christopher Angell ◽  
Sharon Curtis ◽  
Anaïs Ryckenbusch ◽  
Howard Rundle

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.


2018 ◽  
Vol 285 (1883) ◽  
pp. 20180836 ◽  
Author(s):  
Jukka Kekäläinen ◽  
Jonathan P. Evans

‘Sperm competition’—where ejaculates from two or more males compete for fertilization—and ‘cryptic female choice’—where females bias this contest to suit their reproductive interests—are now part of the everyday lexicon of sexual selection. Yet the physiological processes that underlie these post-ejaculatory episodes of sexual selection remain largely enigmatic. In this review, we focus on a range of post-ejaculatory cellular- and molecular-level processes, known to be fundamental for fertilization across most (if not all) sexually reproducing species, and point to their putative role in facilitating sexual selection at the level of the cells and gametes, called ‘gamete-mediated mate choice’ (GMMC). In this way, we collate accumulated evidence for GMMC across different mating systems, and emphasize the evolutionary significance of such non-random interactions among gametes. Our overall aim in this review is to build a more inclusive view of sexual selection by showing that mate choice often acts in more nuanced ways than has traditionally been assumed. We also aim to bridge the conceptual divide between proximal mechanisms of reproduction, and adaptive explanations for patterns of non-random sperm–egg interactions that are emerging across an increasingly diverse array of taxa.


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