scholarly journals Antagonistic selection on body size and sword length in a wild population of the swordtail fish, Xiphophorus multilineatus: potential for intralocus tactical conflict

2021 ◽  
Author(s):  
Melissa Liotta ◽  
Jessica Abbott ◽  
Molly Morris ◽  
Oscar Rios-Cardenas
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Wild Population ◽  
Genetic Correlations ◽  
Reproductive Tactics ◽  
Swordtail Fish ◽  
The Arts ◽  
In The Wild ◽  
Life History Tradeoffs

Alternative reproductive tactics (ARTs) have provided valuable insights into how sexual selection and life history tradeoffs can lead to variation within a sex. However, the possibility that tactics may constrain evolution through intralocus tactical conflict (IATC) is rarely considered. In addition, when IATC has been considered, the focus has often been on the genetic correlations between the ARTs, while evidence that the ARTs have different optima for associated traits and that at least one of the tactics is not at its optima is often missing. Here we investigate selection on three traits associated with the ARTs in the swordtail fish Xiphophorus multilineatus; body size, body shape and the sexually selected trait for which these fishes were named, sword length (elongation of the caudal fin). All three traits are tactically dimorphic, with courter males being larger, deeper bodied and having longer swords, and the sneaker males being smaller, more fusiform and having shorter swords. Using measures of reproductive success in a wild population we calculated selection differentials, linear and quadratic gradients, demonstrate that the tactics have different optima and at least one of the tactics is not at its optima for body size and sword length. Our results provide the first evidence of selection in the wild on the sword, an iconic trait for sexual selection. In addition, given the high probability that these traits are genetically correlated to some extent between the two tactics, our study suggests that IATC is constraining both body size and the sword from reaching their phenotypic optima. We discuss the importance of considering the role of IATC in the evolution of tactical dimorphism, how this conflict can be present despite tactical dimorphism, and how it is important to consider this conflict when explaining not only variation within a species but differences across species as well.

scholarly journals Genetic correlations across genetically determined and developmentally plastic alternative reproductive tactics

2019 ◽  
Author(s):  
Jessica K. Abbott ◽  
Oscar Rios-Cardenas ◽  
Molly Morris
Keyword(s):  
Body Size ◽  
Genetic Correlation ◽  
Genetic Correlations ◽  
Phenotypic Expression ◽  
Alternative Reproductive Tactics ◽  
Phenotypic Trait ◽  
Sexual Antagonism ◽  
Reproductive Tactics ◽  
Genetic Conflict ◽  
Genetically Determined

AbstractAlternative reproductive tactics occur when individuals of the same sex have a suite of morphological and/or behavioural traits that allow them to pursue different reproductive strategies. A common pattern is e.g. the existence of “courter” and “sneaker” tactics within males. We have previously argued that alternative reproductive tactics should be subject to genetic conflict over the phenotypic expression of traits, similar to sexual antagonism. In this process, which we called intra-locus tactical conflict, genetically determined tactics experience conflicting selection on a shared phenotypic trait, such as body size, but a positive genetic correlation between tactics in body size prevents either tactic from reaching its optimum. Recently, other authors have attempted to extend this idea to developmentally plastic alternative reproductive tactics, with mixed results. However, it is not clear whether we should expect intra-locus tactical conflict in developmentally plastic tactics or not. We have therefore run a series of simulation models investigating under what conditions we should expect to see positive estimates of the inter-tactical genetic correlation, since a positive genetic correlation is a prerequisite for the existence of intra-locus tactical conflict. We found that for autosomal, X-linked, and Y-linked genetically-determined tactics, estimated inter-tactical genetic correlations were generally high. However, for developmentally plastic tactics, the genetic correlation depends on the properties of the switching threshold between tactics. If it is fixed, then estimated genetic correlations are positive, but if there is genetic variation in the switch-point, then any sign and magnitude of estimated genetic correlation is possible, even for highly heritable traits where the true underlying correlation is perfect. This means that caution should be used when investigating genetic constraints in plastic phenotypes.

scholarly journals Nestling telomere length does not predict longevity, but covaries with adult body size in wild barn swallows

2013 ◽  
Vol 9 (5) ◽  
pp. 20130340 ◽  
Author(s):  
Manuela Caprioli ◽  
Maria Romano ◽  
Andrea Romano ◽  
Diego Rubolini ◽  
Rosita Motta ◽  
...  
Keyword(s):  
Body Size ◽  
Telomere Length ◽  
Large Body ◽  
Telomere Shortening ◽  
Rearing Conditions ◽  
Age Dependent ◽  
In The Wild ◽  
Barn Swallows ◽  
The Cost

Telomere length and dynamics are increasingly scrutinized as ultimate determinants of performance, including age-dependent mortality and fecundity. Few studies have investigated longevity in relation to telomere length (TL) in the wild and none has analysed longevity in relation to TL soon after hatching, despite the fact that telomere shortening may mostly occur early in life. We show that TL in nestling barn swallows ( Hirundo rustica ) in the wild does not predict longevity. However, TL positively covaries with body size, suggesting that individuals with large TL can afford to grow larger without paying the cost of reduced TL, and/or that benign rearing conditions ensure both large body size and low rates of telomere shortening. Overall, our study hints at a role of TL in developmental processes, but also indicates a need for further analyses to assess the expectation that TL in young individuals predicts longevity in the wild.

scholarly journals It is not always about body size: evidence of Rensch's rule in a male weapon

2021 ◽  
Vol 17 (6) ◽  
pp. 20210234
Author(s):  
Glauco Machado ◽  
Bruno A. Buzatto ◽  
Diogo S. M. Samia
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Potential Role ◽  
Empirical Studies ◽  
Condition Dependence ◽  
Rensch’S Rule ◽  
Evolutionary Pattern ◽  
Rensch's Rule ◽  
Original Proposal

In many species, sexual dimorphism increases with body size when males are the larger sex but decreases when females are the larger sex, a macro-evolutionary pattern known as Rensch's rule (RR). Although empirical studies usually focus exclusively on body size, Rensch's original proposal included sexual differences in other traits, such as ornaments and weapons. Here, we used a clade of harvestmen to investigate whether two traits follow RR: body size and length of the fourth pair of legs (legs IV), which are used as weapons in male–male fights. We found that males were slightly smaller than females and body size did not follow RR, whereas legs IV were much longer in males and followed RR. We propose that sexual selection might be stronger on legs IV length than on body size in males, and we discuss the potential role of condition dependence in the emergence of RR.

scholarly journals Autosomal variation for male body size and sperm competition phenotypes is uncorrelated in Drosophila melanogaster

2008 ◽  
Vol 4 (5) ◽  
pp. 500-503 ◽  
Author(s):  
Rui Zhang ◽  
Linda Amah ◽  
Anthony C Fiumera
Keyword(s):  
Drosophila Melanogaster ◽  
Sexual Selection ◽  
Body Size ◽  
Genetic Correlations ◽  
Male Body ◽  
Substitution Lines ◽  
Male Body Size ◽  
Chromosome Substitution Lines ◽  
Significant Line ◽  
Sexually Antagonistic Coevolution

Correlations between male body size and phenotypes impacting post-copulatory sexual selection are commonly observed during the manipulation of male body size by environmental rearing conditions. Here, we control for environmental influences and test for genetic correlations between natural variation in male body size and phenotypes affecting post-copulatory sexual selection in Drosophila melanogaster . Dry weights of virgin males from 90 second-chromosome and 88 third-chromosome substitution lines were measured. Highly significant line effects ( p <0.001) documented a genetic basis to variation in male body size. No significant correlations were identified between male body size and the components of sperm competitive ability. These results suggest that natural autosomal variation for male body size has little impact on post-copulatory sexual selection. If genetic correlations exist between male body size and post-copulatory sexual selection then variation in the sex chromosomes are likely candidates, as might be expected if sexually antagonistic coevolution was responsible.

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

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.

The role of sexual selection in the loss of sexually selected traits in the swordtail fish Xiphophorus continens

2005 ◽  
Vol 69 (6) ◽  
pp. 1415-1424 ◽  
Author(s):  
Molly R. Morris ◽  
Jason A. Moretz ◽  
Kristen Farley ◽  
Paul Nicoletto
Keyword(s):  
Sexual Selection ◽  
Sexually Selected Traits ◽  
Swordtail Fish ◽  
Selected Traits

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

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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