scholarly journals Sexual size dimorphism and sexual selection in artiodactyls

2020 ◽  
Vol 31 (3) ◽  
pp. 792-797
Author(s):  
Marcelo H Cassini
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Group Size ◽  
Sexual Size Dimorphism ◽  
Alternative Hypothesis ◽  
Mammalian Species ◽  
Generalized Least Squares ◽  
Size Dimorphism ◽  
Selection For

Abstract Sexual size dimorphism is biased toward males in most mammalian species. The most common explanation is precopulatory intramale sexual selection. Large males win fights and mate more frequently. In artiodactyls, previous tests of this hypothesis consisted of interspecific correlations of sexual dimorphism with group size as a surrogate for the intensity of sexual selection (Is). However, group size is not a proper measure of sexual selection for several reasons as is largely recognized in other mammalian taxa. I conducted an interspecific test on the role of sexual selection in the evolution of sexual dimorphism using the variance in genetic paternity as a proxy for the Is. I reviewed the literature and found 17 studies that allowed estimating Is= V/(W2), where V and W are the variance and mean number of offspring per male, respectively. A phylogenetic generalized least squares analysis indicated that dimorphism (Wm/Wf) showed a significant positive regression with the intensity of sexual selection but not group size (multiple r2= 0.40; F3,17= 12.78, P = 0.002). This result suggests that sexual selection may have played a role in the evolution of sexual size dimorphism in Artiodactyla. An alternative hypothesis based on natural selection is discussed.

The evolution of sexual dimorphism in the lizard Anolis polylepis (Iguania): evidence from intraspecific variation in foraging behavior and diet

1996 ◽  
Vol 74 (7) ◽  
pp. 1238-1245 ◽  
Author(s):  
Gad Perry
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Feeding Behavior ◽  
Rain Forest ◽  
Sexual Size Dimorphism ◽  
Costa Rican ◽  
Agonistic Interactions ◽  
Size Dimorphism ◽  
Food Items ◽  
Competing Hypotheses

Two main explanations, intraspecific niche divergence and sexual selection, have been proposed to explain the origin of sexual size dimorphism. To test these competing hypotheses I studied the ecology, feeding behavior, and diet of the lizard Anolis polylepis in a Costa Rican rain forest. Male A. polylepis were significantly larger and heavier than females but ate smaller food items and had lower stomach volumes, despite possessing longer and wider heads. Males were more sedentary than females or juveniles, chose higher perches, and were more likely to be involved in agonistic interactions. Diets of males, females, and juveniles were also significantly different taxonomically. These data are consistent with the sexual selection origin theory but not with an ecological one. Thus, observed dietary differences probably evolved once dimorphism had been attained through sexual selection.

The role of fecundity and sexual selection in the evolution of size and sexual size dimorphism in New World and Old World voles (Rodentia: Arvicolinae)

Oikos ◽  
2015 ◽  
Vol 125 (9) ◽  
pp. 1250-1260 ◽  
Author(s):  
Vicente García-Navas ◽  
Timothée Bonnet ◽  
Raúl Bonal ◽  
Erik Postma
Keyword(s):  
Sexual Selection ◽  
New World ◽  
Sexual Size Dimorphism ◽  
Old World ◽  
Size Dimorphism

scholarly journals Selection for increased male size predicts variation in sexual size dimorphism among fish species

2020 ◽  
Vol 287 (1918) ◽  
pp. 20192640 ◽  
Author(s):  
Curtis R. Horne ◽  
Andrew G. Hirst ◽  
David Atkinson
Keyword(s):  
Sexual Selection ◽  
Fish Species ◽  
Sexual Size Dimorphism ◽  
Male Competition ◽  
Energy Output ◽  
Female Size ◽  
Male Size ◽  
Size Dimorphism ◽  
Fecundity Selection ◽  
Selection For

Variation in the degree of sexual size dimorphism (SSD) among taxa is generally considered to arise from differences in the relative intensity of male–male competition and fecundity selection. One might predict, therefore, that SSD will vary systematically with (1) the intensity of sexual selection for increased male size, and (2) the intensity of fecundity selection for increased female size. To test these two fundamental hypotheses, we conducted a phylogenetic comparative analysis of SSD in fish. Specifically, using records of body length at first sexual maturity from FishBase, we quantified variation in the magnitude and direction of SSD in more than 600 diverse freshwater and marine fish species, from sticklebacks to sharks. Although female-biased SSD was common, and thought to be driven primarily by fecundity selection, variation in SSD was not dependent on either the allometric scaling of reproductive energy output or fecundity in female fish. Instead, systematic patterns based on habitat and life-history characteristics associated with varying degrees of male–male competition and paternal care strongly suggest that adaptive variation in SSD is driven by the intensity of sexual selection for increased male size.

scholarly journals Independent evolution of the sexes promotes amphibian diversification

2015 ◽  
Vol 282 (1803) ◽  
pp. 20142213 ◽  
Author(s):  
Stephen P. De Lisle ◽  
Locke Rowe
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Sexual Size Dimorphism ◽  
Alternative Hypothesis ◽  
Ecological Theory ◽  
Adaptive Landscape ◽  
Extinction Rate ◽  
Independent Evolution ◽  
Threat Status ◽  
The Relationship

Classic ecological theory predicts that the evolution of sexual dimorphism constrains diversification by limiting morphospace available for speciation. Alternatively, sexual selection may lead to the evolution of reproductive isolation and increased diversification. We test contrasting predictions of these hypotheses by examining the relationship between sexual dimorphism and diversification in amphibians. Our analysis shows that the evolution of sexual size dimorphism (SSD) is associated with increased diversification and speciation, contrary to the ecological theory. Further, this result is unlikely to be explained by traditional sexual selection models because variation in amphibian SSD is unlikely to be driven entirely by sexual selection. We suggest that relaxing a central assumption of classic ecological models—that the sexes share a common adaptive landscape—leads to the alternative hypothesis that independent evolution of the sexes may promote diversification. Once the constraints of sexual conflict are relaxed, the sexes can explore morphospace that would otherwise be inaccessible. Consistent with this novel hypothesis, the evolution of SSD in amphibians is associated with reduced current extinction threat status, and an historical reduction in extinction rate. Our work reconciles conflicting predictions from ecological and evolutionary theory and illustrates that the ability of the sexes to evolve independently is associated with a spectacular vertebrate radiation.

Latitudinal clines in sexual selection, sexual size dimorphism, and sex‐specific genetic dispersal during a poleward range expansion

2021 ◽  
Author(s):  
Rachael Y. Dudaniec ◽  
Alexander R. Carey ◽  
Erik I. Svensson ◽  
Bengt Hansson ◽  
Chuan Ji Yong ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Range Expansion ◽  
Sexual Size Dimorphism ◽  
Size Dimorphism ◽  
Latitudinal Clines

scholarly journals Losses of female song with changes from tropical to temperate breeding in the New World blackbirds

2009 ◽  
Vol 276 (1664) ◽  
pp. 1971-1980 ◽  
Author(s):  
J. Jordan Price ◽  
Scott M. Lanyon ◽  
Kevin E. Omland
Keyword(s):  
Sexual Selection ◽  
New World ◽  
Female Song ◽  
Complex Song ◽  
Evolutionary Changes ◽  
Apparent Relationship ◽  
Song Production ◽  
Selection For ◽  
The Tropics

Birds in which both sexes produce complex songs are thought to be more common in the tropics than in temperate areas, where typically only males sing. Yet the role of phylogeny in this apparent relationship between female song and latitude has never been examined. Here, we reconstruct evolutionary changes in female song and breeding latitude in the New World blackbirds (Icteridae), a family with both temperate and tropical representatives. We provide strong evidence that members of this group have moved repeatedly from tropical to temperate breeding ranges and, furthermore, that these range shifts were associated with losses of female song more often than expected by chance. This historical perspective suggests that male-biased song production in many temperate species is the result not of sexual selection for complex song in males but of selection against such songs in females. Our results provide new insights into the differences we see today between tropical and temperate songbirds, and suggest that the role of sexual selection in the evolution of bird song might not be as simple as we think.

scholarly journals Sexual selection and sexual size dimorphism in animals

2021 ◽  
Vol 17 (9) ◽  
pp. 20210251
Author(s):  
Tim Janicke ◽  
Salomé Fromonteil
Keyword(s):  
Sexual Selection ◽  
Sex Difference ◽  
Positive Relationship ◽  
Sexual Size Dimorphism ◽  
Effect Sizes ◽  
Size Dimorphism ◽  
Bateman Gradient ◽  
Mixed Support ◽  
Evolutionary Force ◽  
Length Measurements

Sexual selection is often considered as a critical evolutionary force promoting sexual size dimorphism (SSD) in animals. However, empirical evidence for a positive relationship between sexual selection on males and male-biased SSD received mixed support depending on the studied taxonomic group and on the method used to quantify sexual selection. Here, we present a meta-analytic approach accounting for phylogenetic non-independence to test how standardized metrics of the opportunity and strength of pre-copulatory sexual selection relate to SSD across a broad range of animal taxa comprising up to 95 effect sizes from 59 species. We found that SSD based on length measurements was correlated with the sex difference in the opportunity for sexual selection but showed a weak and statistically non-significant relationship with the sex difference in the Bateman gradient. These findings suggest that pre-copulatory sexual selection plays a limited role for the evolution of SSD in a broad phylogenetic context.

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