Sexual selection on female size in a marine snail, Littorina littorea (L.)

1994 ◽  
Vol 181 (2) ◽  
pp. 145-157 ◽  
Author(s):  
Johan Erlandsson ◽  
Kerstin Johannesson
Keyword(s):  
Sexual Selection ◽  
Littorina Littorea ◽  
Female Size ◽  
Marine Snail

Sexual dimorphism of the major chela and sex ratio as indicators of the mating system in the estuarine snapping shrimp Alpheus colombiensis Wicksten, 1988 (Decapoda: Caridea: Alpheidae)

2020 ◽  
Vol 40 (6) ◽  
pp. 649-656
Author(s):  
Juan C Azofeifa-Solano ◽  
Jeffrey A Sibaja-Cordero ◽  
Ingo S Wehrtmann
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Mating System ◽  
Mate Guarding ◽  
Female Size ◽  
Monogamous Species ◽  
Low Degree ◽  
Adult Sex Ratio ◽  
Snapping Shrimps

Abstract The sexual selection over traits that favor access to mating partners could promote the emergence of sexual dimorphism when the pressure is different between sexes. Monogamous species are considered to have a low degree of sexual dimorphism. The highly diverse snapping shrimps are usually regarded as monogamous, but the mating system has been studied only in few species. We aimed to provide insights into the mating system and sexual dimorphism of Alpheus colombiensisWicksten, 1988. The adult sex ratio was female biased, and solitary ovigerous females were found, suggesting a temporary mate guarding type of mating system. Our results also revealed sexual dimorphism on the snapping claw, which is larger in males than in females. The male’s snapping claw is probably under sexual selection, which can be mediated by male-male competition or female choice. We also estimated the A. colombiensis female size at maturity at 5.2 ± 0.76 mm. Our results contradict the common idea that snapping shrimps are monogamous species, and support that A. colombiensis probably have a temporary mate guarding (e.g., males can sexually interact with more than one female, in opposition to sexual monogamy). This study also sustains the growing evidence that alpheid shrimps display snapping claw sexual dimorphism.

scholarly journals Genetic association between male attractiveness and female differential allocation

2006 ◽  
Vol 2 (3) ◽  
pp. 341-344 ◽  
Author(s):  
Megan L Head ◽  
John Hunt ◽  
Robert Brooks
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Genetic Association ◽  
Reproductive Effort ◽  
Female Preference ◽  
Acheta Domesticus ◽  
Female Size ◽  
Differential Allocation ◽  
Male Attractiveness ◽  
Analogous Manner

Differential allocation of reproductive effort towards offspring of attractive mates is a form of post-copulatory mate choice. Although differential allocation has been demonstrated in many taxa, its evolutionary implications have received little attention. Theory predicts that mate choice will lead to a positive genetic correlation between female preference and male attractiveness. This prediction has been upheld for pre-copulatory mate choice, but whether such a relationship between male attractiveness and female differential allocation exists has never been tested. Here, we show that both female pre-copulatory mate choice and post-copulatory differential allocation are genetically associated with male attractiveness in house crickets, Acheta domesticus . Daughters of attractive males mated sooner and laid more eggs when paired with larger males. These forms of mate choice are strongest in large females, suggesting that costs decrease with increasing female size. The genetic association between attractiveness and differential allocation suggests potential for differential allocation to become exaggerated by coevolutionary runaway processes in an analogous manner to pre-copulatory choice. Sexual selection is thus likely to be stronger than predicted by pre-copulatory choice alone.

scholarly journals Sexual selection on size and shape in Japanese beetles (Popillia japonica)

2020 ◽  
Vol 31 (4) ◽  
pp. 1073-1083 ◽  
Author(s):  
Clint D Kelly
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Mating Success ◽  
Insect Pest ◽  
Popillia Japonica ◽  
Female Size ◽  
Male Body ◽  
Japanese Beetle ◽  
Size Dimorphism ◽  
Selection For

Abstract The mobility hypothesis argues that species in which males compete for mates in scrambles often exhibit female-biased size dimorphism because smaller male body size should increase male mobility and success in searching for mates. Sexual dimorphism can be further exaggerated if fecundity or sexual selection concurrently selects for larger female size. Scramble competition can select for trait characteristics that optimize locomotion; for example, long and slender wings should be favored if aerial speed is important to mating success. I tested these predictions in the scrambling Japanese beetle (Popillia japonica), a female-biased size dimorphic insect pest that is invasive to North America. Multivariate selection analyses support the prediction that smaller body size and larger wings in males benefit their mating success. My analyses also revealed significant selection for larger wings in females but, contrary to prediction, direct sexual selection favors smaller body size in females. These results support the mobility hypothesis and partially explain the evolution of female-biased size dimorphism in this species. Sexual selection favored rounder bodies in females and more tapered bodies in males, whereas, in both sexes, the effect of wing shape appears less important to fitness than wing size.

scholarly journals Sexual dimorphism in the South American water snake Helicops polylepis (Serpentes: Dipsadidae)

2021 ◽  
Vol 20 (1) ◽  
pp. 15-25
Author(s):  
Isla Carol Marialva Camargo ◽  
Jackeline Cristina Palma Veras ◽  
Síria Ribeiro ◽  
Ricardo A. Kawashita-Ribeiro ◽  
Rafael de Fraga ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Prey Availability ◽  
Morphological Characters ◽  
Offspring Size ◽  
Female Size ◽  
South American ◽  
The South ◽  
Water Snake ◽  
Fecundity Selection

Sexual selection, fecundity selection and ecological divergence have been the main explanations proposed for the origin and maintenance of sexual dimorphism. In this study we provide evidence of sexual dimorphism in the South American aquatic snake Helicops polylepis, which is mainly determined by body and head sizes. Males have longer tails and more subcaudal scales, and females have larger body and head and more ventral scales. The sexual dimorphism observed in different morphological characters of H. polylepis occurs in other species of xenodontine snakes and is interpreted as a consequence of sexual selection pressures. Data on growth rates associated with prey availability and female size-related offspring size are necessary to refine our analyzes and test specific hypotheses about the ecological and evolutionary bases of sexual dimorphism in H. polylepis.

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