Dataset Information

The ecology of sexual dimorphism in size and shape of the freshwater blenny Salaria fluviatilis.

ABSTRACT: Sexual selection is considered the major cause of sexual dimorphism, but recent observations suggest that natural selection may play a more important role in the evolution of sex differentiation than previously recognized. Therefore, studying the trade-offs between natural selection and sexual selection is crucial to a better understanding of the ecology underlying the evolution of sexual dimorphism. The freshwater blenny Salaria fluviatilis, a fish inhabiting lakes and rivers around the Mediterranean Sea, displays strong sexual dimorphism in size, shape, and behavior (i.e., larger body and head size for males and higher swimming requirements for females during the reproductive period). We tested for differences in sexual dimorphism in size and shape between the populations from lake and river habitats with the goal of identifying the trade-offs between natural and sexual selection that underlie variations in sexual dimorphism in this species. Our results show i) differences in sexual size dimorphism (SSizeD) in accordance to Rensch's rule (i.e., larger individuals in rivers associated with higher SSizeD), and ii) a decrease in shape differentiation between males and females in lake populations. Together, this suggests that the different environmental conditions between lake and river habitats (e.g., resource limitations, predation pressure, water velocity) affect the relative importance of sexual selection in the display of sexual dimorphism within the species. This study highlights the importance of considering the environmental conditions to which populations are exposed to better understand the ecology underlying the evolution of sexual dimorphism.

SUBMITTER: Laporte M

PROVIDER: S-EPMC5905518 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature

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The ecology of sexual dimorphism in size and shape of the freshwater blenny <i>Salaria fluviatilis</i>.

Laporte Martin M Berrebi Patrick P Claude Julien J Vinyoles Dolors D Pou-Rovira Quim Q Raymond Jean-Claude JC Magnan Pierre P

Current zoology 20170630 2

Sexual selection is considered the major cause of sexual dimorphism, but recent observations suggest that natural selection may play a more important role in the evolution of sex differentiation than previously recognized. Therefore, studying the trade-offs between natural selection and sexual selection is crucial to a better understanding of the ecology underlying the evolution of sexual dimorphism. The freshwater blenny <i>Salaria fluviatilis</i>, a fish inhabiting lakes and rivers around the ...[more]

PMID: 30402058

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Project description:BackgroundThe evolution of sexual size dimorphism (SSD) is likely constrained by life history. Using phylogenetic comparative methods, we examined correlations between SSD among anurans and their life history traits, including egg size, clutch size, mating combat, and parental care behaviour. We used sexual dimorphism index (SDI = Body-size(female) /Body-size(male) -1) as the measurement for SSD. Body size, life history and phylogenetic data were collected from published literature. Data were analysed at two levels: all anuran species and within individual families.ResultsFemale-biased SSD is the predominant form in anurans. SSD decreases along with the body size increase, following the prediction of Rensch's rule, but the magnitude of decrease is very small. More importantly, female body size is positively correlated with both fecundity related traits, egg size and clutch size, and SDI is also positively correlated with clutch size, suggesting fecundity advantage may have driven the evolution of female body size and consequently leads to the evolution of female-biased SSD. Furthermore, the presence of parental care, male parental care in particular, is negatively correlated with SDI, indicating that species with parental care tend to have a smaller SDI. A negative correlation between clutch size and parental care further suggests that parental care likely reduces the fecundity selection pressure on female body size. On the other hand, there is a general lack of significant correlation between SDI and the presence of male combat behaviour, which is surprising and contradictory to previous studies.ConclusionsWe find clear evidence to support the 'fecundity advantage hypothesis' and the 'parental care hypothesis' in shaping SSD in anurans. Nevertheless, the relationships of both parental care and combat behaviour to the evolution of SSD are complex in anurans and the extreme diversity of life history traits may have masked some potential interesting relationships. Our study represents the most comprehensive study of SSD in anurans to date.

Dataset Information

The ecology of sexual dimorphism in size and shape of the freshwater blenny Salaria fluviatilis.

Publications

The ecology of sexual dimorphism in size and shape of the freshwater blenny <i>Salaria fluviatilis</i>.

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