Friday, July 28, 2017

[Ichthyology • 2017] Sex-specific Evolution during the Diversification of Live-bearing Fishes


Samples of fish species from the Poeciliidae family show the diversity in color, fin size and body shape. Kansas State University researchers studied 112 species of these live-bearing fishes and found that males and females evolve differently.


Abstract
Natural selection is often assumed to drive parallel functional diversification of the sexes. But males and females exhibit fundamental differences in their biology, and it remains largely unknown how sex differences affect macroevolutionary patterns. On microevolutionary scales, we understand how natural and sexual selection interact to give rise to sex-specific evolution during phenotypic diversification and speciation. Here we show that ignoring sex-specific patterns of functional trait evolution misrepresents the macroevolutionary adaptive landscape and evolutionary rates for 112 species of live-bearing fishes (Poeciliidae). Males and females of the same species evolve in different adaptive landscapes. Major axes of female morphology were correlated with environmental variables but not reproductive investment, while male morphological variation was primarily associated with sexual selection. Despite the importance of both natural and sexual selection in shaping sex-specific phenotypic diversification, species diversification was overwhelmingly associated with ecological divergence. Hence, the inter-predictability of mechanisms of phenotypic and species diversification may be limited in many systems. These results underscore the importance of explicitly addressing sex-specific diversification in empirical and theoretical frameworks of evolutionary radiations to elucidate the roles of different sources of selection and constraint.


Samples of fish species from the Poeciliidae family show the diversity in color, fin size and body shape. Kansas State University researchers studied 112 species of these live-bearing fishes and found that males and females evolve differently.

  

 Conclusions 
Some of our most basic tenets and enduring theories of evolution have come from systems in which phenotypes or species have diversified in response to putatively clear and strong sources of selection. However, even in those systems, evolutionary dynamics are more complex than previously assumed. Compartmentalizing our understanding of diversification into male or female (or, worse yet, sex averages), natural or sexual selection, phenotypic or species patterns, and micro- or macroevolution provides an incomplete assessment of evolutionary patterns and processes. Only integrative analysis of evolutionary dynamics across these areas will allow us to develop robust understanding of the origins of biodiversity.


Zachary W. Culumber and Michael Tobler. 2017. Sex-specific Evolution during the Diversification of Live-bearing Fishes.
 Nature Ecology & Evolution. DOI: 10.1038/s41559-017-0233-4

A tale of two fishes: Biologists find male, female live-bearing fish evolve differently
 phy.so/419594245 via @physorg_com


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