A tale of two fishes: Biologists find male, female live-bearing fish evolve differently

phys.org | 7/18/2017 | Staff
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Male live-bearing fish are evolving faster than female fish, according to a Kansas State University study, and that's important for understanding big-picture evolutionary patterns.

Researchers Michael Tobler, associate professor of biology, and Zach Culumber, former university postdoctoral research associate and current postdoctoral researcher at Florida State University, studied 112 species of live-bearing fish and found that males and females evolve differently: Female evolution is influenced more strongly by natural selection and the environment, while male evolution is influenced more strongly by sexual selection, which involves characteristics that females find desirable or that make them superior competitors for females.

Tobler - Culumber - Findings - Nature - Ecology

Tobler and Culumber published their findings in the Nature Ecology and Evolution journal article, "Sex-specific evolution during the diversification of live-bearing fishes."

The article includes two main findings: The reasons behind the evolutionary differences in males and females, and the importance of separately analyzing males and females. The findings show the importance of addressing sex-specific differences when studying evolution, the researchers said.

Picture - Males - Females - Species - Terms

"In the big picture, this means that males and females are different and that matters not only within species but also in terms of shaping broad-scale evolutionary outcomes," Tobler said. "Acknowledging that the sexes are different really affects how we make inferences about how evolutionary change has actually unfolded."

Tobler and Culumber spent two and a half years studying more than 100 species of Poeciliidae, or live-bearing fish. Unlike the majority of fish in which females lay eggs that are later fertilized by males, live-bearers—which include species such as mollies, platies, guppies, swordtails and mosquitofish—have internal fertilization. Live-bearers retain eggs during pregnancy and give birth to live young, similar to mammals like humans.

Tobler - Novelty - Study - Evolution - Scientists

Tobler said the novelty of this study is that, when studying evolution, scientists often measure females and males separately and then average measurements of the two sexes together to attempt an overall look...
(Excerpt) Read more at: phys.org
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