Picky females play a critical role in the survival and diversity of species, according to a new Nature study.

Conducted by researchers from the University of B.C. and the International Institute for Applied Systems Analysis in Austria, the study presents the first theoretical model that suggests selective mating can promote the coexistence of species ­ such as frogs, crickets, grasshoppers and fish ­ that share the same ecological adaptations and readily interbreed.

“The focus on ecological adaptation has failed to explain much of the biodiversity we see right before our eyes,” said the study’s first author, Leithen M’Gonigle, a post-doctoral fellow at the University of California at Berkeley, who developed this work while a PhD candidate at UBC.

M’Gonigle said most biodiversity theories have focused on the role played by adaptations to the environment, or the survival of the fittest. But this study suggests species can coexist in the same habitat as long as two conditions are met: the environment must not be homogeneous so females with different mate preferences can occupy different resource hot spots; and second: females must pay a cost for being choosy, either through reduced survival or fecundity.

“The more males she looks at, the higher the cost,” M’Gonigle said. “If she prefers red males and there are a lot of yellows, she uses a lot of energy [looking for a mate or avoiding one].”

These costs reinforce species boundaries, the paper suggests, because females with a particular preference for a mate won’t invade an area dominated by mates the female finds unattractive. The study was based on a different species of cichlids, a fish found in Lake Victoria in Africa.

“This is the first theoretical study showing evolution [of] females’ preference in different traits in males can explain the biodiversity around us.” M’Gonigle said. “Some eat big seeds or little seeds, or it could just be females in one place who prefer tall males or brightly colored ones.

“How an individual chooses a mate can have a big impact on the long term.” (Vancouver Sun)