VANCOUVER, April 3, (Xinhua) -- Picky females play a critical role in the survival and diversity of species, according to a Nature study published on Sunday.
The study was conducted by researchers from the Vancouver-based University of British Columbia and the International Institute for Applied Systems Analysis in Austria.
It presents the first theoretical model demonstrating that selective mating alone can promote the long-term coexistence of ecologically equivalent species with overlapping ranges, such as frogs, crickets, grasshoppers and fish that readily interbreed.
To date, biodiversity theories have focused on the role played by adaptations to the environment: the species best equipped to cope with a habitat would win out, while others would gradually go extinct.
"The focus on ecological adaptation has failed to explain much of the biodiversity we see right before our eyes," says the study's first author Leithen M' Gonigle, a postdoctoral fellow at the University of California at Berkeley.
M' Gonigle said that their model shows that species can stably coexist in the same habitat as long as two simple conditions are met.
"First, the distribution of resources they use must not be uniform, so that groups of females with different mate preferences can occupy different resource hotspots. Second, females must pay a cost for being choosy, through reduced survival or fecundity," says M' Gonigle.
Resource distributions are never uniform over space, even in seemingly homogeneous habitats like grasslands and lakes, said the researchers.
"By being picky, females almost always suffer a cost, because they spend energy either to find a preferred mate or to avoid an undesirable one," says UBC zoologist and co-author Sarah Otto.
According to the researchers, these costs turn out to be crucial for reinforcing species boundaries because they prevent females with a particular preference from invading areas dominated by males they find unattractive.
Overcoming the long-held belief that species can stably coexist only if they differ in their ecological adaptations, this study provides a new explanation for the maintenance of species diversity, according to the authors.