Evolutionary game of rock-paper-scissors may lead to new species

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Washington, Feb 19 (ANI): A new study conducted by researchers at the University of California, Santa Cruz (UCSC), has determined that the evolutionary game of rock-paper-scissors in some animals might lead to the emergence of new species.

The study documents the disappearance of certain morphs of the side-blotched lizard in some populations.

The side-blotched lizard, Uta stansburiana, has three morphs differing in color and mating behavior.

Barry Sinervo, a professor of ecology and evolutionary biology at UCSC, has studied a population of side-blotched lizards near Los Banos, California, for over 20 years.

Ammon Corl, now a postdoctoral researcher at Uppsala University in Sweden, led the new study as a graduate student at UCSC and is first author of the paper.

Previous work by Sinervo and his colleagues showed that competition among male side-blotched lizards takes the form of a rock-paper-scissors game in which each mating strategy beats and is beaten by one other strategy.

Males with orange throats can take territory from blue-throated males because they have more testosterone and body mass.

As a result, orange males control large territories containing many females.

Blue-throated males cooperate with each other to defend territories and closely guard females, so they are able to beat the sneaking strategy of yellow-throated males.

Yellow-throated males are not territorial, but mimic female behavior and coloration to sneak onto the large territories of orange males to mate with females.

Corl found the three color morphs in many places, but not everywhere.

Some populations were missing some of the color morphs.

In the field, the researchers captured lizards to collect tissue samples for DNA analysis and then released them back into the wild.

In the lab, they used the tissue samples to get DNA sequences from all of the lizard populations in the study.

"Based on these sequences, we reconstructed the 'family tree' of the lizard populations and figured out which populations were more closely related to one another. This let us figure out how the mating strategies evolved," Corl said.

The results showed that all three color morphs existed millions of years ago and have persisted since then in many populations.

Over time, however, some branches of the lizard family tree lost some of the color types.

Sinervo has documented the cycling of the rock-paper-scissors game at his main study site for 22 years, with the dominant morph in the population changing every four to five years.

"It's like an evolutionary clock ticking between rock, paper, scissors then back to rock," he said. (ANI)

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