Evolution: The Arms Race Among Venomous Animals is Two-Fold

First Posted: Nov 10, 2015 08:26 AM EST

There may be an arms race occurring among venomous animals. Scientists have made new discoveries about how animal venom evolves, and have found that there's a "two-speed" evolution of animal venom.

Venom is a complex mixture of proteins and other toxic chemicals produced by animals such as snakes and spiders, either to incapacitate their prey or to defend against predators. The influence of positive selection, which is the process by which a protein changes rapidly over evolutionary time scales, when it comes to expanding and diversifying animal venoms is widely recognized.

In contrast to positive selection, the role of purifying selection, which is the selective removal of deleterious genetic changes from a population, has rarely been considered in venom evolution.

In this latest study, the researchers examined venom genes in different animals to unravel the evolutionary strategies of toxin gene families. They analyzed and compared the evolutionary patterns of over 3,500 toxin sequences from 85 gene families.

"Our research shows that while the venoms of ancient lineages evolve more slowly through purifying selection, the venoms in more recent lineages diversify rapidly under the influence of positive selection," said Yehu Moran, one of the researchers, in a news release.

These findings helped researchers create the theory that toxin-producing genes in young venomous group that enter a novel ecological niche experience a strong influence of positive selection that diversifies their toxins, thus increasing their chances to efficiently paralyze relevant prey and predatory species in the new environment. For ancient groups, though, where the venom is already "optimized," this isn't necessary.

The findings reveal a bit more about the evolution of venom and, in particular, show how venom first evolves rapidly and then, once it's optimized, evolves more slowly.

The findings are published in the journal PLOS Genetics.

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TagsSnake, Snakes, Venom, Evolution, Animals, Animal