“Thermoregulatory behavior simultaneously promotes and forestalls evolution in a tropical lizard”

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Martha M. Muñoz and Jonathan B. Losos

Behavioral drive meets behavioral inertia: One behavior has different evolutionary effects on physiology and morphology

Evolution can be both stimulated and halted by an animal’s behavior, according to a groundbreaking study led by a Virginia Tech researcher. It just depends which trait you’re talking about.

The study, appearing in The American Naturalist, shows that behavior can be both a brake and a motor for evolution in a manner where slowing evolution in one trait actually requires accelerating evolution in another, according to Martha Muñoz, a new assistant professor at Virginia Tech, and Jonathan B. Losos of Harvard. Understanding this delicate stop-and-go dance can help scientists predict how animals will adapt to global change such as climate change and habitat degradation.

In the case of the anole lizard of the Dominican Republic, thermoregulation—or the ability to control one’s own body temperature—is crucial to survival. Although it is located in the tropics, the Dominican Republic has lots of mountainous habitat and high elevations that challenge animals like lizards, which cannot regulate their temperature internally, the way that birds and mammals (including people) do.

When the lizards migrated from warm, low elevations to cool, high elevations, body temperature regulation required the lizard to take up a new microhabitat, dwelling on boulders and sheltering in crevices. The lizard also evolved traits important for rock dwelling, such as a flatter skull and shorter legs for skittering into crevices at the first sign of a predator. In other words, the same behavioral switch to boulders that halted physiological evolution also promoted morphological evolution.

In the context of global climate change, these findings suggest that the effects of rising temperatures won’t be limited to directly impacting organisms’ physiology—because of their behavior, it could indirectly impact other features, like their morphology, as well. Such predictions, however, would not have been likely without this new understanding of the multidimensional ways in which behavior impacts evolution. Read the Article