Predator-driven natural selection on risk-taking behavior in anole lizards

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Science  01 Jun 2018:
Vol. 360, Issue 6392, pp. 1017-1020
DOI: 10.1126/science.aap9289

Predation favors the unadventurous

Selection is likely to shape behavior by acting on behavioral differences between individuals. Testing this idea has been challenging. Lapiedra et al. took advantage of a chain of small islands in the Caribbean colonized by anole lizards. A series of repeated behavioral selection experiments were set up in which brown anole populations were established with and without predators. On predator-free islands, animals that were more exploratory were favored, whereas when predators were present, less adventurous animals survived better. Selection for behavior occurred simultaneously with morphological selection but was predominant when predators were present.

Science, this issue p. 1017


Biologists have long debated the role of behavior in evolution, yet understanding of its role as a driver of adaptation is hampered by the scarcity of experimental studies of natural selection on behavior in nature. After showing that individual Anolis sagrei lizards vary consistently in risk-taking behaviors, we experimentally established populations on eight small islands either with or without Leiocephalus carinatus, a major ground predator. We found that selection predictably favors different risk-taking behaviors under different treatments: Exploratory behavior is favored in the absence of predators, whereas avoidance of the ground is favored in their presence. On predator islands, selection on behavior is stronger than selection on morphology, whereas the opposite holds on islands without predators. Our field experiment demonstrates that selection can shape behavioral traits, paving the way toward adaptation to varying environmental contexts.

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