Conservatism of lizard thermal tolerances across evolutionary history and geography (2012)

Undergraduate: Joseph Grigg

Faculty Advisor: Lauren Buckley
Department: Mathematics

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Species may develop similar thermal tolerances via either inheritance in the case of closely related species or via environmental filtering and local adaptation in the case of species inhabiting similar environments. We use global datasets of lizard thermal tolerance to ask whether thermal tolerances are more strongly constrained across evolutionary history or geography. We find that critical thermal maxima are highly conserved with space accounting for a higher proportion of the variation than phylogeny. Notably, thermal tolerance breadth is conserved across the phylogeny despite critical thermal minima showing little niche conservatism. Body temperatures show the greatest degree of conservatism, with phylogeny accounting for most of the variation. This suggests the importance of conservatism of thermoregulatory behavior, which can cause body temperatures to depart markedly from environmental temperatures. Conservatism across lineages of both thermal limits and thermoregulatory behavior suggests that the potential for adaptation to alleviate the impacts of climate change on lizards may be limited.