The Thermal Tolerance of a Tropical Lizard Species
Leal, M. and Gunderson, A.R. 2012. Rapid change in the thermal tolerance of a tropical lizard. The American Naturalist 180: 815-822.
Some 35 years ago, the tropical Caribbean lizard Anolis cristatellus, which is native to an area of xeric forest in northeastern Puerto Rico, was found in Miami, Florida, by Schwartz and Thomas (1975) in a location where minimum temperatures in winter can average 10°C cooler than in Puerto Rico, but where maximum temperatures in summer are much more similar. And taking advantage of this situation, Leal and Gunderson set about to determine if the cold tolerance or critical thermal minimum temperature (CTmin) of the introduced populations had diverged from that of the source populations of A. cristatellus over the 35-year period of their physical separation. And as a check on their experimental procedures, they also conducted studies to see if the critical thermal maximum temperature (CTmax) of the two groups of lizards remained about the same.
The two U.S. researchers report that "the introduced population tolerates significantly colder temperatures (by ~3°C) than does the Puerto Rican source population," while at the same time they found that the maximum temperatures tolerated "did not differ."
In the final sentence of their paper's abstract, Leal and Gunderson write that their results "demonstrate that changes in thermal tolerance occurred relatively rapidly (~35 generations), which strongly suggests that the thermal physiology of tropical lizards is more labile than previously proposed." And, therefore, they write in their paper's final paragraph that "regardless of the mechanism, the adaptive lability of thermal tolerance in A. cristatellus over an ecological timescale" provides "a glimpse of hope for tropical lizards under the current conditions of rapid climate change."
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