Performance of the southernmost lizards of the world: Liolaemus sarmientoi and Liolaemus magellanicus

FERNANDEZ, JIMENA BEATRIZ; IBARGÜENGOYTÍA N. R

San Carlos de Bariloche

Congreso; VI Southern Connection Congress; 2010

The performance in lizards generally increases with body temperature (Tb) but may decline beyond an optimal temperature (To). We studied the thermal sensitivity and performance of L. sarmientoi (N=39) and L. magellanicus (N=15) from 51ºS (Santa Cruz, Argentina). Running speeds were recorded by video camera for long runs (LR, 1m) and sprint runs (SR, 0.2m) in nature at three air temperatures (17, 21, and 30ºC). When air temperatures were low, both species were faster in SRs than in LRs, but at high air temperatures L. sarmientoi was faster at LRs than in SRs. L. magellanicus did not show differences between LRs and SRs at high air temperatures. The To for L. sarmientoi was 36ºC (LR) and 27ºC (SR) and the performance breadth (B80) which equals 80% of To , was 25-36ºC for LRs and 27-31ºC for SRs. The To for L. magellanicus were 34ºC (LR) and 32ºC (SR), and B80 was 30-34ºC for LRs and 27-32ºC for SRs. L. magellanicus and L. sarmientoi show suboptimal adaptation to the harsh environments in the extreme south of Patagonia, and reach their maximum performance only at temperatures above those that occur in their current thermal environment. L. sarmientoi maintained high performance over a broad range of temperatures during LRs and was able to achieve a B80 at low temperatures. In contrast, L. magellanicus has the challenge to attained high performance only over a narrow range of temperatures (both LRs and SRs), a range unlikely to occur in nature.