The effect of body size on the thermoregulation of lizards on hot, dry Mediterranean islands

Body size shapes the overall biology of organisms. We assessed the impact of size on temperature regulation in populations of normal-sized and large-bodied insular Mediterranean lizards (Podarcis gaigeae, Lacertidae). We hypothesized that large lizards would achieve higher body temperatures and thermoregulate more effectively than their smaller kin. Large- and small-bodied lizards share the same thermoregulation pattern, achieving similar body temperatures in the field. Large lizards, however, prefer higher set-point temperatures. Lizards in both populations thermoregulate effectively, but large lizards thermoregulated less effectively than normal-sized lizards. The particular conditions at the islet that harbors the large-bodied population (harsh intraspecific competition) seem to account for this pattern.

► Body, operative and preferred temperatures were measured in lizard populations differing in body size. ► Body mass had no effect on thermoregulation pattern. ► Large lizards prefer higher set-point temperatures and thermoregulate less effectively. ► Strong intraspecific competition in the large-bodied population seem to be the underlying reason.