engleski

Thermoregulation in syntopy ; fine – scale differences in island Podarcis populations

We studied the thermoregulatory behaviour and microhabitat use of the lacertid lizards Podarcis sicula and Podarcis melisellensis on the island Vrgada (East Adriatic, Croatia) during early spring. The sympatry of the two Podarcis species on Vrgada is exceptional in that most other small islands in the Adriatic harbour only one of the two species, likely as the result of competitive exclusion. It is thought that the dominant robust colonizing P. sicula replaces the more slender native P. melisellensis on those islands were it gets a foothold. We here test the hypothesis that on Vrgada, despite apparent syntopy on a macrohabitat scale, P. sicula occupies the better microhabitats and forces P. melisellensis into (thermally) less favourable ones. We measured field body temperatures of active lizards of both species, and compared them to operative temperatures and temperatures selected in laboratory conditions, to compare the accuracy and effectiveness of thermoregulation between the two species. We also estimated the thermal quality of the microhabitats occupied by the two species. In addition, we checked for possible differences in activity cycles and (thermoregulatory) behaviour.

thermoregulation; syntopy; island; Podarcis

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