Document: SIM-3-52-28

Local and regional scale determinants of lizard species diversity patterns.

COOK, S.*

James Cook University, Townsville, Queensland, Australia 4811 ¹

Abstract:
I tested the idea that local species richness was a subset of regional species richness by looking at tropical lizard assemblages at the local scale across habitat types and biogeographic regions in Australia's wet tropics. Levels of species richness at a local (one hectare) scale were found to be significantly higher in eucalypt forest than adjacent rainforest. Using a combined approach of physiological and behavioural tests on individuals and data on regional species diversity and historical forest contractions it was established that the present patterns of species diversity in the rainforest were originally established by extinction patterns due to rainforest contractions during the Pleistocene ice age. These patterns appear to have been maintained by the adaptive constraint of the thermal environment places on the remaining suite of species in the regional pool. Species diversity in eucalypt forest maintained a constant local level within differing regional pools, indicating local, ecological saturation. Thus it appears that while regional scale processes have created the current species patterns in this area, the patterns are being maintained by niche saturation in one habitat type (eucalypt) and adaptive constraint in the other (rainforest). Therefore it appears that in this system ecological and evolutionary processes are constraining species richness, but these two processes are operating to different degrees between habitat types.

Keywords: species richness, scale, historical biogeography, thermal physiology

This abstract is being presented at: 11:00 AM in session:
Oral Session #27: Salamanders, Lizards, and Tortoises.