Dragons Feel the Heat: The Ecology of Malaysian Agamid Lizards in a Human-altered Landscape

Hicks, James J.

Algar, Adam C.

Social Sciences

University of Nottingham

Nottingham, UK

Deforestation in Southeast Asia is predicted to continue at an ever-increasing rate, destroying some of the World’s oldest and most biodiverse terrestrial habitat while plantations, generally depauperate of species diversity, are planted to replace them. Much is known about broad-scale losses of diversity from this process but some species thrive within plantations. Aside from an initial loss of habitat little is known about the mechanistic processes limiting other species from utilising plantations, which create very distinct and novel thermal and structural niches from native forest habitat. Many lizard species are well known as rapid colonisers and are adaptable to novel conditions and SE Asian plantations support dense populations of several species. We examined which amphibian and reptile species are missing from plantations in Northern Peninsular Malaysia. We then focussed on thermal and structural niche axes of the agamid lizard Calotes emma in oil palm and rubber plantations and compared these to native forest gap habitat, in an attempt to explain how and why this species prospers from land use change and more broadly, which traits and characteristics benefit species occupying these environments. Calotes emma shifts its structural niche from being primarily arboreal in forest, to primarily terrestrial in oil palm, with evidence of the expected accompanying changes in ecomorphology. In contrast, we observe stasis in its thermal niche between habitats, suggesting this species was likely thermally pre-adapted to the overall warmer environments of plantations, by occupying forest gaps, and plantations may be more thermally suitable for this species than the historical forest cover of the region. On a broader scale we find species present in plantations are those with distributions with more pronounced dry periods but found no support for previous predictions of thermal niche being a driving factor in a species’ ability to occupy plantations.