Anolis bicaorum is a shade-loving forest lizard endemic to the island of Utila off the coast of Honduras, where it does not coexist with any heat-loving species. However, on other Honduran islands, forest lizards do coexist with heat-loving species, and it is thought climate change may increase competition and favor the heat-loving species on those islands.
Populations of animals do not occur in a vacuum. That is, they occur in biological communities where they have to compete with other species, escape predators, locate prey, woo mates, and resist diseases. All of these challenges that organisms experience on a daily basis are likely to interact with climate change in complex and non-intuitive ways. If we are to accurately predict organismal responses to climate change, we have to understand the climate-dependence of species interactions.
In the Bay Islands of Honduras, I have been studying the thermal ecology of several species ofAnolis lizards occurring in one and two-species communities across 4 islands. I have combined measurements of their thermal physiology with detailed maps of environmental variation across habitat types to predict how populations will respond to climate change-driven changes in humidity, wind speed, and temperature variability. Moreover, I have evaluated the effects of these changes on competition between lizard species. I have shown that separate populations within the same region may differ dramatically in their susceptibility to rapid shifts in climate, and that competition is unlikely to alter these predictions. This is counter to many previous studies that argue most (or all) tropical forest lizards are extremely vulnerable to warming-enhanced competition and are facing imminent extinction. This ongoing research has been generously supported by the international conservation organizationOperation Wallacea since 2007.
Anolis allisoni is a heat-loving, open (or edge) habitat species that may invade the forest and compete with forest species as the climate warms. The individual pictured here is a male A. allisoni from the Honduran island of Roatan.