Character Displacement in Lizards as Revealed by Natural Selection Experiments

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Character displacement describes an ecological pattern where populations of competing species, morphologically similar when occurring in separate habitats, diverge morphologically when occurring in the same habitat. Few studies have experimentally tested the character displacement hypothesis. This project provides a test of a prediction of the character displacement hypothesis by measuring natural selection arising from ecological processes involved in competitive interactions. The investigators will use natural arenas to measure natural selection on body size in two co-occurring lizard species. Transplant experiments will be performed that involve populations of these species that occur in the same and separate habitats. Tests of ecological mechanisms, such as prey size distributions and micro-habitat partitioning, will be integrated with the transplant experiments. Understanding the heritable basis of important traits like body size and growth rate in free-ranging animals is profoundly important for many husbandry programs. This project will contribute to our understanding of the amount of heritable variation in body size in natural populations and how this variation is shaped by natural selection. Results of this project are applicable to husbandry programs that involve two or more species such as aquaculture programs, or free-ranging domesticated programs where some selection might be expected to occur.