What agents of selection shape creatures in the wild? The answer for the brown anole lizard seems to be competition with its fellows, rather than predation from without. Bird or snake predators were included or excluded across six Caribbean islands that ranged from low to high population densities of lizards. Although the presence of predators altered lizard behaviour, it was increases in lizard population density that altered the lizard's phenotype, favouring larger size, longer legs and increased stamina for running.
- Ryan Calsbeek
- Robert M. Cox