EVOLUTIONARY PERSISTENCE OF GROUND-SQUIRREL ANTISNAKE BEHAVIOR - REFLECTIONS

The evolutionary persistence construct considers the possibility that animals retain perceptual biases and behavioral relics from former historic periods of natural selection. As critiqued by Burton (this issue), this construct is suspect because it assumes that perceptual biases can be carried by the animal before it reaches the environment, a view contrary to those who consider behavior to be organism-environment transactions. Burton further argues that the laboratory study result showing that California ground squirrels from habitats where their snake predators are virtually absent behaved like squirrels from a snake-abundant habitat could be an artifact of laboratory conditions. A more parsimonious explanation than evolutionary persistence is that snakes are perceived as generalized anxiety-provoking stimuli, not as specific predators. In response to this critique, evidence is presented that ground squirrel antisnake behavior is indeed functionally specialized for dealing with snakes. Additional study of squirrel populations provides further evidence that antisnake behavior is generally intact in ground squirrel populations experiencing prolonged relaxed selection for many thousands of years. The implications of the evolutionary persistence construct for the theoretical structure of animal-environment mutualism, ideas of direct perception, and the role of memory and cognition in different time scales are discussed.