Spatial and reversal learning in congeneric lizards with different foraging strategies

Environmental demands that require intensive search for mates, food and nes t sites are correlated with efficient spatial memory in many mammalian and avian species. This convergence of evidence has led to the view that spatia l memory, and the neurological structures associated with it, have been sel ected in niches that require memory for the location,of goal objects. Wheth er such evolutionary demands are also correlated with nonspatial abilities that require flexible use of associations similar to those required for spa tial memory has not been well studied. In addition, correlations between ni che types and the use of spatial or nonspatial memory have not been investi gated in nonmammalian, nonavian taxa. In this study, we investigated the re lationship between foraging strategies and performance on two; tasks, one s patial and the other nonspatial, in congeneric lizard species: Acanthodacty lus boskianus, an active forager that collects clumped sedentary prey, and Acanthodactylus scutellatus, a sit-and-wait predator that collects distribu ted mobile prey. The two species did not differ in their performance of a s patial memory task, but A. boskianus, the active forager, performed better on the reversal of a visual discrimination, a nonspatial task. These findin gs question the generality of the spatial adaptation model for vertebrates. We present the pliancy hypothesis, which we developed to account for these results. (C) 1999 The Association for the Study of Animal Behaviour.