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Spatial associative learning in the crevice spiny lizard, Sceloporus poinsettii (Sauria: Iguanidae).

Article Excerpt
Abstract.--Studies were conducted to assess the spatial learning ability of adults of Sceloporus poinsettii. Experimental design was such that it tested the ability (discrimination ratio, DR) of specimens to re-visit sites that had provided food on the previous day. DRs plotted as a proportion of correct responses were significantly greater than chance for all lizards, showing that these animals returned to a location where they had found food 24 hr earlier. This 24 hr period was longer than those previously reported for reptiles on other types of spatial learning tasks. The adaptive significance of spatial learning in lizards is discussed.

The ability of an animal to associate specific locations with the availability of food or some other required resource (spatial learning) would certainly contribute to its overall fitness. Spatial learning has been reported in fish (Reebs 1994), birds (Wilkie & Willson 1992) and mammals (Leonard & McNaughton 1990; Poucet 1993; Janson 1998), as well as insects (Punzo 1985a; 1996; Beugnon et al. 1996) and spiders (Punzo & Kukoyi 1997), but less information is available on amphibians (Brattstrom 1990; Punzo 1991) and reptiles (Burghardt 1977; Brattstrom 1978; Kirkish et al. 1979; Puazo 1985b; Hotlzman et al. 1999). Spatial learning can significantly reduce the amount of time spent in random searching patterns and as a result maximize foraging activities (Stephens & Krebs 1986).

Previous research has suggested that reptiles learn and remember a variety of spatial tasks encountered under natural conditions. These include the location of water and food by turtles (Yeomans 1995) and snakes (Weatherhead & Robertson 1990), the location of escape routes in snakes (Holtzman et al. 1999), orientation and navigation in alligators (Rodda 1985) and lizards (Adler & Phillips 1985), location of conspecifics in lizards (Korning et al. 2000), and homing behavior in sea turtles (Lohmann & Lohmann 1996).

In the present study laboratory experiments were conducted to assess the ability of the crevice spiny lizard, Sceloporus poinsettii, to return to a specific food source based on previous experience (spatial associative learning). This lizard typically inhabits rocky canyons, hillsides and outcrops of limestone or granite, as well as...