Previous experience and substrate matter: Plasticity in burrow digging in a South American wolf spider

Abstract

Burrowing behavior can be affected by substrate conditions such as percentages of minerals, organic substances, granulometry, and biotic factors like densities of burrowing individuals, potential prey, and predators. Allocosa senex is a wolf spider that inhabits sandy areas next to rivers, lakes, and sandy coasts of the Atlantic Ocean in Argentina, Brazil, and Uruguay. This species shows reversal in sexual size dimorphism and sex roles, meaning that females are the smaller, more mobile and courting sex. Though all individuals dig burrows, the burrows of males are longer, and these are the sites where mating and oviposition occurs. The geographical distribution of this species includes coastal areas that differ in substrate granulometry, which could affect the characteristics of the burrows. Our objective was to test the occurrence of digging plasticity in A. senex in response to consecutive digging events and after sequential exposures to substrates with different granulometry. Males tended to enlarge their burrows after repeated digging events. Burrows were shorter on the fine substrate, and individuals showed greater weight loss after digging there. This could suggest that making a burrow in fine substrate is more energetically demanding than in coarse substrate. Individuals of A. senex are able to adapt their digging behavior according to substrate characteristics in order to maximize their fitness.