Dispersal Strategies, genetic diversity, and distribution of two wolf spiders (Araneae, Lycosidae): Potential bio-indicators of ecosystem health of coastal dune habitats of South America

Dispersal strategies are essential for species survival. Animals need to move to search for food, to locate potential sexual partners, to find refuge and escape from predators, and to avoid inbreeding and local competition for resources. The degree of plasticity of those traits will determine the ability of the species or population to respond successfully to changes in the environment, which is particularly important in species with a restricted habitat. Allocosa marindia and Allocosa senex are two nocturnal lycosids that construct burrows along the sandy coasts of Argentina, Brazil, and Uruguay. Both species show a reversal in the typical sex roles and size dimorphism expected in spiders: females are the mobile and courting sex, and males are larger than females. A. marindia and A. senex are strictly associated to coastal sand dunes with scarce native vegetation. During recent decades, the South American coastline has been reduced and disturbed due to urbanism and touristic activities, leading to the isolation of populations of Allocosa species. In the present chapter, we review the available information about the natural history of Allocosa species, providing data about their mechanisms of dispersal, distribution, genetic diversity, and spatial patterns of genetic variation, as well as their role as biological indicators for the coastlines of Southern South America. We integrate information provided by dispersal behavior data, genetic data, and GIS (geographic information systems) and SDMs (species distribution models) tools, and discuss the predictive maps of distribution for each species and their possible fate under a global-warming scenario.