Cataglyphis desert ants: a good model for evolutionary biology in Darwin¿s anniversary year¿A review

Abstract

Cataglyphis ants comprise one of the most characteristic groups of insects in arid regions around the Mediterranean basin and have been intensively studied over the last 30 years. These ants are central-place foragers and scavengers, single-prey loaders that have become a model for insect navigation using sophisticated visual orientation, having lost pheromone orientation. They are highly heat-tolerant ants that forage close to their critical thermal limit during the hottest hours of the day, with their long-chain cuticular hydrocarbons protecting them from desiccation. This is exemplified in two Cataglyphis species, each of which developed different mechanisms for counteracting extreme heat when foraging: polymorphism of workers vs. physiological and behavioral adaptations. Several species in this genus have also become a model for studying nestmate recognition mechanisms. The role of cuticular hydrocarbons and the postpharyngeal gland as a reservoir of hydrocarbons in nestmate recognition was initially discovered mainly in Cataglyphis, including the first experimental demonstration of the Gestalt model of nestmate recognition. These ants possess very acute discrimination capacities, down to individual recognition. Such fine discrimination is seemingly used by ants that rescue from ant-lion traps only those individuals that are their nestmates. Two main reproductive strategies are exhibited by species of this genus: some reproduce classically, by independent colony foundation following nuptial flight, whereas others reproduce by colony fission. Limited dispersion increases competition for access to resources, and local resource competition has been demonstrated. Multiple mating, which had been considered to be rare in ants, has also been reported in all species studied. Finally, the most important discovery in recent years with regard to reproduction strategies in Cataglyphis is probably the occurrence of thelytokous parthenogenesis in both workers and queens. In Cataglyphis cursor, queens are able to produce new queens by thelytoky, a phenomenon that was later found in four other ant species. This ability does not exist in any other Cataglyphis species, attesting to the great variety of reproductive strategies in this genus.