Water availability, piospheres and evolution in African ruminants

Abstract

Water dependency has consequences for the behaviour of African large herbivores from day-to-day and season-to-season. Independently, there have been comparisons made between the water-dependencies of these species and the consequent impact of drinking foci on the savanna landscape. Thus, water dependence is assumed to be detrimental to animals because it restricts their foraging range during the dry season to areas degraded by high utilisation pressures. Piospheres are the utilisation gradients around sources of drinking water (and other foci for animal convergence), and feature daily in the lives of most African ruminants, particularly during the dry season, but have yet to be implicated in the evolution of these animals. Extended historical periods presented climatic conditions similar to contemporary dry seasons suggesting that water dependency and piospheres may have played a role during a timeframe for evolution of a grass consuming diet and its associated water dependent traits by isolating populations of water dependent animals within piospheres. The fossil record may hold evidence of such adaptive changes, as well as phylogenetics and phylopatry in modern watering behaviour which may also reveal how water dependency has influenced the evolution of African large herbivores.