Activity of free-living subterranean blind mole rats Spalax galili (Rodentia: Spalacidae) in an area of supposed sympatric speciation

Abstract

Subterranean rodents forage underground, which is energetically costly. Therefore, they can be expected to economize burrowing activity in response to food supply and soil characteristics. We analyzed the activity of radio-tracked blind mole rats, Spalax galili, on a locality sharply subdivided into harder but relatively food-rich, basaltic soil and softer, relatively food-poor rendzina. It was recently proposed that the mole rats in this locality are undergoing sympatric ecological speciation. We predicted that mole rats from basaltic soil would be less active than those from rendzina as a result of the reduced need for burrowing to reach food. By contrast to our predictions, mole rats from basaltic soil were more frequently located outside the nest and observed pushing soil above ground. We suggest that this is a result of territorial behaviour due to high population density. All mole rats exhibited a unimodal daily activity pattern likely related to temperature. Large males had large but gradually decreasing home-ranges, likely indicating the end of the mating season. We conclude that the ecological differences between the habitats cause behavioural differences in the mole rats, which indicates different selection pressures. The genetic divergence previously found between the populations might have arisen via density-dependent selection.