Seed augmentation has a limited effect on species diversity of sand-dwelling ants

Abstract

Enrichment experiments can provide useful information on the coexistence mechanisms by which resources are shared among species within an assemblage. In this study, we examined the effect of artificial seed augmentation on the diversity of seed-eating ant species at the Mash'abim Sands Nature Reserve in the Negev Desert in Israel. In a two-year experiment, the foraging activity of the different ant species was observed at two-month intervals, during both night and day, in nine plots that were enriched daily with millet and sunflower seeds. Each plot was divided into 20 stations. The nine plots were randomly assigned to each of three seed-enrichment treatments: no seed addition (control); addition of seeds that were available only for ants (Ant); or addition of seeds that were available for both ants and rodents (Ant+Rod). Eight seed-eating ant species were observed at the baits, three of which were specialist seed-eaters, and the other five were generalist species. The results reveal no significant effect of seed augmentation on ant species diversity. However, there was a trend of increase in diversity in the Ant compared to the control plots during the day. This increase contradicts the hypothesis that seed-enrichment in deserts would lead to decreased ant species diversity due to increased inter-specific or inter-taxon competition due to increased territo-riality of either the dominant ant or rodent species, respectively. Our finding agrees with a growing number of studies in ants that revealed either an increase or no change in diversity following artificial resource augmentation.