Intraspecific competition of Allenby gerbils can lead to asymmetric exposure to degraded patches

Pollution is widespread in human-dominated environments, and individual differences within a species, due to differences in sex and competitive ability, may influence exposure to contaminants. However, studies rarely test whether competitive abilities impact exposure to environmental contaminants. We examined how exposure to an environmental pollutant is affected by sex and dominance in Allenby gerbils, Gerbillus andersoni allenbyi . We experimentally provided the gerbils with three different foraging patches—two contained crude-oil-contaminated soil and one with uncontaminated-clean soil. All soils were brought from the `Avrona Nature Reserve in Israel, where two large oil spills occurred, one in 1975 and one in 2014. Thus, one foraging patch contained soil contaminated in 1975, and the other contained soil contaminated in 2014. Previous work indicated a preference among gerbils towards foraging on patches of soil contaminated in 1975, possibly because the texture of the soil facilitated finding seeds. We found that male gerbils experienced greater exposure to the contaminated soils, especially dominant individuals that were capable of monopolizing resource patches. There was a trend for the gerbils to lose body mass during the experiments, but dominant individuals got more access to foraging patches and experienced less severe weight loss. However, we hypothesize that dominant individuals might incur costs of higher exposure to polluted soils in the long term. Overall, our findings reinforce that organisms do not use space randomly, and that this has implications towards their exposure to environmental contaminants.