Sex and sociality in a disconnected world: a review of the impacts of habitat fragmentation on animal social interactions

Despite the extensive literature describing the impacts of habitat fragmentation on the distribution and abundance of species, fragmentation effects on life-history strategies have been relatively understudied. Social interactions are important life-history attributes that have fitness consequences for individuals and have been observed to differ among populations in relation to geographic and demographic variability. Therefore, habitat fragmentation is expected to affect social interactions, and these social impacts or responses may contribute to population viability and broad-scale patterns of distribution and abundance in fragmented landscapes. Here we review the emerging literature on this issue. We focus on the impacts of habitat fragmentation that are expected to, or have been observed to, affect social strategies. These include altered resource distribution (e.g., habitat quality, spatial configuration of patches), interspecific interactions (e.g., predator-prey and host-parasite dynamics, human disturbance), and sex (mate availability and inbreeding risk). The studies we cite identified altered social interactions in response to these influences, including changes to home-range overlap, territoriality, group size, and mating systems. The observed changes to social interactions include passive responses, whereby social interactions are affected by constraints introduced by habitat fragmentation, and adaptive social responses to a modified environment. We suggest that future research could focus on individual fitness benefits and on consequences for population viability of altered social interactions in fragmented environments.