Anthropogenic influences on natural animal mating systems

Anthropogenic influences on the natural world are widespread and well studied from various ecological vantage points. Their behavioural implications, however, are comparatively less well understood. We review four categories of influence on natural animal mating systems: habitat fragmentation, climate change, pollution and selective harvesting. We adopt a predictive approach, first reviewing the ecological determinants of mating system variation and then investigating how these determinants may be affected. Habitat fragmentation and climate change are directly altering the two fundamental predictors of mating system variation: the spatial and temporal distributions of resources. Pollution has implications for mating systems, via, for example, feminizing effects of endocrine disrupters and impeded efficacy of sexual communication. The influences of selective harvesting arise from the removal of phenotypic (and in some cases, genetic) variation in sexually selected traits. The ecological (e.g. by serving as an underlying mechanism contributing to Allee effects) and evolutionary (e.g. by driving microevolutionary trajectories that run counter to sexual selection) consequences of mating system disruption may be severe. The current lack of data, however, makes rigorous assessment of these consequences premature. Nevertheless, there is an analytical framework that can be used to make quantitative predictions, and we argue that applying it more broadly will help improve our understanding of the causes and consequences of anthropogenic influences on natural animal mating systems.