The Influence of Habitat on Intra-Specific Variation in Fish Mating Systems

The diversity of mating systems in fish is unparalleled among vertebrates. This variability is shaped by a long evolutionary history associated with differences in selection pressures and plasticity within species. However, there is also significant intraspecific variability within species, often related to differences in environments among populations. Herein, I explore how habitat features (temperature, oxygen, turbidity and vegetation) and availability of mates or mating resources (nest sites, population density, sex ratio and alternative mating strategies) can affect the distribution of reproductive success in a population. The literature reviewed here indicates that differences in the intensity of sexual selection and variation in mating-system structure can be directly related to differences in breeding habitat. The way in which habitat affects mating-system structure is complex, with both abiotic and biotic factors interacting to influence different aspects of breeding behavior and success. Thus far, our understanding of variation in mating systems in fishes is based on very well-studied species, and more exploration is needed to provide an overview of habitat and mating-system structure. This is critical as we face human-induced changes in breeding habitats that can alter mating systems and potentially affect variation and viability of fish populations.