Natal philopatry and sex-biased dispersal in a nest defence mating system

Sex-biased dispersal is a widespread phenomenon traditionally discussed in terms of the reproductive trade-offs associated with different mating systems. The relationship between sex-biased dispersal and mating systems, however, appears more complex than initially thought, and the generalization of current theory to nonavian/mammalian taxa is increasingly being questioned. We investigate natal philopatry and sex-biased dispersal in smallmouth bass, Micropterus dolomieu, nesting in Lake Opeongo, Ontario, Canada using a reconstructed molecular pedigree and individual tagging data. Sex-specific differences in fine-scale spatial genetic structure detected using multivariate spatial autocorrelation analysis and individual movement patterns were consistent with greater natal philopatry and nest site fidelity among nest-guarding males and female-biased dispersal. Our findings conform to the theoretical predictions for a territorial, nest-guarding species with male parental care. However, key life-history traits that coevolve with mating systems, such as the sex-specific costs of reproduction and parental care, may play a more important role in determining the direction and magnitude of sex-biased dispersal in this species than the mating system per se. Our findings provide insights into the factors regulating population structure in large, heterogeneous natural lakes and provide essential information for bridging the gaps between behavioural ecology, population genetics and dispersal theory. Crown Copyright (c) 2025 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour. All rights are reserved, including those for text and data mining, AI training, and similar technologies.