Individual dietary specialization, where individuals occupy a subset of a population’s wider dietary niche, is a key factor determining a species’ resilience against environmental change. However, the ontogeny of individual specialization, and associated underlying factors (social learning, genetic, and environmental drivers), remain poorly understood. Using a multigenerational dataset of female Scandinavian brown bears followed since birth, we discerned the relative contributions of environmental similarity, genetic heritability, maternal effects, and offspring social learning from the mother to individual specialization. This dataset allowed unique insights into the ontogeny of individual dietary specialization along a continuum from a more herbivorous to a more carnivorous diet in a long-lived omnivore. Specifically, the foraging strategy of offspring was intimately tied to the foraging strategy of their mother, a relationship that lasted up to four years after independence. We interpret this relationship as evidence that social learning plays an important role in shaping an individual’s dietary specialization. Five years into independence, the similarity between the trophic position of mothers and daughters slowly faded, likely due to individual learning and experience during solitary life. In addition, offspring of the same mother also shared similarities in their trophic position, potentially mediated through maternal genetic or environmental effects on body size. This study shows that social learning and maternal effects were more important for individual dietary specialization than environmental composition. We propose a tighter integration of social effects into studies of range expansion and habitat selection under global change.
This study is a result of international collaboration with our colleagues from the Ludwig-Maximilians-Universität in Munich, Senckenberg Biodiversity and Climate Research Centre in Frankfurt, University of Huelva, Doñana Biological Station, Environment and Climate Change Canada, University of Western Ontario, University of Saskatchewan, Goethe University Frankfurt, Norwegian Institute for Nature Research, Swedish University of Agricultural Sciences, University of South-Eastern Norway and University of Natural Resources and Life Sciences in Vienna. More details can be found here https://doi.org/10.1038/s41467-024-54722-z
By Agnieszka Sergiel