Data from: Inbreeding depression across multiple life history traits in a long-lived mammal

Inbreeding depression is widely recognized as a near-universal phenomenon
of high conservation concern, particularly as wild populations continue to
decline. However, most research to date has focused on early life stages,
leaving later-life effects comparatively understudied, especially for wild
populations of long-lived species. The Pyrenean brown bear (Ursus arctos),
characterized by a small population, high levels of inbreeding, and
conflicts with human activities, embodies the conservation challenges
faced by many large mammals. We analyzed 27 years of monitoring data to
quantify inbreeding depression across multiple life stages on survival,
reproduction and dispersal. Our results reveal strong inbreeding
depression effects, particularly in early life stages, including reduction
in litter size and in natal dispersal distance. In adults, more inbred
mothers exhibit lower cub survival. The cumulative effect of inbreeding,
as measured by lifetime breeding success, also shows a negative impact.
These findings highlight the necessity of assessing inbreeding depression
across the entire life cycle to accurately evaluate its threat to
population dynamics and viability. Such comprehensive assessments will
become increasingly essential for wild plant and animal populations
constrained by habitat destruction, human-wildlife conflict, and
harvesting pressures.