title: Effects of inbreeding on fitness-related traits in a small isolated moose population.
abstract: Inbreeding can affect fitness-related traits at different life history stages and may interact with environmental variation to induce even larger effects. We used genetic parentage assignment based on 22 microsatellite loci to determine a 25 year long pedigree for a newly established island population of moose with 20-40 reproducing individuals annually. We used the pedigree to calculate individual inbreeding coefficients and examined for effects of individual inbreeding (f) and heterozygosity on fitness-related traits. We found negative effects of f on birth date, calf body mass and twinning rate. The relationship between f and calf body mass and twinning rate were found to be separate but weaker after accounting for birth date. We found no support for an inbreeding effect on the age-specific lifetime reproductive success of females. The influence of f on birth date was related to climatic conditions during the spring prior to birth, indicating that calves with a low f were born earlier after a cold spring than calves with high f. In years with a warm spring, calf f did not affect birth date. The results suggest that severe inbreeding in moose has both indirect effects on fitness through delayed birth and lower juvenile body mass, as well as separate direct effects, as there still was a significant relationship between f and twinning rate after accounting for birth date and body mass as calf. Consequently, severe inbreeding as found in the study population may have consequences for population growth and extinction risk.
authors: Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology Trondheim, N-7491, Norway ; Departments of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary Science PO-8146 Dep, Oslo, N-0033, Norway.
authors: Hallvard
authors: H
authors: Haanes
authors: Stine S
authors: SS
authors: Markussen
authors: Ivar
authors: I
authors: Herfindal
authors: Knut H
authors: KH
authors: Røed
authors: Erling J
authors: EJ
authors: Solberg
authors: Morten
authors: M
authors: Heim
authors: Liv
authors: L
authors: Midthjell
authors: Bernt-Erik
authors: BE
authors: Sæther
keywords: Alces alces; body mass; genetic variation; inbreeding coefficients; inbreeding depression; life history traits; timing of birth; twinning rate