Severe inbreeding depression in collared flycatchers (Ficedula albicollis)

Loeske E.B. Kruuk*, Ben C. Sheldon, Juha Merilä

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

159 Citations (Scopus)

Abstract

The causes and magnitude of inbreeding depression are of considerable importance for a wide range of issues in evolutionary and conservation biology, but we have only a limited understanding of inbreeding depression in natural populations. Here, we present a study of inbreeding in a large wild population of collared flycatchers (Ficedula albicollis). Inbreeding was rare, to the extent that we detected only 1.04% of 2139 matings over 18 years that resulted in offspring with a non-zero inbreeding coefficient, f > 0. When it did occur, inbreeding caused a significant reduction in the egg-hatching rate, in fledgling skeletal size and in post-fledging juvenile survival, with the number of offspring being recruited to the breeding population from a nest of f=0.25 being reduced by 94% relative to a non-inbred nest. A maximum-likelihood estimate of the number of lethal equivalents per gamete was very high at B = 7.47, indicating a substantial genetic load in this population. There was also a non-significant tendency for inbreeding depression to increase with the strength of selection on a trait. The probability of mating between close relatives (f=0.25) increased throughout the breeding season, possibly reflecting increased costs of inbreeding avoidance. Our results illustrate how severe inbreeding depression and considerable genetic load may exist in natural populations, but detecting them may require extensive long-term datasets.

Original languageEnglish
Pages (from-to)1581-1589
Number of pages9
JournalProceedings of the Royal Society B: Biological Sciences
Volume269
Issue number1500
DOIs
Publication statusPublished - 7 Aug 2002
Externally publishedYes

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