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Inbreeding in the Seychelles warbler: environment-dependent maternal effects
David S Richardson1, Jan Komdeur, Terry Burke
1Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom. david.richardson@uea.ac.uk
Evolution; International Journal of Organic Evolution
|November 4, 2004
Summary
Inbreeding avoidance strategies are complex in Seychelles warblers. While close inbreeding occurred, extrapair paternity may benefit subordinate females by reducing relatedness and mitigating inbreeding depression effects.
Area of Science:
- Evolutionary Biology
- Behavioral Ecology
- Population Genetics
Background:
- Inbreeding can negatively impact wild populations, leading to evolved avoidance mechanisms.
- Extrapair paternity is a potential strategy for females to avoid inbreeding and enhance offspring heterozygosity, especially when social mate choice is limited.
Purpose of the Study:
- To investigate inbreeding avoidance strategies in the Seychelles warbler (Acrocephalus sechellensis).
- To determine the effects of inbreeding and heterozygosity on offspring survival and the role of maternal effects.
Main Methods:
- Studied Seychelles warblers, a cooperatively breeding species.
- Analyzed social and extrapair mating patterns to assess inbreeding avoidance.
- Employed experimental cross-fostering of nestlings to differentiate genetic and maternal effects on survival.
Main Results:
- Close inbreeding occurred in approximately 5% of matings, with no facultative avoidance observed.
- Extrapair paternity was more frequent in subordinate females, reducing close relative matings.
- Inbreeding showed a nearly significant positive effect on individual survival, but low maternal heterozygosity significantly reduced offspring survival, indicating strong maternal effects.
Conclusions:
- Inbreeding avoidance is not strictly facultative in Seychelles warblers.
- Maternal effects, rather than direct inbreeding effects, significantly impact offspring survival.
- Inbreeding depression can manifest complexly, even in bottlenecked populations where allele purging is expected.