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Inbreeding avoidance under different null models of random mating in the great tit
Marta Szulkin1, Przemyslaw Zelazowski, George Nicholson
1Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, UK. marta.szulkin@zoo.ox.ac.uk
The Journal of Animal Ecology
|April 23, 2009
Summary
Great tits do not avoid mating with relatives, even siblings. This study found birds bred with kin more often than expected, despite inbreeding depression. Further research is needed to understand this puzzling behavior.
Area of Science:
- Evolutionary Biology
- Behavioral Ecology
- Population Genetics
Background:
- Inbreeding depression significantly reduces fitness in many populations.
- Dispersal is a key mechanism for inbreeding avoidance.
- Previous studies documented inbreeding depression in great tits (Parus major).
Purpose of the Study:
- To investigate whether great tits actively avoid mating with kin.
- To compare observed mating patterns with null models of random mate choice.
- To understand the genetic structure and inbreeding avoidance strategies in a long-term great tit population.
Main Methods:
- Analysis of 41 years of breeding data from a great tit population.
- Generation of four contrasting models of random mate choice.
- Comparison of observed inbreeding coefficients with simulated distributions under different scenarios.
- Calculation of pedigree-derived F(IS) values.
Main Results:
- No evidence of active inbreeding avoidance was found in the great tit population.
- Birds bred with relatives more frequently than predicted by null models lacking population structure.
- Observed sibling mating occurred more often than expected under any random mating scenario.
- Positive F(IS) values across all scenarios confirmed a lack of inbreeding avoidance.
Conclusions:
- Great tits do not actively avoid mating with kin, including siblings.
- Spatial genetic structure exists, with related individuals closer together, but dispersal does not fully homogenize the population.
- The high frequency of sibling mating is unexpected and warrants further investigation, despite known fitness costs of inbreeding.
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