Temporal variation of heterozygosity-based assortative mating and related benefits in a lesser kestrel population

9 pages, figures, and tables statistics.Heterozygosity as a target of mate choice has received much attention in recent years and there is growing evidence supporting its role in the evolution of mate preferences. In this study we analyse mating patterns in relation to heterozygosity in a lesser kestrel (Falco naumanni) population intensively monitored over six study years (2002–2007). The magnitude of heterozygosity- based assortative mating varied over time, being particularly patent in the last study years (2006, 2007). We have found evidence that this mating pattern entails both direct and indirect-genetic benefits. Clutch size increased with female heterozygosity and more heterozygous males raised a higher number of fledglings particularly in those years when the strength of the heterozygosity-based assortative mating was markedly higher. In the last study year, parent–offspring correlation of heterozygosity was stronger and higher than the expected if individuals would have randomly mated with respect to heterozygosity. Overall, our results offer empirical support to the heterozygous mate hypothesis of sexual selection but suggest that genetic diversity may act as a temporally variable target for mate choice.Primer sequences for microsatellite Fu1 and Fu2 were kindly provided by Jon H. Wetton (Forensic Science Service, UK). Two anonymous referees provided valuable comments that improved the first version of the manuscript. We manipulated and banded lesser kestrels under license from the Spanish institutional authorities (Environmental Agency of Junta de Comunidades de Castilla-La Mancha and the Ringing Office of the Ministry of Environment) and we followed general ethical guidelines for animal welfare and nature conservation. This work received financial support from the projects: CGL2008-0095/BOS (MEC), PAI05-053 (JCCM), and PCI08-0130-3954 (JCCM). The study was funded by a post-doctoral JAE-Doc (CSIC) contract (to J.O. and A.M.), a pre-doctoral fellowship from the Junta de Comunidades de Castilla-La Mancha ⁄ European Social Fund (to G.C.) and a postdoctoral Juan de la Cierva Contract (to R.B.).Peer reviewe