Increase of heterozygosity in a growing population of lesser kestrels

Abstract

The lesser kestrel (Falco naumanni) suffered a sharp population decline over much of its European distribution range in the middle of the twentieth century. Still declining in some areas, the species has recently experienced a notable population recovery in certain regions. We examined the genetic diversity variation in a growing population of lesser kestrels from Central Spain over a 6-year period (2000-2005). The population studied showed a rapid demographic expansion, increasing in the number of both breeding pairs and colonies. Annual average heterozygosity and allelic diversity increased and genetic similarity between potential mates decreased over the study period. Several immigrants regularly arrived in the study area and introduced new alleles into the local population, pointing to immigration as the main cause contributing to the observed genetic recovery.

Figure 1

Map of the study area showing the spatial distribution of lesser kestrel colonies in 2000–2005. Colonies present in the study area since 2000 (black dots), founded after 2000 (green dots) and disappeared since 2000 (red dots) are indicated. Graph illustrates the increasing number of breeding pairs from 2000 to 2005.

Figure 2

Annual average heterozygosity (H_O: red points, solid line; 1−HL: blue points, dashed line) in relation to: (a) year of study; (b) number of breeding pairs in the study lesser kestrel population. Sample size (i.e. the number of genotyped broods) used for calculating annual average heterozygosity is shown in parentheses for each year.