Fynbos fires may contribute to the maintenance of high genetic diversity in orange-breasted sunbirds (Anthobaphes violacea)

The maintenance of genetic diversity in populations is one of the key concerns in wildlife management. Levels of genetic diversity are partly determined by the evolutionary history of a population and partly by environmental factors which affect population size, gene flow and mating systems. In this study, we used microsatellite DNA markers to assess the level of genetic diversity in a population of orange-breasted sunbirds (Anthobaphes violacea), an endemic nectarivore in the fynbos biome at Jonkershoek Nature Reserve, South Africa. We found high levels of genetic diversity in this population, with an average of 19 alleles per locus, and both expected and observed heterozygosities of 0.84. The level of genetic diversity found in this species is comparable to that of Cape sugarbirds (Promerops cafer), a fellow fynbos endemic, but higher than that reported for other species of nectarivorous birds not affected by frequent habitat fires. We suggest that the destruction of flowering plants by fires, forcing birds to disperse, may have contributed to the maintenance of high levels of genetic diversity through encouraging outbreeding in orange-breasted sunbirds and Cape sugarbirds. We also discuss the implications of our findings for management of these species.