Genetic indications of translocated and stocked grey partridges (Perdix perdix): does the indigenous Danish grey partridge still exist?

Abstract

Non-local population stocking can have adverse genetic effects through loss of genetic diversity and introgressive hybridisation in wild populations exploited by man. The grey partridge (Perdix perdix) has been an important European game species for centuries, widely subject to translocation and stocking. After ca 80 years releasing reared grey partridges into Danish wild partridge areas, this study investigated whether an indigenous Danish grey partridge still existed. We predicted that (i) an indigenous Danish partridge would belong to the western European clade (W1) and (ii) would be more closely related to the historical, indigenous grey partridges than to farm bred partridges. These predictions were tested analysing the variation in the mitochondrial control region (CR1) and microsatellite markers in museum samples representing the ancestral indigenous Danish grey partridge, contemporary (recent) wild grey partridges and farmed grey partridges from the five largest farms in Denmark. Phylogeography- and population structure analyses showed traces of the indigenous Danish grey partridges amongst recent wild partridges in certain areas and significant genetic differences between reared, farmed partridges and historical- and recent partridges. The results also showed that the indigenous Danish grey partridges belonged to the western European clade (W1 haplotype). A foreign stocking effect was detected on the remote island of Bornholm, where the current population originated from introduced Danish and Bohemian grey partridges. The loss of haplotype diversity over time in certain geographical areas probably results from serious declines in wild Danish grey partridge numbers in recent decades. This combined with the 2 observation that hybridisation between released stocked and wild partridges can occur may complicate recovery of partridge populations.