Duck's not dead: Does restocking with captive bred individuals affect the genetic integrity of wild mallard (Anas platyrhynchos) population?
Abstract
The genetic integrity of natural populations can be threatened through large-scale introduction of farmed stocks with different genetic or geographic origin. Huge numbers of farm-reared mallard (Anas platyrhynchos, Anatidae) have been introduced into the wild in many European countries since 1970.
Czech breeding facilities currently produce around 200-300,000 ducks annually, exceeding wild numbers by around 10 times. Such facilities, however, were founded with hybrid ducks from outside the Czech Republic.
Three types of DNA markers, two neutral (14 microsatellite DNA loci and the mitochondrial DNA control region) and one under selection (MHC class I locus), were used to genotype mallards from six Czech breeding facilities (n = 131) and seven wild nesting localities (n = 139). We found marked genetic divergence between wild and captive-bred populations, the latter having significantly lower genetic diversity.
Released captive-bred mallards were integrated into breeding wild population through hybridization mediated by high frequency nesting. Overall, our data suggest that release of captive-bred individuals threatens the genetic integrity of wild population.
Massive restocking may also be undesirable as regards public health. Waterfowl are known reservoirs of transmittable pathogens and large-scale restocking could alter immune defence gene frequencies in wild population.
We propose the establishment of a national genetic monitoring programme for breeding facilities.