Temporal components of genetic variation in migrating and wintering American wigeon

Data from allele frequencies of wintering American wigeon (Anas americana) from the Southern High Plains (SHP) of Texas were used to monitor changes in genetic characteristics of the wintering population through time, and to estimate the average proportion of total genetic variation partitioned among parent breeding populations. Wigeon were surveyed electrophoretically for genetic variation at 25 biochemical loci. Changes in total gene diversity were observed throughout the study period (5 October 1988 to 15 March 1989) at numerous loci. Significant temporal changes in the genetic composition of the wintering population were detected, and a minimum of 7% of the total genetic variation in these wigeon was thought to be partitioned among the breeding populations represented on the SHP. A new influx of migrating wigeon, weather-related movements of wigeon, or spatial subdivision of breeding populations on the SHP may be responsible for shifts observed in the genetic characteristics of the wintering population. Significant heterozygote deficiencies in the sample of wintering wigeon suggest that this species maintains some degree of genetic structure on the breeding grounds. Genetic data collected from wintering waterfowl may provide minimum expectations of the degree of genetic subdivision among breeding populations and may help waterfowl biologists to detect changes in the composition of wintering waterfowl populations through time.