Regional and local patterns of genetic variation and structure in yellow-necked mice-the roles of geographic distance, population abundance, and winter severity

Abstract

The goal of this study, conducted in seven large woodlands and three areas with smallwoodlots in northeastern Poland in 2004-2008, was to infer genetic structure inyellow-necked mouse Apodemus flavicollis population and to evaluate the roles ofenvironmental and population ecology variables in shaping the spatial pattern of genetic variation using 768 samples genotyped at 13 microsatellite loci. Genetic variation was very high in all studied regions. The primal genetic subdivision was observedbetween the northern and the southern parts of the study area, which harbored twomajor clusters and the intermediate area of highly admixed individuals. The probability of assignment of individual mice to the northern cluster increased significantlywith lower temperatures of January and July and declined in regions with higherproportion of deciduous and mixed forests. Despite the detected structure, geneticdifferentiation among regions was very low. Fine-scale structure was shaped by thepopulation density, whereas higher level structure was mainly shaped by geographicdistance. Genetic similarity indices were highly influenced by mouse abundance(which positively correlated with the share of deciduous forests in the studied regions) and exhibited the greatest change between 0 and 1 km in the forests, 0 and5 km in small woodlots. Isolation by distance pattern, calculated among regions, washighly significant but such relationship between genetic and geographic distance wasmuch weaker, and held the linearity at very fine scale (∼1.5 km), when analyses wereconducted at individual level.