Widespread gene flow and high genetic variability in populations of water volesArvicola terrestrisin patchy habitats

Abstract

Theory predicts that the impact of gene flow on the genetic structure of populations in patchy habitats depends on its scale and the demographic attributes of demes (e.g. local colony sizes and timing of reproduction), but empirical evidence is scarce. We inferred the impact of gene flow on genetic structure among populations of water voles Arvicola terrestris that differed in average colony sizes, population turnover and degree of patchiness. Colonies typically consisted of few reproducing adults and several juveniles. Twelve polymorphic microsatellite DNA loci were examined. Levels of individual genetic variability in all areas were high (H(O) = 0.69-0.78). Assignments of juveniles to parents revealed frequent dispersal over long distances. The populations showed negative F(IS) values among juveniles, F(IS) values around zero among adults, high F(ST) values among colonies for juveniles, and moderate, often insignificant, F(ST) values for parents. We inferred that excess heterozygosity within colonies reflected the few individuals dispersing from a large area to form discrete breeding colonies. Thus pre-breeding dispersal followed by rapid reproduction results in a seasonal increase in differentiation due to local family groups. Genetic variation was as high in low-density populations in patchy habitats as in populations in continuous habitats used for comparison. In contrast to most theoretical predictions, we found that populations living in patchy habitats can maintain high levels of genetic variability when only a few adults contribute to breeding in each colony, when the variance of reproductive success among colonies is likely to be low, and when dispersal between colonies exceeds nearest-neighbour distances.

Population structure and genetic diversity of greater sage-grouse (Centrocercus urophasianus) in fragmented landscapes at the northern edge of their range

“…Second, disturbance is mainly occurring in the NMRS, but silver sagebrush habitat is naturally patchy (Aldridge and Brigham 2003). Peacock and Ray (2001) and Aars et al (2006) found mammal populations inhabiting patchy habitat retain higher levels of genetic variability compared to high-density continuous populations due to efficient and frequent long-distance dispersal. Both sage-grouse subpopulations exhibit IBD, equivalent diversity, and some long-distance dispersal (Table 3).…”

Colonization patterns of Nematoda on decomposing algae in the estuarine environment: Community assembly and genetic structure of the dominant species Pellioditis marina

“…Although there is a solid theoretical framework explaining the ecological and evolutionary consequences of local colonization and extinction in metapopulations (e.g., Harrison and Hastings 1996;Hanski and Gilpin 1997), including the effect on genetic differentiation among and within demes within a metapopulation (Slatkin 1977;Wade and McCauley 1988;Whitlock and McCauley 1990), empirical studies in natural environments are still quite scarce (Whitlock 1992;Saccheri et al 1998;Aars et al 2006), especially in the marine environment. Theory indicates that the amount of genetic differentiation among demes within a metapopulation is largely dependent upon the mode of founding of new demes within that metapopulation (Wade and McCauley 1988): large propagules with individuals from many demes will cause little genetic differentiation within the metapopulation.…”

Estimating offspring production using capture‐mark‐recapture and genetic methods in red squirrels

“…Moreover, red squirrels from all six populations showed high levels of heterozygosity at the ten loci and gene diversity H E ranged from 0.49 in COG to 0.61 in VAL (Trizio et al 2005). The number of microsatellite loci used to assign parents in this study was within the range of loci used in other vertebrate studies obtaining successful parentage assignment using CERVUS (four microsatellite markers in the canyon mouse, Shurtliff et al 2005; eight markers, Lemos et al 2006; 12-17 markers for a variety of mammals, Aars et al 2006;Castagnasso et al 2007;Lane et al 2008;up to 22 markers in badgers, Dugdale et al 2007).…”

“…In several studies only parents assigned with a 95% probability were considered (e.g., Aars et al 2006;Dugdale et al 2007;Lane et al 2008). In our study system it was impossible to exclude the candidate mothers (CPs) assigned with a 80% confidence (see also Telfer et al 2003).…”

“…In fact, exact determination of potential mothers from morphological parameters of reproductive activity (see Materials and methods) and nearly complete genotyping of candidate mothers in 2002 and 2003 (95% of 59 CPs and 100% of 56 CPs, respectively) allowed us to reduce this source of error (see also Oddou-Muratorio et al 2003;Aars et al 2006;Koch et al 2008). This was further supported by our results: the only three cases, among 125 candidate offspring, of locally born offspring with nondetection of the mother were in VAL in 2002, where three potential mothers were not genotyped.…”