May 28, 2007

2007 Week 21: Ferret Studies in Genetics


Someone was kind enough to post this to the Ferret Genetics group @Yahoo recently, so as a bonus, I decided to introduce them here also.

Mating system and genetic variance in a polygynous mustelid, the European polecat

The population genetic implications of mating system were investigated in European polecat Mustela putorius populations from western France, combining radiotracking survey and allozyme variation analysis. Mating peroid occurred from February to June and polecats showed a strategy of successive polygyny, a male consorting with 1.44 females during a brief period (2.9 days). Relatedness was largely sex biased, females (21%) being almost twice more related than males (13%) suggesting a natal philopatry. Nonetheless, breeding dispersal pattern appeared relatively complex. Males were the sex dispersing but the main strategy for male polecats consisted of short-term mating excursions in adjacent females ranges whereas long-distance dispersal only constituted an alternative breeding strategy. Despite their allozymic polymorphism level reaching 24% at p<0.05 for 38 scored loci, populations showed a high heterozygote deficiency as revealed by the FIS index averaging FIS=0.383. Thus the mating system of such solitary mustelids may be poorly efficient to prevent inbreeding within populations.

Genetic Heterozygosity in Polecat Mustela Putorius Populations from Western France

Allozymic variations were investigated in 49 European polecats Mustela putorius from Western France by starch gel electrophoresis. Out of 31 surveyed loci, eight (25.8%) were shown polymorphic and observed heterozygosity averaged 0.057. Deviations from Hardy–Weinberg equilibrium and heterozygote deficiency suggest that populations were not in panmixia. Heterozygotes for two loci or more totalled 42.9% of individuals. Thus, although carnivores were previously considered as less variable, polecat populations from Western France showed a high genetic variability.

Genetic variability in Danish polecats Mustela putoriusas assessed by microsatellites

Genetic variability and population structure was investigated in 83 European polecats Mustela putorius by means of six microsatellite markers. The samples came from two areas in Denmark, Østjylland and Thy, which are separated by the Limfjord. The genetic diversity (He = 0.583) found in the total sample was similar to those found in other mustelid species and carnivores in general. A heterozygote deficiency, probably due to a Wahlund effect, suggested a further substructuring of the Danish sample. Population genetic substructuring was investigated in three different ways: by means of the program STRUCTURE, Wright’s F-statistics and by an assignment test. All the tests indicate a subdivision of the sample into two distinct groups, which is concordant with the two sampling locations, with an average genetic divergence of FST = 0.126 and RST = 0.1692. The higher genetic diversity found in the Thy population (He = 0.578), as compared to the Østjylland population (He = 0.420), could be explained by assuming two ancient waves of colonisation of the Danish peninsula. Tests for recent bottlenecks were conducted, and the results suggest no evidence of neither population decline nor expansion. Our study is the first one in which microsatellite markers are used on polecat samples, and one locus (mv54) was found to be diagnostic in distinguishing between American mink Mustela vison and European polecat.

Genetic divergence without spatial isolation in polecat Mustela putorius populations

Understanding how genetic divergence could exist without spatial isolation is a fundamental issue in biology. Although carnivores have previously been considered as having a weak genetic variability, polecats Mustela putorius from eight distinct populations exhibited both a strong polymorphism (17.5-22.5%) and a substantial allele effective number reaching Ne=1.12. Heterozygosity ranging from Ho=0.031-0.063 significantly differed among populations, while the mean FIS averaging 0.388 stressed a real deficiency of heterozygotes. Observed heterozygosity levels among populations did not correlate with any habitat types but were clearly associated with habitat diversity index. The habitat structure in polecat home range corresponded to habitat mosaic structure in which discrete habitat types alternated causing multifactorial constraints that may favour heterozygosity. Allozymic frequencies within populations did not vary with dominant habitat. But in the Tyrosinase-1, the rare homozygote BB, resulting in a `dark' phenotype, was found much more in deciduous woods than the homozygote AA showing the `typical' pattern. Thus, the genetic basis for a character differentiation was here evidenced in a remarkable situation without spatial isolation. Further, the very low proportion of heterozygotes for this locus suggests a disruptive effect and supports the prediction of intermediate phenotypes being at a disadvantage. This heterozygote deficit may also result from an assortative mating intra phenotype (homogamy). The divergence in polecat phenotypes showed that genetic differentiation can be induced by subtle variations in environment, a situation that is likely to be frequent in most natural populations, and emphasized the adaptive nature of habitat preference.

Genetic structure of the European polecat (Mustela putorius) and its implication for conservation strategies


During the last century, the European polecat Mustela putorius populations in most of Europe declined and survived in fragmented patches, because of habitat alterations and direct persecution. To assess the genetic consequences of the demographic decline and to describe the spatial pattern of genetic diversity, 250 polecats sampled at seven localities from five European countries - Poland, Denmark (southern Denmark and northern Denmark), Spain, Belgium (eastern and western) and the Netherlands - were screened by means of nine microsatellite loci.

Thanks for stopping in! We hope you'll be back!

Ads make the world go around. Help us out!

Labels: , , , , , , , , , ,


Post a Comment

Subscribe to Post Comments [Atom]

Links to this post:

Create a Link

<< Home