Search

The current range of the root vole (Microtus oeconomus) in Europe has been shaped by climate changes, including the last glaciation. In Central Europe there are two isolated subspecies: M. oeconomus mehelyi and M. oeconomus arenicola occurring in the Pannonian lowland and the Netherlands respectively. M. oeconomus stimmingi is present in the northern part of Central Europe in the continuous range of the species distribution. To establish the influence of the postglacial isolation on the subspecies performance, we sampled 192 individuals at seven sites from the three geographic regions. Individuals were genotyped at 14 microsatellite loci highly polymorphic for all subspecies studied. This is the first extensive research presenting the diversity of M. oeconomus mehelyi from Central Europe at the molecular level. Its genetic diversity (Ar = 6.6, SD = 0.4) as well as effective population size (LDNe = 170, SD = 62) were significantly lower than in the other two subspecies, their average Ar = 7.6, SD = 0.2 and LDNe = 504, SD = 134, suggesting M. oeconomus mehelyi is most threatened with extinction. None of the subspecies showed significant genetic bottleneck signatures. The differential analysis of the genetic structure of various subgroups resulting from clustering analysis was performed to reveal the genetic relationships among individuals within and between geographic regions. We found a closer relation of M. oeconomus stimmingi with each of the isolated subspecies than between them. Moreover, we detected a clear substructure in Pannonian M. oeconomus (two subgroups), that could result from more than one colonization episode.

The EU Habitats Directive prescribes the monitoring of several small mammals on a national scale. A cost-effective way of monitoring these species is by using owl pellet data. Unfortunately, owl pellet data suffer from several methodological difficulties, all associated with the imperfect detection of the presence of prey species. Occupancy models can overcome the difficulties by taking detection into account, but they require temporal replicates. To supply these, we created replicates by splitting each pellet batch into two equal parts. A pellet batch consists of a number of pellets collected together in the field. Here we show how occupancy models can be applied to derive trend estimates from owl pellet data using such half batches as temporal replicates. We justify this approach by showing that the results from occupancy models treating half batches as temporal replicates in a test dataset were similar to the results of treating individual pellets as temporal replicates. The owl species and the number of prey individuals examined were included in the occupancy model applied to all data. We studied eleven small mammal species, two of which showed positive trends in occupancy. The confidence intervals of the trend estimates were satisfactorily small. Our methodological innovations reinforce the usefulness of pellet data for trend estimation in small mammals and increase the feasibility of large-scale monitoring of such species under the Habitats Directive.