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The population genetic structure of Oligoryzomys longicaudatus colilargo was examined at two geographical scales: (a) regional, including five populations of the Argentinean Patagonia separated by 60-315 km and (b) landscape scale, using five populations from different valleys of the locality of Cholila in the subantarctic forest separated by 6-27 km, and a nearby locality of the Patagonian steppe, with an average distance from Cholila of 33 km. Eight microsatellite loci specific for O. longicaudatus were used as genetic markers. At the regional scale, four genetic clusters were detected by the Geneland software. The genetic structure was found to follow a latitudinal pattern. This result was supported by the FST statistic, indicating low levels of current gene flow within the region. At the landscape level, genetic differentiation among the five populations was also found. Estimated migration rates were, in general, low and asymmetrical between nearby populations. Using a causal modeling approach, we detected that the combination of landscape features such as lakes, rivers, urban settlements and roads appear to constrain the dispersal of O. longicaudatus at this scale. This result would explain why nearby populations were so different in their genetic composition. The information about geographic features limiting rodent dispersal provided here could help to design more accurate prevention measures against the expansion of hantavirus pulmonary syndrome. [ABSTRACT FROM AUTHOR]

Betula maximowicziana is a long-lived pioneer tree species in Japanese cool temperate forests that plays an important role in maintenance of the forest ecosystem and has high economic value. Here we assess the wide-range genetic structure of 23 natural populations of B. maximowicziana using 11 simple sequence repeat (SSR) loci. Genetic diversity within populations was relatively low in all populations (mean HE, 0.361; mean allelic richness, 2.80; mean rare allelic richness, 1.02). The population differentiation was also relatively low ( FST, 0.062). Genetic distance-based and Bayesian clustering analysis revealed that the populations examined here could be divided into a southern group and a northern group. Analysis of rare allelic richness and Bayesian clustering revealed evidence for both southern and northern refugia during the last glacial period. Furthermore, a comparison of regional genetic diversity revealed significant clines in allelic richness. In spatial genetic structure evaluation, significant isolation by distance (IBD) was detected among the 23 populations, but not within regions. Moreover, significant population bottlenecks were found in all populations under infinite allele model (IAM) assumptions. These unusual, significant bottlenecks might be because of the processes of postglacial colonization and the species’ characters and/or life history as a long-lived pioneer tree species. The wide-range, regional genetic structure found in this study provides an important baseline for conservation and forest management, including the identification of evolutionarily significant units (ESUs) and/or management units (MUs) of B. maximowicziana. [ABSTRACT FROM AUTHOR]