Phylogeography of the narrow-headed vole Lasiopodomys (Stenocranius) gregalis (Cricetidae, Rodentia) inferred from mitochondrial cytochrome b sequences: an echo of Pleistocene prosperity Abstract A species-wide phylogeographic study of the narrow-headed vole Lasiopodomys (Stenocranius) gregalis was performed using the mitochondrial (mt) cytochrome b gene. We examined 164 specimens from 50 localities throughout the species distribution range. Phylogeographic pattern clearly demonstrates the division into four major mtDNA lineages with further subdivision. The level of genetic differentiation between them was found to be extremely high even for the species level: about 6-11%. The most striking result of our study is extremely high mutation rate of cytb in L. gregalis. Our estimates suggested its value of 3.1 9 10 À5 that is an order of magnitude higher than previous estimates for Microtus species. The mean estimated time of basal differentiation of the narrow-headed vole is about 0.8 Mya. This time estimate is congruent with the known paleontological record. The greatest mitochondrial diversity is found in Southern Siberia where all four lineages occur; therewith, three of them are distributed exclusively in that area. The lineage that is distributed in south-eastern Transbaikalia is the earliest derivate and exhibits the highest genetic divergence from all the others (11%). It is quite probable that with further research, this lineage will turn out to represent a cryptic species. Spatial patterns of genetic variation in populations of the narrow-headed vole within the largest mt lineage indicate the normal or stepping stone model of dispersal to the north and southwest from the Altay region in Middle Pleistocene. Both paleontological data and genetic diversity estimates suggest that this species was very successful during most of the Pleistocene, and we propose that climate humidification and wide advance of tree vegetation at the Pleistocene-Holocene boundary promoted range decrease and fragmentation for this typical member of tundra-steppe faunistic complex. However, we still observe high genetic diversity within isolated fragments of the range.
Rickettsia are intracellular bacteria best known as the causative agents of human and animal diseases. Although these medically important Rickettsia are often transmitted via haematophagous arthropods, other Rickettsia, such as those in the Torix group, appear to reside exclusively in invertebrates and protists with no secondary vertebrate host. Importantly, little is known about the diversity or host range of Torix group Rickettsia. This study describes the serendipitous discovery of Rickettsia amplicons in the Barcode of Life Data System (BOLD), a sequence database specifically designed for the curation of mtDNA barcodes. Out of 184,585 barcode sequences analysed, Rickettsia is observed in approximately 0.41% of barcode submissions and is more likely to be found than Wolbachia (0.17%). The Torix group of Rickettsia are shown to account for 95% of all unintended amplifications from the genus, with a multilocus analysis of these strains revealing this symbiont commonly shifts between distantly related host taxa. A further targeted PCR screen of 1,612 individuals from 169 terrestrial and aquatic arthropod species identified mostly Torix strains (14/16) and supports the "aquatic hotspot" hypothesis for Torix infection. Furthermore, the analysis of Sequence Read Archive (SRA) deposits indicates Torix infections represent a significant proportion of all Rickettsia symbioses. This combination of methods reveals a broad host diversity associated with Torix Rickettsia including phloem-feeding bugs, parasitoid wasps, forest detritivores and vectors of disease. The unknown host effects and transmission strategies of these endosymbionts makes these newly discovered associations important to inform future directions of investigation involving the understudied Torix Rickettsia.
Differences in fur color have been revealed between sables of different age groups identified by the number of annual layers in the canine teeth. In particular, the fur of young of the year is relatively light and contrasts with darker fur in animals of older age groups. The results of analyzing possible causes of this phe nomenon provide evidence that species specific features of inheritance and environmental conditions of the region have a multidirectional effect on the color of sable fur.
Populations from different parts of a species range may vary in their genetic structure, variation and dynamics. Geographically isolated populations or those located at the periphery of the range may differ from those located in the core of the range. Such peripheral populations may harbour genetic variation important for the adaptive potential of the species. We studied the distribution-wide population genetic structure of the Terek Sandpiper Xenus cinereus using 13 microsatellite loci and the mitochondrial DNA (mtDNA) control region. In addition, we estimated whether genetic variation changes from the core towards the edge of the breeding range. We used the results to evaluate the management needs of the sampled populations. Distribution-wide genetic structure was negligible; the only population that showed significant genetic differentiation was the geographically isolated Dnieper River basin population in Eastern Europe. The genetic variation of microsatellites decreased towards the edge of the distribution, supporting the abundant-centre hypotheses in which the core area of the distribution preserves the most genetic variation; however, no such trend could be seen with mtDNA. Overall genetic variation was low and there were signs of past population contractions followed by expansion; this pattern is found in most northern waders. The current effective population size (N e ) is large, and therefore global conservation measures are not necessary. However, the marginal Dnieper River population needs to be considered its † Equal contributors.
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