Microtus Richardsoni Research Articles

Reduced representation approaches produce similar results to whole genome sequencing for some common phylogeographic analyses.

When designing phylogeographic investigations researchers can choose to collect many different types of molecular markers, including mitochondrial genes or genomes, SNPs from reduced representation protocols, large sequence capture data sets, and even whole genomes. Given that the statistical power and accuracy of various analyses are expected to differ depending on both the type of marker and the amount of data collected, an exploration of the variance across methodological results as a function of marker type should provide valuable information to researchers. Here we collect mitochondrial Cytochrome b sequences, whole mitochondrial genomes, single nucleotide polymorphisms (SNP)s isolated using a genotype by sequencing (GBS) protocol, sequences from ultraconserved elements, and low-coverage nuclear genomes from the North American water vole (Microtus richardsoni). We estimate genetic distances, population genetic structure, and historical demography using data from each of these datasets and compare the results across markers. As anticipated, the results exhibit differences across marker types, particularly in terms of the resolution offered by different analyses. A cost-benefit analysis indicates that SNPs collected using a GBS protocol are the most cost-effective molecular marker, with inferences that mirror those collected from the whole genome data at a fraction of the cost per sample.

Genomic Resources for the North American Water Vole (Microtus richardsoni) and the Montane Vole (Microtus montanus).

Voles of the genus Microtus are important research organisms, yet genomic resources are lacking. Such resources would benefit future studies of immunology, phylogeography, cryptic diversity, and more. We sequenced and assembled nuclear genomes from two subspecies of water vole (Microtus richardsoni) and from the montane vole (Microtus montanus). The water vole genomes were sequenced with Illumina and 10× Chromium plus Illumina sequencing, resulting in assemblies with ∼1600,000 and ∼30,000 scaffolds, respectively. The montane vole was also assembled into ∼13,000 scaffolds using Illumina sequencing. Mitochondrial genome assemblies were also performed for both species. Structural and functional annotation for the best water vole nuclear genome resulted in ∼24,500 annotated genes, with 83% of these having functional annotations. Assembly quality statistics for our nuclear assemblies fall within the range of genomes previously published in the genus Microtus, making the water vole and montane vole genomes useful additions to currently available genomic resources.

Complete mitochondrial genome of the water vole, Microtus richardsoni (Cricetidae, Rodentia)

Water voles (Microtus richardsoni) are sensitive species distributed in the mountains of Canada (Alberta, British Columbia), and the United States of America (Idaho, Montana, Oregon, Utah, Washington, and Wyoming). We assembled the complete circular M. richardsoni mitogenome, which is 16,285 bp in length and encodes 13 protein-coding genes, 22 tRNA genes, and two rRNA genes. We estimated the phylogenetic tree of M. richardsoni and 24 related arvicoline species with two outgroup species: Phodopus roborovskii and Cricetus cricetus.

Paleoecological implications of the first prehistoric record of water vole (Microtus richardsoni) from Washington state, USA

AbstractRemains of the North American water vole (Microtus richardsoni) have previously been recovered from late Pleistocene and Holocene deposits in southwestern Alberta, western Montana, and north-central Wyoming. All are within the historically documented modern range of the metapopulation occupying the Rocky Mountains; no ancient remains of this large microtine have previously been reported from the metapopulation occupying the Cascade Range. Four lower first molar specimens from the late Holocene Stemilt Creek Village archaeological site in central Washington here identified as water vole are from the eastern slope of the Cascade Range and are extralimital to the metapopulation found in those mountains. There is no taphonomic evidence indicating long-distance transport of the teeth, and modern trapping records suggest the local absence of water voles from the site area today is not a function of sampling error. The precise age of the Stemilt Creek Village water voles is obscure but climate change producing well-documented late Holocene advances of nearby alpine glaciers could have created habitat conditions conducive to the apparent modest shift in the range of the species represented by the remains.

Metapopulation Biology: Microtus richardsoni in the Rocky Mountain Front Range of Alberta

Populations of the Water Vole (Microtus richardsoni) occur along headwater streamlets at timberline in the Rocky Mountain front ranges of Alberta. At the 2000-m contour riparian distances between potential habitat patches ranged from 749 to 24,651 m, whereas overland distances ranged from 157 to 5104 m. Reproduction is restricted to a snow-free (May–August) period of 60 to 112 d in which females typically produce 1 to 2 litters of 2 to 10 young. Based on home range overlaps, the mating system appears to be polygynous. Over 4 habitat patches and 9 patch-seasons, reproduction was dominated by overwintered adults and began with effective populations (Ne) of 9.2 (4.1 males and 6.8 females) occupying 3- to 4-ha patches of mesic vegetation. Territorial behavior opposes recruitment into these breeding populations. Few males have an opportunity to breed in their natal colony in their 1st summer, but 5% of 1st-litter female young (50% known to be philopatric) may do so. Young of subsequent litters, including any born to 1st-litter females, are unlikely to breed in the season of their birth. Episodes of predation may facilitate settlement and breeding of philopatric young of the year, or “floaters” of unknown origin. In a typical colony, breeding generated a mean surplus above replacement (potential emigrants) of 8 males and 6 females. Disappearance rates of overwintered adults (the number of voles present in 1 trapping session and not in the next divided by the number of intervening days) remained low until August. Disappearance of the 1st cohort of young averaged 1.8%/d for females and 3.7 %/d for males. Young persisting into September in their natal colonies were the most likely to be present in the following spring. The socially determined window for recruitment appears limited to late summer and early fall. Winter trapping indicated that low temperatures and heavy snow cover inhibit movement between habitat patches during the winter months. The limited genetic analysis available indicates that variation is maintained in local gene pools despite restriction to small isolated habitat patches, small effective population sizes, and territorial behavior. Conservation concerns may arise due to the habitat specificity of M. richardsoni and the constraints on population dynamics and gene flow imposed by the small size and isolation of habitat patches and the harshness of the subalpine environment.

INVESTIGATING THE EVOLUTIONARY HISTORY OF THE PACIFIC NORTHWEST MESIC FOREST ECOSYSTEM: HYPOTHESIS TESTING WITHIN A COMPARATIVE PHYLOGEOGRAPHIC FRAMEWORK

We examine the evolution of mesic forest ecosystems in the Pacific Northwest of North America using a statistical phylogeography approach in four animal and two plant lineages. Three a priori hypotheses, which explain the disjunction in the mesic forest ecosystem with either recent dispersal or ancient vicariance, are tested with phylogenetic and coalescent methods. We find strong support in three amphibian lineages (Ascaphus spp., and Dicampton spp., and Plethodon vandykei and P. idahoensis) for deep divergence between coastal and inland populations, as predicted by the ancient vicariance hypothesis. Unlike the amphibians, the disjunction in other Pacific Northwest lineages is likely due to recent dispersal along a northern route. Topological and population divergence tests support the northern dispersal hypothesis in the water vole (Microtus richardsoni) and northern dispersal has some support in both the dusky willow (Salix melanopsis) and whitebark pine (Pinus albicaulis). These analyses demonstrate that genetic data sampled from across an ecosystem can provide insight into the evolution of ecological communities and suggest that the advantages of a statistical phylogeographic approach are most pronounced in comparisons across multiple taxa in a particular ecosystem. Genetic patterns in organisms as diverse as willows and salamanders can be used to test general regional hypotheses, providing a consistent metric for comparison among members of an ecosystem with disparate life-history traits.

INVESTIGATING THE EVOLUTIONARY HISTORY OF THE PACIFIC NORTHWEST MESIC FOREST ECOSYSTEM: HYPOTHESIS TESTING WITHIN A COMPARATIVE PHYLOGEOGRAPHIC FRAMEWORK

We examine the evolution of mesic forest ecosystems in the Pacific Northwest of North America using a statistical phylogeography approach in four animal and two plant lineages. Three a priori hypotheses, which explain the disjunction in the mesic forest ecosystem with either recent dispersal or ancient vicariance, are tested with phylogenetic and coalescent methods. We find strong support in three amphibian lineages (Ascaphus spp., and Dicampton spp., and Plethodon vandykei and P. idahoensis) for deep divergence between coastal and inland populations, as predicted by the ancient vicariance hypothesis. Unlike the amphibians, the disjunction in other Pacific Northwest lineages is likely due to recent dispersal along a northern route. Topological and population divergence tests support the northern dispersal hypothesis in the water vole (Microtus richardsoni) and northern dispersal has some support in both the dusky willow (Salix melanopsis) and whitebark pine (Pinus albicaulis). These analyses demonstrate that genetic data sampled from across an ecosystem can provide insight into the evolution of ecological communities and suggest that the advantages of a statistical phylogeographic approach are most pronounced in comparisons across multiple taxa in a particular ecosystem. Genetic patterns in organisms as diverse as willows and salamanders can be used to test general regional hypotheses, providing a consistent metric for comparison among members of an ecosystem with disparate life-history traits.

The Status, Habitat, and Response to Grazing of Water Vole Populations in the Big Horn Mountains of Wyoming, U.S.A.

Microtus richardsoni, the water vole, was listed as a sensitive species in Region 2 of the USDA Forest Service in 1994. Historical records indicate water voles were found in the Big Horn Mountains, but little was known about their current status. The purpose of this study was to locate water voles in the Big Horn Mountains of Wyoming, develop a habitat profile, and evaluate the extent to which livestock grazing affects them. Accessible creeks with habitat requirements for water voles were surveyed. Water voles were not captured below 2440 m. Grazed and ungrazed sites occupied by water voles were matched and analyzed for percent plant cover, dry weight biomass, riparian classification, mean stream depth, channel type, elevation, precipitation, and temperature. Capture success was significantly greater in ungrazed areas. Percent cover by ferns and thallophytes was significantly greater in areas where water voles were more abundant, and bare ground was significantly greater at grazed locations. Water voles were most abundant on Rosgen B or E streams with a willow/wet Carex riparian class that is found on relatively undisturbed sites with stable, well-developed soils and bank structure. In the Big Horn Mountains, water vole captures were low in comparison to the Beartooth Mountains and synergistic effects of grazing and drying might negatively impact this species.

Microgeographic variation in allozymes and mitochondrial DNA ofMicrotus richardsoni, the water vole, in the Beartooth Mountains of Montana and Wyoming, U.S.A.

Microtus richardsoni, the water vole, is listed as a sensitive species within region 2 of the USDA Forest Service. Because it is a sensitive species, the water vole's ability to disperse becomes an important management concern in terms of its population viability. Both allozyme and mitochondrial DNA analyses were used to study microgeographic population structure within a group of populations from four adjacent watersheds of the Beartooth Mountains of Montana and Wyoming. Of 31 protein loci examined, only ADH, EST-1, and SOD-1 were polymorphic. ADH and EST-1 were in Hardy–Weinberg equilibrium, but SOD-1 was not. Mitochondrial DNA was found to be polymorphic with 9 restriction enzymes. The size of the fragments produced by each restriction enzyme was estimated and ordered into a site map. In total, 51 sites were found with 9 restriction enzymes resulting in 29 different haplotypes from 142 individuals. Shared haplotypes were geographically contiguous except for one. There was no significant difference in genetic distance among water voles from the Beartooth Mountains, and only the outgroup from Togwotee Pass in the Absaroka Mountains of Wyoming had significant genetic distance. This suggests the possibility of dispersal between water voles from the contiguous watersheds of the Beartooth Mountains but not between the Beartooth Mountains and Togwotee Pass populations.

Microgeographic variation in allozymes and mitochondrial DNA of <i>Microtus richardsoni</i>, the water vole, in the Beartooth Mountains of Montana and Wyoming, U.S.A.

Microgeographic variation in allozymes and mitochondrial DNA of <i>Microtus richardsoni</i>, the water vole, in the Beartooth Mountains of Montana and Wyoming, U.S.A.

Impact of Precipitation and Grazing on the Water Vole in the Beartooth Mountains of Montana and Wyoming, U.S.A.

This paper examines the influence of increased precipitation levels and grazing on the demographics of Microtus richardsoni. Water voles were trapped and marked during the summers of 1990, 1991, and 1992 along four headwater watersheds of the Clark's Fork of the Yellowstone River in Wyoming and Montana. The summer of 1992 had more than double the precipitation of either 1990 or 1991. During the wet summer of 1992, capture success was significantly greater, as was the proportion of young voles captured. In 1992, several factors contributed to increased water vole populations. There were significantly more indications of male reproductive activity. Class I water voles (13–49 g) of both sexes showed signs of reproductive activity indicating they were reaching sexual maturity at smaller body mass. Significantly more embryos/trap-killed female were found. In 1995, the water vole was listed as a sensitive species because it is rare and requires specific alpine riparian habitat that is declining and may be damaged by poor grazing practices. Capture success was significantly greater, and there were significantly more young water voles in ungrazed drainages. Measured indicators of reproductive activity did not vary significantly between grazed and ungrazed drainages. Grazing might affect survival of young water voles and should be studied further.

Reproduction and Population Dynamics of the Water Vole, Microtus richardsoni

Populations of Microtus richardsoni were livetrapped from June 1977 through December 1980 in the eastern Front Range of the Canadian Rocky Mountains. Three hundred and twenty-three animals were captured 1,099 times at four study sites. Population densities within streamside habitats ranged from 0.2 to 12.2 voles/ha. Seasonal recruitment increased population size from 0.8 to 6.2 times. Sex ratios for both young and overwintered water voles were 1:1. The 3–3.5 months of mating activity began during the last week of May or the first 2 weeks in June (first conceptions) and ended during August or early September (last conceptions). Young first entered the trappable population during the 1st week of July. Overwintered females produced a maximum of two litters per season, each with a mean size of five young. Approximately 26% of the young of the year, primarily voles from the season's first litters, bred before their first winter.

Water vole Microtus richardsoni (Mammalia, Rodentia) from the Late Pleistocene of Alberta

A Late Pleistocene specimen of the water vole has been recovered from a cave in the Rocky Mountains of southwestern Alberta. Pleistocene records for this species are rare and this specimen is probably the oldest known. The evolutionary history of Microtus richardsoni, although yet uncertain, is tentatively discussed. Information is gained concerning the paleoenvironment of southwestern Alberta during late(?) mid-Wisconsinan time.

Plant and Mannal Changes on a Clearcut In West‐Central Oregon

Plant composition and coverage and small mammal populations were compared in virgin forest (control) and clearcut (experimental) areas from April 1954 to October 1965. Changes in ground cover vegetation were modest on the control area but marked on the experimental area. A late fall burn on the experimental area may have retarded herbaceous plant establishment. Nearly half of the herbaceous species were invaders not found in the virgin Douglas—fir (Pseudotsuga menziesii) forest. Ground plant coverage was less than 23% in the virgin forest; 1 year after the clearcut area was burned, the cover was 2%; and by 10 years it was above 53%. Woody plant coverage (mostly sprouts) was slightly more abundant the first 2 years after burning. Herbaceous species then became dominant for a 3—year period, after which woody plants gradually gained dominance. Deer mice (Peromyscus maniculatus) increased on the experimental area soon after the burn. The populations varied from an estimated 0.9 to 12.8 animals per acre and fluctuated widely and irregularly. Townsend's chipmunk (Eutamias townsendii), Oregon vole (Microtus oregoni), and snowshoe hare (Lepus americanus) populations also increased on the area at different periods after the burn. Trownbridge's shrews (Sorex trowbridgii), vagrant shrews (Sorex vagrans), and ermine (Mustela erminea) were present on both areas in relatively low numbers. Redback voles (Clethrionomys occidentalis), Douglas' squirrels (Tamiasciurus douglasii), and northern flying squirrels (Glaucomys sabrinus) were not found on the clearcut. California ground squirrels (Spermophilus beecheyi) migrated to the clearcut and established a modest population. Richardson's voles (Microtus richardsoni), jumping mice (Zapus trinotatus), bushy—tailed woodrats (Neotoma cinerea), and a pika (Ochotona princeps) were visitors.

Notes Relative to the Fluctuation in Numbers of Microtus richardsoni richardsoni about Alta Lake and Pemberton Valley, B. C.

Notes Relative to the Fluctuation in Numbers of Microtus richardsoni richardsoni about Alta Lake and Pemberton Valley, B. C.