The European natterjack toad (Bufo calamita) has declined rapidly in recent years, primarily due to loss of habitat, and in Denmark it is estimated that 50% of the isolated populations are lost each ...decade. To efficiently manage and conserve this species and its genetic diversity, knowledge of the genetic structure is crucial. Based on nine polymorphic microsatellite loci, the genetic diversity, genetic structure and gene flow were investigated at 12 sites representing 5-10% of the natterjack toad localities presently known in Denmark. The expected heterozygosity (H E) within each locality was generally low (range: 0.18-0.43). Further analyses failed to significantly correlate genetic diversity with population size, degree of isolation and increasing northern latitude, indicating a more complex combination of factors in determining the present genetic profile. Genetic differentiation was high (overall θ = 0.29) and analyses based on a Bayesian clustering method revealed that the dataset constituted 11 genetic clusters, defining nearly all sampling sites as distinct populations. Contemporary gene flow among populations was undetectable in nearly all cases, and the failure to detect a pattern of isolation by distance within major regions supported this apparent lack of a gene flow continuum. Indications of a genetic bottleneck were found in three populations. The analyses suggest that the remaining Bufo calamita populations in Denmark are genetically isolated, and represent independent units in a highly fragmented gene pool. Future conservation management of this species is discussed in light of these results.
The walrus (Odobenus rosmarus) is in some current systematic schemes divided into three subspecies: O. r. rosmarus in the North Atlantic, O. r. divergens in the North Pacific and O. r. laptevi in the ...Laptev Sea. These three subspecies have been described as differing in body size, but the taxonomic status of O. r. laptevi is disputed. The current study applies molecular and morphometric methods to assess the taxonomic status of O. r. laptevi and to analyse the systematic and phylogeographic relationships between the three purported walrus subspecies. Tusk length and tusk circumference were measured from the few skulls available of O. r. laptevi, and the obtained values were within the ranges reported for Pacific walruses. Thus, morphologically, subspecies status for O. r. laptevi is not supported according to the Amadon–Mayr ‘75% rule’. Phylogenetic analyses and haplotype networks based on mitochondrial nucleotide sequence data of NADH dehydrogenase 1, 16S rRNA, cytochrome oxidase I and the d‐loop of the control region of the historic O. r. laptevi bone material and contemporary O. r. rosmarus and O. r. divergens showed that the Laptev Sea walrus groups with individuals from the North Pacific. Thus, the mitochondrial sequence data do not support the recognition of three walrus subspecies as reciprocally monophyletic evolutionary units with independent evolutionary histories. Only O. r. rosmarus and O. r. divergens meet this criterion with the present sampling. Accordingly, we recommend that Odobenus r. laptevi be abandoned and the Laptev walrus instead be recognized as the westernmost population of the Pacific walrus, Odobenus r. divergens. However, further research is recommended to assess whether the Laptev walrus could be considered as a significant unit in terms of conservation and management, since it is unique in several ecological parameters.
Molecular Method for Determining Sex of Walruses Fischbach, Anthony S; Jay, Chadwick V; Jackson, James V ...
The Journal of wildlife management,
11/2008, Letnik:
72, Številka:
8
Journal Article
Recenzirano
We evaluated the ability of a set of published trans-species molecular sexing primers and a set of walrus-specific primers, which we developed, to accurately identify sex of 235 Pacific walruses ...(Odobenus rosmarus divergens). The trans-species primers were developed for mammals and targeted the X- and Y-gametologs of the zinc finger protein genes (ZFX, ZFY). We extended this method by using these primers to obtain sequence from Pacific and Atlantic walrus (O. r. rosmarus) ZFX and ZFY genes to develop new walrus-specific primers, which yield polymerase chain reaction products of distinct lengths (327 and 288 base pairs from the X- and Y-chromosome, respectively), allowing them to be used for sex determination. Both methods yielded a determination of sex in all but 1–2% of samples with an accuracy of 99.6–100%. Our walrus-specific primers offer the advantage of small fragment size and facile application to automated electrophoresis and visualization.
Denmark lies on the edge of the distributional range of the brown hareLepus europaeus Pallas, 1778, where population differentiation is most likely to occur. A total of 369 brown hares from eight ...geographically distinct Danish European brown hare populations were used to study the genetic population structure. In all, 480bp of the mitochondrial D-loop were sequenced in both directions. Observed genetic diversity (π) was relatively low (π=0.41%) while haplotype diversity (h=0.808) and the number of unique haplotypes (19) were similar to levels found in other European brown hare populations. The observed population structure was pronounced (pairwise conventionalFST and ϕst ranged between 6.9–57% and 5–69.8%, respectively). There was no correlation between the geographic and the genetic distance. Population structure was influenced by genetic drift, anthropogenic effects (eg translocation and escapes from hare-farms) and by post-glacial recolonization from southern refuges or refuges north east of the Black Sea. Analysis of historical population expansion/fluctuation events indicated that the populations have experienced different demographic events in the recent past. Relatively high sequence divergence between some populations might be explained by multiple recolonization events after the last Pleistocene glaciations or by stocking effects. Colonization from southern refuges was supported by the observation that haplotype 2 in the Danish brown hare was identical to the central European ancestral haplotype c07.
A genetic study to determine the population structure of minke whales Balaenoptera acutorostrata in Greenland, the Central and NE Atlantic and the North Sea was carried out on a sample of 306 ...individuals. Samples were analysed by sequencing the D-loop in mtDNA and using 16 polymorphic nuclear microsatellite markers. Muscle samples from a total of 154 minke whales, caught between 6 May and 31 October 1998 by Greenland and Norwegian licensed whalers within 6 areas of the North Atlantic, were analysed (West Greenland, n = 44; Jan Mayen, n = 24; Svalbard, n = 16; the Barents Sea, n = 33; Vesteraalen/Lofoten on the coast of northwestern Norway, n = 14, and the North Sea, n = 23). In addition, 30 minke whales sampled in East Greenland during 1996, 1997 and 1999 were included. Furthermore, 122 minke whales caught in West Greenland in 3 different years (1982, 1996 and 1997) were analysed to determine potential inter-annual variation within a sampling area. The lack of inter-annual variation in West Greenland suggests that the minke whales summering in the area year after year belong to the same sub-population. The study indicated the existence of 4 genetically differentiated sub-populations: (1) West Greenland, (2) Central North Atlantic-East Greenland-Jan Mayen area, (3) NE Atlantic (Svalbard, the Barents Sea and northwestern Norway), and (4) North Sea. It is suggested that these sub-populations have been isolated by discontinuities between regions, i.e. each of the sub-populations has evolved in response to regional differences in ecological conditions (oceanography, ice cover, prey type and prey availability).
Climate change is expected to result in range shifts and habitat fragmentation for many species. In the Arctic, loss of sea ice will reduce barriers to dispersal or eliminate movement corridors, ...resulting in increased connectivity or geographic isolation with sweeping implications for conservation. We used satellite telemetry, data from individually marked animals (research and harvest), and microsatellite genetic data to examine changes in geographic range, emigration, and interpopulation connectivity of the Baffin Bay (BB) polar bear (Ursus maritimus) subpopulation over a 25‐year period of sea‐ice loss. Satellite telemetry collected from n = 43 (1991–1995) and 38 (2009–2015) adult females revealed a significant contraction in subpopulation range size (95% bivariate normal kernel range) in most months and seasons, with the most marked reduction being a 70% decline in summer from 716,000 km2 (SE 58,000) to 211,000 km2 (SE 23,000) (p < .001). Between the 1990s and 2000s, there was a significant shift northward during the on‐ice seasons (2.6° shift in winter median latitude, 1.1° shift in spring median latitude) and a significant range contraction in the ice‐free summers. Bears in the 2000s were less likely to leave BB, with significant reductions in the numbers of bears moving into Davis Strait (DS) in winter and Lancaster Sound (LS) in summer. Harvest recoveries suggested both short and long‐term fidelity to BB remained high over both periods (83–99% of marked bears remained in BB). Genetic analyses using eight polymorphic microsatellites confirmed a previously documented differentiation between BB, DS, and LS; yet weakly differentiated BB from Kane Basin (KB) for the first time. Our results provide the first multiple lines of evidence for an increasingly geographically and functionally isolated subpopulation of polar bears in the context of long‐term sea‐ice loss. This may be indicative of future patterns for other polar bear subpopulations under climate change.
Abstract
Following protection measures implemented since the 1970s, large carnivores are currently increasing in number and returning to areas from which they were absent for decades or even ...centuries. Monitoring programmes for these species rely extensively on non‐invasive sampling and genotyping. However, attempts to connect results of such studies at larger spatial or temporal scales often suffer from the incompatibility of genetic markers implemented by researchers in different laboratories. This is particularly critical for long‐distance dispersers, revealing the need for harmonized monitoring schemes that would enable the understanding of gene flow and dispersal dynamics.
Based on a review of genetic studies on grey wolves
C
anis lupus
from
E
urope, we provide an overview of the genetic markers currently in use, and identify opportunities and hurdles for studies based on continent‐scale datasets.
Our results highlight an urgent need for harmonization of methods to enable transnational research based on data that have already been collected, and to allow these data to be linked to material collected in the future. We suggest timely standardization of newly developed genotyping approaches, and propose that action is directed towards the establishment of shared single nucleotide polymorphism panels, next‐generation sequencing of microsatellites, a common reference sample collection and an online database for data exchange.
Enhanced cooperation among genetic researchers dealing with large carnivores in consortia would facilitate streamlining of methods, their faster and wider adoption, and production of results at the large spatial scales that ultimately matter for the conservation of these charismatic species.
A genetic study to determine the population structure of minke whalesBalaenoptera acutorostratain Greenland, the Central and NE Atlantic and the North Sea was carried out on a sample of 306 ...individuals. Samples were analysed by sequencing the D-loop in mtDNA and using 16 polymorphic nuclear microsatellite markers. Muscle samples from a total of 154 minke whales, caught between 6 May and 31 October 1998 by Greenland and Norwegian licensed whalers within 6 areas of the North Atlantic, were analysed (West Greenland, n = 44; Jan Mayen, n = 24; Svalbard, n = 16; the Barents Sea, n = 33; Vesterålen/Lofoten on the coast of northwestern Norway, n = 14, and the North Sea, n = 23). In addition, 30 minke whales sampled in East Greenland during 1996, 1997 and 1999 were included. Furthermore, 122 minke whales caught in West Greenland in 3 different years (1982, 1996 and 1997) were analysed to determine potential inter-annual variation within a sampling area. The lack of inter-annual variation in West Greenland suggests that the minke whales summering in the area year after year belong to the same sub-population. The study indicated the existence of 4 genetically differentiated sub-populations: (1) West Greenland, (2) Central North Atlantic-East Greenland-Jan Mayen area, (3) NE Atlantic (Svalbard, the Barents Sea and northwestern Norway), and (4) North Sea. It is suggested that these sub-populations have been isolated by discontinuities between regions, i.e. each of the sub-populations has evolved in response to regional differences in ecological conditions (oceanography, ice cover, prey type and prey availability).
Variation in foetal and postnatal sex ratios was examined jointly with the 1986-1988 Faroese international research programme on the ecology and status of the long-finned pilot whale (Globicephala ...melas). Data were obtained from 58 schools of whales landed in the Faroe Islands from 1958 to 1992. The sample includes 505 embryos and foetuses. Variation in foetal sex ratios was analysed according to gestational age, mother's age and years. Foetal and postnatal sex ratios from pilot whales off the Faroe Islands also were compared with those obtained off Newfoundland by Sergeant (1962).
The overall foetal sex ratio was biased significantly towards more females than males. The proportion of male foetuses declined as the size of foetuses increased. Females older than 25 yrs of age in comparison to younger females bore more female than male foetuses. From birth, through the three first years oflife, selection acted mainly against females and parity was observed again in the age group 3 and maintained until the age group 10. Annual variation may occur. For similar season, at a 30-year interval, foetal sex ratio differed significantly between the Faroes and Newfoundland (46.9% and 58.8%, respectively, more male foetuses).
The relative higher mortality of male than female foetuses suggest that a significant overall foetal mortality occurs, which has to be taken into account when estimating fecundity.
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