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1.
The distribution of otters (Lutra lutra) in Europe is largely fragmented, mainly due to historic anthropogenic causes. Nevertheless, in eastern Germany a large coherent area is inhabited by a viable otter population. In this paper, the mitochondrial genome of 81 otters is studied by RFLP analysis of PCR-amplified 1.5 and 2.5 kb long fragments, particularly to estimate the amount of genetic variability of European otters, and to identify possible geographical population subsets for conservation management. No restriction site polymorphism was detected within the control region (1.5 kb), but polymorphism of cleaving sites in the 2.5 kb fragment could be assigned to three haplotypes. Two occurred exclusively in a comparatively small area northwest and west of Berlin, which may be considered a region of increased genetic variability in otters. The low level of mtDNA variability in European otters might be due to genetic drift in postglacial founder populations with long-term low densities, and continuous historical overhunting. 相似文献
2.
The decline of the European otter (Lutra lutra) seems to be related to environmental contamination especially with polychlorinated biphenyls (PCBs). Only a limited number of tissue samples from otters killed accidently as traffic victims or drowned in fishnets are available for residue analysis. Calculating the levels of PCBs in otter tissues from concentrations in fish and scats would be a very valuable tool to estimate potential risks for this endangered species. PCB levels measured in otter livers, scats and fish from a Middle European otter population were used to examine the suitability of mathematical models for calculating PCB concentrations in otter liver from fish concentrations and from scat levels. Our results suggest that the models and input parameters currently used to calculate PCB concentrations in otters to estimate risks do not predict mean concentrations in otter livers in our Middle European study area, giving lower concentrations than actually analysed in the tissues. Possible causes for the observed discrepancy between measured and calculated values are discussed. 相似文献
3.
《Biological conservation》1986,38(4):293-304
A survey of the huillin or southern river otter Lutra provocax distribution was made in Lanin, Puelo and Los Alerces National Parks. Signs of otters were found at only 4 of 175 sites visited and all of these were in the south of Lanin. According to local people the species occurred in all three National Parks until 25–40 years ago.The main reason for the loss of huillines seems to be intensive hunting in the past.The geography and structure of the hydrological basins may help explain the lack of recolonisation by huillines from remnant populations. Signs of mink Mustela vison were found in both Puelo and Los Alerces and, while mink could not have been responsible for the decline of the otter, they may hinder re-establishment of otter populations. Human disturbance and tourism are not thought to have a significant impact on huillin distribution although remote refuges should be maintained, and our results show the importance of good coastal vegetation cover for permanent populations of the species.It is clear that the only important and permanent population of huillines in Argentina, between 39°S and 43°S, occurs at Nahuel Huapi National Park, which was surveyed in 1982–1983. This population is now of critical importance for the conservation of the species, which should retain its ‘endangered’ status in Argentina. Measures to implement huillin conservation are proposed. 相似文献
4.
D.B. Siniff Thomas D. Williams Ancel M. Johnson David L. Garshelis 《Biological conservation》1982,23(4):261-272
Two oiling experiments were conducted from 1977–1979 on sea otters Enhydra lutris in Prince William Sound, Alaska. In the first experiment, four captured otters were fitted with radio-transmitters and released following contamination of their pelage with 25 cc of Prudoe Bay crude oil; a fifth individual was oiled and cleaned with detergent prior to being released. For all experimental animals activity increased dramatically during the first week following treatment; this effect was accentuated in the otter cleaned with detergent. Most of the increase in activity corresponded to increased grooming, whereas the feeding pattern (as measured by dive time analysis) did not change. It appeared that all experimental otters survived the first experiment, probably because only a small portion of the pelage was treated, and because food resources in the study area were abundant. In the second experiment we observed behavioural reactions of two otters in an above-ground swimming pool which was partly covered with crude oil. Both otters spent very little time on the oiled side of the pool (less than 1 minute per hour), but occasionally surfaced in it for brief periods and eventually became contaminated. One of these individuals was not cleaned and died within 24 h of first encounter with the oil; the other was cleaned and released with a radio-transmitter that failed shortly afterwards. 相似文献
5.
《Biological conservation》1986,35(2):187-194
Because the survey of distribution of faeces (spraints) of otters is so frequently used in the assessment of otter populations and otter habitat use, we have studied the spatial relation between sprainting and various criteria of otter activity and presence. In a marine habitat on Shetland spraints were found to be associated with otter holts and habitat features, such as freshwater pools. There was no correlation between sprainting and the frequency of use of an area by otters. This casts doubt on the use of spraint surveys as a method to assess habitat utilisation by otters. It is argued that, with reservation, spraint surveys may be used for comparing otter populations between large stretches of river, or coast, with similar vegetation and physiography. 相似文献
6.
The influence of acidification on otters (Lutra lutra) was assessed in three regions of Scotland. A total of 72 stretches of 1000 m of riverbank were searched for all signs of otters on three occasions. Water chemistry was determined and habitat was assessed for its suitability to otters. A further series of water samples were collected after a period of very heavy rain in midwinter; conductivity and pH were measured and total Al was determined on a filtered, acidified sample. Otters were recorded at all sites. There were highly significant correlations between use by otters of stretches (measured in terms of marking intensity) and both pH and conductivity, with pH accounting for the greatest proportion of variation in otter signs in a stepwise multiple regression. The relation between otter signs and water quality was greatest in Galloway, the region with significantly more acid waters. There were significantly fewer signs of otters in stretches with minimum pH thought to be detrimental to fish populations for two regions, Galloway and Sutherland. 相似文献
7.
Sarah A. Sonsthagen Timothy J. Coonan Brian C. Latta George K. Sage Sandra L. Talbot 《Biological conservation》2012,146(1):116-122
Gene flow can have profound effects on the genetic diversity of a founding population depending on the number and relationship among colonizers and the duration of the colonization event. Here we used data from nuclear microsatellite and mitochondrial DNA control region loci to assess genetic diversity in golden eagles of the recently colonized Channel Islands, California. Genetic diversity in the Channel Island population was low, similar to signatures observed for other recent colonizing island populations. Differences in levels of genetic diversity and structure observed between mainland California and the islands suggests that few individuals were involved in the initial founding event, and may have comprised a family group. The spatial genetic structure observed between Channel Island and mainland California golden eagle populations across marker types, and genetic signature of population decline observed for the Channel Island population, suggest a single or relatively quick colonization event. Polarity in gene flow estimates based on mtDNA confirm an initial colonization of the Channel Islands by mainland golden eagles, but estimates from microsatellite data suggest that golden eagles on the islands were dispersing more recently to the mainland, possibly after reaching the carrying capacity of the island system. These results illustrate the strength of founding events on the genetic diversity of a population, and confirm that changes to genetic diversity can occur within just a few generations. 相似文献
8.
Efficiency of conservation shortcuts: an investigation with otters as umbrella species 总被引：1，自引：0，他引：1
The use of shortcuts is widespread in conservation practices to help ensure biodiversity conservation with minimal expenditures. An umbrella species is a species whose conservation confers protection to a large number of naturally co-occurring species. The aim of this study is to test the usefulness of the umbrella species concept for conservation management. As our umbrella, we chose a wide-ranging and flagship species, the European otter (Lutra lutra). Otters are widely distributed predators with numerous genera and species, so otter occurrence could virtually be used as “umbrella” in every freshwater habitat. To test the usefulness of the concept, we investigated whether an umbrella species might protect other species in the long term. We compared (1) bird and amphibian species richness in 1993 and in 2003 on nine sites where otters were monitored for 20 years, and (2) bird, amphibian and mollusc species richness between the previous sites and nine bio-equivalent sites where no otter occurrence has been detected for 20 years. The study was carried out for two spatial scales: total otter home range and core areas (most intensely exploited areas). Our results show that species richness was significantly different between years on sites inhabited by otters. However, we showed that biodiversity did not differ between pairs of bio-equivalent sites inhabited or deserted by otters, whatever the estimation method. Our results cast doubt on the validity of umbrella species use as an objective tool for conservation. However, the keystone functional role that otters could play in ecosystems might be an interesting way to reconsider the purpose of the umbrella species concept. 相似文献
9.
K.A. Witzenberger 《Biological conservation》2008,141(12):3059-3068
Animal relocations have become a common tool in nature conservation, but the genetic consequences of such projects have rarely been studied in insects. As both natural and artificial formation of new populations may lead to genetic drift (founder effect), decreased genetic diversity and increased rates of inbreeding, genetic analyses can provide valuable information to evaluate the success of a relocation project. The field cricket (Gryllus campestris) has been subjected to reintroduction and translocation projects in England and northern Germany. Here, we present a microsatellite study on the population genetics of one recently established population of this species in comparison with several older populations and some recently colonized sites. Our results show that the translocation did not result in a significant loss of genetic diversity, when compared to source and other natural populations suggesting that translocation of a high number of nymphs from different subpopulations may be a suitable method to decrease the loss of genetic diversity and reduce the risk of inbreeding. Furthermore, the translocation had no negative effect on the source population, which reached a new maximum population size in 2006. An assignment test showed that individuals from the translocated population (F4 generation) were still assigned to the source populations, whereas two young subpopulations that originated by natural colonization from the central population about ten years ago already formed separate genetic clusters. As the strong fragmentation of G. campestris populations in northern Germany hampers natural colonization of newly created potential habitats, translocation projects seem to be an appropriate method to preserve this species. 相似文献
10.
The transplant of sea otters to British Columbia from Alaska has survived a decade but without increase in population numbers, i.e. 70 + animals. The stock has split into two groups, the northernmost of which is close to the release site. This group maintains a 9-km2 triangular home range in summer located amongst offshore reefs. The range is occupied by females with pups, dependent juveniles and sub-adults. Adult males are scattered nearby. Storms can induce coastward movement. The range is patrolled daily for feeding and sleeping by many of the occupying animals. Feeding was predominantly on the butter clam Saxidomus giganteus. Feed stocks of sea-urchins have reduced dramatically since 1972. The site is accessible and can provide research opportunities. 相似文献
11.
David Jenkins 《Biological conservation》1981,20(2):123-132
Habitats for inclusion within otter havens are illustrated from a case-history study on the middle part of the Aberdeenshire River Dee. The environment is divided into breeding and rearing areas and places for non-breeding otters. One good location for a haven incorporating all three habitats includes 12–13 km of river and two nearly lochs. In this area, part of the river bank is inaccessible, and there are secluded islands and deep woods. Havens should include tiny tributaries leading to shelter where otters are likely to have their young. An otter haven in mid-Deeside planned to incorporate all these habitats may be regarded as a model for conservation that could be followed in other similar environments elsewhere. 相似文献
12.
Roads can have two important effects on populations that impact genetic variation: reduced gene flow and reduced abundance. Reduced gene flow (“barrier effects”) due to road avoidance behavior or road mortality can lead to reduced genetic diversity because genetic drift is enhanced in fragmented populations. Road mortality can also reduce population abundance (“depletion effects”) whenever road-caused mortality outpaces recruitment, also lowering diversity even when barrier effects are inconsequential. Although roads are expected to affect both genetic diversity and fragmentation, most research focuses only on fragmentation. Furthermore, in studies that do investigate road effects on genetic diversity, correlations are usually attributed to barrier effects and little attention is paid to the potentially confounding influence of mortality-caused depletion effects. Here we investigate the relative importance of barrier and depletion effects on genetic diversity of populations separated by a road by performing coalescent simulations wherein these two road effects are varied independently. By simulating wide ranging rates of migration and population decline, we also determine how the importance of these forces changes depending on their relative magnitude. We show that the vast majority of potential variation in genetic diversity is governed by depletion (mortality) rather than barrier effects. We also show that unless migration is sufficiently high and population decline due to mortality is sufficiently low, increasing migration across roads will generally not recoup genetic variation lost due to road mortality. We argue that the genetic effects of road-mediated mortality have been underappreciated and should be more often considered before prioritizing road-mitigation measures. 相似文献
13.
本研究利用20对微卫星引物对鳜（Sinipelrca chuatsi）原种群体和养殖群体进行遗传多样性分析。结果表明,在鳜原种群体中检测到多态性位点14个,养殖群体11个。在两个群体中共检测到等位基因数96个,其中原种群体检测到等位基因数53个,每个位点的等位基因数在1～7之间,平均有效等位基因数为2．7390;养殖群体检测到等位基因数43个,每个位点的等位基因数在1-6之间,平均有效等位基因数为2．1284。原种群体的平均观察杂合度0．5708,Nei氏期望杂合度0．5295,平均多态信息含量PIC0．5353;养殖群体的平均观察杂合度0．3839,Nei氏期望杂合度0．4011,平均多态信息含量PIC0．5043。因此,与养殖群体相比,鳜原种群体仍有丰富的遗传多样性。本研究可为鳜种质资源的保护、监测和遗传育种提供分子水平上的数据。 相似文献
14.
In a survey of central Portugal during August 1980, otters were found to be widespread with signs of animals 70% of the 90 stations visited. Otters were present on major rivers and their tributaries, on small streams connecting pools and at fetid pools in semi-dry river beds. The greatest densities of marking sites and signs were found around fetid pools. Snakes, as well as fish, were found to be important prey items. The survival, in good numbers, of the otter in Portugal may be due in part to the limited use of agricultural chemicals. 相似文献
15.
William H. Drury 《Biological conservation》1974,6(3):162-169
An operational definition of rare species might include the specification that it either occurs in widely separated, small sub-populations so that interbreeding between sub-populations is seriously reduced, or is restricted to a single population. It has usually been assumed that depauperization of habitat and reduction of genetic material have occurred in rare species, but recent studies of electrophoretically identified genetic polymorphisms suggest that some small populations and some inbreeding populations may retain considerable heterogeneity. Because different populations of a species tend to differ in genetic composition, one would expect the number of sub-populations to be more important for the population's security than the total population size. Specialization of an isolated inbreeding population to a restricted homogeneous habitat under pressure of competition should have serious ecological consequences. This reasoning suggests several conclusions. The protection of an isolated, reduced population in its present state may encourage further specialization and conservatism. In rehabilitating a relict population a first step might be to encourage it to break up into largely, but not completely, independent sub-populations. In a breeding programme, variability should be deliberately promoted as well as quick turnover between the breeding population and the wild. Very high mortality of released individuals must be expected, because it is the rule in the wild even in a rapidly increasing population. 相似文献
16.
Sean. D. Schoville Tate S. Tustall Vance T. Vredenburg Adam R. Backlin Elizabeth Gallegos Dustin A. Wood Robert N. Fisher 《Biological conservation》2011,(7):2031-2040
Severe population declines led to the listing of southern California Rana muscosa (Ranidae) as endangered in 2002. Nine small populations inhabit watersheds in three isolated mountain ranges, the San Gabriel, San Bernardino and San Jacinto. One population from the Dark Canyon tributary in the San Jacinto Mountains has been used to establish a captive breeding population at the San Diego Zoo Institute for Conservation Research. Because these populations may still be declining, it is critical to gather information on how genetic variation is structured in these populations and what historical inter-population connectivity existed between populations. Additionally, it is not clear whether these populations are rapidly losing genetic diversity due to population bottlenecks. Using mitochondrial and microsatellite data, we examine patterns of genetic variation in southern California and one of the last remaining populations of R. muscosa in the southern Sierra Nevada. We find low levels of genetic variation within each population and evidence of genetic bottlenecks. Additionally, substantial population structure is evident, suggesting a high degree of historical isolation within and between mountain ranges. Based on estimates from a multi-population isolation with migration analysis, these populations diversified during glacial episodes of the Pleistocene, with little gene flow during population divergence. Our data demonstrate that unique evolutionary lineages of R. muscosa occupy each mountain range in southern California and should be managed separately. The captive breeding program at Dark Canyon is promising, although mitigating the loss of neutral genetic diversity relative to the natural population might require additional breeding frogs. 相似文献
17.
William R. Wengeler Douglas A. Kelt Michael L. Johnson 《Biological conservation》2010,143(5):1144-1153
The introduction of lake trout (Salvelinus namaycush) to Yellowstone Lake in Yellowstone National Park has contributed to a significant decline in the endangered Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri), leading to concern over the persistence of this subspecies but also to piscivorous predators in this community. We assessed the impact of lake trout on a key piscivore, the river otter (Lontra canadensis) in two lakes in Yellowstone National Park. Yellowstone Lake continues to support a native cutthroat trout population, although the recent introduction of lake trout has dramatically impacted the cutthroat trout population. Nearby Lewis Lake has an entirely introduced fish fauna of lake trout, brown trout (Salmo trutta), and Utah chub (Gilia atraria) but lacks cutthroat trout. Analysis of otter scat from Yellowstone Lake implicated trout (lake or cutthroat trout) as a major prey item (57% of scat), whereas stable isotopes identified longnose suckers (Catostomus catostomus) as the primary prey there (58% of diet). By contrast, scat from Lewis Lake implicated minnows, presumably Utah chub, as the primary prey for otters occupying that lake (86%), while stable isotopes implicated brown trout (64%) over both lake trout and Utah chub (36% combined). Our data establish the importance of alternative prey to otters and suggest that lake trout-induced reductions in cutthroat trout may not be catastrophic for otter populations here. These data do not necessarily exonerate lake trout, as their impact on other species, most notably grizzly bears (Ursus arctos) and piscivorous birds, has been documented to be substantial, and further data on the nutritional value of alternate prey are required to confirm or refute a working hypothesis that otter populations will continue to thrive in the face of the lake trout invasion. 相似文献
18.
Understanding the causes that determine the spread and subsequent population trends of invasive species is important as it can help predict and manage their impact, as well as advance the theory of invasion. The American mink Mustela vison is a riparian mustelid and an invasive species in several countries. Mink have been introduced to England in the early decades of the last century and have been expanding their range until the mid-eighties. Since then, however, the number of sites occupied by mink has been declining. We investigated three possible causes of such a decline: (1) A downtrend of the fur farming industry; (2) An increase of European polecats Mustela putorius; (3) An increase of Eurasian otters Lutra lutra. Mink trends were derived from data collected by the National Otter Survey, a large-scale long-term survey of the whole of England from 1977 to 2002. We discuss how the observed decline in the number of sites occupied by mink may be due to a combination of an actual decrease in the distribution and density of mink and to a change in the focus of mink activities away from water, rather than to a change in their marking behaviour. Taken together, our results suggest that the decline of mink is related to an increase in the native otter population through interspecific competition, although at a local level also other factors may be important. As the otter population is still increasing, it is likely that the number of sites occupied by mink will continue to decline, a process that may be beneficial to aquatic and semi-aquatic species suffering from mink predation. 相似文献
19.
Martha Desmond 《Biological conservation》2004,116(2):235-242
Chihuahuan Desert grasslands are important wintering grounds for grassland and shrub-adapted birds. Many species belonging to these assemblages are currently exhibiting population declines. One area recognized for its importance to biological diversity, including grassland birds, is the Janos-Nuevo Casas Grandes black-tailed prairie dog (Cynomys ludovicianus) complex in northwestern Chihuahua, Mexico, an area containing 58 colonies with 30,000 ha of prairie dogs. This is one of the largest remaining prairie dog complexes and the only intact complex in the Chihuahuan Desert. In its current condition, a large percentage of this complex is of reduced value to wildlife. Overgrazing on communal (ejido) lands has resulted in areas being comprised of annual grasses and forbs. The density of active prairie dog burrows and banner-tailed kangaroo rat (Dipodomys spectabilis) mounds as well as avian diversity and abundance were lower on ejido lands than an adjacent private ranchland with and without prairie dogs. Few avian species used overgrazed portions of the prairie dog colony. Community similarity among plot types was low due to different management practices and differences on and off colony. To retain, and in many instances restore the biological diversity of this important region it is essential to work with local ejidos on grazing management. 相似文献
20.
Kim M. Parsons Les R. NobleRobert J. Reid Paul M. Thompson 《Biological conservation》2002,108(2):175-182
Concern has been expressed over the status of the bottlenose dolphin population that uses the Moray Firth and adjacent waters in NE Scotland. Consequently, part of this population's range has been proposed as a Special Area of Conservation. Efforts to manage and monitor the status of this population require information on the level of genetic diversity within the population and its genetic relatedness to neighbouring populations to appropriately designate units for management and monitoring. Here we examine mitochondrial genetic diversity within the NE Scotland population, and compare this to other regions around the UK and Ireland. Sequence analysis of 549bp of the mitochondrial DNA control region identified eight unique haplotypes in a sample of 29 individuals. Analysis of molecular variance suggests that the Moray Firth population is genetically more closely related to Welsh animals than to its nearest neighbour population in west Scotland. Furthermore, measures of within-population genetic diversity were markedly lower in the Moray Firth than any other sampled region. The low levels of mtDNA genetic variability observed and its apparent geographic isolation provide further support for the precautionary approach currently being applied to the management of this population, despite the lack of direct evidence of harm. 相似文献