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1.
We studied dispersal in 27 radio-collared Florida panthers Puma concolor coryi in southern Florida from 1986 to 2000. Male dispersal was longer (mean=68.4 km) than that of females (mean=20.3 km), tended to be circular, frustrated, and of insufficient length to ameliorate inbreeding. Females were philopatric and established home ranges that were less than one home range width away from their natal ranges. All females were successful in establishing territories, whereas males were successful 63% of the time. Dispersing panthers avoided moving toward the southeast and into an area of limited forest cover. Independence and the initiation of dispersal occurred at about 14 months of age and lasted for an average of 7.0-9.6 months for females and males, respectively. On average, Florida panthers disperse shorter distances than are typical for western populations of Puma concolor. A recent increase in long distance male dispersal events may be related to an increase in reproduction and population density resulting from the introduction of female cougars P. c. stanleyana into south Florida. Although the population exhibits the behavioral ability to colonize nearby vacant range, females have yet to do so. Successful dispersal to these areas could be facilitated by habitat restoration and translocation of females.  相似文献   

2.
The endangered fish species Anaecypris hispanica is restricted to eight disjunct populations in the Portuguese Guadiana drainage. The genetic structure of these populations was studied in order to determine levels of genetic variation within and among populations and suggest implications for conservation of the species. Based on five microsatellite loci, the null hypothesis of population homogeneity was tested. Tests for genetic differentiation revealed highly significant differences for pairwise comparisons between all populations, and substantial overall population subdivision (FST=0.112). All sampled populations contained unique alleles. Our findings indicate marked genetic structuring and emphasise limited dispersal ability. The high levels of genetic diversity detected within and among A. hispanica populations suggest, however, that the observed fragmentation and reduction in population size of some populations during the last two decades, has impacted little on levels of genetic variability. Data imply that most A. hispanica populations should be managed as distinct units and that each has a high conservation value containing unique genetic variation. It is argued that geographic patterns of genetic structuring indicate the existence of eight management units.  相似文献   

3.
Levels of genetic variation and intrapopulation genetic structures of Leontice microrhyncha S. Moore (Berberidaceae) were assessed for six populations in South Korea, representing the southern most range of a species found in Northeast China and the Korean peninsula. Detected genetic diversity (Hes) was very low (0.024) and FIS values showed large heterozygote deficiencies. The small percentage of polymorphic loci and numbers of alleles per locus suggest that L. microrhyncha has a history of severe or long-lasting population bottlenecks that have eroded genetic diversity. This study suggests that the Korean population appears to consist of two historically isolated and independently evolving populations. It seems likely that these groups have been isolated and unstable for a significant period of time. However, the effects of recent habitat fragmentation on the historically disjunct and fragmented population system found in L. microrhyncha were not those predicted from the lack of significant relationships between population-level patterns of genetic variation and population sizes. Most non-unique genotypes were shared by most individuals and the lower level of diversity, high levels of inbreeding and population differentiation as well as high rate of seed production indicated that this species is autogamous and self-compatible and probably largely selfing. Therefore, to preserve extant genetic variation, all populations must be protected across the small geographic range of the species to retain both allelic and genotypic diversity.  相似文献   

4.
Understanding metapopulation dynamics in large carnivores with naturally fragmented populations is difficult because of the large temporal and spatial context of such dynamics. We coupled a long-term database of visitor sighting records with an intensive 3-year telemetry study to describe population dynamics of recolonization by black bears (Ursus americanus) of Big Bend National Park in Texas during 1988-2002. This population, which occurs within a metapopulation in western Texas and northern Mexico, increased from a single pair of known breeding-age animals in 1988 to 29 bears (including 6 females of breeding age) in March 2000 (λ = 1.25/year). A migration and dispersal event in August-December 2000 reduced the population to 2 adult females and as few as 5-7 individuals. One-way movement distances from the study area during this event averaged 76 km for females (n = 7) and 92 km for males (n = 4), and 3 animals conducted migrations of at least 154, 178, and 214 km, respectively. Our observations exemplify the importance of stochastic events on demographics of small populations and highlight the potential scale of bear movement among montane islands of southwestern North America. They also provide insight into the use of dispersal data in parameterizing metapopulation models for large carnivores.  相似文献   

5.
Trillium camschatcense, a long-lived common woodland herb, has been experiencing intensive habitat fragmentation over the last century in eastern Hokkaido, Japan. We examined the genetic diversity and population genetic structure of 12 fragmented populations with different population sizes using allozyme electrophoresis. The percentage of polymorphic loci and mean number of alleles per locus were positively related to population size, probably due to the stochastic loss of rare alleles (frequency of q<0.1) in small populations. Populations with 350 flowering plants or fewer had lost almost all of their rare alleles. While the heterozygosity and inbreeding coefficient were not related to population size, some small populations showed relatively high inbreeding coefficients. In spite of the low genetic differentiation among overall populations (FST=0.130), local population structuring was recognized between the two geographically discontinuous population groups. Within groups, sufficient historical gene flow was inferred, whereas a low dispersal ability of this species and geographical separation could produce apparent differentiation between groups.  相似文献   

6.
The European mink (Mustela lutreola) is one of the most threatened carnivores in Europe, with fragmented populations in Belarus, Russia and Romania, as well in south-western France and northern Spain. Many populations have become extinct recently, or are declining. We investigated mitochondrial DNA variation, using the complete D-loop region, and concentrating on the west European population. The aim was two-fold: to use the genetic information to advise on the conservation of European mink, and to begin to understand their history through the Pleistocene. Captive breeding and re-introduction programmes are underway, so it is particularly vital to know whether the West European population should be treated separately. We find that European mink probably colonised from a single refugium after the last glaciation. West European populations may be fixed for a single haplotype, also suggesting a common origin. Despite this evidence for gene flow, following the precautionary principle we suggest that mink from the three geographically separate populations (Romania, Eastern and Western Europe) should be managed separately, for the moment.  相似文献   

7.
The roosts of many IUCN-listed cave-roosting bat species are under threat from tourist development in SE Europe and other regions of the world. Much-needed conservation strategies require, among other information, an understanding of their roost movements and population dynamics, which can now be obtained relatively quickly using advanced models. We have studied the long-fingered bat, Myotis capaccinii, an obligate cave-dweller, in Dadia National Park, Greece. The species formed colonies of up to a few thousand individuals and was highly mobile, frequently switching summer roosts up to 39 km apart, even during late pregnancy. The bats migrated to distant hibernacula including a cave in Bulgaria 140 km NW of the Park. Adult recapture probabilities varied with season and sex: low female recapture rates in autumn, relative to spring and summer, indicated non-random temporary emigration following nursery colony dispersal. The opposite pattern was seen in males: increasing recapture rates in the autumn suggest that males gather in these roosts to mate with females in transit. Adult survival (0.86-0.94) was similar in females and males, similar in winter and summer, and comparable to recent estimates for other bats based on similar modelling techniques. Sex-based differences in juvenile recapture suggest female philopatry and male-biased dispersal. Our work shows that protection of M. capaccinii roosts must extend beyond the Park’s and indeed the country’s boundaries: its conservation requires large-scale, trans-national integrated conservation plans. Our results will apply to many other warm-temperate species with similar life history cycles.  相似文献   

8.
When habitats are declining, niche segregation by demographic groups, such as the two sexes, can have a profound impact on the extinction risk of a species as a whole. Thus, differences in the requirements of demographic groups are of importance in conservation. We combined behavioural and genetic data to investigate whether the sexually segregated parti-colored bat (Vespertilio murinus) exhibits sex-specific niche partitioning. We use our data to evaluate implications for conservation of this potentially vulnerable species in Switzerland, the western boundary of its range. Using radio-telemetry, we found sex-specific differences in habitat use. Foraging females strongly relied on lakes while foraging males displayed more flexibility in their habitat use. Moreover, males covered significantly larger foraging areas than females. Sequencing 341 base pairs of the mitochondrial D-loop of 247 individuals revealed sex-specific differences in the genetic structure of colonies, but no such difference was observed for three nuclear micro-satellite markers. We found high mtDNA diversity in two Swiss male colonies and one German female colony, but low mtDNA diversity in two Swiss female colonies. Our genetic data suggest that considerable gene flow occurs via male dispersal and mating. At the same time immigration of females into the existing female colonies in Switzerland is rare compared to the immigration of new males into male colonies. Since we found the sexes in Vespertilio murinus to differ markedly in their ecology, population genetics, and behaviour, we conclude that sex-specific conservation plans are required to protect this species efficiently.  相似文献   

9.
Tropical rainforests are becoming increasingly fragmented and understanding the genetic consequences of fragmentation is crucial for conservation of their flora and fauna. We examined populations of the toad Rhinella ornata, a species endemic to Atlantic Coastal Forest in Brazil, and compared genetic diversity among small and medium forest fragments that were either isolated or connected to large forest areas by corridors. Genetic differentiation, as measured by FST, was not related to geographic distance among study sites and the size of the fragments did not significantly alter patterns of genetic connectivity. However, population genetic diversity was positively related to fragment size, thus haplotype diversity was lowest in the smallest fragments, likely due to decreases in population sizes. Spatial analyses of genetic discontinuities among groups of populations showed a higher proportion of barriers to gene flow among small and medium fragments than between populations in continuous forest. Our results underscore that even species with relatively high dispersal capacities may, over time, suffer the negative genetic effects of fragmentation, possibly leading to reduced fitness of population and cases of localized extinction.  相似文献   

10.
We examined visiting patterns of pollinators of Betonica officinalis L. (Lamiaceae) in experimentally fragmented calcareous grasslands and corresponding control plots at two study sites (Movelier and Nenzlingen) in the north-western Swiss Jura mountains. Fragments (1.5×1.5 m) were isolated by a 5-m wide strip of frequently mown vegetation while the control plots were situated in the adjacent undisturbed vegetation. The most common pollinator, the bumblebee Bombus veteranus (Apidae), visited fragments 53.7% less frequently than control plots. Furthermore, a change in foraging behaviour of Bombus veteranus was observed. In fragments the bumblebees visited more inflorescences, flew longer total visiting distances and the visiting time per patch tended to be higher than in control plots. The distribution of angles between arrival and departure direction (turning angles) differed from a uniform distribution in fragments but not in control plots. The increased directionality of bumblebee flight might be due to a decrease in floral rewards. Our results show that small-scale habitat fragmentation can affect plant pollination at two levels both relevant for plant fitness. First, lower visitation rates indicate a limitation of pollinators which might result in reduced seed set of the pollinated plant. Second, changes in pollinator behaviour might reduce pollen dispersal among flowers, increase inbreeding and hence reduce genetic variability in populations of this bumblebee pollinated plant.  相似文献   

11.
Between 1930 and 2003 with emphasis on the 1940s maize landraces (Zea mays L. ssp. mays) from all over Switzerland were collected for maintenance and further use in a new Swiss breeding program. The genetic relationship and diversity among these accessions stored in the Swiss gene bank is largely unknown. Our hypothesis was that due to the unique geographic, climatic, and cultural diversity in Switzerland a diverse population of maize landraces had developed over the past three centuries. The aims were to characterize the genetic diversity of the Swiss landraces and their genetic relationship with accessions from neighbouring regions as well as reviewing their history, collection, and maintenance. The characterization and grouping was based on analyses with ten microsatellite markers. Geographic, cultural, and climatic conditions explained a division in two distinct groups of accessions. One group consisted of landraces collected in the southern parts of Switzerland. This group was related to the Italian Orange Flints. The other group contained accessions from northern Switzerland which were related to Northern European Flints in particular German Flints. Historic evidence was found for a frequent exchange of landraces within the country resulting in a lack of region-specific or landrace-specific genetic groups. The relatively large separation between the accessions, indicated by high F ST (0.42), might be explained partly by a bottleneck during the collection and maintenance phase as well as by geographical and cultural separation of north and south of the country. Due to the high genetic diversity, the accessions here are a potential resource for broadening the European flint pool.  相似文献   

12.
In the UK, Euphydryas aurinia exists in fragmented habitat patches, and undergoes population fluctuations as a result of a larval parasitoid. Its range is declining in the UK and conservation is thought to require a landscape approach since populations spread over large areas in some years and contract to core breeding patches in others. We examined populations at a range of geographic scales using allozyme electrophoresis to look for evidence of gene flow and differences in genetic diversity among populations. Nationally, our FST value was 0.1542 but between population groups within the suspected colonisation range of the butterfly (ca. 20 km), FST values were not significantly different from zero. Genetic diversity in terms of number of alleles and heterozygosity was reasonably high in natural populations (He=0.267) but low in an introduced, isolated population. We infer that migration between closely spaced subpopulations (in a metapopulation) maintains a high genetic effective population size (large number of individuals in a population that contribute genes to the next generation) which offsets any local reductions in population numbers due to stochastic extinctions or parasitoid effects. We therefore conclude that effective conservation of the species must seek to provide networks of suitable habitat for groups of subpopulations, rather than maintaining habitat for isolated populations.  相似文献   

13.
Impatiens noli-tangere is scarce in the UK and probably only native to the Lake District and Wales. It is the sole food plant for the endangered moth Eustroma reticulatum. Significant annual fluctuations in the size of I. noli-tangere populations endanger the continued presence of E. reticulatum in the UK. In this study, variation in population size was monitored across native populations of I. noli-tangere in the English Lake District and Wales. In 1998, there was a crash in the population size of all metapopulations in the Lake District but not of those found in Wales. A molecular survey of the genetic affinities of samples in 1999 from both regions and a reference population from Switzerland was performed using AFLP and ISSR analyses. The consensus UPGMA dendrogram and a PCO scatter plot revealed clear differentiation between the populations of I. noli-tangere in Wales and those in the Lake District. Most of the genetic variation in the UK (HT=0.064) was partitioned between (GST=0.455) rather than within (HS=0.034) regions, inferring little gene flow occurs between regions. There was similar bias towards differentiation between metapopulations in Wales, again consistent with low levels of interpopulation gene flow. This contrasts with far lower levels of differentiation in the Lake District which suggests modest rates of gene flow may occur between populations. It is concluded that in the event of local extinction of sites or populations, reintroductions should be restricted to samples collected from the same region. We then surveyed climatic variables to identify those most likely to cause local extinctions. Climatic correlates of population size were sought from two Lake District metapopulations situated close to a meteorological station. A combination of three climatic variables common to both sites explained 81-84% of the variation in plant number between 1990 and 2001. Projected trends for these climatic variables were used in a Monte Carlo simulation which suggested an increased risk of I. noli-tangere population crashes by 2050 at Coniston Water, but not at Derwentwater. Implications of these findings for practical conservation strategies are explored.  相似文献   

14.
Species that are rare when first described present a practical management problem because it may be unclear whether the taxon is in the final stages of an anthropogenic decline, or is naturally uncommon, and each scenario dictates a distinct approach to management. We analysed mitochondrial and microsatellite DNA data with population genetic and phylogeographic tools to distinguish between these possibilities in a rare lizard from southern New Zealand. Grand skinks, Oligosoma grande, are large rock-dwelling lizards that have a fragmented distribution consisting of a western and eastern cluster of populations separated by ca. 120 km. This distribution could result from human disturbance, pre-human climatic and vegetation changes, or both. All populations were highly genetically structured (overall FST 0.171, RST 0.235), indicating that populations were demographically independent and skinks are unlikely to expand their range without human intervention. In addition, the current fragmented distribution is likely to have both historical and recent anthropogenic elements. Two eastern populations showed evidence of being historically large (high θ mtDNA genetic diversity), although they are now small, supporting anecdotal data that grand skinks have declined in historical times. However, eastern and western populations were reciprocally monophyletic for mtDNA lineages, suggesting long independent evolutionary histories that predate the arrival of humans in New Zealand. Eastern and western populations fulfil many criteria to be considered as evolutionarily significant units, but such a classification must be balanced against addressing more immediate threats to the species’ survival, such as introduced predators.  相似文献   

15.
In parasite-host dynamics, parasites exert frequency-dependent selection on their hosts by favouring rare alleles that may confer resistance against infection. Therefore host populations that suffer strong parasite stress should maintain higher levels of genetic variability. We studied the Lumbricus terrestris-Monocystis sp. host-parasite system at a microgeographical scale. Using three polymorphic microsatellite loci on one large earthworm population sampled at 26 different sites (281 genotypes), we tested the relationship between parasite load and genetic variation in natural samples of the common earthworm L. terrestris. Our analysis yielded the following: (1) parasite load varied significantly across sites in this population; (2) there was no consistent evidence for heterozygote deficiency (observed heterozygosities ranged between 0.74 and 0.87), indicating a low level of inbreeding; (3) there was no significant genetic structuring among sample sites; (4) we could not identify a significant association between parasite load and population genetic diversity; (5) there was considerable population differentiation (15.17%) between our German samples and a Canadian L. terrestris reference population. Our study provides insight into the population genetics of one of the most economically important soil organisms on a microgeographic scale.  相似文献   

16.
The objective of this study was to estimate the dispersal rate in an organism assumed to be confined to tree stands with unbroken continuity. We used the lichen-forming ascomycete Cliostomum corrugatum, which is largely confined to old oak stands. Five populations, with pairwise distances ranging from 6.5 to 83 km, were sampled in Östergötland, south-eastern Sweden. DNA sequence data from an intron in the small subunit nuclear ribosomal RNA gene was obtained from 85 samples. Nearly all molecular variance (99.6%) was found within populations and there were no signs of isolation-by-distance. The absolute number of immigrants per population per generation (estimated to 30 years), inferred by Bayesian MCMC, was found to be between 1 and 5. Altogether, evidence suggests abundant gene flow in the history of our sample. A simulation procedure demonstrated that we cannot know whether effective dispersal is ongoing or if it ceased at the time when oaks started to decrease dramatically around 400 years BP. However, a scenario where effective dispersal ceased already at the time when the postglacial reinvasion of oak had reached the region around 6000 years BP is unlikely. Vegetation history suggests that the habitat of C. corrugatum was patchily distributed in the landscape since the early Holocene. Combined with the high dispersal rate estimate, this suggests that the species has been successful at frequently crossing distances of at least several kilometres and possibly that it has primarily been limited by the availability of habitat rather than by dispersal.  相似文献   

17.
Madagascar’s diverse and mostly endemic fauna and flora suffer from recent landscape changes that are primarily caused by high levels of human activities. The loss and fragmentation of forest habitats are well known consequences of human activities. In this study, we investigate the effects of forest fragmentation on presence, abundance and genetic diversity in a larger-bodied lemur species, Lepilemur edwardsi, in northwestern Madagascar. In addition, we characterized the genetic differentiation among populations and demographic changes. We found L. edwardsi at only 13 (76.5%) of 17 visited sites, 11 of which were situated in the Ankarafantsika National Park (ANP). We captured between two and 17 individuals per site. We sequenced the mtDNA d-loop of all samples and genotyped 14 microsatellite loci in two exemplary populations for demographic analyses. A negative influence on forest fragmentation could be detected, since the fragments had a lower genetic diversity than sites in the ANP. Genetic differentiation between populations ranged from low to high but was almost always significant. A typical pattern of isolation-by-distance could not be detected and the data could rather be interpreted as results of random genetic drift. The data furthermore revealed signals of a demographic collapse of about two orders of magnitude in the two exemplary sites. This decline probably started during the last few hundred years of intensified human disturbances and population growth. Given the results of this study, urgent conservation actions are needed and should concentrate on an effective protection of the few remaining populations in order to ensure the long-term survival of L. edwardsi.  相似文献   

18.
The greatest extent of genetic variation and outcrossing for Lycopersicon pimpinellifolium occurs in northern Peru. This is also the area most affected by EI Niño Southern Oscillation (ENSO). Using morphological and the molecular markers SSRs and AFLPs, we studied the genetic structure of L. pimpinellifolium populations collected after the ENSO event of 1997–1998. This was the most intense in the last century and caused a vast increase in the size of L. pimpinellifolium populations. Populations in the area surveyed were not regionally differentiated. We did not find any cline or eco-geographic association for genetic diversity, and positive correlations between genetic and geographic distances were found only at very short distances. Flooding and water streams caused by ENSO might have facilitated a periodical seed migration from distant areas. Gene flow between populations could then occur, facilitated by the increase in the population sizes of plants and pollinators and by the high levels of stigmatic exsertion. Results revealed a significant lack of heterozygotes in comparison with those expected in a panmictic population without consanguinity. A high degree of endogamy was found in all populations. In this context, endogamy can be explained by the occurrence of crosses between relatives rather than by autogamy. In an area intensely disturbed by ENSO, we found a population that had not been reported by earlier collectors in this region. This yellow-fruited population remained morphologically and molecularly differentiated from all L. pimpinellifolium and L. esculentum populations analyzed.  相似文献   

19.
We studied the genetic diversity, gene flow and population structure among 18 populations of the clonal bryophyte Trichocolea tomentella located in Finland, Lithuania, the UK and Canada using DNA fingerprinting methods. T. tomentella is a habitat-limited, unisexual hepatic, which occupies spring and mesic habitats in woodland. The relatively small populations are increasingly fragmented with a high risk for extinction for extrinsic reasons. The presence of relatively high levels of genetic diversity regardless of population size highlights the role of even small remnant populations as important sources of genetic diversity in T. tomentella. The long-term accumulation of genotypes and somatic mutations may explain the observed levels of diversity. Gene flow among populations seems to be infrequent indicating dispersal limitation also on the relatively small spatial scale. Colonization within populations is not affected by isolation by distance suggesting the occurrence of random short-range dispersal of detached vegetative fragments. The population structure study confirmed the low mortality rates of shoots indicating a long life span of the clones in favourable conditions. Efficient ramet production by branching is likely to operate against interspecific competition. To conclude, T. tomentella appears to persist well in undisturbed habitats due to clonal regeneration, although restricted dispersal capacity is likely to prevent successful (re-)colonization in the potential habitat patches of recovering forest landscapes. The implications of the results for conservation are introduced.  相似文献   

20.
This study investigates the contribution of the traditional land-use system “sheep herding” (transhumance) to the gene flow among populations. Three sheep trails with altogether 12 calcareous grassland sites were chosen for the analysis of the tussock grass Bromus erectus, which is known to be the species with the highest rate of dispersal via sheep fleece. Each trail links two to four isolated populations. Allozymes were chosen as genetic markers. Six loci were used, five of which were polymorphic. While genetic variability within populations was found to be quite high (averaged h=0.352), only little between-population differentiation was measured (GST=5.5%). Despite this, the UPGMA-dendrogram of Nei's genetic distance shows genetic similarity relations largely congruent with the sheep herding trails. However, a (more) detailed comparison reveals several differences between genetic patterns and trail system. Hence, additional factors other than dispersal by sheep are regarded as being responsible for exchange of genes, and sheep herding is considered to have only minor importance for the genetic patterns of the investigated species. The comparison of Bromus erectus to species with the same life history traits (i.e. pollination by wind, a perennial life cycle, and autopolyploid constitution) shows similar values, thus providing further evidence for the relatively small contribution of dispersal via sheep fleece.  相似文献   

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