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1.
A general concern for the conservation of endangered species is the maintenance of genetic variation within populations, particularly when they become isolated and reduced in size. Estimates of gene flow and effective population size are therefore important for any conservation initiative directed to the long-term persistence of a species in its natural habitat. In the present study, 10 microsatellite loci were used to assess the level of genetic variability among populations of the Komodo dragon Varanus komodoensis. Effective population size was calculated and gene flow estimates were compared with palaeogeographic data in order to assess the degree of vulnerability of four island populations. Rinca and Flores, currently separated by an isthmus of about 200 m, retained a high level of genetic diversity and showed a high degree of genetic similarity, with gene flow values close to one migrant per generation. The island of Komodo showed by far the highest levels of genetic divergence, and its allelic distinctiveness was considered of great importance in the maintenance of genetic variability within the species. A lack of distinct alleles and low levels of gene flow and genetic variability were found for the small population of Gili Motang island, which was identified as vulnerable to stochastic threats. Our results are potentially important for both the short- and long-term management of the Komodo dragon, and are critical in view of future re-introduction or augmentation in areas where the species is now extinct or depleted. 相似文献
2.
Ciofi C Tzika AC Natali C Watts PC Sulandari S Zein MS Milinkovitch MC 《Molecular ecology resources》2011,11(3):550-556
Multiplex PCR assays for the coamplification of microsatellite loci allow rapid and cost-effective genetic analyses and the production of efficient screening protocols for international breeding programs. We constructed a partial genomic library enriched for di-nucleotide repeats and characterized 14 new microsatellite loci for the Komodo monitor (or Komodo dragon, Varanus komodoensis). Using these novel microsatellites and four previously described loci, we developed multiplex PCR assays that may be loaded on a genetic analyser in three separate panels. We tested the novel set of microsatellites for polymorphism using 69 individuals from three island populations and evaluated the resolving power of the entire panel of 18 loci by conducting (i) a preliminary assignment test to determine population(s) of origin and (ii) a parentage analysis for 43 captive Komodo monitors. This panel of polymorphic loci proved useful for both purposes and thus can be exploited for fine-scale population genetic analyses and as part of international captive breeding programs directed at maintaining genetically viable ex situ populations and reintroductions. 相似文献
3.
Cupressus chenggiana S. Y. Hu (Cupressaceae) is an endemic and endangered conifer species in southwest China. In order to study the population
genetics and design the effective conservation methods, we aimed to develop microsatellite primers for this species in the
present study. We developed eight new microsatellite loci for this species through biotin capture method. Polymorphism of
each locus was further assessed in 18 individuals from three geographically distant populations. The number of alleles per
locus ranged from 6 to 11 with an average of 8.13. The observed and expected heterozygosities ranged from 0.219 to 0.296 and
from 0.374 to 0.470, with averages of 0.254 and 0.417, respectively. We further found that three of nine microsatellite loci
developed previously for another congeneric species showed polymorphic banding patters. We performed primer-crossing tests
of these loci in the other two congeneric species which are closely related to C. chenggiana (C. gigantea and C. duclouxiana). These microsatellite markers would be effective for analyzing genetic diversity and population genetic structure of this
species and its morphological differentiation with the close relatives. 相似文献
4.
Evaluating environmental,demographic and genetic effects on population‐level survival in an island endemic
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Deni Purwandana Achmad Ariefiandy M. Jeri Imansyah Claudio Ciofi David M. Forsyth Andrew M. Gormley Heru Rudiharto Aganto Seno Damien A. Fordham Graeme Gillespie Tim S. Jessop 《Ecography》2015,38(10):1060-1070
The population dynamics of island species are considered particularly sensitive to variation in environmental, demographic and/or genetic processes. However, few studies have attempted to evaluate the relative importance of these processes for key vital rates in island endemics. We integrated the results of long‐term capture–mark–recapture analysis, prey surveys, habitat quality assessments and molecular analysis to determine the causes of variation in the survival rates of Komodo dragons Varanus komodoensis at 10 sites on four islands in Komodo National Park, Indonesia. Using open population capture–mark–recapture methods, we ranked competing models that considered environmental, ecological, genetic and demographic effects on site‐specific Komodo dragon survival rates. Site‐specific survival rates ranged from 0.49 (95% CI: 0.33–0.68) to 0.92 (0.79–0.97) in the 10 study sites. The three highest‐ranked models (i.e. ΔQAICc < 2) explained ~70% of variation in Komodo dragon survival rates and identified interactions between inbreeding coefficients, prey biomass density and habitat quality as important explanatory variables. There was evidence of additive effects from ecological and genetic (e.g. inbreeding) processes affecting Komodo dragon survival rates. Our results indicate that maintaining high ungulate prey biomass and habitat quality would enhance the persistence of Komodo dragon populations. Assisted gene flow may also increase the genetic and demographic viability of the smaller Komodo dragon populations. 相似文献
5.
Dahai Gao Qian Wang Yuxia Wu Haiyan Xu Qiushi Yu Jianquan Liu 《Conservation Genetics》2008,9(4):953-955
Thellungiella
salsuginea (Brassiaceae) is a typical halophyte which can tolerate extreme cold, drought, and salinity. In order to understand the adaptive
evolution of this species in the arid habitats, it is important to know its genetic structure. In this study, 17 polymorphic
microsatellite loci were isolated and characterized from an enrichment genomic library of this species. We further assessed
the polymorphisms of each locus in 18 individuals from nine geographically distant populations. The number of alleles per
locus ranged from six to fourteen. The observed and expected heterozygosity ranged from 0.17 to 0.28 and 0.32 to 0.45, respectively.
These markers have been crossly checked in another congeneric species, T. halophila. These microsatellite markers will be useful for investigating population genetics and adaptive evolution of this species
and morphological divergence between and it and the closely related species. 相似文献
6.
Roberta Lecis A. Ferrando J. Ruiz-Olmo S. Mañas X. Domingo-Roura 《Conservation Genetics》2008,9(5):1149-1161
The population genetic structure of an invasive species in Spain, the American mink (Mustela vison), was investigated using microsatellite DNA markers. This semi-aquatic carnivore, originating from North America, was imported
into Europe for fur farming since the beginning of the 20th century. Due to massive escapes, farm damages, deliberate releases
and/or accidents, feral mink populations were established in the aquatic ecosystems of many European countries, including
Spain. We genotyped 155 American mink originating from the Spanish regions Basque Country, Catalonia, Castilla-Leon, Aragon,
Valencia and Galicia using 10 polymorphic microsatellite loci to highlight population genetic structure, distribution and
dispersal. M. vison populations in Spain appear differentiated and not yet connected by gene flow. Bayesian clustering analyses and spatial analyses
of molecular variance detected four inferred clusters, overall coinciding with the sampled geographical localities. Preliminary
testing shows moderate to large estimated effective population sizes. Molecular analyses result useful to provide baseline
data for further research on the evolution of invasive mink populations, as well as support local management strategies and
indirectly benefit the conservation of threatened species in Spain, such as the endangered European mink (Mustela lutreola), and the polecat (Mustela putorius), which share the habitat with the American mink.
This paper is dedicated to the memory of Xavier Domingo-Roura. 相似文献
7.
Manja U. Böhme Norbert Schneeweiß Uwe Fritz Martin Schlegel Thomas U. Berendonk 《Conservation Genetics》2007,8(3):555-563
Edge and central populations can show great differences regarding their genetic variation and thereby also in their probability
of extinction. This fact might be of great importance for the conservation strategies of endangered species. In this study
we examine the level of microsatellite variability within three threatened edge populations of the green lizard subspecies
Lacerta viridis viridis (Laur.) in Brandenburg (Germany) and compare the observed variation to other edge and central populations within the northern
species range. We demonstrate that the northernmost edge populations contain less genetic variation in comparison to the central
population. However, there were no observable significant differences to the other edge population included in this study.
Surprisingly, we observed a high genetic differentiation in a small geographical range between the three endangered populations
in Brandenburg, which can be explained by processes like fragmentation, isolation, genetic drift and small individual numbers
within these populations. We also detected unique genetic variants (alleles), which only occurred in these populations, despite
a low overall genetic variation. This study demonstrates the potential of fast evolving markers assessing the genetic status
of endangered populations with a high resolution. It also illustrates the need for a comparative analysis of different regions
within the species range, achieving a more exact interpretation of the genetic variation in endangered populations. This will
aid future management decisions in the conservation of genetic diversity in threatened species. 相似文献
8.
James P. Strange Lionel Garnery Walter S. Sheppard 《Journal of Insect Conservation》2008,12(5):527-537
A population of honey bees (Apis mellifera mellifera L.) with an annual colony brood cycle adapted to a locally abundant floral source in the Landes region of Southwest France
is the subject of genetic conservation efforts. This population is maintained by local beekeepers in an area that experiences
both an annual seasonal influx of non-local colonies and the permanent culture of imported stock. However, some colonies native
to the Landes do not have the adapted brood cycle and their status as ecotypic are in question. The present study used morphology,
mitochondrial DNA and microsatellites to characterize the endemic population and suggests further genetic conservation strategies.
These methods yielded different degrees of discrimination of native and imported colonies and provided a powerful suite of
tools for local resource managers. Colonies from the Landes could be differentiated from non-local French A. m. mellifera populations using morphometric analysis, and from non-native and reference populations using mtDNA and microsatellites. Seven
morphological characters were identified by discriminant analysis as informative for delineating the Landes ecotype from other
A. m. mellifera populations. Mitochondrial haplotypes for the population were characterized and five microsatellite loci were found to be
informative in characterizing the Landes population. Asymmetric gene flow detected with microsatellite alleles was observed
to be 5.5–5.9% from imported to native stocks of honey bees while introgression of native microsatellite alleles into imported
colonies was 21.6%. 相似文献
9.
The razor clam (Sinonovacula constricta) is an important aquacultured bivalve in China. The natural populations of this species are decreasing quickly. To facilitate
studies on genetic diversity and population structure of wild populations, microsatellites were isolated from a CA enriched
genomic library. Eight microsatellite loci were polymorphic in 30 individuals from Chongming in Shanghai, China. The number
of alleles per polymorphic locus varied from 6 to 13 and the values of observed heterozygosity and expected heterozygosity
ranged from 0.350 to 1.000 and from 0.602 to 0.902, respectively. These microsatellites are being used in studying population
differentiation and genetic diversity for effective conservation and management genetic resources of S. constricta. 相似文献
10.
Carmen Bouza Jaime Castro Paulino Martínez Rafaela Amaro Carlos Fernández Paz Ondina Adolfo Outeiro Eduardo San Miguel 《Conservation Genetics》2007,8(4):937-948
A genetic analysis of freshwater pearl mussel Margaritifera margaritifera populations from NW Spain, a peripheral area of its European distribution, was carried out using microsatellite markers.
These populations were formerly reported as genetically differentiated on the basis of growth and longevity studies. Ten loci
previously characterized in populations from central Europe were used to comparatively analyze the genetic variability at
the southern edge of the species’ range. Iberian pearl mussel populations showed very low genetic variability and significant
high genetic differentiation. Half of the total genetic diversity observed appeared to be distributed between populations,
which suggested a highly structured adaptive potential in pearl mussel at the southern peripheral distribution of the species.
Population distinctiveness was evidenced by assignment tests, which revealed a high accuracy of individual assignments to
their population of origin. All data suggested low effective population size and major effects of genetic drift on population
genetic structure. In order to avoid further loss of genetic variation in biologically distinctive populations from NW Spain,
prioritization of genetic resources of this species is required for conservation and management. 相似文献
11.
Chinese alligator (Alligator sinensis) is a critically endangered species endemic to China. In this study, the extent of genetic variation in the captive alligators
of the Changxing Reserve Center was investigated using microsatellite markers derived from American alligators. Out of 22
loci employed, 21 were successfully amplified in the Chinese alligator. Sequence analysis showed loci in American alligators
had a bigger average size than that of the Chinese alligators and the longest allele of an individual locus almost always
existed in the species with longer stretch of repeat units. Eight of the 22 loci were found to be polymorphic with a total
of 26 alleles present among 32 animals scored, yielding an average of 3.25 alleles per polymorphic locus. The expected heterozygosity
(H
E) ranged at a moderate level from 0.4385 to 0.7163 in this population. Compared to that in the American alligators, a lower
level of microsatellite diversity existed in the Changxing population as revealed by about 46% fewer alleles per locus and
smaller H
E at the homologous loci. The average exclusion power and the ability to detect shared genotypes and multiple paternity were
evaluated for those markers. Results suggested that when the polymorphic loci were combined, they could be sensitive markers
in genetic diversity study and relatedness inference within the Chinese alligator populations. The level of genetic diversity
present in the current Changxing population indicated an important resource to complement reintroductions based on the individuals
from the other population. In addition, the microsatellite markers and their associated diversity characterized in this population
could be utilized to further investigate the genetic status of this species. 相似文献
12.
Berchemiella wilsonii var. pubipetiolata (Rhamnaceae) is an endangered plant with only four remnant populations in eastern China. Population genetic information is
essential for understanding population history and formulating conservation strategies for this species. Thirteen microsatellite
loci were used to investigate genetic variation and population structure of the four remnant populations. Moderate levels
of expected heterozygosity (H
E = 0.466–0.543) and low allelic diversity (A = 3.1–3.6 and A
R = 2.2–2.4, respectively) were observed within populations. Bottleneck tests found three out of four populations to deviate
from mutation-drift equilibrium under the two-phase model (TPM), suggesting a recent population decline, which is congruent
with known demographic history. The evolutionary history of the species seems dominated by genetic drift rather than gene
flow. Low historical gene flow was inferred from several different approaches and N
m ranged from 0.582 by the private allele method to 0.783 by the coalescent method. Contemporary gene flow was also found to
be even lower for only one first generation migrant was detected with individual-based assignment analysis. Restricted pollen
and seed dispersal as well as a recent decline in population size associated with habitat fragmentation may have contributed
to low levels of historical and contemporary gene flow, and resulted in a high genetic differentiation. Under this scenario,
Berchemiella wilsonii var. pubipetiolata populations are expected to display more pronounced population genetic structure in the future as a result of increased inbreeding
and genetic drift. 相似文献
13.
The ultimate goal of ecological restoration is to create a self-sustaining ecosystem that is resilient to perturbation without
further assistance. Genetic variation is a prerequisite for evolutionary response to environmental changes. However, few studies
have evaluated the genetic structure of restored populations of dominant plants. In this study, we compared genetic variation
of the restored populations with the natural ones in Cyclobalanopsis myrsinaefolia, a dominant species of evergreen broadleaved forest. Using eight polymorphic microsatellite loci, we analyzed samples collected
from restored populations and the donor population as well as two other natural populations. We compared the genetic diversity
of restored and natural populations. Differences in genetic composition were evaluated using measurements of genetic differentiation
and assignment tests. The mean number of alleles per locus was 4.65. Three parameters (A, A
R, and expected heterozygosity) of genetic variation were found to be lower, but not significantly, in the restored populations
than they were in the natural populations, indicating a founder effect during the restoration. Significant but low F
ST
(0.061) was observed over all loci, indicating high gene flow among populations, as expected from its wind-pollination. Differentiation
between the two restored populations was smallest. However, differences between the donor population and the restored populations
were higher than those between other natural populations and the restored populations. Only 13.5% and 25.7% individuals in
the two restored populations were assigned to the donor population, but 54.1 and 40% were assigned to another natural population.
The genetic variation of the donor population was lowest, and geographic distances from the restoration sites to the donor
site were much higher than the other natural populations, indicating that the present donor likely was not the best donor
for these ecological restoration efforts. However, no deleterious consequences might be observed in restored populations due
to high observed heterozygosity and high gene flow. This study demonstrates that during the restoration process, genetic structures
of the restored populations may be biased from the donor population. The results also highlight population genetic knowledge,
especially of gene flow-limited species, in ecological restoration. 相似文献
14.
The genetic effects of population bottlenecks have been well studied theoretically, in laboratory studies, and to some extent, in natural situations. The effects of serial population bottlenecks (SPBs), however, are less well understood. This is significant because recurrent population bottlenecks are likely to be a common feature of the life history of many species. The lack of understanding of SPBs in natural populations has certainly been hampered by a lack of good examples where it can be studied. We report the results of a study into island populations of North Island Saddleback (Philesturnus carunculatus rufusater) that have undergone 13 translocations since 1964, all but one of these has been deliberate and for which detailed records are available. We have examined nine island populations of this passerine bird, from the source population, three first-order bottlenecked and five second-order bottlenecked populations. We examine variation in these nine populations using multilocus minisatellite DNA markers, together with Mendelian loci comprising six microsatellite DNA loci and a variable isozyme locus. Despite the generally low level of genetic variation in the Saddleback source population, we were able to detect a pattern of significant changes in both the mean number of minisatellite DNA bands per individual and the frequency of alleles at the Mendelian loci, with increasing population bottlenecks. This study generally shows that in a natural population, SPBs result in more pronounced genetic changes than do single population bottlenecks by themselves, thereby highlighting their importance for the conservation of rare and endangered species. 相似文献
15.
The Australian freshwater cod genus, Maccullochella is represented by three species: Murray cod, M. peelii
peelii, eastern freshwater cod, M. ikei, and trout cod, M.macquariensis. Seven novel microsatellite loci from M. ikei and six previously published loci from M. peelii peelii were tested on wild populations of Murray, eastern and trout cod. Levels of polymorphism varied between species with 13 loci
polymorphic in Murray cod, 9 in trout cod and 7 in eastern cod. Observed heterozygosities ranged from 0.053 to 0.842. This
suite of microsatellite loci will facilitate future studies of the genetic status of wild and hatchery bred populations of
Maccullochella. 相似文献
16.
Natural populations of the endangered western barred bandicoot (Perameles bougainville) now exist on only two islands in Shark Bay, Western Australia. Our aim was to investigate genetic diversity in natural,
reintroduced, and captive populations of the bandicoots and to assess the extent of divergence between the populations. The
contemporary isolation of the natural populations has resulted in heterogeneity of allele frequency between the islands, which
has acted to maintain a higher combined diversity than would be expected from either population on its own. These findings
highlight how remnant island populations can act as genetic reservoirs to maximize diversity for reintroductions into a species
former range. Although diversity is high between island populations, diversity within populations, based on six microsatellite
loci, are amongst the lowest ever recorded for populations of marsupials. The mtDNA sequence data indicate that the two remaining
natural populations show only minor divergence from each other, with the five haplotypes separated by just single base pairs.
The reintroduced population and captive colonies show evidence for the loss of diversity related to genetic drift operating
on small isolated populations. 相似文献
17.
Qiushi Yu Dongyuan Zhang Dongshi Wan Haiyan Xu Changming Zhao 《Conservation Genetics》2008,9(4):1019-1022
Pugionium (Brassicaceae) is a small Central-Asian endemic genus with four tentative species described before. All of them grow in the
desert habitat and have been considered as important psammophytes for evolutionary studies and ecological restorations. However,
the wild resources of these species have been declined because of overexploitation. In this study, 12 polymorphic microsatellite
loci have been developed for P. dolabratum Maxim, and the performance of primer pairs amplifying these loci in related three species has also been tested. The number
of alleles in 18 individuals from 13 geographically distant populations ranged from three to seven per locus. The observed
and expected heterozygosities varied from 0.17 to 0.30 and from 0.32 to 0.48, respectively. We further performed cross-priming
tests in the remaining three species of this genus, P. cornutum, P. calcaratum and P. cristatum. These newly recovered microsatellite loci will be useful for studying the population genetics and adaptive evolution of
these endangered psammophytes in the desert. 相似文献
18.
Knowledge of the levels of genetic diversity maintained in natural populations can play a central role in conservation programmes,
particularly in threatened habitats or species. Fluctuations in population size can lead to loss of variation and, consequently,
increase the risk of extinction. We have examined whether such a genetic bottleneck has occurred in populations of two species
in the seagrass genus Zostera, which are believed to have been affected by an outbreak of wasting disease at the start of the last century. A test for
heterozygote excess at five nuclear microsatellite loci did not suggest the occurrence of a genetic bottleneck, but analysis
of seven chloroplast microsatellite loci and sequence data from two regions did suggest a bottleneck in the chloroplast genome.
Extremely low levels of between-population diversity suggest that all subpopulations can be treated as a single management
unit for each species. Comparable levels of nuclear genetic diversity were found in the three populations of the primarily
sexual Zostera marina var. angustifolia studied but a wider range of within-population diversity was found in Zostera noltii, which displays both sexual and vegetative reproductive strategies. This may be due to an increase in sexual recruitment
due to localised fresh water inflow into the study site near to the most diverse population. Such populations should be prioritised
as source material for any replanting or remediation due to natural or anthropogenic loss of Zostera beds in the area. 相似文献
19.
Genetiana crassicaulis is one of famous Chinese medicinal plant. The over-collection for its root has caused its dramatic reduction. In order to
devise adequate conservation and management strategies for this species, it is important to characterize its genetic diversity
and understand its population structure. Here, 10 polymorphic microsatellite markers have been developed. AC/TG microsatellite
was enriched by combining biotin capture method. Polymorphism of each locus was assessed in 30 individuals from six populations.
The number of alleles ranged from 2 to 9 and the expected heterozygosity ranged from 0.32 to 0.78. 相似文献
20.
Subspecific taxa of species complexes can display cryptic morphological variation, and individuals and populations can often
be difficult to identify with certainty. However, accurate population identification is required for comprehensive conservation
and breeding strategies and for studies of invasiveness and gene flow. Using five informative microsatellite markers and a
Bayesian statistical approach, we developed an efficient polymerase chain reaction-based diagnostic tool for the rapid identification
of individuals and populations of the Acacia saligna species complex of Western Australia. We genotyped 189 individuals from 14 reference populations previously characterised
based on morphology and used these data to investigate population structure in the species complex. High total genetic diversity
(H
T = 0.729) and high population differentiation (θ = 0.355) indicated strong intraspecific structuring. With the provision of prior population information, the reference data
set was optimally resolved into four clusters, each corresponding to one of the four main proposed subspecies, with very high
membership values (Q > 97%). The reference data set was then used to assign individuals and test populations to one of the four subspecies. Assignment
was unequivocal for all test individuals from two populations of subsp. lindleyi and for all but one individual of subsp. stolonifera. Individuals from populations of subsp. saligna and subsp. pruinescens showed a degree of genetic affinity for the two subspecies in their assignments, although the majority of individuals were
correctly assigned to subspecies. The diagnostic tool will assist in characterising populations of A. saligna, especially naturalised and invasive populations of unknown origin. 相似文献