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1.
To gather information on intraspecific phylogeography for use in conservation programs for the endangered species Primula sieboldii in Japan, we analyzed sequence variation in five noncoding regions of chloroplast DNA. Twenty-two distinct haplotypes were recognized in total. The distribution of most haplotypes was geographically confined, but one haplotype was widely distributed throughout northern Japan, and several haplotypes were found in geographically distant regions. Three major clades were revealed by phylogenetic analysis of the haplotypes. Clade I was distributed in Kyushu and central Honshu, clade II in western Honshu and Hokkaido, and clade III from central Honshu to Hokkaido. According to analysis of molecular variance, 59.9% of the total cpDNA variation existed among regions, 32.5% among populations within regions, and 7.6% within populations. Therefore, if genetic conservation of the species is valued, transplanting of P. sieboldii among regions should be avoided. Multiple lineages often existed even in geographically narrow areas (e.g., within a 20-km range), so transplantation between adjacent populations in restoration activities should be carefully designed so as not to change the gene pool of local populations significantly. Also, the geographical distribution of cpDNA haplotypes may allow us to confirm the origin of plants collected for commercial purposes. 相似文献
2.
The red kite (Milvus milvus) occurs in a relatively small area in the southwestern Palearctic region, with population strongholds in Central Europe. Following strong human persecutions at the beginning of the 20th century, populations have receded, particularly in peripheral areas and islands. In order to describe and compare levels of genetic diversity and phylogeographic patterns throughout its entire distribution in Europe, sequence variation of a 357 bps part of the mitochondrial DNA control region was assessed in eight populations and 105 individuals. Overall, results indicate that population declines have affected red kite mtDNA variation. We found low levels of genetic diversity (values of nucleotide diversity ranging from 0 in Majorca island to 0.0062 in Central Europe), with only 10 distinct haplotypes, separated by low levels of genetic divergence (mean sequence divergence = 0.75%). Highest haplotype and nucleotide diversities match with demographic expectations, and were found in Central European and Central Spanish samples, where present strongholds occur, and lowest values in the declining southern Spanish and insular samples. Φst estimates indicated moderate gene flow between populations. Phylogeographic patterns and mismatch distributions analyses suggest central European regions may have been colonized from southern glacial refugia (in the Italian or Iberian peninsulas). Interspecific phylogenetic comparisons and divergence date estimates indicated the genetic split between the red kite and its closely related species, the black kite (Milvus migrans), might be relatively recent. The low level of genetic variation found in the red kite mitochondrial control region, compared to the black kite, is likely the result of relatively recent divergence (associated with founder events), successive bottlenecks and small population sizes. As there are several ongoing projects aimed at reinforcing populations in countries such as the United Kingdom, Italy or Spain, our results may prove useful for the genetic management of the species. 相似文献
3.
Samuel Zschokke Georg F.J. Armbruster Sylvain Ursenbacher Bruno Baur 《Biological conservation》2011,144(11):2702-2709
The management of rare and endangered species in the wild and in captivity requires an understanding of the characterization of the genetic units within each species and their relationships to each other. The Indian rhinoceros (Rhinoceros unicornis) is an endangered species with a current population size of c. 2800 individuals. We analyzed 26 individuals of known origin kept in captivity and 21 wild ranging individuals of the two remnant large wild populations in Assam (India) and Nepal employing mitochondrial and microsatellite markers to determine whether the two geographically isolated populations show distinct patterns of genetic diversity, and whether the genetic diversity of the populations is influenced by past demographic bottlenecks. We identified 10 different mitochondrial D-loop haplotypes, of which 4 were specific to the Assam population (10 sequences examined) and 6 specific to the Nepal population (19 sequences). Similarly, the microsatellite analysis demonstrated a strong genetic differentiation between the Assam and Nepal populations and allowed to assign each individual to its origin with high confidence. Furthermore, our analyses revealed the occurrence of a bottleneck in the Assam population long before the reported bottleneck in 1908, and it revealed that the Nepal population is a recent (probably post-glacial) colonization. In summary, the extent of genetic divergence between the two remnant R. unicornis populations suggests separate conservation programs (even for captive individuals) as long as the persistence of the entire species is not severely threatened. The microsatellite markers can also be used to determine the origin of confiscated material such as horns. 相似文献
4.
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
5.
Linda M. Broadhurst Andrew G. Young Robert Forrester 《Biological conservation》2008,141(11):2843-2856
Genetic and demographic studies of fragmented populations of common plant species often reveal negative impacts that are likely to constrain persistence. Examining species that are broadly representative of functional groups within fragmented landscapes is one approach to providing a better understanding of how these processes will influence vegetation persistence. Acacias are a significant component of the Australian flora, with Acacia dealbata being a common and representative species of fragmented landscapes across New South Wales. Previous reproductive assessments of fragmented A. dealbata populations indicated significant constraints for small populations through low reproductive output mediated by fertilisation success. This study examined genetic diversity, mating system, and progeny growth parameters of the seed crops produced by these populations to assess whether further constraints to persistence could be detected. Spatially explicit simulation studies were also conducted to assess the persistence likelihood of fragmented populations. Landscape parameters such as population size and plant density were useful predictors for some of the genetic and demographic responses, but a poor response signal was generally observed. Strong evidence for a self-incompatibility mechanism was observed in A. dealbata and is likely to be the major driver of population persistence. Self-incompatibility in small populations limits mate availability and eliminates inbred progeny early in the reproductive cycle leading to poor reproductive output. The simulation data provides further evidence that mate limitation in smaller populations (<200 plants and 40 S alleles) constrains reproductive output and persistence. These data indicate that introducing new germplasm to smaller populations can dramatically improve their persistence likelihood. 相似文献
6.
Pilgerodendron uviferum (Cipres de las Guiatecas, Cupressaceae) is a long-lived conifer, endemic to southern Chile and Argentina, reaching a southern limit in Tierra del Fuego. Remnant populations are generally fragmented and highly disturbed because of exploitation for timber, grazing and fire. The extent of genetic variation within and between 16 populations of this species, distributed throughout its range, was assessed using random amplified polymorphic DNA (RAPD) markers. Eight 10-mer primers produced a total of 84 scorable markers, 30 of which (35.7%) were polymorphic. AMOVA indicated that 18.6% of the variation recorded was attributable to differences between populations, a relatively high value compared with other conifers from the region. Pair-wise Phist comparisons between populations were all significant at P<0.05, with one exception, highlighting a high degree of population differentiation. Values of Shannon's diversity index (S) differed significantly among populations (P=0.002, ANOVA), values ranging from 0.337 to 0.716, suggesting that some populations are currently characterised by very low genetic variability. Current patterns of genetic variation were related to biogeographic history and human impact. The high degree of population differentiation recorded here highlights the need for additional conservation measures for this species, both in terms of incorporating further populations into the protected areas, and the restoration of severely degraded populations, to ensure their continued viability. 相似文献
7.
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
8.
Getachew Melaku Teklehaimanot Haileselassie Tileye Feyissa Samuel Kiboi 《Genetic Resources and Crop Evolution》2013,60(3):1047-1056
Data from microsatellite markers have been extensively used for both in situ and ex situ conservation strategies by determining the level of genetic diversity of natural populations that can widen the gene pool of cultivated plants. Such conservation practices are based on understanding of the between and within population genetic variations and partitioning populations on the basis of geographic origin. Therefore, the objective of this study was to assess the genetic diversity of Oryza longistaminata Chev. et Roehr and how this variation is partitioned within and between the eight O. longistaminata populations found in the different geographic regions of Ethiopia using simple sequence repeat markers. Five microsatellite markers in 320 samples generated 64 alleles that revealed the presence of large amount of genetic variability (Ho = 0.225; He = 0.768; Na = 7.375; Ne = 6.565 and P = 0.744). The F-statistics detected by the microsatellite loci showed Fst = 0.064 and Fis = 0.743 and there was no population in Hardy–Weinberg equilibrium. The genetic diversity results obtained from this data indicated that there are high levels of genetic diversity in the populations of O. longistaminata studied and it is higher within than between populations. Among the eight populations sampled, five populations were identified as priorities for conservation strategies. Thus, national collection and conservation strategies need to consider these populations. 相似文献
9.
Oryzomys couesi cozumelae is an endemic, threatened rodent from Cozumel Island, Mexico. We estimated its genetic diversity and structure by analyzing microsatellite loci in 228 samples from 12 sampling sites widely distributed throughout the island. Unexpected high levels of genetic and allelic diversity were found: a total of 54 alleles, an average of 10.8 alleles per locus, and high heterozygosity values (mean HO = 0.624, HE = 0.690 and HNei = 0.689). These values are higher than those reported for small sized insular mammals, higher than that found in 37 individuals of the mainland O. couesi from southern Mexico (HO = 0.578) that we analyzed for comparative purposes, and similar to those of other mainland small mammal populations. Despite factors that affect Cozumel’s biota, such as exotic predators and competitors, hurricanes, seasonal population fluctuations and anthropogenic activities, no evidence of genetic bottlenecks was found. A significant population structure was observed and a model of isolation-by-distance was supported. Our findings render O. c. cozumelae a high conservation value, not only for its high genetic diversity and structure, but because available data suggests that its population has declined significantly in recent years. Further habitat fragmentation and population isolation could result in a higher genetic structure and loss of genetic diversity. The protection of habitat, the maintenance of habitat connectivity and the removal of introduced competitors and predators are a conservation priority. Acknowledging that the genetic structure of populations has crucial conservation implications, the present genetic information should be taken into account in management plans for the conservation of O. c. cozumelae. 相似文献
10.
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
11.
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
12.
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
13.
Knowledge of the genetic and demographic consequences of rarity is crucial when evaluating the effects of habitat loss and fragmentation on population viability, and for creating management plans in rare plant species. Reduction in population size and in the number of populations can lead to decreased genetic diversity and increased inbreeding. Genetic diversity is often correlated with fitness and is frequently used to identify populations of greatest conservation concern, or those that may be good candidates for ex situ conservation programs. However, an association between these factors is not always clear, and crossing studies evaluating whether there is phenotypic differentiation among populations in fitness related traits can inform managers of suffering populations or good sources for ex situ materials. Crossing studies can also evaluate the potential for genetic rescue to boost fitness in suffering populations. To address these questions, we conducted two generations of controlled crosses between populations of the extremely rare and fragmented sunflower, Helianthus verticillatus. We measured achene viability, germination, survival, and pollen viability (F1 only) in 176 F1 and 159 F2 families. The populations were differentiated with respect to phenotypic fitness measures with one population having significantly lower achene viability and germination. Also, the potential for genetic rescue was observed as gene flow into the less fit population resulted in higher fitness measures in both the F1 and F2. Results are discussed with respect to the importance of combining genetic marker data with crosses and the implications for conservation in disjunct populations of rare species. 相似文献
14.
American ginseng (Panax quinquefolius) is a native North American medicinal plant that is becoming increasingly vulnerable despite government harvest restrictions. To better understand the genetic diversity and gene flow of American ginseng, we studied RAPD variation in cultivated and wild populations. Classical and Bayesian analogues of genetic diversity statistics were estimated in seven wild and two cultivated populations. The wild populations were more highly structured (G stβ = 0.41) than the cultivated populations (G stβ = 0.24). The genetic diversity within populations ranged from H eβ = 0.05 to 0.38. Based on genetic pairwise distances, six of the wild populations clustered with the locally-derived cultivated population, while one wild population was more similar to the non-local cultivated population than the local populations. This wild population was highly diverse (P = 1.0; U = 1.0) suggesting that it was supplemented from exotic seed. A set of eight RAPD markers was identified that differentiated plants of local and non-local origin. As a conservation strategy, we recommend that regional gene banks be established based on molecular and geographic diversity to preserve the locally adapted germplasm. These regional gene banks would serve as a conservation tool and also provide a source of genes for genetic improvement of cultivated ginseng. 相似文献
15.
16.
Assessing levels of genetic diversity, connectivity and historical demography for threatened species provides important information for conservation management. We used a combination of the mitochondrial ND4 gene and seven microsatellite markers to examine both historical and recent population genetic structure and demography of the threatened alpine she-oak skink, Cyclodomorphus praealtus. This species is restricted to the “sky islands” of the Australian alpine region. Based on mtDNA, the New South Wales and Victorian regions are reciprocally monophyletic and highly divergent, with among population variation of 0.9 and net sequence divergence of 4.28%, which suggests that they should be considered separate Evolutionary Significant Units for management purposes. The mtDNA data also indicate historical connectivity between the three Victorian populations. However, a model-based clustering analysis of microsatellite genotypes identified strong population structure in Victoria, with three distinct populations that have no current inter-population gene flow. This suggests that the Victorian populations are effectively isolated from each other, and is indicative of very low dispersal capacity and a high degree of habitat specialisation. This is reinforced by the substantially lower genetic diversity within the lowest elevation population compared to the other higher elevation populations. We found no genetic signature of major changes in effective population size. These data provide a baseline for assessing future impacts of climate change on the genetic structure of this alpine endemic species. 相似文献
17.
Chinese sika deer, Cervus nippon, are currently threatened by habitat loss, fragmentation and human hunting, which has led to the extinction of three subspecies in the wild. The remaining subspecies subsist in the narrow regions of Jilin, Heilongjiang, Sichuan, Gansu, Jiangxi, Anhui, and Zhejiang provinces. In order to design effective conservation strategies for the Chinese sika deer, we have investigated genetic diversity, population structure and gene flow in the Chinese sika deer populations by analyzing ≈995 base pairs of the mitochondrial DNA (mtDNA) control region in 59 individuals sampled from the northeast of China, Sichuan, Jiangxi and Zhejiang. Chinese sika deer exhibited low mtDNA diversity and high gene flow among the four populations, and showed no strong geographical structure. The analyses of mtDNA variation among individuals of sika deer identified only two main phylogenetic groups even though three subspecies were sampled. These data singles out the Zhejiang population as being highly genetically distinct and worthy of separate conservation consideration. Therefore, it is recommended that a breeding program for the Zhejiang population be established. 相似文献
18.
Munronia delavayi Franch. (Meliaceae) is a vulnerable perennial species that is narrowly distributed and endemic to the dry-hot valley of the middle/lower Jinsha River. However, 12 hydropower stations are currently scheduled to be built in the middle and lower Jinsha River drainage and their distribution overlaps with the range of M. delavayi. The construction of these hydropower stations will cause flooding of the adjacent habitats that support M. delavayi and will change the local ecological environment, which may result in a new and dangerous situation for the survival of this species. Our aim was to evaluate the population structure and propose the most suitable conservation strategy for M. delavayi to support its adaptive potential. In this study, we collected 70 individuals from seven populations that covered most of the geographic range along the Jinsha River and investigated the population diversity, genetic structure and demographic history of this species by analyzing the variations in one mitochondrial marker (18sf-5sr), two non-coding chloroplast DNA regions (trnT-trnL, trnS-trnG), and one nuclear DNA marker (Gs687f-994r). As a result, three mitotypes, nine chlorotypes and six haplotypes with high genetic diversity (H T = 0.580, 0.774 and 0.740) were detected based on mtDNA, cpDNA and nDNA and a strong genetic structure (F ST = 0.855 and 0.545) was detected based on cpDNA and nDNA. Our study also indicated that habitat fragmentation and limited gene flow may result in the genetic differentiation of this species and that the population distributed in Qiaojia, Yongshan and Panzhihua should be proactively protected based on the conservation genetic analysis. 相似文献
19.
Genetic markers, controlled pollinations and chromosome analysis were used to examine the breeding system, clonal structure, genetic diversity and cytological complexity of populations of the endangered sub-alpine forb Rutidosis leiolepis. Results show that R. leiolepis: (1) has a strong sporophytic self-incompatibility system; (2) exhibits significant clonality and that the importance of vegetative reproduction increases at higher altitudes; (3) is genetically diverse, but that variation within populations decreases and differentiation among populations increases with altitude; and (4) is diploid with 2n=22 throughout its geographic range. Based on these results, low altitude populations around Cooma and Happy Valley should be made priority areas for in situ conservation in the Species Recovery Plan currently being developed by the New South Wales National Parks and Wildlife Service because they exhibit the most sexual reproduction and highest levels of genetic variation within the species. They may also be demographically more viable in the long term, having larger effective population sizes and less likelihood of mate limitation due to low S allele richness than high altitude populations. Sampling strategies for ex situ conservation should vary from large collections within populations at low altitudes to smaller collections spread across populations at higher altitudes where more of the genetic diversity is partitioned among sites. This should give maximum representation of the species' gene pool for minimum sampling effort. 相似文献
20.
Andrea Coppi 《Biological conservation》2008,141(8):2000-2011
Although several plants endemic to Corsica and Sardinia are included in various redlists, no attempts have been made to analyse their genetic diversity with molecular techniques. Genus Anchusa occurs with seven taxa in either mountain or coastal habitats of the two islands, but the very restricted range and low population size pose these endemisms in a very precarious conservation status. Highly variable markers (AFLP) were therefore used to analyse the patterns and levels of genetic diversity in a sample of 11 populations from the entire range of the group.Results indicate the separation between a mountain genic pool including Anchusa formosa, Anchusa capellii and Anchusa montelinasana, and four groups of coastal accessions. In spite of small size, mountain taxa show low interpopulation differentiation (Fst = 0.02) and relatively high intrapopulation genetic variation (0.365), while coastal accessions showed on average a stronger differentiation (mean Fst = 0.20) and a lower diversity (0.281), possibly due to higher rates of inbreeding. The particularly low levels of variation found in A. sardoa, A. littorea and A. crispa ssp. maritima from the Coghinas bay are likely due to a historical decrease of populations and to bottleneck events caused by loss of habitat and natural stochastic factors on sand dune ecosystems. While habitat maintenance and regulation of grazing by domestic herbivores should be sufficient to ensure the persistence of the mountain endemics, additional actions of in situ and ex situ conservation are needed for the critically endangered coastal species A. sardoa and A. littorea. A. crispa showed a relatively high variation, especially on Corsica. No correlation between population size and genetic variation was found in the latter species, highlighting the importance of the small patches for its conservation. Also, the genetic separation between subspecies crispa and maritima stresses the need of keeping them distinct in redlists and conservation actions on Sardinia. 相似文献