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1.
Genetic structure and diversity can reveal the demographic and selective forces to which populations have been exposed, elucidate genetic connections among populations, and inform conservation strategies. Beds of the clonal marine angiosperm Zostera marinaL. (eelgrass) in Chesapeake Bay (Virginia, USA) display significant morphological and genetic variation; abundance has fluctuated widely in recent decades, and eelgrass conservation is a major concern, raising questions about how genetic diversity is distributed and structured within this metapopulation. This study examined the influence of bed age (<65years versus<6years) and size (>100ha versus<10ha) on morphological and genetic (allozyme) structure and diversity within Chesapeake Bay eelgrass beds. Although both morphology and genetic diversity varied significantly among individual beds (F
ST=0.198), neither varied consistently with bed age or size. The Chesapeake eelgrass beds studied were significantly inbred (mean F
IS=0.680 over all beds), with inbreeding in old, small beds significantly lower than in other bed types. Genetic and geographic distances within and among beds were uncorrelated, providing no clear evidence of isolation by distance at the scale of 10's of km. These results suggest that local environmental conditions have a greater influence on plant morphology than do bed age or size. They support the hypotheses that eelgrass beds are established by multiple founder genotypes but experience little gene flow thereafter, and that beds are maintained with little loss of genetic diversity for up to 65 years. Since phenotypic and genotypic variation is partitioned among beds of multiple ages and sizes, eelgrass conservation efforts should maximize preservation of diversity by minimizing losses of all beds. 相似文献
2.
Ranunculus nipponicus (Makino) Nakai is a vulnerable aquatic macrophyte in the Kinki district, which is the southernmost distribution of this species
in Japan. The genetic diversity and structure within and among eleven extant populations were assessed using the inter-simple
sequence repeats (ISSR) polymerase chain reaction in association with combinations of propagation pattern (clonal and/or seeds)
and genotypic geographical structure. In total, 53 bands were amplified, of which 18 (34%) were polymorphic. Analysis of the
ISSR bands identified 46 genotypes among 81 individuals from one stream population and 72 distinct genotypes among 147 individuals
in the Kinki district. An unweighted pair group method with arithmetic mean (UPGMA) dendrogram showed some unity among upstream
and downstream subpopulations within one stream and eleven populations. The Shannon index of genetic diversity was 0.109 for
one stream population and 0.313 for total genetic diversity, suggesting relatively high genetic diversity. Analysis of molecular
variance (AMOVA) revealed that 84.1% of the total genetic diversity occurred among populations and the remaining diversity
(15.9%) occurred within populations. Significant genetic differentiation occurred among populations in the Kinki district.
These results suggest that conservation of each population is important for maintaining genetic diversity of R. nipponicus in this district.
An erratum to this article can be found at 相似文献
3.
Samantha M. Wisely Rachel M. Santymire Travis M. Livieri Sara A. Mueting JoGayle Howard 《Conservation Genetics》2008,9(2):389-399
Population augmentation with translocated individuals has been shown to alleviate the effects of bottlenecks and drift. The
first step to determine whether restoration for genetic considerations is warranted is to genetically monitor reintroduced
populations and compare results to those from the source. To assess the need for genetic restoration, we evaluated genetic
diversity and structure of reintroduced (n = 3) and captive populations of the endangered black-footed ferret (Mustela nigripes). We measured genotypic changes among populations using seven microsatellite markers and compared phenotypic changes with
eight morphometric characters. Results indicated that for the population which rapidly grew post-reintroduction, genetic diversity
was equivalent to the captive, source population. When growth languished, only the population that was augmented yearly maintained
diversity. Without augmentation, allelic diversity declined precipitously and phenotypic changes were apparent. Ferrets from
the genetically depaupertate population had smaller limbs and smaller overall body size than ferrets from the two populations
with greater diversity. Population divergence (F
ST = 0.10 ± 0.01) was surprisingly high given the common source of populations. Thus, it appears that 5–10 years of isolation
resulted in both genotypic divergence and phenotypic changes to populations. We recommend translocation of 30–40 captive individuals
per annum to reintroduction sites which have not become established quickly. This approach will maximize the retention of
genetic diversity, yet maintain the beneficial effects of local adaptation without being swamped by immigration. 相似文献
4.
Arctophila fulva var. pendulina is a rare endemic perennial grass confined to seashore and riverbank meadows around the Bothnian Bay, the northernmost part
of the Baltic Sea. The number of A. fulva populations has decreased during the last few decades in Finland and Sweden, and nowadays there are only eight populations
left in the drainage area of the Bothnian Bay. We investigated the distribution of genetic variation within and between six
subpopulations in the largest remaining population at Liminka Bay, Finland, using amplified fragment length polymorphism (AFLP)
markers. Relatively high amounts of variation were found in the subpopulations, the mean Nei’s expected heterozygosity being
typical (0.267) for an outcrossing species. Despite the fact that no seedlings or viable seeds of A. fulva have been found in the previous field studies, the observed high genotypic diversity suggested that sexual reproduction has
played an important role at some time during the history of the studied A. fulva population. Analysis of population structure revealed a low level of genotypic differentiation (ΦST=0.046) between subpopulations, and also significant sub-structuring within subpopulations. Isolation-by-distance between
subpopulations was present on scales larger than 1 km. The overall pattern of genetic variation within and between subpopulations
suggest that the population has characters of both stepping-stone and metapopulation models. Because our results suggested
that subpopulations are more or less ephemeral, the conservation and management effort in this species should be targeted
to conservation of the required habitat of the species instead of extant subpopulations. 相似文献
5.
Michael W. Lloyd Robert K. BurnettJr. Katharina A. M. Engelhardt Maile C. Neel 《Conservation Genetics》2012,13(3):753-765
The goal of ecological restoration is to re-establish self-sustaining ecosystems that will resist future perturbation without
additional human input. We focus here on the re-establishment of submersed aquatic macrophyte beds in the restoration of the
Chesapeake Bay estuary. Degraded environmental conditions are often to blame for poor bed establishment, but genetic factors
could also be contributing to low survival. We quantified the effect of restoration practices on genetic diversity in the
submersed aquatic plant species Vallisneria americana Michx. (Hydrocharitaceae) in the Chesapeake Bay. In 2007, we collected 440 shoots from 8 restored/natural site pairs and
4 restoration stock repositories, and genotyped those individuals at 10 microsatellite loci. Restoration practices do not
appear to negatively impact genetic diversity, and basic measures of genetic diversity within restored sites overlap with
natural sites. However, small population size of restored sites, significant inbreeding coefficients within 3 sites, and low
overlap of allele composition among sites provide cause for concern. These problems are relatively minor, and we propose several
corrections that would alleviate them altogether. Managers should be encouraged by our findings as well as the current state
of the genetic diversity within V. americana restoration efforts. 相似文献
6.
Two small cyprinid fishes, Hemigrammocypris rasborella and Pseudorasbora pumila subsp. (sensu Nakamura 1963), inhabit similar habitats and often occur sympatrically in the Ise Bay basin, central Honshu
Island, Japan. Their genetic population structures were revealed, using sequence data from the mitochondrial cytochrome b gene, and then compared. Hemigrammocypris rasborella populations in the Ise Bay area formed a monophyletic group that has been isolated from eastern (Tenryu River) and western
(Lake Biwa–Yodo River) populations at least for several hundred thousand years. Pseudorasbora pumila subsp., endemic to the Ise Bay area, was estimated to have become isolated from its sister subspecies, P. p. pumila, about 5 million years ago. Both H. rasborella and P. pumila subsp. had centers of genetic diversity around the Okazaki Plain in the eastern part of the basin and showed trans-bay distribution
of haplotypes or haplotype groups. Their common population structure was explained by geological features in the Ise Bay area,
in which a large paleo-river system developed in regression periods, suggesting gene flow among populations of each species
in the mid to lower reaches of the paleo-river. Based on the estimated expansion or divergence time, however, not all populations
experienced gene flow during the Last Glacial. In contrast to the maintenance of high genetic diversity in H. rasborella, almost all populations of P. pumila subsp. have lost mitochondrial DNA genetic diversity. This implies that effective population size of P. pumila subsp. tended to be smaller, probably because of differences in reproductive ecology, even though the two species have been
exposed to similar environmental changes. For conservation of the two species, genetic and adaptive differentiation among
local populations should be considered, and attention should be paid to inbreeding depression, especially in P. pumila subsp.
An erratum to this article can be found at 相似文献
7.
Serene Hargreaves Nigel Maxted Ryoko Hirano Michael Abberton Leif Skøt Brian V. Ford-Lloyd 《Conservation Genetics》2010,11(4):1317-1326
Island populations are often thought to be more susceptible to the loss of genetic diversity as a consequence of limited population
size and genetic drift, greater susceptibility to detrimental stochastic events and low levels of immigration. However the
geographic isolation of islands may create refuges for native crop species whose genetic diversity is threatened from the
genetic erosion occurring in mainland areas as a result of crop-wild gene flow and genetic swamping. Many UK islands remain
uncharacterised in terms of plant genetic diversity. In this study we compared the genetic diversity of mainland populations
and landraces of Trifolium repens with wild populations collected from the islands surrounding the UK, including the island of Hirta in the St Kildan archipelago.
Individuals from St Kilda represent a unique conservation resource, with populations both highly differentiated from UK mainland
populations and genetically distinct from cultivated varieties, whilst able to retain diversity through limited human influence
on the islands. In contrast, there is relative genetic similarity of wild UK populations to cultivated forms highlighted in
mainland populations, but with geographic barriers preventing complete homogenisation of the mainland UK genepool. We underline
the need for conservation priorities to include common species that are threatened by gene flow from cultivation, and draw
attention to the potential of islands to preserve natural levels of genetic diversity. 相似文献
8.
S. J. Välilä K. E. Knott E. P. Ieshko A. E. Veselov J. K. Taskinen 《Biology Bulletin》2017,44(1):92-98
The freshwater pearl mussel Margaritifera margaritifera L. is one of the most endangered freshwater mussels in the world. Effective conservation of threatened species requires not only ecological, but also genetic information from the target species and populations. Since low genetic diversity can reduce the ability of a species to adapt to environmental changes, maintaining genetic diversity has been identified as one of the key elements in successful conservation programs. We examined genetic variation of the freshwater pearl mussel from the River Vuokkijoki, Karelia, Russia. We sequenced a fragment of the cytochrome c oxidase subunit I gene (COI) from 22 individuals and compared the data to 32 previously published COI sequences available in GenBank. We identified 10 different COI haplotypes in the sequenced samples, three of which had not been previously reported. Our results show that the River Vuokkijoki has high genetic diversity and suggest that the colonization of this northern freshwater pearl mussel population might have occurred from multiple and even distant refugia. Therefore, the freshwater pearl mussel population of the River Vuokkijoki is valuable for the conservation of the whole species. 相似文献
9.
Commiphora wightii is a medicinally important endangered species endemic to the Thar Desert of Rajasthan, India and adjoining areas of Pakistan.
The populations of this species are declining sharply because of its extensive use as a natural herb. Random amplified polymorphic
DNA analysis was conducted to find the genetic variation among 7 populations of C. wightii. Of the 100 random primers screened, 44 primers yielded 220 loci. Statistical analysis indicated low genetic diversity (H
pop = 0.0958; I = 0.1498; mean polymorphic loci = 14.28%), and high genetic differentiation among the populations (G
ST = 0.3990; AMOVA Φ
ST of 0.3390; Bayesian θ
(II) = 0.3002). The low genetic diversity may be due to geographic isolation and restricted gene flow (N
m = 0.7533) between the fragmented populations. Unsustainable utilization of the plant has fragmented the population continuum
which served the purpose of genetic exchange between populations. Mantel’s test was performed which revealed a highly significant
positive correlation between genetic and geographic distance (r
2 = 0.614, P = 0.023) among the populations studied. Low variation can also be attributed to poor seed setting and the slow growth pattern
of the species, which is also an apomict. In UPGMA dendrogram the Commiphora wightii samples were divided into two major and one minor cluster. These findings can serve as a guide to preserving the genetic
resources of this medicinal plant species. 相似文献
10.
Kouichi Kawamura Masashi Kubota Miki Furukawa Yasushi Harada 《Conservation Genetics》2007,8(5):1163-1176
The amago salmon, Oncorhynchus masou ishikawae, is an endemic subspecies of O. masou in Japan. Owing to the extensive stocking of hatchery fish throughout Japan, indigenous populations of O. m. ishikawae are now on the verge of extinction. We examined the genetic effects of stocking hatchery fish on wild populations in the
River Koza, Japan, using microsatellite and mitochondrial DNA (mtDNA) markers. For mtDNA, haplotype mt1, which is common in
wild populations, was present exclusively in isolated wild populations assumed to be unaffected by previous stocking, while
it was never observed in hatchery fish. Genetic diversity was much higher in wild populations in the stocked area, which shared
many mtDNA haplotypes with hatchery fish, than in isolated wild populations with haplotype mt1. Pairwise F
ST estimates based on microsatellites showed significant differentiation among the isolated populations with many microsatellite
loci monomorphic. Significant deviation from Hardy–Weinberg equilibrium was observed in wild populations in the area subject
to stocking, where a Bayesian-based assignment test showed a high level of introgression with hatchery fish. These results
suggest that wild populations with haplotype mt1, which became isolated through anthropogenic environmental change in the
1950–1960s, represent indigenous populations of O. m. ishikawae in the River Koza. They have low genetic diversity, most likely caused by genetic bottlenecks following damming and environmental
deterioration, while stocking of hatchery fish over the past 30 years apparently had a large impact on the genetic structure
of wild populations in the main channel of the River Koza. 相似文献
11.
Elizabeth S. MacAvoy Lorna M. McGibbon James P. Sainsbury Hayley Lawrence Carol A. Wilson Charles H. Daugherty Geoffrey K. Chambers 《Conservation Genetics》2007,8(2):305-318
Tuatara (Sphenodon spp) populations are restricted to 35 offshore islands in the Hauraki Gulf, Bay of Plenty and Cook Strait of New Zealand.
Low levels of genetic variation have previously been revealed by allozyme and mtDNA analyses. In this new study, we show that
six polymorphic microsatellite loci display high levels of genetic variation in 14 populations across the geographic range
of tuatara. These populations are characterised by disjunct allele frequency spectra with high numbers of private alleles.
High F
ST (0.26) values indicate marked population structure and assignment tests allocate 96% of all individuals to their source populations.
These genetic data confirm that islands support genetically distinct populations. Principal component analysis and allelic
sequence data supplied information about genetic relationships between populations. Low numbers of rare alleles and low allelic
richness identified populations with reduced genetic diversity. Little Barrier Island has very low numbers of old tuatara
which have retained some relictual diversity. North Brother Island’s tuatara population is inbred with fixed alleles at 5
of the 6 loci. 相似文献
12.
We confront patterns in the chorology and diversity of freshwater and limnoterrestrial Rotifera with predictions following
from the recently revived ubiquity theorem on the distribution of microscopic organisms. Notwithstanding a strong taxonomic
impediment and lack of data, both bdelloid and monogonont rotifers appear to conform to the hypothesis’ predictions that local
diversity is relatively high compared to global diversity and that cosmopolitism is important. To the contrary, however, a
latitudinal diversity gradient is obvious, and endemicity is present, and exhibits diverse patterns. This is illustrated by
the case of Keratella rotifers, in which we identify purported relict endemicity hotspots in the east Palaearctic (China) and in temperate and
cold regions of the southern hemisphere, and a recent radiation in North America. The apparent paradox may result from an
antagonism between rotifer’s high population sizes and presence of potentially highly efficient propagules, versus pre-emption
of habitats and local adaptation by resident populations, specific dispersal ability, and ecological and geographical factors.
We conclude that distribution patterns of microscopic organisms, as represented by rotifers, most likely span the whole range
of alternatives, from full cosmopolitanism to local endemism, and suggest that studying this diversity is more productive
to come to an understanding of their chorology and diversity.
Special Issue: Protist diversity and geographic distribution. Guest editor: W. Foissner. 相似文献
13.
Victor Galhano Daniela R. de Figueiredo Artur Alves António Correia Mário J. Pereira José Gomes-Laranjo Francisco Peixoto 《Hydrobiologia》2011,663(1):187-203
Studies of cyanobacterial nostocacean taxa are important to the global scientific community, mainly because a significant number of beneficial strains that belong to
the order Nostocales fix atmospheric nitrogen, thus contributing to the fertility of agricultural soils worldwide, while others
behave as nuisance microorganisms in aquatic ecosystems due to their involvement in toxic bloom events. However, in spite
of their ecological importance and environmental concerns, their identification and taxonomy are still problematic and doubtful,
often being based on current morphological and physiological studies, which generate confusing classification systems and
usually vary under different conditions. Therefore, the present research aimed to investigate through a polyphasic approach
differences in morphological, biochemical and genotypic features of three nostocacean cyanobacterial strains isolated from
central-western Portuguese shallow freshwater bodies. Morphometric, genetic (16S rRNA, nifH and hetR fragments) and biochemical (fatty acid methyl ester; FAME profiles) data were used to characterize the strains. Morphological
analysis and sequencing of 16S rRNA fragments showed that the strains belonged to Anabaena cylindrica (UTAD_A212), Aphanizomenon gracile (UADFA16) and Nostoc muscorum (UTAD_N213) species. These strains showed clear distinct morphological and genetic features, allowing easy allocation to
their respective genera. The same happened by using partial sequences of hetR and nifH genes, in spite of the scarcity of deposited sequences. Biochemical characterization showed that the FAME profiles obtained
were consistent with both morphological and molecular analyses. It was suggested that the ratio of monounsaturated to polyunsaturated
FAMEs, together with the unsaturation index, could be used as genus-specific chemotaxonomic biomarkers. 相似文献
14.
Using the aquatic macrophyte <Emphasis Type="Italic">Vallisneria americana</Emphasis> (wild celery) as a nutrient bioindicator 总被引:1,自引:0,他引:1
Human sewage and septic waste are significant sources of nutrient loading to many aquatic ecosystems. Ecologically relevant
nitrogen sources can be traced by analyzing nitrogen stable isotope ratios (δ15N signatures) in aquatic plants. Elevated δ15N signatures can suggest increased uptake of nitrogen derived from human and/or animal waste. In the current study, Vallisneria americana, a freshwater angiosperm, was collected from several locations in Upper Saranac Lake, NY, USA. Samples were also collected
from Lake George, NY and the Sassafras River, MD, USA. Plant material was analyzed for δ15N and % N; some samples were also analyzed for δ13C, % C, and % P. Results suggest that there is variation in septic inputs to Upper Saranac Lake, with some areas of the lake
receiving more input than others. Results also show that increased watershed population density is correlated with elevated
δ15N signatures of Vallisneria americana. Taken together, these results suggest that nitrogen stable isotope analysis of aquatic plant tissue is an effective method
for assessing and monitoring septic inputs to freshwater ecosystems. 相似文献
15.
The present study focuses on the geographic distribution and biodiversity of the Chlorococcales in Patagonian lakes, covering a latitudinal transect. Two different approaches are considered (a) a review of the historical
records of Chlorococcales in Patagonia and (b) the analysis of the morphology-based species diversity, ecological remarks, and geographic distribution
of the chlorococcalean species recorded in 33 aquatic environments during surveys 2007 and 2008. A total of 308 chlorococcalean
species were recorded throughout a 60-year period in Patagonian freshwater systems, encountering the highest chlorococcalean
richness in lakes and shallow lakes located in the more intensively sampled areas. In our surveys 2007–2008, 72 chlorococcalean
taxa were registered, among which 80% are worldwide distributed, about 19% are restricted to cold temperate areas in both
hemispheres and one species (Pediastrum patagonicum) is one of the taxa probably endemic for Patagonia. The chlorococcalean richness in relation to the environmental factors,
revealed that it is directly correlated with the trophic status of the water bodies (chl a: r = 0.52 and DIN: r = 0.47; P < 0.05). The latitude was inversely correlated with the species richness (r = −0.40; P < 0.05), and the chlorococcalean biodiversity of the Andean lakes (mean value: 3.64) was significantly lower (P = 0.0022) than that of the lakes from the Patagonian Plateau (mean value: 9.62). In this study we observed a decreasing trend
in the biodiversity of Chlorococcales with increasing latitude, which fits in the existing ecological pattern described for different groups of organisms. 相似文献
16.
A. Ribeiro M. Gouveia A. Bessa A. Ferreira A. T. Magumisse M. Manjate T. Faria 《Russian Journal of Genetics》2010,46(8):967-975
The production of sunflower suffered a major decline in Mozambique after its independence in 1975. Civil war, human activities
and environmental damage subjected the species to an ecological stress contributing to reduce the number and size of wild
populations. As this reduction is often related to a loss of genetic variation we estimated the genetic diversity within and
among populations of wild Helianthus from five districts of Mozambique using RAPD markers. The 44 accessions studied grouped into four major clusters exhibiting
structured variability with regard to geographic origin. A high level of genetic diversity (He = 0.350 and I = 0.527) was retained at the population level. The genetic variation among populations was high (59.7%), which is consistent
with low gene flow (Nm = 0.338). The proportion of total genetic diversity residing among these populations should be kept in mind to devise different
conservation strategies in order to preserve these populations. Currently wild Helianthus genetic resources present in Maputo and Sofala are on the edge of extinction mainly due to excessive urbanization. Therefore,
conservation of what remains of this plant genetic diversity is essential for sustainable utilization and can be useful for
breeding programs. 相似文献
17.
Oryza rufipogon Griff. occurs widely in aquatic ecosystem of tropics and subtropics of monsoon Asia as well as Southern China. It is a vital
gene source for rice breeding programs. Many populations of the species, unfortunately, have drastically diminished because
of the disappearance of aquatic habitats as a result of human disturbance. In order to determine patterns of genetic variation
at two stages of the life-cycle in the wild rice species, we investigated allozyme variation of four natural populations in
China. Two southern populations have significant asexual reproduction while two other northern marginal populations show a
mixed reproduction in China. At 22 allozyme loci, a significantly lower genetic diversity was observed in the ratoons than
in the seeds of the two southern populations, whereas a significantly higher genetic diversity was found in the ratoons than
in the seeds of the two northern marginal populations. The results suggest that the variation of reproductive system is probably
associated with their patterns of genetic variation in the species. Moreover, a significantly higher genetic differentiation
among populations found in the ratoons than in the seeds may stem from pollen-mediated gene flow among them. Finally, we propose
suggestions for conservation management of the endangered species. 相似文献
18.
Zhou HF Zheng XM Wei RX Second G Vaughan DA Ge S 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2008,117(7):1181-1189
The cross compatible wild relatives of crops have furnished valuable genes for crop improvement. Understanding the genetics
of these wild species may enhance their further use in breeding. In this study, sequence variation of the nuclear Lhs1 gene was used to investigate the population genetic structure and gene flow of Oryza rufipogon and O. nivara, two wild species most closely related to O. sativa. The two species diverge markedly in life history and mating system, with O. rufipogon being perennial and outcrossing and O. nivara being annual and predominantly inbreeding. Based on sequence data from 105 plants representing 11 wild populations covering
the entire geographic range of these wild species, we detected significantly higher nucleotide variation in O. rufipogon than in O. nivara at both the population and species levels. At the population level the diversity in O. rufipogon (Hd = 0.712; θ
sil = 0.0017) is 2–3 folds higher than that in O. nivara (Hd = 0.306; θ
sil = 0.0005). AMOVA partitioning indicated that genetic differentiation among O. nivara populations (78.2%) was much higher than that among O. rufipogon populations (52.3%). The different level of genetic diversity and contrasting population genetic structure between O. rufipogon and O. nivara might be explained by their distinct life histories and mating systems. Our simulation using IM models demonstrated significant
gene flow from O. nivara to O. rufipogon, indicating a directional introgression from the annual and selfing species into the perennial and outcrossing species. The
ongoing introgression has played an important role in shaping current patterns of genetic diversity of these two wild species.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Castilleja levisecta (Scrophulariaceae), the golden paintbrush, is an insect-pollinated herbaceaous perennial found in the Pacific Northwest. Currently restricted to two island populations off British Columbia and nine populations (eight on islands) in Washington, C. levisecta is a rare species threatened with extinction. Allozymes were used to describe genetic diversity and structure in these eleven populations. Despite its threatened status and small geographic range, exceptionally high levels of genetic diversity are maintained within C. levisecta. All sixteen of the loci resolved were polymorphic within the species (Ps=100%), while the mean percentage of loci polymorphic within populations (Pp) was 65.7%. The mean number of alleles per polymorphic locus (APs) was 2.94 within the species and averaged 2.38 within populations (APp). Genetic diversity (Hes) was 0.285 for the species, whereas mean population genetic diversity (Hep) was 0.213. Smaller populations had, on average, fewer observed alleles and less genetic diversity. A significant negative correlation (r = –0.72) was found between genetic identity and geographic distance, indicating reduced gene flow between distant populations. The most geographically isolated population was one of the larger populations, one of the most genetically diverse and the most genetically divergent. A wide range of pairwise population genetic identities (I = 0.771 – 0.992) was found, indicating considerable genetic divergence between some populations. Overall, 19% of the total genetic diversity was distributed among populations. Results of this survey indicate that genetic augmentation of existing populations is unnecessary. The high allelic diversity found for the species and within its populations holds promise for conservation and restoration efforts to save this rare and threatened plant species. 相似文献
20.
Genetic and genotypic variabilities of a rare relict aquatic plant Nelumbo komarovii Grossh. from six natural populations of Primorsky krai (Russia) were assessed using isozyme analysis. The highest genetic and genotypic diversities were observed in the Razdol’noe and Okeanskaya populations, which can be explained by cross-pollination participation in the seed formation for maintenance of the Razdol’noe population size and by sowing seeds from different habitats for the Okeanskaya population. Low polymorphism at the population level (P = 8.97, HO = 0.055, HE = 0.039) is determined by the history of existence of the species from the Tertiary Period as well as by the influence of gene drift. Clonal renewal plays a decisive role in the propagation of N. komarovii in most natural populations. 相似文献