首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
A genetic survey of Barbus cyri populations from two biogeographical endorheic basins (Caspian Sea and Urmia Lake) was carried out using a mitochondrial marker (partial D-loop) in order to ascertain intra- and inter-population genetic diversity, population demography and to address their genetic structure which is the key to conservation action planning. Analyses were conducted on sequences obtained from 68 individuals collected from 10 sampling sites, from two basins. By means of morphological characteristics all specimens collected from the Caspian Sea basin were ascribed to Barbus cyri. Genetic diversity values (h and π) of sampling groups were all different from 0 (in Babolrud River population) to 0.857 (in Kalibar River population). Population connectivity and colonization patterns of the studied area were inferred from an analysis of molecular variance distribution and evolutionary relationships among haplotypes. The results point to different levels of isolation among sampling groups due to ecological and anthropogenic factors and the effect of an artificial barrier on genetic variability and conservation status of the population. Finally, this study confirms the uncertainty associated with systematic classification of Barbus spp. based on morphological characters due to the phenotypic plasticity of the species.  相似文献   

2.
Pithecopus megacephalus is a reticulated monkey–frog species endemic to the highlands of the Espinhaço Mountain Range in southeastern Brazil, an important centre of endemism in South America. This species has a discontinuous distribution and is considered “data-deficient” by the IUCN Red List, raising concerns about its conservation. Understanding the historical dynamics and connectivity of P. megacephalus populations can provide guidelines for preservation of this species in the wild. To investigate the population dynamics of P. megacephalus, we obtained multilocus DNA data for 55 individuals from different locations along the species’ known distribution. Spatial population structure, genetic diversity and demographic parameters were evaluated using population genetic and phylogeographical tools. We also evaluated its extent of occurrence and area of occupancy to investigate extinction risk of this species. We found genetic structure along P. megacephalus’ spatial distribution in the South Espinhaço Mountain Range corresponding to three population groups: northern, central and southern. Our results could provide important data on geographic distribution and population dynamics for a Data Deficient species. Therefore, we suggest these population data, together with the species’ limited occurrence in sky island environments could be used for a more accurate classification of P. megacephalus in the IUCN list, and conservation strategies for the species should be planned accordingly.  相似文献   

3.
Plant diversity is decreasing mainly through anthropogenic factors like habitat fragmentation, which lead to spatial separation of remaining populations and thereby affect genetic diversity and structure within species. Twenty populations of the threatened grassland species Crepis mollis were studied across Germany (578 individual plants) based on microsatellite genotyping. Genetic diversity was significantly higher in populations from the Alpine region than from the Central Uplands. Furthermore, genetic diversity was significantly positively correlated with population size. Despite smaller populations in the Uplands there were no signs of inbreeding. Genetic differentiation between populations was moderate (F ST?=?0.09) and no isolation by distance was found. In contrast, large-scale spatial genetic structure showed a significant decrease of individual pairwise relatedness, which was higher than in random pairs up to 50 km. Bayesian analyses detected three genetic clusters consistent with two regions in the Uplands and an admixture group in the Alpine region. Despite the obvious spatial isolation of the currently known populations, the absence of significant isolation by distance combined together with moderate population differentiation indicates that drift rather than inter-population gene flow drives differentiation. The absence of inbreeding suggests that pollination is still effective, while seed dispersal by wind is likely to be impaired by discontinuous habitats. Our results underline the need for maintaining or improving habitat quality as the most important short term measure for C. mollis. For maintaining long-term viability, establishing stepping stone habitats or, where this is not possible, assisted gene flow needs to be considered.  相似文献   

4.
Landscape attributes often shape the spatial genetic structure of species. As the maintenance of genetic connectivity is increasingly a conservation priority, the identification of landscape features that influence connectivity can inform targeted management strategies. The northern quoll (Dasyurus hallucatus) is a carnivorous marsupial that has experienced dramatic population declines in recent decades. To inform management of surviving D. hallucatus populations across north-western Australia we examined the genetic structure of populations, and identified landscape features that influence gene flow within the Kimberley region. We sampled 249 individuals from 28 populations in three regions of north-western Australia, including the Kimberley, Pilbara and Kakadu. Genetic structuring was evident between the three regions and to a lesser extent between the north and central Kimberley. Landscape genetic analysis of Kimberley populations suggest this structuring may be due in part to the indirect effects of differences in rainfall between these two areas. Also, D. hallucatus populations with large areas of open habitat between them tended to be more genetically similar. Managing threats such as the occurrence of intense and frequent fires, and the density of introduced herbivores, could support the persistence of D. hallucatus populations, particularly in areas with high rainfall and flat terrain, where greater genetic connectivity confers a better chance of long-term population survival.  相似文献   

5.
Genetic structure and genetic diversity are key population characteristics that can inform conservation decisions, such as delineating management units or assessing potential risks for inbreeding depression. Evidence of genetic structuring or low genetic diversity in the critically endangered snail kite (Rostrhamus sociabilis plumbeus) would have implications for monitoring and planning decisions. Recent work on understanding connectivity across the snail kite range indicated that there is less dispersal between northern and southern parts of the current range, and that dispersal is shaped by individual habitat preference. We examine whether there is neutral genetic structure and the amount of genetic variation in the population by non-lethally sampling 235 nestlings from unique nests across the entire breeding range between 2013 and 2014. Data on 15 microsatellite revealed low diversity (e.g., N a?=?2.54, H e?=?0.37) and range-wide panmixia based on AMOVA, Bayesian clustering, spatial autocorrelation, isolation by distance, and spatially explicit ordination analyses. Our results emphasize that long-term recovery goals and management strategies should be based on viewing snail kites as a single genetic population, despite evidence for non-random dispersal between wetlands over ecological time scales. These results also highlight the need to understand potential effects of low genetic diversity on population dynamics and viability of snail kites. More broadly, these results add to the growing evidence for potential discrepancies between dispersal and genetic patterns, emphasizing that care should be taken if using one to interpret the other, particularly for widely-ranging species.  相似文献   

6.
Geranium molle is known as Dovefoot Geranium or Awnless Geranium. Dovefoot Geranium is a low-growing herb with pink flowers and sharply toothed leaves. Dovefoot Geranium is native to Eurasia and has been introduced to many habitats of the world. This species is very similar to G. robertianum but its palmate-like leaves and bilobed petals show differences. This plant is considered to be anodyne, astringent and vulnerary. We have no information on its population genetic structure, genetic diversity, and morphological variability in Iran. Therefore, due to the importance of these plant species, we performed a combination of morphological and molecular data for this species. For this study, we used 132 randomly collected plants from 18 geographical populations in 4 provinces. Genetic diversity parameters were determined in these populations. STRUCTURE analysis and K-Means clustering identified 14 gene pools in the country and revealed isolation by distance among the studied populations. The Mantel test showed correlation between genetic and geographical distance. AMOVA revealed a significant genetic difference among populations and showed that 40% of total genetic variation was due to within-population diversity. The consensus tree of both molecular and morphological data identified divergent populations. These data may be used in future breeding and conservation of this important medicinal plant in the country.  相似文献   

7.
Examining the spatial genetic structure of cryptic species occupying challenging terrain can afford otherwise unattainable insights into ecological and evolutionary processes, such as population dynamics and dispersal patterns; information important for optimising conservation management. Using 13 microsatellite markers, we evaluated patterns of fine-scale gene flow and the spatial extent of genetic structuring of rock wren (Xenicus gilviventris), a threatened alpine passerine endemic to mountainous regions of the South Island, New Zealand. Through spatial autocorrelation analysis, we found that the ‘genetic patch size’, i.e. the distance over which individuals were not genetically independent, was surprisingly large (c. 70 km), given the rock wren’s limited flight ability. By estimating recent migration rates among sampling locations we also found asymmetries in gene flow indicative of source–sink dynamics. An area with intensive deer and predator control, in the Murchison Mountains, Fiordland, appears to be a particularly important source of migrants for other populations. These findings suggest that management to maintain connectivity is required across relatively large spatial scales and source populations may be those where introduced mammals are managed.  相似文献   

8.
Fragmentation of habitat can decrease resource availability and restrict movement among geographic areas. Persistence in fragmented landscapes depends on the maintenance of connectivity among populations, without which genetic diversity may decrease and lead to population declines. Bees are particularly vulnerable to the negative effects of low genetic diversity so it is important to understand patterns of dispersal for native bees living in fragmented areas. I used population genetic techniques to characterize patterns of genetic diversity and dispersal for the orchid bee Euglossa imperialis within and among forest fragments in southern Costa Rica, in which the furthest two fragments were 226 km from one another. In addition, I compared results of population genetic analyses conducted with all bees sampled, and results from analyses conducted with a reduced dataset containing only one individual per full sibling family from each site. For both datasets genetic diversity was low within forest fragments, with expected heterozygosity averaging 0.28 for the full dataset and 0.29 for the dataset containing only one full sibling per site. I found no evidence that deforested areas restricted dispersal; pairwise estimates of genetic differentiation \(F_{\text{ST}}^{\prime }\) among forest fragments averaged 0.01 for the full dataset, and 0 for the dataset containing only one full sibling per site. Genetic distance among sites within forest fragments was significantly correlated to geographic distance for the full dataset, but there was no significant correlation for the dataset that contained only one individual from each full sibling family. This suggests that family structure can drive results of analyses of genetic structure, although reductions in sample sizes following removal of full siblings may have reduced power to detect genetic structure. Despite no evidence for restricted dispersal, the low genetic diversity found suggests that E. imperialis may be an important candidate for future conservation monitoring.  相似文献   

9.
Species endemic to sky island systems are isolated to mountain peaks and high elevation plateaux both geographically and ecologically, making them particularly vulnerable to the effects of climate change. Pressures associated with climate change have already been linked to local extinctions of montane species, emphasizing the importance of understanding the genetic diversity and population connectivity within sky islands systems for the conservation management of remaining populations. Our study focuses on the endangered alpine skink Pseudemoia cryodroma, which is endemic to the Victorian Alps in south-eastern Australia, and has a disjunct distribution in montane habitats above 1100 m a.s.l. Using mitochondrial DNA (mtDNA) and microsatellite loci, we investigated species delimitation, genetic connectivity and population genetic structure across the geographic range of this species. We found discordance between genetic markers, indicating historical mtDNA introgression at one of the study sites between P. cryodroma and the closely related, syntopic P. entrecasteauxii. Molecular diversity was positively associated with site elevation and extent of suitable habitat, with inbreeding detected in three of the five populations. These results demonstrate the complex interaction between geography and habitat in shaping the population structure and genetic diversity of P. cryodroma, and highlight the importance of minimising future habitat loss and fragmentation for the long-term persistence of this species.  相似文献   

10.
In the southwestern United States (US), the Rio Grande chub (Gila pandora) is state-listed as a fish species of greatest conservation need and federally listed as sensitive due to habitat alterations and competition with non-native fishes. Characterizing genetic diversity, genetic population structure, and effective number of breeders will assist with conservation efforts by providing a baseline of genetic metrics. Genetic relatedness within and among G. pandora populations throughout New Mexico was characterized using 11 microsatellite loci among 15 populations in three drainage basins (Rio Grande, Pecos, Canadian). Observed heterozygosity (HO) ranged from 0.71–0.87 and was similar to expected heterozygosity (0.75–0.87). Rio Ojo Caliente (Rio Grande) had the highest allelic richness (AR = 15.09), while Upper Rio Bonito (Pecos) had the lowest allelic richness (AR = 6.75). Genetic differentiation existed among all populations with the lowest genetic variation occurring within the Pecos drainage. STRUCTURE analysis revealed seven genetic clusters. Populations of G. pandora within the upper Rio Grande drainage (Rio Ojo Caliente, Rio Vallecitos, Rio Pueblo de Taos) had high levels of admixture with Q-values ranging from 0.30–0.50. In contrast, populations within the Pecos drainage (Pecos River and Upper Rio Bonito) had low levels of admixture (Q = 0.94 and 0.87, respectively). Estimates of effective number of breeders (N b ) varied from 6.1 (Pecos: Upper Rio Bonito) to 109.7 (Rio Grande: Rio Peñasco) indicating that populations in the Pecos drainage are at risk of extirpation. In the event that management actions are deemed necessary to preserve or increase genetic diversity of G. pandora, consideration must be given as to which populations are selected for translocation.  相似文献   

11.
Astragalus argaeus is critically endangered endemic species growing only on Erciyes Mountain in Kayseri. Inter simple sequence repeat (ISSR) markers were chosen to detect the genetic diversity in four populations of A. argaeus. Ten primers were used to assess the diversity among 96 genotypes collected from the four localities in Erciyes Mountain. A total of 78 bands were scored, of which 44 (55.8%) were polymorphic. The unweighted pair group method arithmetic average (UPGMA) and principle component analysis (PCoA) showed moderate genetic diversity at the species and population level. The percentages of polymorphic bands (PPB) ranged from 53.8 to 61.5 (58.01%?±?3.2) and average gene diversity (h) at the population and species level was estimated to be 0.17 and 0.23, respectively. The Shannon’s information index (SI) ranged from 0.24 to 0.29 at the population level and was 0.35 at the species level. The determined gene flow (Nm) was 1.83. The UPGMA tree indicated that the four populations were not genetically distinct obviously. In analysis of molecular variance (AMOVA), the percentage of the variance was 38.72% among populations and 61.28% within populations. The data which small population size, habitat fragmentation and moderate levels of genetic diversity demonstrate that A. argaeus possess threat of extinction if its narrow habitat is destroyed.  相似文献   

12.
We investigated genetic diversity and population structure of the Sitka periwinkle Littorina sitkana along the coastlines of the northwestern Pacific (NWP) to evaluate the possibility of trans-Pacific colonization of this species from the NWP to the northeastern Pacific (NEP) after the Last Glacial Maximum. We sampled L. sitkana from 32 populations in the NWP, and sequenced a region of the mitochondrial cytochrome b oxidase gene for population genetic analyses. The results were compared with those of previous reports from the NEP. The genetic diversity of L. sitkana was much higher in the NWP than in the NEP. Genetic connectivity between the NWP and NEP populations was indicated by an extremely abundant haplotype in the NEP that was also present in eastern Hokkaido and the Kuril Islands. To confirm these results, we compared sequences of the longest intron of the aminopeptidase N gene (APN54) in the nuclear genome in four populations of L. sitkana in the NWP with previous results from the NEP. Again, much higher genetic diversity was found in the NWP than in the NEP and genetic connectivity was supported between the Kuril Islands and the NEP. These results imply postglacial colonization of this species from the NWP to the NEP, probably along the Kuril and Aleutian Island chains. This study is the first report of possible trans-Pacific postglacial colonization of a direct-developing gastropod, inferred from genetic data.  相似文献   

13.
To establish a management plan for endangered and rare species, genetic assessment must first be conducted. The genetic characteristics of plant species are affected by demographic history, reproductive strategy, and distributional range as well as anthropological effects. Abies koreana E. H. Wilson (Pinaceae), Korean fir, is endemic to Korea and found only in sub-alpine areas of the southern Korean Peninsula and Jejudo Island. This species has been designated as critically endangered by the International Union for Conservation of Nature due to a continuous decline in its range and population fragmentation. We genotyped 176 individuals from seven natural populations and two afforested populations on the Korean Peninsula using 19 microsatellite loci. STRUCTURE analysis revealed two genetic clusters in natural populations (F st  = 0.040 and R st  = 0.040) despite low differentiation. We did not detect a significant reduction in genetic diversity or the signature of a genetic bottleneck despite population fragmentation and small population size. We deduced that this species exhibits a metapopulation structure, with the population on Jirisan Mountain acting as a source of genetic diversity for other local small populations on the Korean Peninsula, through contemporary asymmetric gene flow. However, the majority of afforested individuals on the Korean Peninsula originated from a different gene cluster. Thus, we recommend a conservation strategy that maintains two genetically unique clusters.  相似文献   

14.
Understanding patterns of genetic diversity and population structure for rare, narrowly endemic plant species, such as Pinguicula ionantha (Godfrey’s butterwort; Lentibulariaceae), informs conservation goals and can directly affect management decisions. Pinguicula ionantha is a federally listed species endemic to the Florida Panhandle in the southeastern USA. The main goal of our study was to assess patterns of genetic diversity and structure in 17 P. ionantha populations, and to determine if diversity is associated with geographic location or population characteristics. We scored 240 individuals at a total of 899 AFLP markers (893 polymorphic markers). We found no relationship between the estimated population size with either of two measures of diversity (proportion of loci polymorphic, P = 0.37; Nei’s gene diversity, P = 0.50). We also found low levels of population genetic structure; there was no clear relationship of genetic isolation by distance (P = 0.23) and only a small (but significant) proportion of genetic variation was partitioned amongst regions (2.4 %, P = 0.02) or populations (20.8 %, P < 0.001). STRUCTURE analysis found that the model with two inferred clusters (K = 2) best described the AFLP data; the dominant cluster at each site corresponded to the results from PCoA and Nei’s genetic distance analyses. The observed patterns of genetic diversity suggest that although P. ionantha populations are isolated spatially by distance and both natural and anthropogenic barriers, some gene flow occurs among them or isolation has been too recent to leave a genetic signature. The relatively low level of genetic diversity associated with this species is a concern as it may impair fitness and evolutionary capability in a changing environment. The results of this study provide the foundation for the development of management practices that will assist in the protection of this rare carnivorous plant.  相似文献   

15.
16.
Stenotopic specialization to a fragmented habitat promotes the evolution of genetic structure. It is not yet clear whether small-scale population structure generally translates into large-scale intraspecific divergence. In the present survey of mitochondrial genetic structure in the Lake Tanganyika endemic Altolamprologus (Teleostei, Cichlidae), a rock-dwelling cichlid genus comprising A. compressiceps and A. calvus, habitat-induced population fragmentation contrasts with weak phylogeographic structure and recent divergence among genetic clades. Low rates of dispersal, perhaps along gastropod shell beds that connect patches of rocky habitat, and periodic secondary contact during lake level fluctuations are apparently sufficient to maintain genetic connectivity within each of the two Altolamprologus species. The picture of genetic cohesion was interrupted by a single highly divergent haplotype clade in A. compressiceps restricted to the northern part of the lake. Comparisons between mitochondrial and nuclear phylogenetic reconstructions suggested that the divergent mitochondrial clade originated from ancient interspecific introgression. Finally, ‘isolation-with-migration’ models indicated that divergence between the two Altolamprologus species was recent (67–142 KYA) and proceeded with little if any gene flow. As in other rock-dwelling cichlids, recent population expansions were inferred in both Altolamprologus species, which may be connected with drastic lake level fluctuations.  相似文献   

17.
Genetic variability of yellow potato cyst nematode G. rostochiensis from three Russian populations (Karelia, Vladimir oblast, and Moscow oblast) was investigated using two types of nuclear markers. Using RAPD markers identified with the help of six random primers (P-29, OPA-10, OPT-14, OPA-11, OPB-11, and OPH-20), it was possible to distinguish Karelian population from the group consisting of the populations from two adjacent regions (Moscow oblast and Vladimir oblast). Based on the combined matrix, containing 294 RAPD fragments, dendrogram of genetic differences was constructed, and the indices of genetic divergence and partition (P, H, and G st), as well as the gene flow indices N m between the nematode samples examined, were calculated. The dendrogram structure, genetic diversity indices, and variations of genetic distances between single individuals in each population from Karelia and Central Russia pointed to genetic isolation and higher genetic diversity of the nematodes from Karelia.Based on polymorphism of rDNA first intergenic spacer ITS1, attribution of all populations examined to the species G. rostochiensis was proved. Small variations of the ITS1 sequence in different geographic populations of nematodes from different regions of the species world range did not allow isolation of separate groups within the species. Possible factors (including interregional transportations of seed potato) affecting nematode population structure in Russia are discussed.  相似文献   

18.
Using RAPD markers, polymorphism and differentiation of genomic DNA was examined in seven natural populations of Chironomus plumosus from Europe, Siberia, and North America. All these populations showed high polymorphism of genomic DNA. The Palearctic and Nearctic populations of this species were not statistically significantly different in the genomic DNA polymorphism level. The genetic distance (GD), which characterizes the extent of intraspecific differentiation of population genetic structure, was determined among the natural populations of C. plumosus. The genetic distance was on average 0.245. It was demonstrated that genetic structures of the Palearctic and Nearctic populations of C. plumosus was differentiated to a higher extent than in Palearctic. However, the genetic distances between the populations from different zoogeographical zones (0.313) did not exceed the level characteristic of the among-population differences, which do not disturb the species genetic integrity.  相似文献   

19.
Insight into a species’ native and introduced range is essential in understanding the invasion process. Genetic diversity, propagule pressure and environmental conditions all have been recognised as playing a determinant role in invasion success. Here, we aimed to investigate the genetic diversity and population genetic structure (using the COI mtDNA gene region and 22 nDNA microsatellite markers) of the Asian green mussel Perna viridis within its potential native range in Asia and at introduced locations in the USA and the Caribbean. We also analyse genetic data from vessel intercepts and an incursion. By doing so, we aimed to identify genetic signatures that could allow to track vessel samples to their source and provide further insight into potential high-risk invasive populations or areas. Three top hierarchical clusters were identified using the individual-based Bayesian clustering method in STRUCTURE, corresponding to populations in three world regions: (1) USA and Caribbean, (2) India and (3) Southeast Asia. Within Southeast Asia, additional analysis indicate a shallow genetic differentiation of three subgroups consisting of (3a) Thailand, (3b) Taiwan and Hong-Kong, and (3c) a cluster of Singapore–Indonesia samples. Overall, the population structure found in this study suggests that the markers used could be useful in identifying source populations, particularly between the three mains world regions. Most surprisingly however, this study shows that the genetic diversity of samples collected from vessel intercepts and incursions did not differ significantly from established populations in Southeast Asia. In this region, in addition to the high vessel connectivity and number of P. viridis transported, all sampled populations are likely to pose a comparable risk in terms of genetic diversity. The present work represents the most comprehensive population genetic study of P. viridis, and the first to address the potential genetic introduction risk posed by populations of this species. The information and genetic markers in this study constitute a valuable addition to the tools already used to infer on potential high-risk source populations of P. viridis. They should therefore prove useful for biosecurity surveillance and management actions directed at this species.  相似文献   

20.
The cognizing of connectivity among small mammal populations across heterogeneous landscapes is complicated due to complex influences of landscape and anthropogenic factors on gene flow. A landscape genetics approach offers inferences on how landscape features drive population structure. Through a landscape genetics approach, we investigated influences of geographical, environmental, and anthropogenic features on populations of Apodemus agrarius, the striped field mouse, the prime vector of hemorrhagic fever by a landscape genetic approach. We identified landscape features that might affect the population structure of striped field mice by analyzing microsatellite markers of 197 striped field mice from 21 populations throughout South Korea. We developed Maximum-likelihood population effects models based on landscape distances and resistance matrices and pairwise FST values for meta-populations of striped field mouse. We also conducted Mantel and partial Mantel tests to investigate geographic patterns of genetic similarities. In Mantel and partial Mantel tests, the FST was significantly correlated with all three models of movement; movement cost, Euclidian distance and least-cost distance, although the magnitudes of correlations varied. The 4 top-ranked models included three variables; temperature, precipitation and one human disturbance factor (population). We did not attain a significant effect for anthropogenic factors on genetic similarities among populations in the Korean striped field mouse, but we confirmed a significant association for genetic similarity with climatic features (temperature and precipitation).  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号