共查询到20条相似文献,搜索用时 15 毫秒
1.
S. FOITZIK S. BAUER S. LAURENT P. S. PENNINGS 《Journal of evolutionary biology》2009,22(12):2470-2480
Genetic diversity and spatial structure of populations are important for antagonistic coevolution. We investigated genetic variation and population structure of three closely related European ant species: the social parasite Harpagoxenus sublaevis and its two host species Leptothorax acervorum and Leptothorax muscorum. We sampled populations in 12 countries and analysed eight microsatellite loci and an mtDNA sequence. We found high levels of genetic variation in all three species, only slightly less variation in the host L. muscorum. Using a newly introduced measure of differentiation (Jost’s Dest ), we detected strong population structuring in all species and less male‐biased dispersal than previously thought. We found no phylogeographic patterns that could give information on post‐glacial colonization routes – northern populations are as variable as more southern populations. We conclude that conditions for Thompson’s geographic mosaic of coevolution are ideal in this system: all three species show ample genetic variation and strong population structure. 相似文献
2.
F. Van Rossum 《Plant biology (Stuttgart, Germany)》2009,11(5):725-737
In order to conserve forest plant species under the particularly high constraints that represent urban surroundings, it is necessary to identify the key factors for population persistence. This study examined within‐ and between‐population pollen dispersal using fluorescent dye as pollen analogue, and genetic variation and structure using 15 allozyme loci in Centaurium erythraea, an insect‐pollinated, early‐successional forest biennial herb occurring in a peri‐urban forest (Brussels urban zone, Belgium). Dye dispersal showed an exponential decay distribution, with most dye transfers occurring at short distances (<15 m), and only a few long‐distance events (up to 743 m). Flowers of C. erythraea are mainly visited by Syrphids (Diptera) and small bees, which are usually considered as short‐distance pollen dispersers, and occasionally by bumblebees, which are usually longer‐distance pollen dispersers. Small and large dye source populations differed in dye deposition patterns. The populations showed low genetic diversity, high inbreeding coefficients (FIS) and high genetic differentiation (FST), suggesting restricted gene flow, which can be expected for an early‐successional biennial species with a predominantly selfing breeding system and fluctuating population sizes. The positive relationship between recruitment rate and allelic richness and expected heterozygosity, and the absence of significant correlations between genetic variation and population size suggest seedling recruitment from the seed bank, contributing to maintain genetic diversity. Long‐distance dye dispersal events indicate pollinator movements along urban forest path and road verges. These landscape elements might therefore have a potential conservation value by contributing to connectivity of early‐successional species populations located in patchy open habitats. 相似文献
3.
Populations of the endangered giant kangaroo rat, Dipodomys ingens (Heteromyidae), have suffered increasing fragmentation and isolation over the recent past, and the distribution of this unique
rodent has become restricted to 3% of its historical range. Such changes in population structure can significantly affect
effective population size and dispersal, and ultimately increase the risk of extinction for endangered species. To assess
the fine-scale population structure, gene flow, and genetic diversity of remnant populations of Dipodomys ingens, we examined variation at six microsatellite DNA loci in 95 animals from six populations. Genetic subdivision was significant
for both the northern and southern part of the kangaroo rat’s range although there was considerable gene flow among southern
populations. While regional gene diversity was relatively high for this endangered species, hierarchical F-statistics of northern
populations in Fresno and San Benito counties suggested non-random mating and genetic drift within subpopulations. We conclude
that effective dispersal, and therefore genetic distances between populations, is better predicted by ecological conditions
and topography of the environment than linear geographic distance between populations. Our results are consistent with and
complimentary to previous findings based on mtDNA variation of giant kangaroo rats. We suggest that management plans for this
endangered rodent focus on protection of suitable habitat, maintenance of connectivity, and enhancement of effective dispersal
between populations either through suitable dispersal corridors or translocations. 相似文献
4.
Asymmetric gene flow and the evolutionary maintenance of genetic diversity
in small,peripheral Atlantic salmon populations 总被引:4,自引:4,他引:0
Small populations may be expected to harbour less genetic variation than large populations, but the relation between census
size (N), effective population size (N
e), and genetic diversity is not well understood. We compared microsatellite variation in four small peripheral Atlantic salmon
populations from the Iberian peninsula and three larger populations from Scotland to test whether genetic diversity was related
to population size. We also examined the historical decline of one Iberian population over a 50-year period using archival
scales in order to test whether a marked reduction in abundance was accompanied by a decrease in genetic diversity. Estimates
of effective population size (N
e) calculated by three temporal methods were consistently low in Iberian populations, ranging from 12 to 31 individuals per
generation considering migration, and from 38 to 175 individuals per generation if they were regarded as closed populations.
Corresponding N
e/N ratios varied from 0.02 to 0.04 assuming migration (mean=0.03) and from 0.04 to 0.18 (mean=0.10) assuming closed populations.
Population bottlenecks, inferred from the excess of heterozygosity in relation to allelic diversity, were detected in all
four Iberian populations, particularly in those year classes derived from a smaller number of returning adults. However, despite
their small size and declining status, Iberian populations continue to display relatively high levels of heterozygosity and
allelic richness, similar to those found in larger Scottish populations. Furthermore, in the R. Asón no evidence was found
for a historical loss of genetic diversity despite a marked decline in abundance during the last five decades. Thus, our results
point to two familiar paradigms in salmonid conservation: (1)␣endangered populations can maintain relatively high levels of
genetic variation despite their small size, and (2) marked population declines may not necessarily result in a significant
loss of genetic diversity. Although there are several explanations for such results, microsatellite data and physical tagging
suggest that high levels of dispersal and asymmetric gene flow have probably helped to maintain genetic diversity in these
peripheral populations, and thus to avoid the negative consequences of inbreeding. 相似文献
5.
Microsatellite variation was determined for three Danish and three Dutch populations of the haploid moss species Polytrichum formosum to gain insight into the relative importance of sexual vs. asexual reproduction for the amount and structure of genetic variation. In general, low levels of microsatellite variation were observed within this species. Even when estimated for polymorphic loci only, the levels of microsatellite variability (P=90.6, A=4.3 and HS=0.468) within populations were on average lower than those reported for most other plant species. In contrast, genotypic diversity was high within each of the examined populations, indicating that sexual reproduction is a very important determinant of the genetic structure of P. formosum within populations. In agreement with previous findings for allozyme data, no significant genetic differentiation (FST=0.028, RST=0.015) was observed neither between populations nor between regions approximately 450 km apart (Denmark vs. the Netherlands). These low levels of population differentiation observed for both types of genetic markers are probably best explained by a high level of effective spore dispersal (gene flow) between populations. Therefore, also on a large geographical scale sexual reproduction is the most important determinant of the genetic structure of P. formosum, despite the high potential to reproduce clonally. 相似文献
6.
Meher A. Ony Marcin Nowicki Sarah L. Boggess William E. Klingeman John M. Zobel Robert N. Trigiano Denita Hadziabdic 《Ecology and evolution》2020,10(8):3655-3670
Forest fragmentation may negatively affect plants through reduced genetic diversity and increased population structure due to habitat isolation, decreased population size, and disturbance of pollen‐seed dispersal mechanisms. However, in the case of tree species, effective pollen‐seed dispersal, mating system, and ecological dynamics may help the species overcome the negative effect of forest fragmentation. A fine‐scale population genetics study can shed light on the postfragmentation genetic diversity and structure of a species. Here, we present the genetic diversity and population structure of Cercis canadensis L. (eastern redbud) wild populations on a fine scale within fragmented areas centered around the borders of Georgia–Tennessee, USA. We hypothesized high genetic diversity among the collections of C. canadensis distributed across smaller geographical ranges. Fifteen microsatellite loci were used to genotype 172 individuals from 18 unmanaged and naturally occurring collection sites. Our results indicated presence of population structure, overall high genetic diversity (HE = 0.63, HO = 0.34), and moderate genetic differentiation (FST = 0.14) among the collection sites. Two major genetic clusters within the smaller geographical distribution were revealed by STRUCTURE. Our data suggest that native C. canadensis populations in the fragmented area around the Georgia–Tennessee border were able to maintain high levels of genetic diversity, despite the presence of considerable spatial genetic structure. As habitat isolation may negatively affect gene flow of outcrossing species across time, consequences of habitat fragmentation should be regularly monitored for this and other forest species. This study also has important implications for habitat management efforts and future breeding programs. 相似文献
7.
8.
I. Hensen C. Kilian V. Wagner W. Durka J. Pusch K. Wesche 《Plant biology (Stuttgart, Germany)》2010,12(3):526-536
Stipa capillata L. (Poaceae) is a rare grassland species in Central Europe that is thought to have once been widespread in post‐glacial times. Such relict species are expected to show low genetic diversity within populations and high genetic differentiation between populations due to bottlenecks, long‐term isolation and ongoing habitat fragmentation. These patterns should be particularly pronounced in selfing species. We analysed patterns of random amplified polymorphic DNA (RAPD) variation in the facultatively cleistogamous S. capillata to examine whether genetic diversity is associated with population size, and to draw initial conclusions on the migration history of this species in Central Europe. We analysed 31 S. capillata populations distributed in northeastern, central and western Germany, Switzerland and Slovakia. Estimates of genetic diversity at the population level were low and not related to population size. Among all populations, extraordinarily high levels of genetic differentiation (amova : φST = 0.86; Bayesian analysis: θB = 0.758) and isolation‐by‐distance were detected. Hierarchical amova indicated that most of the variability was partitioned among geographic regions (59%), or among populations between regions when the genetically distinct Slovakian populations were excluded. These findings are supported by results of a multivariate ordination analysis. We also found two different groups in an UPGMA cluster analysis: one that contained the populations from Slovakia, and the other that combined the populations from Germany and Switzerland. Our findings imply that S. capillata is indeed a relict species that experienced strong bottlenecks in Central Europe, enhanced by isolation and selfing. Most likely, populations in Slovakia were not the main genetic source for the post‐glacial colonization of Central Europe. 相似文献
9.
Nelli Rnk Veli‐Matti Pakanen Donald Blomqvist Victor Degtyaryev Mikhail Golovatin Gennady Isakov Natalia Karlionova Aija Lehikoinen Vladimir Morozov Sergey Paskhalny Angela Pauliny Pavel Pinchuk Pentti Rauhala Pavel Tomkovich Evgeny Zakharov Kari Koivula Laura Kvist 《Ibis》2019,161(3):632-647
Populations from different parts of a species range may vary in their genetic structure, variation and dynamics. Geographically isolated populations or those located at the periphery of the range may differ from those located in the core of the range. Such peripheral populations may harbour genetic variation important for the adaptive potential of the species. We studied the distribution‐wide population genetic structure of the Terek Sandpiper Xenus cinereus using 13 microsatellite loci and the mitochondrial DNA (mtDNA) control region. In addition, we estimated whether genetic variation changes from the core towards the edge of the breeding range. We used the results to evaluate the management needs of the sampled populations. Distribution‐wide genetic structure was negligible; the only population that showed significant genetic differentiation was the geographically isolated Dnieper River basin population in Eastern Europe. The genetic variation of microsatellites decreased towards the edge of the distribution, supporting the abundant‐centre hypotheses in which the core area of the distribution preserves the most genetic variation; however, no such trend could be seen with mtDNA. Overall genetic variation was low and there were signs of past population contractions followed by expansion; this pattern is found in most northern waders. The current effective population size (Ne) is large, and therefore global conservation measures are not necessary. However, the marginal Dnieper River population needs to be considered its own management unit. In addition, the Finnish population warrants conservation actions due to its extremely small size and degree of isolation from the main range, which makes it vulnerable to genetic depletion. 相似文献
10.
Enzyme and dispersal polymorphisms of the saltmarsh carabid beetles Pogonus chalceus and Dicheirotrichus gustavii were studied in European populations varying in size and in isolation in space and time. D. gustavii, a constantly fullwinged species, has a larger genetic diversity and a smaller genetic differentiation between populations
than the wing-polymorphic P. chalceus. Clear relationships between population or site characteristics and genetic structure were not observed, except for the special
position taken by some small populations in both species. The dispersal power of P. chalceus in small populations is larger than in large populations, suggesting that these populations are unstable and/or young. Small
populations, however, do not always show a lower genetic diversity than large populations, as would be expected from genetic
drift. Dispersal power in P. chalceus declines with increasing age of the saltmarsh, probably due to continuous emigration of winged individuals. Age and size
of saltmarshes, although difficult to study independently, both appear to be important in determining the genetic structure
of saltmarsh beetles. Maximum diversity in both parameters is therefore recommended as an optimal nature conservation strategy.
Received: 22 September 1997 / Accepted: 29 December 1997 相似文献
11.
Anthropogenic fragmentation may not alter pre‐existing patterns of genetic diversity and differentiation in perennial shrubs 下载免费PDF全文
Many plant species have pollination and seed dispersal systems and evolutionary histories that have produced strong genetic structuring. These genetic patterns may be consistent with expectations following recent anthropogenic fragmentation, making it difficult to detect fragmentation effects if no prefragmentation genetic data are available. We used microsatellite markers to investigate whether severe habitat fragmentation may have affected the structure and diversity of populations of the endangered Australian bird‐pollinated shrub Grevillea caleyi R.Br., by comparing current patterns of genetic structure and diversity with those of the closely related G. longifolia R.Br. that has a similar life history but has not experienced anthropogenic fragmentation. Grevillea caleyi and G. longifolia showed similar and substantial population subdivision at all spatial levels (global F′ST = 0.615 and 0.454; Sp = 0.039 and 0.066), marked isolation by distance and large heterozygous deficiencies. These characteristics suggest long‐term effects of inbreeding in self‐compatible species that have poor seed dispersal, limited connectivity via pollen flow and undergo population bottlenecks because of periodic fires. Highly structured allele size distributions, most notably in G. caleyi, imply historical processes of drift and mutation were important in isolated subpopulations. Genetic diversity did not vary with population size but was lower in more isolated populations for both species. Through this comparison, we reject the hypothesis that anthropogenic fragmentation has impacted substantially on the genetic composition or structure of G. caleyi populations. Our results suggest that highly self‐compatible species with limited dispersal may be relatively resilient to the genetic changes predicted to follow habitat fragmentation. 相似文献
12.
Abstract. Differences in genetic variability of several small, isolated populations of four fern species in a restricted area in the Swiss lowlands reflect differences in breeding system, population size, the degree of population fragmentation, and ecological requirements. The investigated populations of Asplenium septentrionale show only little genetic variability (isozyme variation) without gene flow among populations (based on the banding pattern of multi-locus phenotypes), and they persist for long periods despite the small population sizes. In Asplenium ruta-muraria, genetic variability is correlated with age. Young populations show no genetic variation, while old populations show some. All individuals of Polypodium vulgare investigated, either epiphytic or epilithic, share exactly the same enzyme phenotype. The results for these three species can be related to predominance of inbreeding, lack of inbreeding depression, polyploidy, long-distance dispersal, production of large amounts of diaspores, single-spore colonization, and perennial life cycles. Genetic variability in these three species does not seem to be absolutely necessary for the maintenance of their populations. Ecological and demographic factors are considered to be more important. An isolated, glacial relict population of diploid Asplenium viride shows high variability in two out of eight enzyme systems, which may be due to prevailing outbreeding. We discuss aspects of the importance of genetics and life history for conservation biology. 相似文献
13.
Berchemiella wilsonii var. pubipetiolata (Rhamnaceae) is an endangered plant with only four remnant populations in eastern China. Population genetic information is
essential for understanding population history and formulating conservation strategies for this species. Thirteen microsatellite
loci were used to investigate genetic variation and population structure of the four remnant populations. Moderate levels
of expected heterozygosity (H
E = 0.466–0.543) and low allelic diversity (A = 3.1–3.6 and A
R = 2.2–2.4, respectively) were observed within populations. Bottleneck tests found three out of four populations to deviate
from mutation-drift equilibrium under the two-phase model (TPM), suggesting a recent population decline, which is congruent
with known demographic history. The evolutionary history of the species seems dominated by genetic drift rather than gene
flow. Low historical gene flow was inferred from several different approaches and N
m ranged from 0.582 by the private allele method to 0.783 by the coalescent method. Contemporary gene flow was also found to
be even lower for only one first generation migrant was detected with individual-based assignment analysis. Restricted pollen
and seed dispersal as well as a recent decline in population size associated with habitat fragmentation may have contributed
to low levels of historical and contemporary gene flow, and resulted in a high genetic differentiation. Under this scenario,
Berchemiella wilsonii var. pubipetiolata populations are expected to display more pronounced population genetic structure in the future as a result of increased inbreeding
and genetic drift. 相似文献
14.
Population fragmentation is often correlated with loss of genetic diversity and reduced fitness. Obligate out-crossing (dioecy)
is expected to enhance genetic diversity, reduce genetic differentiation, and avoid inbreeding depression through frequent
gene flow. However, in highly fragmented populations dioecy has only diminishing effects upon genetic structure as pollination
limitations (e.g. flight distance of pollinators) most often restrict inter-population gene flow in insect pollinated species.
In fragmented dry grasslands in northeastern Germany, we analysed genetic structure, fitness, and habitat quality of the endangered
dioecious Silene otites (Caryophyllaceae). Using AFLP markers, a high level of differentiation among ten populations was found (F
st = 0.36), while the intra-population genetic diversities (H
E = 0.165–0.240) were similar as compared to hermaphroditic species. There was neither a correlation between geographic and
genetic distance nor between genetic diversity and population size, which indicates reduced gene flow among populations and
random genetic drift. Plant size was positively correlated with genetic diversity. Seed set and number of juveniles were positively
related to population size. Higher total coverage resulted in reduced plant fitness, and the number of juveniles was negatively
correlated to cryptogam cover. Additionally, we found a sex ratio bias towards more male plants in larger populations. Overall,
our results indicate that on a regional geographic scale dioecy does not necessarily prevent genetic erosion in the case
of habitat fragmentation, especially in the absence of long distance seed and pollen dispersal capacity. 相似文献
15.
Bryophytes seem particularly suitable to investigate genetic diversity in relation to habitat disturbance due to their large
employment as bioindicators and to the recent application of molecular markers to moss population studies. Genetic variation
and structure were analysed in seven urban, extraurban and remote populations of Leptodon smithii, an epiphytic moss of Quercus ilex, a phanerogamic species of Mediterranean climax vegetation. A total of 210 individual shoots were DNA extracted and amplified
with internal simple sequence repeat (ISSR) primers, and 54 haplotypes were identified. An uneven distribution of haplotype
number and frequencies was observed among sites, with a higher number of haplotypes and more homogeneous haplotype frequencies
in the extraurban/remote populations. Molecular diversity indices were overall higher in the extraurban sites than in the
urban ones. Multilocus linkage disequilibrium values were in line with the occurrence of sexual/asexual reproduction in the
seven populations. The isolation-by-distance model was not supported by Mantel test among sites; however, within-population
fixation index (FST) highlighted a clear relation between genetic and physic distances among trees, suggesting a limited dispersal range for
L. smithii’s spores. The genetic structure was mainly affected by population size, wood structure and extent, and genetic drift consequent
to habitat fragmentation and human-induced disturbance. 相似文献
16.
Population history plays an important role in shaping contemporary levels of genetic variation and geographic structure. This is especially true in small, isolated range‐margin populations, where effects of inbreeding, genetic drift and gene flow may be more pronounced than in large continuous populations. Effects of landscape fragmentation and isolation distance may have implications for persistence of range‐margin populations if they are demographic sinks. We studied four small, disjunct populations of ponderosa pine over a 500‐year period. We coupled demographic data obtained through dendroecological methods with microsatellite data to discern how and when contemporary levels of allelic diversity, among and within‐population levels of differentiation, and geographic structure, arose. Alleles accumulated rapidly following initial colonization, demonstrating proportionally high levels of gene flow into the populations. At population sizes of approximately 100 individuals, allele accumulation saturated. Levels of genetic differentiation among populations (FST and Jost's Dest) and diversity within populations (FIS) remained stable through time. There was no evidence of geographic genetic structure at any time in the populations' history. Proportionally, high gene flow in the early stages of population growth resulted in rapid accumulation of alleles and quickly created relatively homogenous genetic patterns among populations. Our study demonstrates that contemporary levels of genetic diversity were formed quickly and early in population development. How contemporary genetic diversity accumulates over time is a key facet of understanding population growth and development. This is especially relevant given the extent and speed at which species ranges are predicted to shift in the coming century. 相似文献
17.
River network architecture,genetic effective size and distributional patterns predict differences in genetic structure across species in a dryland stream fish community 下载免费PDF全文
Tyler J. Pilger Keith B. Gido David L. Propst James E. Whitney Thomas F. Turner 《Molecular ecology》2017,26(10):2687-2697
Dendritic ecological network (DEN) architecture can be a strong predictor of spatial genetic patterns in theoretical and simulation studies. Yet, interspecific differences in dispersal capabilities and distribution within the network may equally affect species’ genetic structuring. We characterized patterns of genetic variation from up to ten microsatellite loci for nine numerically dominant members of the upper Gila River fish community, New Mexico, USA. Using comparative landscape genetics, we evaluated the role of network architecture for structuring populations within species (pairwise FST) while explicitly accounting for intraspecific demographic influences on effective population size (Ne). Five species exhibited patterns of connectivity and/or genetic diversity gradients that were predicted by network structure. These species were generally considered to be small‐bodied or habitat specialists. Spatial variation of Ne was a strong predictor of pairwise FST for two species, suggesting patterns of connectivity may also be influenced by genetic drift independent of network properties. Finally, two study species exhibited genetic patterns that were unexplained by network properties and appeared to be related to nonequilibrium processes. Properties of DENs shape community‐wide genetic structure but effects are modified by intrinsic traits and nonequilibrium processes. Further theoretical development of the DEN framework should account for such cases. 相似文献
18.
Many threatened species suffer reduced genetic diversity as a result of small population size and isolation. However, species
with a persistent seed bank may be buffered against genetic loss as seed banks are expected to accumulate the reproductive
output of many seasons. For fire-dependent species in decline, prescribed ecological burning may be a means to stimulate germination
and recover genetic diversity stored in the seed bank, providing a demographic and genetic rescue effect. Here we investigated
the effectiveness of this strategy in a small, isolated and inbred population of the endangered shrub, Acacia pinguifolia. We surveyed genetic diversity and structure of remnant populations of A. pinguifolia and monitored regeneration before and after burning. Germination was stimulated by fire, but seedling numbers 18 months post-fire
were low and barely above the number of adults killed by the fire. Genetic diversity was marginally higher in the post-fire
seedling cohort than the pre-fire adults (HE = 0.1 vs. 0.09, respectively). Outcrossing rates of open-pollinated seed from surrounding plants suggested moderately high
levels of self-fertilisation (t
m
= 0.65) and analysis of fine-scale genetic structure implied pollen and seed dispersal over distances of several metres,
suggesting that restricted gene flow and inbreeding may act to limit genetic diversity in the seed bank. We conclude that
prescribed burning has not been immediately successful as a recovery strategy for this relictual population of A. pinguifolia, though future monitoring may detect additional recruits. Alternative conservation strategies, including performing inter-population
crosses, may be required to restore genetic diversity and ameliorate extinction risks. 相似文献
19.
Consequences of multiple mating‐system shifts for population and range‐wide genetic structure in a coastal dune plant 下载免费PDF全文
Evolutionary transitions from outcrossing to selfing can strongly affect the genetic diversity and structure of species at multiple spatial scales. We investigated the genetic consequences of mating‐system shifts in the North American, Pacific coast dune endemic plant Camissoniopsis cheiranthifolia (Onagraceae) by assaying variation at 13 nuclear (n) and six chloroplast (cp) microsatellite (SSR) loci for 38 populations across the species range. As predicted from the expected reduction in effective population size (Ne) caused by selfing, small‐flowered, predominantly selfing (SF) populations had much lower nSSR diversity (but not cpSSR) than large‐flowered, predominantly outcrossing (LF) populations. The reduction in nSSR diversity was greater than expected from the effects of selfing on Ne alone, but could not be accounted for by indirect effects of selfing on population density. Although selfing should reduce gene flow, SF populations were not more genetically differentiated than LF populations. We detected five clusters of nSSR genotypes and three groups of cpSSR haplotypes across the species range consisting of parapatric groups of populations that usually (but not always) differed in mating system, suggesting that selfing may often initiate ecogeographic isolation. However, lineage‐wide genetic variation was not lower for selfing clusters, failing to support the hypothesis that selection for reproductive assurance spurred the evolution of selfing in this species. Within three populations where LF and SF plants coexist, we detected genetic differentiation among diverged floral phenotypes suggesting that reproductive isolation (probably postzygotic) may help maintain the striking mating‐system differentiation observed across the range of this species. 相似文献
20.
Sylvain Ursenbacher Caren Alvarez Georg F. J. Armbruster Bruno Baur 《Conservation Genetics》2010,11(4):1265-1271
Understanding patterns of genetic structure is fundamental for developing successful management programmes for isolated populations
of threatened species. Trochulus caelatus is a small terrestrial snail endemic to calcareous rock cliffs in the Northwestern Swiss Jura Mountains. Eight microsatellite
loci were used to assess the effect of habitat isolation on genetic population structure and gene flow among nine populations
occurring on distinct cliffs. We found a high genetic differentiation among populations (mean F
ST = 0.254) indicating that the populations are strongly isolated. Both allelic richness and effective population size were
positively correlated with the size of the cliffs. Our findings support the hypothesis that T. caelatus survived on ice-free cliffs during the Pleistocene glacier advancements from the Alps. Due to the establishment of beech
and pine forest under recent, temperate climate conditions, dispersal between cliffs is no longer possible for rock-dwelling
snails such as T. caelatus. Our results provide basic data for developing a conservation action plan for this endangered gastropod species. 相似文献