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1.
Deborah A. Randall John P. Pollinger Kifle Argaw David W. Macdonald Robert K. Wayne 《Conservation Genetics》2010,11(1):89-101
We used demographic, spatial, and microsatellite data to assess fine-scale genetic structure in Ethiopian wolves found in
the Bale Mountains and evaluated the impact of historical versus recent demographic processes on genetic variation. We applied
several analytical methods, assuming equilibrium and nonequilibrium conditions, to assess demography and genetic structure.
Genetic variation (H
E = 0.584–0.607, allelic richness = 4.2–4.3) was higher than previously reported for this species and genetic structure was
influenced by geography and social structure. Statistically significant F
ST values (0.06–0.08) implied differentiation among subpopulations. STRUCTURE analyses showed that neighbouring packs often
have shared co-ancestry and spatial autocorrelation showed higher genetic similarity between individuals within packs and
between individuals in neighbouring packs compared to random pairs of individuals. Recent effective population sizes were
lower than 2n (where n is the number of packs) and lower than the number of breeding individuals with N
e
/N ratios near 0.20. All subpopulations have experienced bottlenecks, one occurring due to a rabies outbreak in 2003. Nevertheless,
differentiation among these subpopulations is consistent with long-term migration rates and fragmentation at the end of the
Pleistocene. Enhanced drift due to population bottlenecks may be countered by higher migration into disease-affected subpopulations.
Contemporary factors such as social structure and population bottlenecks are clearly influencing the level and distribution
of genetic variation in this population, which has implications for its conservation. 相似文献
2.
Pondberry, Lindera melissifolia, is an endangered and partially clonally reproducing shrub species found in isolated populations that inhabit seasonally
wet depressions in forested areas of the lower Mississippi River alluvial valley and southeastern regions of the United States.
With eleven microsatellite loci, we quantified population genetic differentiation and diversity among 450 genets in 10 locations
distributed across pondberry’s range. We used estimates of F
st and Jost’s D
est to measure genetic differences between populations and between geographic regions. The largest pairwise regional difference
was found between eastern and western regional population groups (F
st = 0.23, D
est = 0.67), with the northern-most population groups in each region exhibiting larger divergence from each other than the southern-most
population groups. Genetic diversity was lowest in the Sand Pond Conservation Area (A
e = 1.9, H
e = 0.36), which was the northern-most pondberry population, and highest in the Francis Marion National Forest (A
e = 4.1, H
e = 0.69), although we identified only 17 genets in that admixed population. Following adjustments for estimated null allele
frequencies, we identified heterozygote excess in four eastern populations and found no evidence for inbreeding in any population.
The observed patterns of differentiation indicate a phylogeography that exhibits an Appalachian Mountain discontinuity coupled
with northward migrations along the Southern Atlantic Coastal Plain and into the Mississippi Alluvial Plain. The genetic consequences
of this proposed phylogeographical structure may affect selection of germplasm sources for population reestablishment programs
across pondberry’s range. 相似文献
3.
Yaisel Juan Borrell David Bernardo Gloria Blanco Emilia Vázquez José Antonio Sánchez 《Conservation Genetics》2008,9(4):807-819
Rivers in Asturias (northern Spain) constitute the southern limit of the distribution of Atlantic salmon (Salmo salar L.) in Europe, a biological resource facing one of the more serious challenges for conservation today. In this work, eight microsatellite
loci have been used to analyse samples collected in 1993 and 1999 from four Asturian rivers (Esva, Narcea, Sella, and Cares),
obtaining information about the temporal and the spatial genetic variation in these populations and, in addition, estimations
of their effective population sizes. The temporal analysis revealed a general decrease in all the estimated genetic variability
parameters when samples from 1993 (mean A
(1993) = 6.47, mean H
O(1993) = 0.472, mean H
E(1993) = 0.530) were compared with those obtained in 1999 (mean A
(1999) = 6.16, mean H
O(1999) = 0.460, mean H
E(1999) = 0.490). This reduction was particularly notable for the case of the Esva river. Our results pointed to a pattern of spatial
genetic differentiation inside the Asturian region (F
ST (1993) = 0.016 P < 0.01; F
ST (1999) = 0.023 P < 0.01). Using the standard Temporal Method we found estimates of N
e^
(Esva) = 75.1 (33.2–267.2); N
e^
(Cares) = 96.6 (40.0–507.5), N
e^
(Sella) = 106.5 (39.1–9396.4) and N
e^
(Narcea) = 113.9 (42.0–3693.3). The use of likelihood-based methods for the N
e^ estimations improved the results (smaller CIs) for the Esva and Cares rivers (N
e^
(Esva) = 63.9 (32.3–165.3); N
e^
(Cares) = 76.4 (38.8–202.0) using a Maximum likelihood approach) and suggested the presence of larger populations for the Sella and
Narcea rivers (N
e^≈200). These results showed that the Asturian Atlantic salmon populations (in particular Esva and Cares river populations)
could be close to the conservation genetic borderline for avoiding inbreeding depression although we discuss some implications
of the analysis of temporal genetic change in populations with overlapping generations. 相似文献
4.
J. V. Bryant D. Gottelli X. Zeng X. Hong B. P. L. Chan J. R. Fellowes Y. Zhang J. Luo C. Durrant T. Geissmann H. J. Chatterjee S. T. Turvey 《Molecular ecology》2016,25(15):3540-3556
Evidence‐based conservation planning is crucial for informing management decisions for species of extreme rarity, but collection of robust data on genetic status or other parameters can be extremely challenging for such species. The Hainan gibbon, possibly the world's rarest mammal, consists of a single population of ~25 individuals restricted to one protected area on Hainan Island, China, and has persisted for over 30 years at exceptionally low population size. Analysis of genotypes at 11 microsatellite loci from faecal samples for 36% of the current global population and tissue samples from 62% of existing historical museum specimens demonstrates limited current genetic diversity (Na = 2.27, Ar = 2.24, He = 0.43); diversity has declined since the 19th century and even further within the last 30 years, representing declines of ~30% from historical levels (Na = 3.36, Ar = 3.29, He = 0.63). Significant differentiation is seen between current and historical samples (FST = 0.156, P = 0.0315), and the current population exhibits extremely small Ne (current Ne = 2.16). There is evidence for both a recent population bottleneck and an earlier bottleneck, with population size already reasonably low by the late 19th century (historical Ne = 1162.96). Individuals in the current population are related at the level of half‐ to full‐siblings between social groups, and full‐siblings or parent–offspring within a social group, suggesting that inbreeding is likely to increase in the future. The species' current reduced genetic diversity must be considered during conservation planning, particularly for expectations of likely population recovery, indicating that intensive, carefully planned management is essential. 相似文献
5.
We tested the cross-amplification of 26 microsatellites developed for passerines and an additional three developed for Gallinula species in eight European Coots from two populations. Sixteen microsatellite markers successfully amplified, of which nine
were polymorphic with 2–6 alleles (mean 3.7 alleles) and an expected heterozygosity (H
e) ranging from 0.375 to 0.805 (mean H
e = 0.589). On average, we found 2.22 alleles/locus and a mean H
e of 0.440 in one nest, and 2.56 alleles/locus and a mean H
e of 0.494 in the other one. These nine polymorphic markers could be of potential use in studies of genetic variability, population
structure and reproductive strategy of European Coots. 相似文献
6.
Wesley K. Savage 《Conservation Genetics》2008,9(6):1707-1710
Habitat loss is the single greatest threat to persistence of the critically threatened California tiger salamander (Ambystoma californiense). To aid management plans that designate critical habitat for this species, I developed and characterized 21 tetranucleotide
microsatellite markers using two native populations in Santa Barbara and Alameda Counties. Allelic variation and average heterozygosities
were lower in the endangered Santa Barbara population (allele range 1–4, mean 2.4; H
O = 0.308 H
E = 0.288) compared with the threatened Alameda population (allele range 2–10, mean 6.7; H
O = 0.712, H
E = 0.722). In-depth population studies using these markers will provide vital information for plans to assign critical habitat
that optimize gene flow among breeding populations, as well as for identifying non-native hybrid genotypes that threaten native
A. californiense stocks. Beyond the conservation goals for A. californiense, the close phylogenetic relationships within the tiger salamander complex also suggest a broad utility for population studies
using these markers. 相似文献
7.
Daria Ezgeta-Balić Melita Peharda Christopher A. Richardson Marina Kuzmanić Nedo Vrgoč Igor Isajlović 《Helgoland Marine Research》2011,65(4):457-465
The age, growth, and population structure of the smooth clam Callista chione were determined from samples collected by hydraulic dredge and SCUBA at four locations in the eastern Adriatic during 2007
and 2008. The age of 436 clam shells was determined from internal growth lines present in shell sections, and the timing of
growth line formation was ascertained from monthly collections of clams to occur between August and September when sea water
temperatures were maximal. In addition, age of 30 older individuals was verified with acetate peels of polished and etched
shell sections. Differences were apparent in the age structure and growth rates of clams collected from the four locations
studied. Von Bertalanffy growth (VBG) curves obtained for clams from these locations were L
t
= 72.4 (1−e−0.25(t − 2.68)) (Rab Island), L
t
= 74.5 (1−e−0.15(t + 0.57)) (Pag Bay), L
t
= 79.3 (1−e−0.34(t − 0.97)) (Cetina estuary), and L
t
= 82.5 (1−e−0.11(t + 2.88)) (Kaštela Bay). The age of the clams ranged between 3 and 44 years; median clam ages were similar at three of the four locations
(14, 12, and 12 years, respectively), but was significantly lower in the Cetina estuary (4 years). The VBG growth constants
recorded from clams were within the range of values obtained for this species by previous authors. The observed local differences
in population structure indicate different levels of exploitation and illustrate the need to establish long-term strategies
for a sustainable exploitation of smooth clams in the Croatian Adriatic. 相似文献
8.
José F. Vázquez Trinidad Pérez Francisco Quirós José R. Obeso Jesús Albornoz Ana Domínguez 《The Journal of wildlife management》2012,76(5):957-965
The Cantabrian capercaillie (Tetrao urogallus cantabricus) occupies the southwestern edge of the grouse family distribution range in Eurasia. It is endemic to the Cantabrian Mountains in northwestern Spain and is geographically isolated and separated from the neighboring population in the Pyrenees by a distance of 300 km. Over the last decades, the population has undergone a dramatic decline and is now threatened with extinction. This study presents the genetic analysis of the Cantabrian capercaillie population using non-invasive samples. We performed genotyping of 45 individuals using 20 microsatellites and a sex marker. The data highlight the need for using a large number of markers when considering fragmented small populations. Genetic diversity (HE = 0.50) and average number of alleles (3.40) in the population were low. The population is fragmented into 2 clusters (FST = 0.113) that fit with areas on both sides of the transportation ways that divide its range. Both clusters exhibited additional heterozygote deficits. Geographical distance was negatively correlated with genetic relatedness (r = −0.44, P ≤ 0.001). The data show a recent decline in effective population size that can be related to an ongoing process of population reduction and fragmentation. Conservation actions should focus on the protection of local demes by maintaining a dense network of suitable patches to maximize reproductive output and the number of potential dispersers to reconnect the 2 subpopulations. © 2012 The Wildlife Society. 相似文献
9.
Endangered species worldwide exist in remnant populations, often within fragmented landscapes. Although assessment of genetic
diversity in fragmented habitats is very important for conservation purposes, it is usually impossible to evaluate the amount
of diversity that has actually been lost. Here, we compared population structure and levels of genetic diversity within populations
of spotted suslik Spermophilus suslicus, inhabiting two different parts of the species range characterized by different levels of habitat connectivity. We used microsatellites
to analyze 10 critically endangered populations located at the western part of the range, where suslik habitat have been severely
devastated due to agriculture industrialization. Their genetic composition was compared with four populations from the eastern
part of the range where the species still occupies habitat with reasonable levels of connectivity. In the western region,
we detected extreme population structure (F
ST = 0.20) and levels of genetic diversity (Allelic richness ranged from 1.45 to 3.07) characteristic for highly endangered
populations. Alternatively, in the eastern region we found significantly higher allelic richness (from 5.09 to 5.81) and insignificant
population structure (F
ST = 0.03). As we identified a strong correlation between genetic and geographic distance and a lack of private alleles in the
western region, we conclude that extreme population structure and lower genetic diversity is due to recent habitat loss. Results
from this study provide guidelines for conservation and management of this highly endangered species. 相似文献
10.
V. V. Efremov 《Russian Journal of Genetics》2005,41(5):548-552
The effect of subdivision on the effective size (N
e) of the early-run sockeye salmon Oncorhynchus nerka population of Lake Azabach’e (Kamchatka Peninsula) has been studied. The mode of this effect is determined by the relative productivity of the subpopulations and its magnitude, by the rate of individual migration among subpopulations and genetic differentiation. If the contributions of subpopulations (offspring numbers) are different, genetic differentiation can reduce the N
e of the subdivided population. At equal subpopulation contributions, genetic differentiation always increases the N
e of the subdivided population in comparison with a panmictic population. We have found that all sockeye salmon subpopulations of Azabach’e Lake produce equal offspring numbers contributing to the next generation. The genetic differentiation between sockeye salmon subpopulations is low, and the subdivision increases the N
e of the early-run race with reference to the sum of the effective sizes of the subpopulations by as little as 2%.__________Translated from Genetika, Vol. 41, No. 5, 2005, pp. 680–685.Original Russian Text Copyright © 2005 by Efremov. 相似文献
11.
Population subdivision due to habitat loss and modification, exploitation of wild populations and altered spatial population
dynamics is of increasing concern in nature. Detecting population fragmentation is therefore crucial for conservation management.
Using computer simulations, we show that a single sample estimator of N
e based on linkage disequilibrium is a highly sensitive and promising indicator of recent population fragmentation and bottlenecks,
even with some continued gene flow. For example, fragmentation of a panmictic population of N
e = 1,000 into demes of N
e = 100 can be detected with high probability after a single generation when estimates from this method are compared to prefragmentation
estimates, given data for ~20 microsatellite loci in samples of 50 individuals. We consider a range of loci (10–40) and individuals
(25–100) typical of current studies of natural populations and show that increasing the number of loci gives nearly the same
increase in precision as increasing the number of individuals sampled. We also evaluated effects of incomplete fragmentation
and found this N
e-reduction signal is still apparent in the presence of considerable migration (m ~ 0.10–0.25). Single-sample genetic estimates of N
e thus show considerable promise for early detection of population fragmentation and decline. 相似文献
12.
Kiyoshi Ishida 《Ecological Research》2008,23(6):995-1003
Inbreeding depression is one of the major selective forces driving the evolution of mating systems. Previous theories predict
that long-lived plants will show a negative correlation between inbreeding depression and the level of inbreeding (as determined
by an inbreeding coefficient) at maturity, but the extent of this correlation may vary among life stages because of variation
in the genetic basis for inbreeding depression at different stages. To test this prediction, I used electrophoretic allozyme
analysis and pollination experiments to examine the fixation index (F
is) at maturity and inbreeding depression in the early and late life stages of two populations with different outcrossing rates
of a highly self-fertilizing tree, Magnolia obovata. The magnitude of inbreeding depression for early survival (δ
e) in an outcrossing population (t
m = 0.51; F
is = −0.015) was higher (δ
e = 0.97) than that in an inbreeding population (t
m = 0.18; F
is = 0.15; δ
e = 0.38). From these results, I estimated that both populations exhibited high inbreeding depression for late survival (δ
l) (0.94 in the outcrossing population and 0.93 in the inbreeding one) and lifetime survival (δ
t) (0.99 and 0.96, respectively). My results and previously published data demonstrate the predicted relationship between inbreeding
depression and the level of inbreeding for early survival, but not for late survival. This suggests that there is a differential
genetic basis for inbreeding depression at different life stages. The inbreeding depression for late survival appears to play
a central role in the maintenance of reproductive traits that promote outcrossing in M. obovata. 相似文献
13.
Effect of the Aegean Sea barrier between Europe and Asia on differentiation in Juniperus drupacea (Cupressaceae)
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Karolina Sobierajska Krystyna Boratyńska Anna Jasińska Monika Dering Tolga Ok Bouchra Douaihy Magda Bou Dagher‐Kharrat Ángel Romo Adam Boratyński 《Botanical journal of the Linnean Society. Linnean Society of London》2016,180(3):365-385
Juniperus drupacea is an eastern Mediterranean mountain tree with a disjunct geographical range. We hypothesized that this disjunct occurrence (the Peloponnese in Europe and the Taurus and Lebanon Mountains in Asia) should be reflected in the patterns of genetic and morphological diversity and differentiation. Nuclear microsatellite markers (nSSR) and biometric variables of the cones and seeds were examined on material sampled from four populations in Europe and eight in Asia. The Asian populations were characterized by a higher level of genetic diversity than the European populations. The genetic differentiation among populations was moderate but significant (FST = 0.101, P < 0.001). According to the clustering performed with BAPS, six genetically and geographically groups of populations were found: I and II from the Peloponnese; III from the Taurus Mountains; IV and V from the Anti‐Taurus Mountains; and VI from the Lebanon Mountains. The level of genetic differentiation among these six groups (4.30%, P = 0.012) probably reflects long‐lasting genetic isolation during the Pleistocene, as limited genetic admixture was found. In accordance with genetic analysis, the biometric investigations indicated a high level of morphological divergence between the European and Asian populations of the species, with further differentiation between the populations from the Taurus and Lebanon Mountains. 相似文献
14.
José G. García-Franco Valeria Souza Luis E. Eguiarte Victor Rico-Gray 《Plant Systematics and Evolution》1998,210(3-4):271-288
The genetic population structure inBdallophyton bambusarum, an endoparasite, was studied in ten subpopulations from a subdeciduous tropical forest in Veracruz Mexico. The sample was analyzed using seven polymorphic loci in cellulose acetate electrophoresis. Isozyme data indicated that the subpopulations ofB. bambusarum contained high genetic variability (Hep = 0.452 ± 0.045, S.E.). Our analysis suggests that almost each inflorescence ofB. bambusarum is an individual. The subpopulations studied were genetically similar (average Nei's genetic identity 0.941 ± 0.051 and F
st
values 0.097 ± 0.026), suggesting that genetic differentiation among subpopulations was small. Direct estimates of effective population size was derived from observations of three fluorescent dyes, and from the genetic neighborhood area derived from these data. The neighborhood area, multiplied by the total density of individuals, gave an Ne = 124.84 plants, and when corrected to consider the proportion of males and females gave an Ne = 118.59 individuals. An indirect estimate of Nm was obtained from the F
st
values (mean Nm=2.037), giving an indirect estimate of the effective population size Nb = 12.8 individuals. Both values are relatively high when compared to other plant studies. The gene flow and/or effective populations size of the studied subpopulations ofB. bambusarum are believed to be large enough to prevent differentiation among subpopulations due to genetic drift. 相似文献
15.
《Mammalian Biology》2014,79(4):268-276
The Balkans are one of the last large refugia for brown bear (Ursus arctos) populations in Europe, and Bulgaria, in particular, contains relatively large areas of suitable brown bear habitat and a potential population of more than 600 individuals. Despite this, the majority of brown bear research remains focused on bear populations in Central and Western Europe. We provide the first assessment of genetic population structure of brown bears in Bulgaria by analysing tissue samples (n = 16) as well as samples collected with noninvasive genetic methods, including hair and faecal samples (n = 189 and n = 163, respectively). Sequence analysis of a 248 base pair fragment of the mitochondrial control region showed that two highly divergent mitochondrial European brown bear lineages form a contact zone in central Bulgaria. Furthermore, the analysis of 13 polymorphic microsatellite markers identified 136 individuals and found substantial genetic variability (He = 0.74; NA = 8.9). The combination of both genetic markers revealed the presence of weak genetic substructure in the study area with considerable degrees of genetic admixture and the likely presence of migration corridors between the two subpopulation in the Rhodope Mountains and Stara Planina as evidenced from the genetic detection of two male long-distance dispersers. A detailed assessment from densely collected samples in the Rhodope Mountains resulted in a population size estimate of 315 (95% CI = 206–334) individuals, indicating that not all available habitat is presently occupied by bears in this region. Efficient management plans should focus on preserving connectivity of suitable habitats in order to maintain gene flow between the two Bulgarian brown bear subpopulations. 相似文献
16.
Joerns Fickel Oleg A. Bubliy Anja Stache Tanja Noventa Adam Jirsa Marco Heurich 《Mammalian Biology》2012,77(3):211-220
Anthropogenic impact such as overhunting and habitat fragmentation has reduced the total red deer population (Cervus elaphus) across Europe. In Germany remaining subpopulations are even confined to designated areas with limited or no gene flow among them. Red deer populations inhabiting the Bavarian–Bohemian forest ecosystem had been divided by a fortified State border between Germany and former Czechoslovakia. To assess red deer genetic diversity more than two decades after the removal of the fortifications, we analysed a population from the Bavarian Forest National Park, Germany, and one from the National Park ?umava, Czech Republic, using 11 microsatellite loci and a 910 bp long section of the mitochondrial control region (mtDNA). Bayesian analyses of microsatellite allele frequencies favoured the presence of a single population in the Bavarian-Bohemian forest ecosystem over other population genetic structures. This admixture was supported by a lack of population pairwise differentiation between German and Czech red deer microsatellite genotypes in the analysis of molecular variance (AMOVA, FST = 0.009, p = 0.383). Contrastingly, AMOVA revealed a highly significant matrilinear differentiation of mtDNA between the two samples (ΦST = 0.285, p = 0.002), whereby German red deer belonged predominantly to haplogroup A (western Europe) and Czech red deer predominantly to haplogroup C (eastern Europe). In combination, these findings indicated a high degree of philopatry by does and extensive gene flow across the former border mediated by stags. They also identified the Bavarian–Bohemian forest ecosystem as part of a suture zone between western and eastern European red deer matrilines. 相似文献
17.
The Baekdudaegan, a mountain range that runs north to south along the Korean Peninsula, has been suggested to harbor important glacial refugia for boreal and temperate plant species. A series of allozyme-based genetic studies supports this trend. A large effective population size (Ne) is suggested as one of major factors contributing to maintaining moderate or high levels of within-population genetic variation in these plant species. To test this hypothesis, we examined the levels and patterns of allozyme diversity, tested recent bottlenecks, and estimated recent migration rates in 10 subpopulations (collected within a distance of ca. 640 m) of the boreal Lilium cernuum at Mt. Deokhang, in the central part of the Baekdudaegan. We found high levels of within-population genetic variation as well as a low between-population genetic differentiation (He = 0.206 and FST = 0.019). Based on the FST estimate and mean recent migration rate, we approximately calculated a total effective population size of 508 across 10 subpopulations. Consistent with this, we found no evidence of recent bottlenecks in the subpopulations. This study reveals that subpopulations of L. cernuum at Mt. Deokhang are effectively large (on the order of hundreds), and that high levels of gene flow occur among them, probably due to the species' high potential for seed dispersal. These demographic and life-history traits, coupled with its high levels of genetic diversity, suggests that this cold-adapted species would have found large refugial areas in these mountains (i.e., macrorefugia) during the Last Glacial Maximum. 相似文献
18.
Delphinium staphisagria is an endemic annual or biennial herb from the Mediterranean Basin, widely distributed in isolated populations of variable
size. We evaluated the allozyme diversity of 31 populations along its distribution range via starch gel electrophoresis, assaying
12 enzyme systems and scoring 17 loci. The low levels of genetic variability detected (A = 11.8, A
p = 1.6, H
o = 0.026, H
e = 0.057), are discussed in relation to the life-history traits of the species, such as short life-span, selfing or gravity
seed dispersion. Other factors influencing genetic diversity, such as evolutionary history and spreading are also considered.
Due to its historical medicinal uses, this plant has probably become widespread in the Mediterranean area. Human-mediated
distribution could have promoted few migrant genotypes, recent founder events and long distance dispersal. These events would
explain the genetic homogeneity found within and among populations, as well as the absence of a clear biogeographic structure.
The limited genetic variability, the high genetic similarity among populations and the dysploidy of this species make it worthy
of conservation. Management strategies are proposed mainly to preserve its genetic pool. 相似文献
19.
Distribution of mating‐type alleles and genetic variability in field populations of Leptosphaeria maculans in western Canada
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Zhongwei Zou Xuehua Zhang Wannakuwattewaduge Gerard Dilantha Fernando 《Journal of Phytopathology》2018,166(6):438-447
Leptosphaeria maculans is the most important fungal pathogen of canola (Brassica napus, oilseed rape) that causes the devastating stem canker in canola fields of western Canada. The population genetic structure of L. maculans, represented by nine subpopulations from a 6‐year period and three different provinces in western Canada, was determined using ten minisatellite markers. Isolates collected at different locations in six consecutive years had an even distribution of MAT1‐1 and MAT1‐2 across the nine subpopulations. All subpopulations of L. maculans exhibited a moderate gene diversity (H = 0.356–0.585). The majority of the genetic variation occurred within subpopulations. Approximately 8% and 4% of the variations were distributed between sampling year and location, respectively. Genetic distance (FST) results, using analysis of molecular variation (AMOVA), indicated that subpopulation pairing within isolates by year ranged from FST = 0.010 to 0.109, and the location subpopulation ranged from FST = 0.038 to 0.085. Bayesian clustering analyses of multiloci inferred two distinct clusters in all the subpopulations examined. This study indicates a relatively high degree of gene exchange between the different L. maculans isolates. Our results suggest that this can occur in the wide growing areas of canola fields in western Canada. This gene exchange produced different gene allele frequencies and divergence between populations. 相似文献
20.
The Utah prairie dog (Cynomys parvidens), listed as threatened under the United States Endangered Species Act, was the subject of an extensive eradication program throughout its range during the 20th century. Eradication campaigns, habitat destruction/fragmentation/conversion, and epizootic outbreaks (e.g., sylvatic plague) have reduced prairie dog numbers from an estimated 95,000 individuals in the 1920s to approximately 14,000 (estimated adult spring count) today. As a result of these anthropogenic actions, the species is now found in small isolated sets of subpopulations. We characterized the levels of genetic diversity and population genetic structure using 10 neutral nuclear microsatellite loci for twelve populations (native and transplanted) representative of the three management designated “recovery units,” found in three distinct biogeographic regions, sampled across the species' range. The results indicate (1) low levels of genetic diversity within colonies (He = 0.109–0.357; Ho = 0.106‐ 0.313), (2) high levels of genetic differentiation among colonies (global FST = 0.296), (3) very small genetic effective population sizes, and (4) evidence of genetic bottlenecks. The genetic data reveal additional subdivision such that colonies within recovery units do not form single genotype clusters consistent with recovery unit boundaries. Genotype cluster membership support historical gene flow among colonies in the easternmost West Desert Recovery Unit with the westernmost Pausaugunt colonies and among the eastern Pausaugunt colonies and the Awapa Recovery unit to the north. In order to maintain the long‐term viability of the species, there needs to be an increased focus on maintaining suitable habitat between groups of existing populations that can act as connective corridors. The location of future translocation sites should be located in areas that will maximize connectivity, leading to maintenance of genetic variation and evolutionary potential. 相似文献