Genetic diversity and differentiation in six species of the genus Rhinanthus (Orobanchaceae)

The intricate genus Rhinanthus L. contains many taxonomically unresolved taxa. The assessment of genetic diversity may clarify the differentiation and taxonomic relationships between species and help to determine their mating system, which is important for understanding the future prospects of populations and species. Isozymes were used to assess the mating system, genetic diversity, and differentiation in R. rumelicus, R. osiliensis, R. wagneri, R. alectorolophus, and R. angustifolius from sect. Cleistolemus and R. minor from sect. Rhinanthus. Genetic diversity at species level was found to be higher in widespread R. angustifolius and R. rumelicus compared with insular endemic R. osiliensis. Positive inbreeding coefficient revealed dominant inbreeding in endemic R. osiliensis and R. wagneri. We also detected a significant departure from Hardy–Weinberg equilibrium in some populations of R. rumelicus and R. angustifolius. The common R. alectorolophus and R. minor and several populations of R. rumelicus and R. angustifolius displayed a mixed mating mode. Six studied species divided into three distinct clusters. Rhinanthus alectorolophus was the most differentiated taxon among the investigated species. The species of sect. Cleistolemus formed two distinct groups. The first cluster consisted only of R. alectorolophus while another comprised R. rumelicus, R. osiliensis, R. wagneri, and R. angustifolius, indicating their close affinity. Thus, our isozyme results call into question the monophyly of section Cleistolemus and the taxonomic position of R. alectorolophus.     

Rhinanthus plants found in calcareous fens on Gotland (Sweden): Are they related to Rhinanthus osiliensis from Saaremaa (Estonia)?

Rhinanthus osiliensis is a narrow endemic growing in calcareous spring fens on the island Saaremaa, Estonia. Plants very similar to R. osiliensis have been found in Sweden on the island of Gotland. Fifteen microsatellite markers were used to characterize genetic variation within R. osiliensis and the unknown taxon from Gotland. Results were compared with common Rhinanthus minor and Rhinanthus angstifolius. Our results showed that genetic diversity was remarkably lower in the Rhinanthus sp. from Gotland compared to Estonian endemic R. osiliensis. The microsatellite loci we used distinguished four studied species. In total, 46 species-specific alleles were found. The Neighbor-Joining dendrogram based on Nei's genetic distances, the Bayesian clustering analysis and the principle coordinate analysis showed that R. osiliensis and Rhinanthus sp. from Gotland are genetically differentiated and could not be the same species. In addition, endemic R. osiliensis was closer to widespread R. angustifolius. Further genetic comparison between unknown Rhinanthus sp. and local R. angustifolius and R. minor from Gotland is necessary for determine the species status and checking the possible alternative hypothesis about the origin of the unclear taxon.     

Population genetic diversity and species relationships in the genus Rhinanthus L. based on microsatellite markers

The genus Rhinanthus L. is complex, containing many taxonomically unresolved taxa. In this paper we studied genetic variation and species relationships in 15 populations of six Rhinanthus species from three sections. For this purpose, we developed new microsatellite primers for R. osiliensis and used them to investigate genetic variation in two narrow endemics (R. osiliensis, R. javorkae) and in four widespread species (R. rumelicus R. wagneri, R. angustifolius and R. minor). Species‐specific private alleles were found in all species except R. osiliensis and R. angustifolius. The Bulgarian endemic R. javorkae showed the lowest genetic variation, followed by widespread R. minor and Estonian endemic R. osiliensis. Rhinanthus javorkae and R. minor were genetically most differentiated. Section Cleistolemus is weakly structured genetically, indicating close affinity between R. osiliensis, R. rumelicus, R. wagneri and R. angustifolius.     

Population genetics of <Emphasis Type="Italic">Penstemon albomarginatus</Emphasis> (Plantaginaceae), a rare Mojave Desert species of conservation concern

Penstemon albomarginatus is a psammophytic endemic of the Mojave Desert, found only in deep sand and dune habitats of San Bernardino County, California, Mohave County, Arizona, and Clark and Nye Counties in Nevada. We used six microsatellite loci to assess genetic differentiation and diversity for 228 individuals across the 12 known populations of this rare species. A slight heterozygote deficiency was found in two populations, but most populations show no signs of inbreeding. Results show a geographic pattern of northern populations being more closely related to one another compared to all other geographic regions. Genetic diversity was greatest in the southern populations, with decreasing amounts of diversity observed with latitude. In general, the geographic pattern of genetic diversity among all populations suggests a post-glacial dispersal from south-to-north. Our results are discussed in the framework of anthropogenic pressures on deep sand habitats of the Mojave Desert.     

Patterns of Genetic Variation across Altitude in Three Plant Species of Semi-Dry Grasslands

Background

Environmental gradients caused by altitudinal gradients may affect genetic variation within and among plant populations and inbreeding within populations. Populations in the upper range periphery of a species may be important source populations for range shifts to higher altitude in response to climate change. In this study we investigate patterns of population genetic variation at upper peripheral and lower more central altitudes in three common plant species of semi-dry grasslands in montane landscapes.

Methodology/Principal Findings

In Briza media, Trifolium montanum and Ranunculus bulbosus genetic diversity, inbreeding and genetic relatedness of individuals within populations and genetic differentiation among populations was characterized using AFLP markers. Populations were sampled in the Swiss Alps at 1800 (upper periphery of the study organisms) and at 1200 m a.s.l. Genetic diversity was not affected by altitude and only in B. media inbreeding was greater at higher altitudes. Genetic differentiation was slightly greater among populations at higher altitudes in B. media and individuals within populations were more related to each other compared to individuals in lower altitude populations. A similar but less strong pattern of differentiation and relatedness was observed in T. montanum, while in R. bulbosus there was no effect of altitude. Estimations of population size and isolation of populations were similar, both at higher and lower altitudes.

Conclusions/Significance

Our results suggest that altitude does not affect genetic diversity in the grassland species under study. Genetic differentiation of populations increased only slightly at higher elevation, probably due to extensive (historic) gene flow among altitudes. Potentially pre-adapted genes might therefore spread easily across altitudes. Our study indicates that populations at the upper periphery are not genetically depauperate or isolated and thus may be important source populations for migration under climate change.     

Microsatellite variation and structure of 28 populations of the common wetland plant, Lychnis flos-cuculi L., in a fragmented landscape

Habitat fragmentation is known to cause genetic differentiation between small populations of rare species and decrease genetic variation within such populations. However, common species with recently fragmented populations have rarely been studied in this context. We investigated genetic variation and its relationship to population size and geographical isolation of populations of the common plant species, Lychnis flos-cuculi L., in fragmented fen grasslands. We analysed 467 plants from 28 L. flos-cuculi populations of different sizes (60 000-54 000 flowering individuals) in northeastern Switzerland using seven polymorphic microsatellite loci. Genetic differentiation between populations is small (F(ST) = 0.022; amova; P < 0.001), suggesting that gene flow among populations is still high or that habitat fragmentation is too recent to result in pronounced differentiation. Observed heterozygosity (H(O) = 0.44) significantly deviates from Hardy-Weinberg equilibrium, and within-population inbreeding coefficient F(IS) is high (0.30-0.59), indicating a mixed mating breeding system with substantial inbreeding in L. flos-cuculi. Gene diversity is the only measure of genetic variation which decreased with decreasing population size (R = 0.42; P < 0.05). While our results do not indicate pronounced effects of habitat fragmentation on genetic variation in the still common L. flos-cuculi, the lower gene diversity of smaller populations suggests that the species is not entirely unaffected.     

Divergent selection along climatic gradients in a rare central European endemic species,Saxifraga sponhemica

Background and Aims The effects of habitat fragmentation on quantitative genetic variation in plant populations are still poorly known. Saxifraga sponhemica is a rare endemic of Central Europe with a disjunct distribution, and a stable and specialized habitat of treeless screes and cliffs. This study therefore used S. sponhemica as a model species to compare quantitative and molecular variation in order to explore (1) the relative importance of drift and selection in shaping the distribution of quantitative genetic variation along climatic gradients; (2) the relationship between plant fitness, quantitative genetic variation, molecular genetic variation and population size; and (3) the relationship between the differentiation of a trait among populations and its evolvability.Methods Genetic variation within and among 22 populations from the whole distribution area of S. sponhemica was studied using RAPD (random amplified polymorphic DNA) markers, and climatic variables were obtained for each site. Seeds were collected from each population and germinated, and seedlings were transplanted into a common garden for determination of variation in plant traits.Key Results In contrast to previous results from rare plant species, strong evidence was found for divergent selection. Most population trait means of S. sponhemica were significantly related to climate gradients, indicating adaptation. Quantitative genetic differentiation increased with geographical distance, even when neutral molecular divergence was controlled for, and Q_ST exceeded F_ST for some traits. The evolvability of traits was negatively correlated with the degree of differentiation among populations (Q_ST), i.e. traits under strong selection showed little genetic variation within populations. The evolutionary potential of a population was not related to its size, the performance of the population or its neutral genetic diversity. However, performance in the common garden was lower for plants from populations with reduced molecular genetic variation, suggesting inbreeding depression due to genetic erosion.Conclusions The findings suggest that studies of molecular and quantitative genetic variation may provide complementary insights important for the conservation of rare species. The strong differentiation of quantitative traits among populations shows that selection can be an important force for structuring variation in evolutionarily important traits even for rare endemic species restricted to very specific habitats.     

Contemporary pollen-mediated gene immigration reflects the historical isolation of a rare,animal-pollinated shrub in a fragmented landscape

Fragmentation is generally considered to have negative impacts on widespread outbreeders but impacts on gene flow and diversity in patchy, naturally rare, self-compatible plant species remain unclear. We investigated diversity, gene flow and contemporary pollen-mediated gene immigration in the rare, narrowly distributed endemic shrub Calothamnus quadrifidus ssp. teretifolius. This taxon occurs in an internationally recognized biodiversity hotspot subjected to recent human-induced fragmentation and the condition of the remnants ranges from intact to highly degraded. Using microsatellites, we found that inbreeding, historically low gene flow and significant population differentiation have characterized the genetic system of C. quadrifidus ssp. teretifolius. Inbreeding arises from self-pollination, a small amount of biparental inbreeding and significant correlation of outcross paternity but fecundity was high suggesting populations might have purged their lethals. Paternity analyses show that pollinators can move pollen over degraded and intact habitat but populations in both intact and degraded remnants had few pollen parents per seed parent and low pollen immigration. Genetic diversity did not differ significantly between intact and degraded remnants but there were signs of genetic bottlenecks and reduced diversity in some degraded remnants. Overall, our study suggests human-induced fragmentation has not significantly changed the mating system, or pollen immigration to, remnant populations and therefore genetic connectivity need not be the highest conservation priority. Rather, for rare species adapted to higher levels of inbreeding, conservation efforts may be best directed to managing intact habitats and ecosystem processes.     

Differentiation among populations of the Rhodiola iremelica Boriss. (Grassulaceae) in the Southern Urals

Isoenzyme markers and polyacrylamide gel electrophoresis have been used to study the genetic structure of populations of Rhodiola iremelica Boriss. (Grassulaceae), a southern Ural endemic protected by the state and included in the Red Data Book of Bashkortostan Republic. A relatively large genetic variation at the species level has been found. The subdivision among populations (F _ST = 0.115) is higher than in most cross-pollination angiosperms. No consistent pattern has been observed in the spatial distribution of its genetic variation. The relatively high differentiation among samples of R. iremelica characterized by small effective population sizes, may be accounted for by genetic drift, inbreeding, and a restricted gene flow. To preserve the population gene pool, in situ protection of the species in nature is insufficient. It seems advisable to create synthetic populations ex situ and reintroduce them into nature.     

Low genetic diversity but local genetic differentiation in endemic Minasia (Asteraceae) species from Brazil

Espinhaço Range is a Brazilian chain of mountains, extremely rich in endemic species. Minasia has six species, all perennial herbs endemic to this range. Twenty-two populations were sampled from all Minasia species and assayed for allozyme variation. The species showed low genetic variation, compatible with the expectation for endemics. Genetic identities in Serra do Cipó and Diamantina were high, even between populations of different species. On the other hand M. cabralensis, from Serra do Cabral, was more differentiated from the other species. We also observed a marked genetic differentiation within M. cabralensis. Most strikingly, two close populations of this species showed very different allele frequencies. Our findings highlight the importance of local differentiation in campos rupestres. The observed genetic structure indicates that substantial portions of genetic diversity could be lost with the extinction of only one population, which is especially threatening considering the already low genetic diversity.     

Dwindling genetic diversity in European ground squirrels?

The European ground squirrel (Spermophilus citellus) is endangered and in decline. Populations are increasingly fragmented, and only a coordinated conservation effort at the European level may guarantee its long-term survival. To obtain a general population genetic picture on a larger geographic scale, we screened 117 individuals from seven local populations in Hungary, Romania, and Austria for allelic variation at eleven microsatellite loci. We found a high (23.4%) proportion of private alleles, and a moderate to somewhat elevated level (15.27%) of partitioning of genetic diversity among populations, compared to that found in many other terrestrial mammals. Genetic variability was significantly higher than in earlier studied Czech populations that are considered genetically depleted, but significantly lower than in undisturbed populations of S. suslicus and S. brunneus, that are similar to the European ground squirrel in their ecological requirements, reproductive biology, and social organization. Genetic diversity was also lower than in most presumably “undisturbed” populations of other Sciurid species. This, together with the observed level and pattern of genetic differentiation among populations, such as no significant increase of genetic differentiation with geographic distance and similar variance of genetic differentiation between populations independent of geographic distance, indicated the prevalence of relatively strong drift effects for all populations. A Bayesian STRUCTURE analysis and a factorial correspondence analysis concordantly revealed a fairly complex genetic composition of local populations, but no major geographic trend in the pattern of the genetic composition. Overall, the results suggest disintegration of local colonies that might earlier have been more connected genetically. The STRUCTURE analysis also suggested anthropogenic translocations among single Hungarian populations. Our data on genetic diversity and its distribution do not object to such conservation measures. Translocation of individuals particularly from nearby populations may increase the chances of survival of small and isolated populations and counteract inbreeding at low densities.     

High Genetic Differentiation of Hippophae rhamnoides ssp. yunnanensis (Elaeagnaceae), a Plant Endemic to the Qinghai-Tibet Plateau

RAPD markers were used to detect genetic diversity and population genetic differentiation of Hippophae rhamnoides ssp. yunnanensis, a sea buckthorn endemic to the Qinghai-Tibet plateau. The genetic parameters of percentage of polymorphic bands (92.86%), Nei’s gene diversity (h, 0.255), and Shannon’s index (I, 0.397) indicated high genetic diversity in this subspecies. The subpopulation differentiation suggested that 45.9% of genetic variation was among populations. High genetic differentiation among populations was also detected using AMOVA (47.02%). The main factors responsible for high genetic differentiation are probably related to natural geographic barriers among populations, gene drift, and limited gene flow caused by restricted pollen flow and seed flow. A Mantel test indicated that geographic distances were significantly correlated with genetic distances. The UPGMA phenogram based on Nei’s unbiased genetic distances and the result of three-dimensional model plots performed by principal coordinate analysis also supported the correlation. Altitude, however, did not have any clear effect on genetic differentiation.     

Genetic diversity and structure of the endangered species Megaleranthis saniculifolia in Korea as revealed by allozyme and ISSR markers

The genetic diversity and structure of 12 populations of Megaleranthis saniculifolia, a rare endemic Korean plant, were analyzed using 14 allozyme loci coding 10 enzymes and 78 ISSR loci using seven primers. The genetic diversity of M. saniculifolia at the species level was similar to that observed in out-crossing and long-lived perennials, while at the population level, it was significantly low. The high F _IS value of many populations as well as homozygote excess occurred relatively evenly in many populations in relation to the Hardy-Weinberg expectation, suggesting that inbreeding was occurring within the M. saniculifolia populations. The degree of genetic differentiation based on the two markers was high, and there was no correlation between geographic and genetic distance. Bayesian cluster analysis did not reveal any remarkable geographic trends. Positive correlations were observed between genetic diversity (H _e and h) and population size. Therefore, low genetic diversity within the population and high population differentiation of M. saniculifolia were closely related to the influence of genetic drift, particularly in highly isolated populations. In addition, the fixation of the main alleles at several loci in the opposite direction provided good evidence for genetic drift. The genetic diversity of M. saniculifolia could be compromised if the distribution area or the size of the population were further reduced. In particular, the isolated populations that are fragmented within an area could be at high risk of extinction due to accelerated inbreeding or genetic drift. Considering this, a close monitoring of the population size and of the changes in the genetic structure must be performed. Some practical measures for genetic conservation are also proposed.     

Genetic footprints of habitat fragmentation in the extant populations of Sinojackia (Styracaceae): implications for conservation

Sinojackia, a member of the family Styracaceae, is an endangered genus endemic to China. The number of populations and population size of Sinojackia have decreased sharply because of habitat fragmentation and destruction. We studied the genetic diversity of extant populations in two different cohorts (adult and seedling) using eight microsatellite markers to investigate the genetic footprints of habitat fragmentation in four recognized Sinojackia spp. and to develop appropriate conservation measures. Data on intrapopulational genetic diversity suggest that Sinojackia populations have maintained relatively high levels of genetic diversity and low levels of genetic differentiation despite severe fragmentation. The high genetic diversity may be explained by the outcrossing mating system and high longevity of Sinojackia spp. The amount of genetic variation is not associated with population size, which was also supported by bottleneck analysis. In the species studied, there was no significant difference in the genetic diversity between the two cohorts analysed. However, inbreeding increased from adult trees to seedling populations, suggesting that the higher proportion of biparental inbreeding in the recent generations of seedlings is the result of restricted current genetic flow caused by habitat fragmentation. Average seed set per population was not significantly correlated with either population size or genetic diversity. Conservation management should aim to monitor inbreeding and outbreeding depression carefully to ensure the in situ and ex situ conservation of Sinojackia spp. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, ?? , ??–??.     

The genetic signature of ecologically different grassland Lepidopterans

The level of genetic diversity found for species is strongly influenced by properties of the species’ ecology, abundance and behaviour (as dispersal). To address this coherence, we selected twenty-two grassland butterfly and burnet moth species, which were previously analysed by allozyme electrophoresis (using 15–25 loci per species) over a study area in western Germany with adjoining areas of Luxembourg and north-eastern France. For this study area, we calculated the species’ specific climatic niche breadths and derived various ecological parameters from literature and own field observations. The obtained parameters of genetic diversity (heterozygosity, number of alleles and percentage of polymorphic loci), genetic differentiation (D _est as well as F _ST and F _IS values as proxis for genetic differentiation among populations and inbreeding within populations), as well as ecological and climatic niche dimensions did not show significant differences among the different Lepidoptera families; therefore taxonomic assignment apparently has a negligible influence on the genetic structure of taxa. Genetic diversity and differentiation showed a significant correlation with the ecological and climatic niche-breadth of species in many cases: generalistic species with rather unspecific ecological characteristics and climatic niche had higher genetic diversities and tend to have lower differentiation and inbreeding, whereas specialist taxa (i.e. with narrow ecological and climatic niches) have lower genetic diversities and higher differentiation and inbreeding. The results might reflect contrasting population structures of specialist species with lower abundances compared with the more common generalists. The more restricted and isolated occurrence of specialists might consequence a reduction in genetic diversity and an increase in genetic differentiation among local populations. In contrast, generalists with unspecific habitat requirements occur in higher abundances and in consequence show a more homogenous genetic structure with higher diversities.     

Reintroduction of the endangered and endemic plant species Cochlearia bavarica—Implications from conservation genetics

Population reintroduction is a common practice in conservation, but often fails, also due to the effects of inbreeding or outbreeding depression. Cochlearia bavarica is a strongly endangered plant species endemic to Bavaria in Germany, constantly declining since the late 1980s. Therefore, population reintroduction is intended. In this study, we analyzed genetic diversity within and genetic differentiation between all 32 remnant populations of the species in Swabia and Upper Bavaria using amplified fragment length polymorphisms. Our aim was to increase reintroduction success by providing data to avoid negative effects of inbreeding and outbreeding and to preserve the natural genetic pattern of the species. Genetic diversity within populations was low but similar to other rare and endemic species and varied strongly between populations but did not depend on population size. Our analysis revealed a strong geographic pattern of genetic variation. Genetic differentiation was strongest between Swabia and Upper Bavaria and at the population level, whereas differentiation between subpopulations was comparatively low. Isolation by distance and genetic differentiation was stronger among populations from Upper Bavaria than from Swabia. From the results of our study, we derived recommendations for a successful reintroduction of the species. We suggest using rather genetically variable than large populations as reintroduction sources. Moreover, the exchange of plant material between Swabia and Upper Bavaria should be completely avoided. Within these regions, plant material from genetically similar populations should preferably be used for reintroduction, whereas the exchange among subpopulations seems to be possible without a negative impact on genetic variation due to natural gene flow.     

Genetic variability,management, and conservation implications of the critically endangered Brazilian pitviper Bothrops insularis

Information on demographic, genetic, and environmental parameters of wild and captive animal populations has proven to be crucial to conservation programs and strategies. Genetic approaches in conservation programs of Brazilian snakes remain scarce despite their importance for critically endangered species, such as Bothrops insularis, the golden lancehead, which is endemic to Ilha da Queimada Grande, coast of São Paulo State, Brazil. This study aims to (a) characterize the genetic diversity of ex situ and in situ populations of B. insularis using heterologous microsatellites; (b) investigate genetic structure among and within these populations; and (c) provide data for the conservation program of the species. Twelve informative microsatellites obtained from three species of the B. neuwiedi group were used to access genetic diversity indexes of ex situ and in situ populations. Low‐to‐medium genetic diversity parameters were found. Both populations showed low—albeit significant—values of system of mating inbreeding coefficient, whereas only the in situ population showed a significant value of pedigree inbreeding coefficient. Significant values of genetic differentiation indexes suggest a small differentiation between the two populations. Discriminant analysis of principal components (DAPC) recovered five clusters. No geographic relationship was found in the island, suggesting the occurrence of gene flow. Also, our data allowed the establishment of six preferential breeding couples, aiming to minimize inbreeding and elucidate uncertain parental relationships in the captive population. In a conservation perspective, continuous monitoring of both populations is demanded: it involves the incorporation of new individuals from the island into the captive population to avoid inbreeding and to achieve the recommended allelic similarity between the two populations. At last, we recommend that the genetic data support researches as a base to maintain a viable and healthy captive population, highly genetically similar to the in situ one, which is crucial for considering a reintroduction process into the island.     

Genetic diversity,sexual condition,and microhabitat preference determine mating patterns in Sphagnum (Sphagnaceae) peat‐mosses

In bryophytes, the possibility of intragametophytic selfing creates complex mating patterns that are not possible in seed plants, although relatively little is known about patterns of inbreeding in natural populations. In the peat‐moss genus Sphagnum, taxa are generally bisexual (gametophytes produce both sperm and egg) or unisexual (gametes produced by separate male and female plants). We sampled populations of 14 species, aiming to assess inbreeding variation and inbreeding depression in sporophytes, and to evaluate correlations between sexual expression, mating systems, and microhabitat preferences. We sampled maternal gametophytes and their attached sporophytes at 12–19 microsatellite loci. Bisexual species exhibited higher levels of inbreeding than unisexual species but did generally engage in some outcrossing. Inbreeding depression did not appear to be common in either unisexual or bisexual species. Genetic diversity was higher in populations of unisexual species compared to populations of bisexual species. We found a significant association between species microhabitat preference and population genetic diversity: species preferring hummocks (high above water table) had populations with lower diversity than species inhabiting hollows (at the water table). We also found a significant interaction between sexual condition, microhabitat preference, and inbreeding coefficients, suggesting a vital role for species ecology in determining mating patterns in Sphagnum populations. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115 , 96–113.     

Lack of congruence between morphometric evolution and genetic differentiation suggests a recent dispersal and local habitat adaptation of the Madeiran lizard Lacerta dugesii

Genetic differentiation among nine populations of the endemic lizard Lacerta dugesii Milne-Edwards 1829 (Lacertidae) from four groups of islands constituting the Archipelago of Madeira, was investigated by protein electrophoresis at 23 enzyme loci. Among twenty polymorphic loci, the total genetic diversity was due primarily to intra-population variation. The allele and genotypic frequencies among populations showed some heterogeneity, allowing the species to present a structuring pattern compatible with their geographical clustering. Some evidence suggests that selection acting on some loci in different ecological conditions may be responsible for the clustering of the populations studied. There was no apparent isolation effect expected under an "island" model of population divergence, and no correlation was found between genetic and geographic distances among populations. Morphological variation of the proposed three L. dugesii subspecies is not congruent with the allozyme analysis. This most probably suggests a rapid colonization of the islands followed by a strong effect of selection operating over the morphological characters used to define the subspecies.     

Genetic Variability and Population Structure of Disanthus cercidifolius subsp. longipes (Hamamelidaceae) Based on AFLP Analysis

Disanthus cercidifolius subsp. longipes is an endangered species in China. Genetic diversity and structure analysis of this species was investigated using amplified fragments length polymorphism (AFLP) fingerprinting. Nei''s gene diversity ranged from 0.1290 to 0.1394. The AMOVA indicated that 75.06% of variation was distributed within populations, while the between-group component 5.04% was smaller than the between populations-within-group component 19.90%. Significant genetic differentiation was detected between populations. Genetic and geographical distances were not correlated. PCA and genetic structure analysis showed that populations from East China were together with those of the Nanling Range. These patterns of genetic diversity and levels of genetic variation may be the result of D. c. subsp. longipes restricted to several isolated habitats and “excess flowers production, but little fruit set”. It is necessary to protect all existing populations of D. c. subsp. longipes in order to preserve as much genetic variation as possible.