Patterns of allozyme variation in Nordic Pilosella

Patterns of allozyme variation have been investigated in 101 clones representing most of the morphological variation (and taxa) found in the amphi-apomictic genus Pilosella Hill. in the Nordic countries. Levels of variation were very high, both within narrowly defined taxa and within the whole data-set, but the correlation between a morphology-based taxonomy and patterns of allozyme variation was very weak. Almost all enzyme bands were found in more than one taxon and the differences between broadly defined species in terms of the frequency of bands were generally small. Cluster analyses did not perfectly recover any taxon but there were some tendencies for samples of some broadly defined taxa (e.g. P. officinarum s. l., and P. cymosa ssp. cymosa) to cluster together. It is concluded that there is considerable gene-flow among virtually all Nordic morpho-types of Pilosella and this is considered an argument for applying a very broad species concept in this genus.Financial support for the present study has been recieved from Stiftelsen Harald E. Johanssons minnesfond at the Royal Swedish Academy of Sciences.     

Patterns of morphometric and allozyme variation in Aedes albopictus

A survey of microgeographic variation using morphometric and allozyme analyses was conducted on 19 US populations of Aedes albopictus (Skuse) (Diptera: Culicidae), a mosquito that was recently introduced into the US. There was considerable variation within and among populations both in morphometric traits and allele frequencies. A multivariate discriminant analysis enabled the separation of populations into distinct groups; separation among the populations in the morphometric analysis was incomplete with an average of 70% of the individuals being correctly classified. In the allozyme analysis, the discrimination was complete. The populations from Texas were placed close together in the morphometric analysis, whereas in the allozyme analysis a geographic clustering of populations could not be detected. A test of association between the distance matrices derived from the morphometric and allozyme analyses was statistically nonsignificant. The results are discussed in the context of the colonization of the US by A. albopictus. The possible factors underlying the differences in the patterns of variation derived from morphometric and allozyme analyses are also discussed.     

Allozyme variation and population differentiation of the Aconitum delavayi complex (Ranunculaceae) in the Hengduan Mountains of China

The Aconitum delavayi complex is a group of four climbing species with trisect-leaves occurring in the Hengduan Mountains. The species of this complex are highly localized on very narrow regions with quite small population sizes. Because of rapid environmental changes recently in the Hengduan Mountains, this complex shows complicated morphological variability, which makes it difficult to delimit species. In the present study, 10 enzyme systems coding for 14 putative loci were employed to detect the interspecific and intraspecific genetic variation of the complex. In addition to low genetic diversity within all eight populations surveyed, the results indicate that A. episcopale is a distinct species because of high genetic identities among its three populations. Very low genetic divergence among populations of A. stapfianum and A. delavayi suggests that the two species should be treated as a single one.     

Flavonoid variation of theAconitum jaluense complex (Ranunculaceae) in Korea

Thirteen flavonoid compounds were isolated and identified from five Korean species in theA. jaluense complex; they were glycosylated derivatives of the flavonols kaempferol, quercetin, and isorhamnetin, and of the flavone apigenin. The flavonoid data revealed the presence of two entities in the complex in Korea; one includesA. jaluense s. str. and the other includes the remaining four species which have identical flavonoid profiles. Based on these results, in conjunction with evidence from the morphology, it is suggested that the taxa should be recognized as two sub-species ofA. jaluense s. l. The flavonoid data also provide strong evidence for the occurrence of hybridization betweenA. jaluense s. str. andA. japonicum subsp.napiforme at Mt. Chiri in southern Korea.     

Reproductive morphology ofMegaleranthis saniculifolia Ohwi (Ranunculaceae) and its systematic implications

To confirm the taxonomic treatment ofMegaleranthis saniculifolia Ohwi, an endemic genus and species in Korea, we compared its reproductive morphological characteristics with those ofTrollius and other genera within the Ranunculaceae. Although its external morphology might suggest thatMegaleranthis differs fromTrollius, Calathodes, and etc., we found no distinctly different features in this genus. Likewise, previous studies of their pollen structures, chromosome data, and petal morphology have indicated no differences betweenMegaleranthis andTrollius. In fact, related genera share similar characteristics, such as a tetrasporangia anther, glandular tapetum, simultaneous cytokinesis, an anatropous and bitegmic ovule, embryo sac formation of thePolygonum type, exarillate and copious albuminous seed, and several apocarps. Although the unique feature of having both tenuinucellate and crassinucellate ovules simultaneously may initially seem particular toMegaleranthis, it is present in other genera of the same family. Therefore, based on this evidence of reproductive morphology and other information, we suggest thatM. saniculifolia is closely related toTrollius, and should be included within that genus, i.e., asT. chosenensis Ohwi. Nevertheless, we have tentatively placedMegaleranthis within its own monotypic and endemic genus until definitive data become available.     

Genetic variation, genetic structure and effective population size in the tropical holoparasitic endophyteBdallophyton bambusarum (Rafflesiaceae)

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 (H_ep = 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 N_e = 124.84 plants, and when corrected to consider the proportion of males and females gave an N_e = 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 N_b = 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.     

Genetic variation and population structure in Korean endemic species: III.Hosta minor (Liliaceae)

Hosta minor, an insect-pollinated and rhizomatous herbaceous perennial, occurs in eastern and southern Korean Peninsula. AlthoughH. minor is a Korean endemic species and most populations of the species are scattered, the species maintains considerably high levels of genetic variation within the species, with a moderate level of variation (14%) found among populations. Nineteen of the 29 putative loci resolved (66%) were polymorphic within the species, the mean number of alleles per locus was 2.10 across all populations and averaged 1.68 within populations. In addition, genetic diversity was a considerably higher (for species and population level, mean estimates of genetic diversity were 0.275 and 0.230, respectively) than the average for other long-lived herbaceous perennials. Indirect estimate of the number of migrants per generation (Nm=1.03, calculated from mean G_ST) was moderate. Factors contributing to the high levels of genetic diversity found within populations ofH. minor include population maintenance via sexual and asexual modes of reproduction, primarily outcrossing breeding system, long generation time, probable ancient polyploid origin of the species, and moderate levels of seed dispersal by wind. Human disturbance in South Korea such as road and apartment constructions appears to be the major threat to this genetically diverse species.     

Microsatellite variation within and among recently fragmented populations of the golden lion tamarin (Leontopithecus rosalia)

Four variable microsatellite loci were used toexamine the genetic diversity and differentiation of golden lion tamarins (Leontopithecus rosalia) in four populations recently isolated by habitat fragmentation. Using Rst estimates of genetic differentiation, a considerable genetic divergence was detected among these populations, with an averagedifferentiation of 31%. Significant differences in allele number among these populations were found. However, the heterozygosity among these populations was not statistically different. These results suggestthat loss in allele diversity was faster than loss in heterozygosity. Conservation implications, particularly for golden lion tamarins, are then discussed. Loss of allelic diversity might be as serious a concern to endangered species as heterozygosity or inbreeding.     

Distribution of allozyme variation inVicia benghalensis (Leguminosae) suggests the existence of two genepools

InVicia benghalensis two biotypes differing in biochemical and cytological features were identified in previous studies. It was hypothesized that these biotypes could also vary in reproductive behaviour and be genetically isolated. To better understand this issue, 25 distinct samples were studied using allozymes. Nine enzyme systems, accounting for 15 putative loci, were scored. The data obtained were analysed using population diversity parameters; Nei's genetic distance was calculated and used to construct a dendrogram. Principal component analysis was conducted to verify the dendrogram and to determine which alleles had stronger influence on the grouping of populations. The analyses demonstrated that the two previously identified biotypes are genetically different: Nei's distance between the two groups is larger than the distance within each group. Three-dimensional plotting of the first three principal components corroborates this division. Genetic diversity parameters confirm that the two biotypes also differ in outcrossing rates. These results denote the existence of two highly divergent genepools inV. benghalensis and suggest that a speciation process may be acting. The consequence of the present findings on the management of gene bank collections is analysed.     

Levels and patterns of genetic variation in the endangered species Abronia macrocarpa

Genetic variation was evaluated in the federally endangered species Abronia macrocarpa (large-fruited sand-verbena), an herbaceous perennial restricted to deep sandy soils and endemic to three counties of east-central Texas. Seven of the ten known populations were sampled and analyzed using starch gel electrophoresis of eight enzymes coded by 18 interpretable loci. Duplicate gene expression was observed for four loci, suggesting polyploid ancestry for the lineage that includes A. macrocarpa. Values for estimators of genetic polymorphism within populations (ranges: P = 38.9%-61.1%, A = 1.7-2.1, H = 0.122-0.279) exceeded average values for seed plants (P = 34.2%, A = 1.53, H = 0.113). Genotype proportions at most loci in most populations were in Hardy-Weinberg equilibrium, consistent with obligate outcrossing previously documented for this species; exceptions could be attributed to population substructure. Values of F(ST) tended to be high, ranging from 0.021 to 0.481 for individual loci (mean F(ST) = 0.272), indicating substantial divergence and limited gene flow among populations, despite their close geographic proximity. Pairwise values of Nei's genetic identity between populations ranged from 0.799 to 0.975 and tended to be influenced by geographic proximity of population pairs. Collectively, these data suggest a long history of isolation among populations that have not been subjected to bottlenecks. Isolation of A. macrocarpa populations apparently results from the disjunct occurrence of suitable habitat and perhaps has been accentuated by human disturbance.     

High levels of allozyme variation within populations and low allozyme divergence within and among species of Hemerocallis (Liliaceae)

Thirty populations from five species of Hemerocallis in Korea were analyzed by starch gel electrophoresis to measure genetic diversity and to determine genetic population structure and the amount of genetic divergence within and between species at 12 isozyme loci. In addition, Moran's I spatial autocorrelation statistics were used to examine the spatial distribution of allozyme polymorphisms in populations of H. thunbergii and H. hakuunensis. Populations of five Korean species maintain high levels of genetic variation and little differentiation among populations and species. Mean expected heterozygosities range from 0.165 in H. hongdoensis, an island endemic, to 0.265 in H. taeanensis, and a total of 81 alleles across the 12 loci were detected in the five species. G(ST) values for each of the five species were low, ranging from 0.051 in H. taeanensis to 0.078 in H. hakuunensis. Mean intraspecific Nei's genetic identities (I) between populations of the five species were all above 0.97. However, a considerable level of heterozygote deficiencies within populations was detected, ranging from 0.242 to 0.411 measured as F(IS) statistics. This deficiencies may be due to inbreeding, limited pollen and seed dispersal, or from the pooling of subpopulations that differ in allele frequencies. A small spatial scale population substructuring (<12 m) was found in H. thunbergii and H. hakuunensis. A group of populations from each of the five previously designated Hemerocallis species (based on their morphology, ecology, and phenology) agrees with our allozyme data, though pairwise comparisons among species had high I values (from 0.862, H. middendorffii vs. H. hongdoensis, to 0.969, H. thunbergii vs. H. taeanensis). This is attributed to the presence of the same high-frequency alleles in different species at seven loci. In addition, no "diagnostic allele" that appears in all populations of one species, but is absent in other species, was detected at the 12 isozyme loci. These all suggest that species of Hemerocallis in Korea may have recently derived from an ancestor or progenitor harboring high levels of genetic diversity.     

Mating system and genetic diversity of a rare desert legume Ammopiptanthus nanus (Leguminosae)

Ammopiptanthus nanus is an endangered evergreen shrub endemic to the deserts of central Asia and plays an important role in delaying further desertification. We examined allozyme variation and AFLP diversity in A. Nanus populations and investigated the mating system of this species using progeny arrays assayed for poly-morphic allozyme loci. Mating system analysis in the Keyi'eryongke'er population showed low levels of out-crossing, and strong inbreeding depression. Low levels of genetic variation were detected at both population (allozyme, Pp=14.0%,A=1.14, He=0.031; AFLP, Pp=14.5%, Shannon's information index I=0.063) and species (allozyme, Pp=21.1%,A=1.21, He=0.040; AFLP, Pp=20.9%, I=0.083) levels; while moderate genetic differentia-tion existed among populations, as indicated by allozymes (GST=0.081) and AFLP (GST=0.151-0.193). Founder effect, bottlenecks in evolutionary history, the mixed mating system and co-ancestry may have influenced the level of genetic diversity in A. Nanus. Markers of both types provide new insights for conservation management, indicating that the Biao'ertuokuoyi and Keyi'eryongke'er populations should be given priority for in situ conser-vation and regarded as seed sources for ex situ conservation.     

Comparison of genetic diversity between narrowly endemic shrub Menziesia goyozanensis and its widespread congener M. pentandra (Ericaceae)

Menziesia goyozanensis, a Japanese kindof fool's huckleberry, is a shrub speciesendemic only to Mt. Goyo in northern Japan.This species is listed as `criticallyendangered' in the Red Data Book of wild plantsin Japan, and only a single population has yetbeen discovered. The allozyme diversity andRAPD variation of Menziesia pentandrawere eight- and threefold greater than those ofM. goyozanensis, respectively, althoughwe examined only five populations representinga part of the distribution of M.pentandra. Because the environment surroundingthe population of M. goyoznaensis seemsto be stable at present, it is not necessary toplan an urgent ecological conservation practicefor the species. However, considering that thehabitat of M. goyozanensis is very smalland large vegetative disturbances occasionallyoccur in cool temperate forests, in which thespecies dwells, ex situ conservation isessential.     

Population Genetic structure ofPotentilla fragariodes var.major (Rosaceae) in Korea

The genetic diversity and population structure of eighteenPotentilla fragariodes var.major (Rosaceae) populations in Korea were determined using genetic variations at 22 allozyme loci. The percent of polymorphic loci within the enzymes was 66.7%. Genetic diversity at the species level and at the population level was high (Hes = 0.203; Hep = 0.185, respectively), whereas the extent of the population divergence was relatively low (G_ST = 0.069). F_IS, a measure of the deviation from random mating within the 18 populations, was 0.075. An indirect estimate of the number of migrants per generation (Nm = 3.36) indicated that gene flow was high among Korean populations of the species. In addition, analysis of fixation indices revealed a slight heterozygote deficiency in some populations and at some loci. Wide geographic ranges, perennial herbaceous nature and the persistence of multiple generations are associated with the high level of genetic variation. AlthoughP. fragariodes var.major usually propagated by asexually-produced ramets, we could not rule out the possibility that sexual reproduction occurred at a low rate because each ramet may produce terminal flowers. Mean genetic identity between populations was 0.983. It is highly probable that directional movement toward genetic uniformity in a relatively homogeneous habitat operates among Korean populations ofP. fragariodes var.major.     

Allozyme variation and population genetic structure of Betula alnoides from Guangxi,China

Allozyme variation and population genetic structure of Betula alnoides Buch. Ham. ex D. Don in 11 natural populations from Guangxi Zhuang Autonomous Region, China, were investigated by starch gel electrophoresis. Variation at 15 loci from 10 enzyme systems was analyzed. Allozyme analysis revealed a high level of genetic variation in this species, with percentage of polymorphic loci (P _p ), the average number of alleles per locus (A _p ), and the expected heterozygosity (H _ep ) being 55.2%, 2.0, and 0.204, respectively, which exceeds the average level among out-crossing wind-pollinated woody species at the population level. At the species level, P _s , A _s , and H _es were 60.0%, 2.67, and 0.206, respectively.The observed heterozygosity (H _op ) was higher than H _ep , indicating the existence of natural selection against homozygotes. The negative fixation index (F = –0.216) implied a significant excess of heterozygosity at the population level. Among-population differentiation (F _ST ) accounted for 4.0% of the total variation. No significant correlation was detected between the genetic distance and geographic distance among populations. Extensive gene flow was inferred, based on the allozyme data )N _m = 6.000 from F _ST , N _m = 5.605 from the private allele method). The results demonstrated that the fragmentation status of B. alnoides had no remarkable effects on the population genetic structure of this species. Some populations are recommended for both in situ genetic conservation and germplasm collection for breeding programs.     

Patterns of allozyme diversity in several selected rare species in Korea and implications for conservation

Because some endemic plants appear to be adapted to a narrow setof environmental conditions with limited genetic diversity, an analysis ofpopulation genetic structure is necessary to fully evaluate the impact of rarityon genetic variation. Listed as endangered species in Korea, only fewpopulations of Abeliophyllum distichum, Leonticemicrorhyncha, Bupleurum euphorbioides, andBerchemia berchmiaefolia were found. A reduced level ofgenetic variation in B. berchemiaefolia is consistent withthe occurrence of a genetic bottleneck and inbreeding. Leonticemicrorhyncha differed dramatically from other taxa in its observed level of geneticvariation, probably due to its predominant selfing. The level ofallozyme variation maintained by A. distichum was high forendemic species. Compared to species with similar traits, A.distichum maintained a relatively higher genetic diversity, probably dueto floral heteromorphism and preferred outcrossing. Bupleurumeuphorbioides maintained a higher genetic diversity due to outcrossing,but at the individual locus, deficiency of heterozygosity prevailed. Probablyinbreeding between local neighborhoods was frequent because A.distichum and B. euphorbioides were pollinatedby small fly species which might be less effective as a pollen dispersal, andtheir visits were extremely scarce and controlled by the weather conditions.Since much of the species-to-species variation in genetic diversity is due tothe specific ecological and evolutionary history of a species, any managementplan developed should be based on historical changes in the population size anddistribution to better predict the amounts and patterns of genetic diversity.     

Low levels of allozyme differentiation betweenPyxidanthera (pyxie-moss) taxa (Diapensiaceae)

TwoPyxidanthera morphs of questionable taxonomic rank are described in the eastern United States. We analyzed leaf samples from ninePyxidanthera populations (four of each morph and one with intermediate morphology) for 13 allozyme loci. Our results do not support differentiation of the two morphs at the species level. Mean genetic identity among populations was high ( = 0.97), and typical of that found for conspecific populations. The proportion of total genetic diversity found among populations was low (G_ST = 0.079). Several low frequency alleles were confined to each of the morphs, being found in some of the populations of each morph, but not all.     

唐松草属五新种

该文描述了毛茛科唐松草属五新种:(1)小花唐松草,发现自贵州东北部,与多枝唐松草近缘,区别为其小叶较小,雄蕊较少,花丝较短,呈狭条形。(2)新宁唐松草,发现自湖南南部,与爪哇唐松草近缘,区别为本种的雄蕊花丝呈狭条状棒形,花只含3~6枚心皮。(3)短蕊唐松草,发现自河南东南部,在体态上与爪哇唐松草十分相似,区别为本种的雄蕊很短,花丝呈丝形,花只含4~6枚心皮。(4)毛蕊唐松草,发现自四川北部,与长柄唐松草有密切的亲缘关系,区别为本种的茎和花梗被短柔毛,萼片被缘毛,花药不具短尖头,子房密被短柔毛。(5)小金唐松草,发现自四川西部,与白茎唐松草在亲缘关系上甚为相近,区别为本种的小叶被微硬毛,雄蕊花丝呈狭条形,花药顶端无短尖头或具极小短尖头,心皮较小,长仅2.4 mm,柱头无翅。     

四川毛茛科二新种——乌头属一新种和唐松草属一新种

该文描述了自四川西部发现的毛茛科二新种,包括四川乌头属一新种,即泸定乌头(Aconitum ludingense W.T.Wang),此新种隶属于乌头属乌头亚属,以及四川唐松草属一新种,即狭药唐松草(Thalictrum stenantherum W.T.Wang),给出了此新种与其近缘种六脉萼唐松草之间的形态区别.