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1.
The genus Hippophae comprises 7 species and 8 subspecies according to the latest classification, and has shown enormous ecological, nutrient
and medicinal values. Here we analyzed the phylogenetic relationships among 15 taxa of the genus by comparing sequences of
the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (nrDNA). ITS sequences in Hippophae varied in length from 651 bp to 666 bp. The aligned sequences were 690 bp in length and 269 (39.0%) were variable sites with
150 being parsimony-informative. The amount of polymorphism observed within a taxon was extremely low in most taxa except
for two putative hybrid species. The aligned sequences were analyzed by maximum parsimony (MP) and neighbor-joining (NJ) methods.
In the strict consensus trees of parsimony analysis, the monophyly of Hippophae was supported by 100% bootstrap value. H. tibetana was at the basal position of the genus, and the remaining taxa formed two clades with high bootstrap support. The first clade
included subspecies of H.␣rhamnoides and the other one consisted of remaining species. Parsimony analysis also suggested that the species H. tibetana, H. neurocarpa and H.␣salicifolia were all distinct. Although the sequence divergence among subspecies of H. rhamnoides was also remarkably high, the molecular data supported the monophyly of H. rhamnoides when H. rhamnoides subsp. gyantsensis Rousi was excxluded. The NJ trees showed essentially the same topology. The taxonomical arrangement that divided the genus
into two sections was not supported based on the ITS sequences. However, the hybrid origin of H. goniocarpa and H. litangensis proposed previously was supported by the present ITS data.
Received January 7, 2002; accepted May 10, 2002 Published online: November 22, 2002
Addresses of the authors: Kun Sun, Xuelin Chen, Ruijun Ma, Qin Wang, Institute of Botany, Northwest Normal University, Lanzhou
730070, China. Changbao Li, Song Ge (e-mail: gesong@ns.ibcas.ac.cn or song_ge@hotmail.com), Laboratory of Systematic and Evolutionary
Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China. 相似文献
2.
The mode of reproduction, pollen production, chromosome numbers, genetic variation (RAPD, allozymes) and overall similarity
were studied in 6 species of Hieracium sect. Alpina in the Tatry Mts. (the Western Carpathians, Slovakia). All species were confirmed to be agamospermous and, except of H. krivanense and H. slovacum, lacking pollen grains. For the first time, a chromosome number is reported for H. krivanense (2n=4x=36). Considerable genetic variation was revealed in H. alpinum and a correlation between geographic and genetic distances was found in this species. Between-population variation in RAPD
and allozyme phenotypes was found in H. pinetophilum and H. crassipedipilum. In all other species, allozyme and RAPD variation was low or absent. With few exceptions, the species differ in their allozyme
as well as RAPD patterns. The relatedness of one population of endemic H. slovacum and H. halleri was confirmed. It is shown, that Carpathian species of the H. fritzei group are derived from at least two ancestors.
Received July 3, 2000; accepted June 24, 2002 Published online: November 20, 2002
Addresses of the authors: H. Štorchová, (e-mail: storchova@ueb.cas.cz) Institute of Experimental Botany, Academy of Sciences
of the Czech Republic, Rozvojová 135, CZ-165 00 Praha 6, Czech Republic. I. V. Bartish, J. Chrtek Jr., J. Kirschner, M. Tetera,
J. Štěpánek, Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Pruhonice, Czech Republic. 相似文献
3.
The evolutionary history of Fagus in western Eurasia: Evidence from genes, morphology and the fossil record 总被引:2,自引:0,他引:2
T. Denk G. Grimm K. Stögerer M. Langer V. Hemleben 《Plant Systematics and Evolution》2002,232(3-4):213-236
Fagus (beech) is among the most abundant and economically important genera of broad-leaved trees in northern hemisphere temperate
forests. The number of modern taxa present in Europe and Asia Minor has long been a matter of debate and up to five species
have been recognised. To resolve taxonomic and phylogenetic relationships we conducted morphological and molecular genetic
analyses in western Eurasiatic taxa and evaluated palaeontological evidence. To place our findings from western Eurasiatic
populations in a broader context additional East Asiatic and North American species of the same subgenus Fagus as well as two species of the subgenus Engleriana were included in our study.
The morphological features exhibited in western Eurasiatic populations of Fagus show a west-east gradient that is characterised by strongly overlapping variability between geographical races. Fagus populations from Asia Minor exhibit an even higher variability that is also reflected in their genetic variability of nuclear
rDNA internal transcribed spacer (ITS) sequences. The intraspecific genetic variability recorded here is in conflict with
previous ITS studies in Fagus. The high amount of ITS polymorphism within Fagus from western Eurasia along with the clinal variation observed for morphological characters suggest the presence of only a
single species, Fagus sylvatica L., in Europe and Asia Minor. Previously recognised taxa such as F. orientalis Lipsky and Fagus moesiaca (Maly) Czeczott should therefore be treated as synonyms of Fagus sylvatica. Although species belonging to the subgenus Engleriana were genetically distinct from species of the subgenus Fagus, relationships within the subgenus Fagus could not be clearly resolved. A reason for this could be the low rate of diversification in Fagus during the early phase of range expansion of the genus in the Oligocene period as indicated by the uniformity of leaf and
cupule/nut fossils. This may account for the low overall ITS divergence and the high degree of polymorphism encountered in
the subgenus Fagus and points to a late differentiation of western Eurasiatic and eastern Asiatic species. Area disruptions during the Pleistocene
and the post-glacial recolonisation of western Europe appear to have caused the west-east gradient that is apparent in modern
Fagus of western Eurasia but absent in Late Tertiary ancestors of Fagus sylvatica.
Received June 22, 2001 Accepted February 25, 2002 相似文献
4.
R. S. Pasquet 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(6-7):1104-1119
The cowpea [Vigna unguiculata (L.) Walp.] is a morphologically and genetically variable species composed of wild perennial, wild annual, and cultivated
forms that are mainly used for edible seeds and pods. In this study, genetic variation in 199 germplasm accessions of wild
and cultivated cowpea was evaluated using an allozyme analysis. The results from this survey showed that wild cowpea exhibits
genetic variation perfectly fitted with the existing morphological classification. The cowpea gene-pool is characterized by
its unusually large size. It encompasses taxa (ranked as subspecies) that could be considered as different species considering
the high genetic distances observed between accessions belonging to different taxa. These subspecies can be classified into
three groups characterized by their breeding systems: perennial outcrossers, perennial out-inbreds, and inbred annuals. Allozyme
data confirm this grouping. Perennial outcrossers look primitive and are more remote from each other and from perennial out-inbreds.
Within this large gene-pool, mainly made of perennial taxa, cultivated cowpeas (ssp. unguiculata var. unguiculata) form a genetically coherent group and are closely related to annual cowpeas (ssp. unguiculata var. spontanea) which may include the most likely progenitor of cultivated cowpeas.
Received: 15 June 1998 / Accepted: 29 September 1998 相似文献
5.
The internal transcribed spacers (ITS1 and ITS2) of nuclear ribosomal DNA were amplified and sequenced from 19 samples representing
all species of the genus Mercurialis and two outgroup species, Ricinus communis and Acalypha hispida. The length of ITS1 in the ingroups ranged from 223 to 246 bp and ITS2 from 210 to 218 bp. Sequence divergence between pairs
of species ranged from 1.15% to 25.88% among the ingroup species in the combined data of ITS1 and ITS2. Heuristic phylogenetic
analyses using Fitch parsimony on the combined data of ITS1 and ITS2 with gaps treated as missing generated 45 equally parsimonious
trees. The strict consensus tree was principally concordant with morphological classification. Within the genus, the ITS sequences
recognised two main infrageneric clades: the M. perennis complex including three Eurasian stoloniferous species (M.␣leiocarpa, M. ovata and M. perennis) and the western Mediterranean group including eight both annual and perennial species. Of the western Mediterranean clade,
the annual and perennial species grouped respectively into two different groups, and the annual life form is revealed as a
synapomorphic character derived from perennial, whereas in the Eurasian clade ITS phylogeny suggested M. leiocarpa as basal clade sister to M.␣perennis and M. ovata. ITS phylogeny failed to resolve the relationships among the different cytotypes of M. ovata and M. perennis. ITS phylogeny also suggested rapid karyotypic evolution for the genus. The karyotypic divergence among the perennial species
of western Mediterranean region did not corroborate the nucleotide sequence divergence among the species. Optimisation of
chromosome numbers onto the ITS phylogeny suggested x=8 to be the ancestral basic chromosome number of the genus. ITS phylogeny
confirmed that the androdioecy of M. ambigua is derived from dioecy. The nucleotide heterozygosity and additivity in ITS sequences clearly confirm the interspecific hybridisation
in the genus Mercurialis.
Received December 22, 2001; accepted May 21, 2002?Published online: November 14, 2002
Address of the authors: Martin Kr?henbühl, Yong-Ming Yuan (correspondence) and Philippe Küpfer, Institut de Botanique, Laboratoire
de botanique évolutive, Université de Neuchatel, Emile-Argand 11, CH-2007 Neuchatel, Suisse. (e-mail: yong-ming.yuan@unine.ch) 相似文献
6.
M. Koch 《Plant Systematics and Evolution》2002,232(1-2):35-49
Significant geographic partitioning of genetic variation within Cochlearia bavarica was found within populations from Allg?u and SE Bavaria (Germany) exhibiting significant genetic differentiation. It has
been demonstrated that allohexaploid C. bavarica evolved via hybridization between diploid C. pyrenaica and tetraploid C. officinalis. Presently, only C. pyrenaica is distributed throughout inland Central Europe. It has been concluded that C. bavarica is of inter- or postglacial origin, and its speciation was not influenced by human activities. Isozyme analysis revealed
that there is a correlation between interpopulational genetic distances and geographic distances among C. bavarica populations from both regions, and which is not the case for C. pyrenaica in Germany and Austria. Only high alpine C. excelsa is significantly differentiated among the diploid taxa analysed here. Geographically structured distribution of alleles and
their frequencies in C. bavarica populations could not be explained with the distribution of these alleles in C.
pyrenaica. The presented findings favour disruption of a former wider distribution area rather than migration of C.
bavarica or a polytopic origin of this species.
Received April 17, 2001 Accepted February 1, 2002 相似文献
7.
Little is known about genetic variation in members of the genus Aesculus (Hippocastanaceae), in particular A. flava (yellow buckeye) and A. glabra (Ohio buckeye). Here, three synthetic DNA probes (composed of tandemly repeated, core sequences) that reveal alleles at multiple
variable-number tandem-repeat (VNTR) loci in these two species were used to investigate: 1) levels of genetic variation in
one stand of A. flava and three isolated stands of A. glabra; 2) whether the stands of A. glabra are genetically differentiated from one another; 3) whether there has been selection for more heterozygous individuals through
time in one stand each of A. flava and A. glabra; and 4) whether a possible genetic bottleneck had occurred during the formation of either species of Aesculus.
First, variation of VNTR genetic markers within and among three populations of A. glabra separated by 60–180 km was examined. In each one hectare (ha) population, 22 individuals were randomly sampled. Among the
three populations, the mean number of bands scored per individual was 80.35 and the average number of estimated loci surveyed
was 54.17. Mean similarity and estimated heterozygosity within populations ranged from 0.634 to 0.743 and from 0.342 to 0.486,
respectively. The mean similarity across populations was 0.657, while the mean estimated heterozygosity across populations
was 0.484 for A. glabra. The most isolated site was the most genetically differentiated as indicated by differences in levels of similarity, heterozygosity,
and Fst value comparisons.
In a separate experiment, genetic variation in 22 large (reproductively mature; dbh > 8 cm) individuals was compared with
that in 22 small (not yet reproductive; dbh < 1 cm) individuals collected within one ha stands for both A. flava and A. glabra. Mean similarity values among large versus small individuals of A. flava were 0.665 versus 0.662, while for A. glabra the corresponding values were 0.686 versus 0.691, respectively. Permutation tests of these similarity data detected no evidence
for size class genetic differentiation in either species (both p-values > 0.050). Further, permutation tests for the number
of bands per individual (average band number should be higher in more heterozygous individuals) detected no significant differences
between size classes for either species. Thus, evidence of pronounced inbreeding and/or selection altering population genetics
within small relative to large individuals was not detected.
In addition, comparable similarity and heterozygosity values between these two closely related species (which still maintain
an active zone of hybridization) suggests that either: 1) no extreme genetic bottleneck has accompanied the formation of these
species from a common ancestor; or 2) signs of such a bottleneck have largely been eliminated. These studies demonstrate the
utility of multilocus VNTR DNA probes for investigating genetic variation within and among plant populations, between size
classes within a population, and between closely related species.
Received May 15, 1998 Accepted September 11, 2001 相似文献
8.
Although Korean Adonis has been traditionally recognized as Adonis amurensis Regel and Radde with various infraspecific taxa described, its taxonomic identity is still in dispute. We investigated the
genetic variation in 60 individuals from 12 populations in Korea to elucidate the taxonomic identity of the Korean Adonis complex. Random amplified polymorphic DNA (RAPD) analysis revealed that Korean Adonis comprises three species: A. amurensis, A. pseudoamurensis, and A. multiflora. Adonis amurensis is distributed in northern central inland regions of Korea and A. pseudoamurensis is found in southern parts of the Korean peninsula. Adonis multiflora grows only on Cheju Island, which is the southernmost part of Korea. Phylogenetic analysis of nuclear ribosomal internal
transcribed spacer (ITS) sequences partially supported the presence of three Adonis taxa in Korea as detected by RAPD analysis. The Adonis population on Jangbong Island located in the West Sea, which was referred to as A. pseudoamurensis on the basis of morphological examination, was separated from the other populations of A. pseudoamurensis. Otherwise, the molecular evidence is well congruent with the recent morphological study that proposes that Korean Adonis consists of these three species.
Received: November 6, 2001 / Accepted: February 26, 2002 相似文献
9.
R. Cronn M. Brothers K. Klier P. K. Bretting J. F. Wendel 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(4):532-545
The annual sunflower (Helianthus annuus L.) is a morphologically and genetically variable species composed of wild, weedy, and domesticated forms that are used for
ornament, oilseed, and edible seeds. In this study, we evaluated genetic variation in 146 germplasm accessions of wild and
domesticated sunflowers using allozyme analysis. Results from this survey showed that wild sunflower exhibits geographically
structured genetic variation, as samples from the Great Plains region of the central United States were genetically divergent
from accessions from California and the southwestern United States. Sunflower populations from the Great Plains harbored greater
allelic diversity than did wild sunflower from the western United States. Comparison of genetic variability in wild and domesticated
sunflower by principal coordinate analysis showed these groups to be genetically divergent, in large part due to differences
in the frequency of common alleles. Neighbor-Joining analyses of domesticated H. annuus, wild H. annuus and two closely related wild species (H. argophyllus T. & G. and H. petiolaris Nutt.) showed that domesticated sunflowers form a genetically coherent group and that wild sunflowers from the Great Plains
may include the most likely progenitor of domesticated sunflowers.
Received: 2 December 1996/Accepted: 4 April 1997 相似文献
10.
E. Hörandl 《Plant Systematics and Evolution》2002,233(1-2):65-78
In the partly apomictic Ranunculus cassubicus group, a subgroup of the R. auricomus complex, two species were studied by morphometric analyses: R. cassubicifolius W. Koch (with three diploid and two autotetraploid sexual populations), and R. carpaticola Soó (with three diploid sexual populations and a hexaploid apomictic one). Multidimensional scaling analyses (MDS) of individuals,
boxplots and cluster analyses of populations revealed a differentiation of R. cassubicifolius and R. carpaticola, whereby in MDS the hexaploid apomictic individuals are partly intermediate between R. cassubicifolius and R. carpaticola. The cytodemes of R. cassubicifolius showed no morphological and only a weak genetic differentiation. A comparison of morphology, isozymes, reproductive system
and ploidy levels showed only partly congruence of data sets in respect of grouping populations, thus illustrating the problem
to find criteria for a taxonomic concept. A treatment of the apomictic population as a separate group is indicated by all
data sets, afterwards R. cassubicifolius and diploid R. carpaticola represent two other well-defined groups. Canonical variate analysis including all characters confirmed the three suggested
groups as significantly different and showed that a total of 89.3% of individuals are correctly classified; number of teeth
of stem leaf segments and number of petals are the most discriminating characters. Herbarium studies confirm the morphological
differentiation yielded from population samples. The three population groups are even better separated in a canonical variate
analysis of isozyme data (presence/absence of 25 alleles) of the same material, here 92.6% of individuals are correctly classified.
Morphology and isozyme data suggest that the hexaploid apomict originated from hybrids of R. cassubicifolius and diploid R. carpaticola and must be excluded from the sexual taxa; the final classification and naming of the apomicts must be left for further studies
on a larger material. The sexual taxa should be classified as separate species. Herbarium studies indicate that R. carpaticola s.str. is widespread over the Carpathians and might include other populations hitherto ascribed to other microspecies as
well.
Received November 20, 2001; accepted May 10, 2002 Published online: September 13, 2002 相似文献
11.
Vicia ser. Vicia, which includes the Vicia sativa aggregate, was studied by observing morphological variation. The study is an attempt to resolve the taxonomic relationships
within the Vicia sativa aggregate by novel investigations along with a synthesis of the results obtained by previous researchers. The study has included
some accessions and characters used previously, but has drawn accessions from a wider geographical range than has been attempted
previously. Cluster analysis on the basis of 53 morphological characters justified the delimitation of four species within
the series and six subspecies within the Vicia sativa aggregate. Accessions from South Asia could easily be incorporated in the classification, but some of the accessions from
North Africa showed morphological differences. The morphometric data were coded using the gap weighting method of Thiele (1993)
and used in a phylogenetic analysis to study the relationships between the taxa. The phylogenetic analysis, using 33 variables,
showed Vicia pyrenaica closely related to Vicia sativa subsp. amphicarpa. A dichotomous key and a multi-access key to aid the identification of the taxa in the series are presented.
Received January 21, 2002; accepted November 8, 2002 Published online: March 20, 2003 相似文献
12.
The genetic identities among several Echinospartum species and the genetic effects of isolation, small population size and decline in the restricted Echinospartum algibicum were studied both at adult and soil seed bank stages. The allozyme data support, to a large extent, population genetic predictions
for genetic divergence. The genetic diversity parameters studied demonstrated that the aboveground population of E. algibicum is genetically less diverse than E. ibericum and E. barnadesii. Genetic identity between E. ibericum and E. barnadesii was very high, decreasing to levels considered typical for co-generic taxa between E. ibericum and E. algibicum. With regard to the soil seed bank of E. algibicum, this showed higher genetic variability than the adult population, greater extent of homozygosity, and significantly different
allele frequencies at some loci. Despite the small population size, E. algibicum population maintains relatively high levels of genetic diversity both at adult and seed bank stages.
Received July 2, 2001 Accepted October 11, 2001 相似文献
13.
Giuseppe C. Zuccarello Alan T. Critchley Jennifer Smith Volker Sieber Genevieve Bleicher Lhonneur John A. West 《Journal of applied phycology》2006,18(3-5):643-651
The systematics and taxonomy of Kappaphycus and Eucheuma (Solieriaceae) is confused and difficult due to morphological plasticity, lack of adequate characters to identify species and commercial names of convenience. These taxa are geographically widely dispersed through cultivation. Commercial, wild and herbarium sources were analysed; molecular markers provided insights into taxonomy and genetic variation, and where sources of genetic variation may be located. The mitochondrial cox2-3 and plastidal RuBisCo spacers were sequenced. There is a clear genetic distinction between K. alvarezii (“cottonii”) and K. striatum (“sacol”) samples. Kappaphycus alvarezii from Hawaii and some samples from Africa are also genetically distinct. Our data also show that all currently cultivated K. alvarezii from all over the world have a similar mitochondrial haplotype. Within Eucheuma denticulatum (“spinosum”) most African samples are again genetically distinct. Our data also suggest that currently cultivated E. denticulatum may have been “domesticated” several times, whereas this is not evident for the cultivated K. alvarezii. The present markers used do not distinguish all the morpho-types known in cultivation (e.g. var. tambalang, “giant” type) but do suggest that these markers may be useful to assess introductions and species identification in samples. 相似文献
14.
HPLC-UV and HPLC-MS investigations of phenolic acids and flavonoids in flowerheads of 84 samples of 76 taxa belonging to
66 species of Hieracium resulted in the identification of three phenolic acids (chlorogenic acid, 3,5-dicaffeoyl quinic acid, 4,5-dicaffeoyl quinic
acid) and six flavonoids (apigenin 4′-O-β-D-glucuronide, isoetin 4′-O-β-D-glucuronide, luteolin, luteolin 7-O-β-D-glucoside, luteolin 7-O-β-D-glucuronide, luteolin 4′-O-β-D-glucoside). The contents of these secondary metabolites were quantified by HPLC using quercetin and cynarin as internal
standards. In contrast to the previously investigated genera Leontodon and Crepis, cichoric acid and caffeoyl tartaric acid were not found in any of the investigated Hieracium taxa. Results of HPLC analyses revealed only a limited degree of qualitative variation between the different taxa, and luteolin
7-O-β-D-glucuronide and isoetin 4′-O-β-D-glucuronide were the only compounds, which were not detectable in some of the investigated taxa. Quantitative patterns
of phenolics differed markedly between particular taxa and Principal Component Analysis of the quantification results yielded
separate clusters for the members of the subgenera Hieracium and Pilosella.
Received January 23, 2001 Accepted October 11, 2001 相似文献
15.
M. J. Salinas A. T. Romero G. Blanca R. de la Herrán M. Garrido-Ramos C. Ruíz-Rejón C. Morales M. Ruíz-Rejón V. Suárez 《Plant Systematics and Evolution》2003,237(3-4):153-164
To solve problems concerning the status of the taxa described in the genus Sarcocapnos, we have conducted a study using morphological, pollen morphology (light microscopy), cytogenetic and molecular techniques.
Focusing on the last technique, we have sequenced ITS-1 and ITS-2 of nuclear rDNA. The species differ basically according
to 5 morphological traits (leaf shape, flower spur, corolla colour, corolla size, and crest of the stigmatic surface). The
cytogenetic analyses indicated n=16 to be the standard chromosome number. The ITS analyses showed that the genus is monophyletic,
defining two main well-supported clades, one containing S. saetabensis and S. enneaphylla, and one containing the rest of the species. In this second clade, S. speciosa, S. pulcherrima, and S. baetica subsp. ardalii are related, as are S. integrifolia, S. crassifolia subsp. crassifolia, and S. crassifolia subsp. atlantis; S. baetica subsp. baetica forms a trichotomy with the foregoing groups. S. speciosa is shown to be a species separate from S. crassifolia subsp. crassifolia, as in the case of S. baetica with respect to S. integrifolia. Palynologically, the parameters used enabled us to establish clear differences between the taxa, often corroborating the
macromorphological and genetic data. The flower spur has been reduced several times in different groups of the genus, for
which the classifications established on the basis of this trait are paraphyletic.
Received July 16, 2002; accepted December 11, 2002 Published online: March 31, 2003 相似文献
16.
A. R. Davis 《Plant Systematics and Evolution》2003,238(1-4):169-181
Investigations of the effects of two global events – elevated CO2 levels and enhanced ultraviolet-B (UV-B) radiation – on floral nectar production are reviewed from twelve dicotyledonous
families. Furthermore, to allow comparisons between nectary morphology and nectar production in treated plants of these fifteen
species, new data on floral nectary structure are provided for Malcolmia maritima (L.) R. Br. (Brassicaceae) and Scabiosa columbaria L. (Dipsacaceae). All but the last taxon possessed mesenchymatic floral nectaries with surface stomata. Few clear relationships
existed between nectary morphology and various physiological responses to CO2 or UV-B enrichment, indicating that species responded notwithstanding nectary structure itself. Overall, nectar-solute concentration
was least affected by elevated CO2 or UV-B radiation; consequently, changes in nectar volume were responsible for differences in nectar-sugar production per
flower. Three species of Fabaceae experienced no change in floral nectar production upon exposure to elevated CO2. To date, no study of enhanced UV-B radiation reported a consistent reduction in floral nectar production; three species
of Brassicaceae responded differently, but various levels of ozone depletion were simulated. Experimentation with more taxa
– including those possessing nectary types such as septal (gynopleural) nectaries (e.g. many monocotyledons) or aggregations
of glandular trichomes – and expanding such physiological studies to species possessing extrafloral nectaries, are recommended.
Received August 8, 2002; accepted November 23, 2002
Published online: June 2, 2003 相似文献
17.
Variation at seven microsatellite loci was investigated in three local E. alaskanus populations from Norway and microsatellite variation was compared with allozyme variation. The percentage of polymorphic
loci was 81%, the mean number of alleles per polymorphic locus was 5.7 and expected heterozygosity was 0.37. An F-statistic
analysis revealed an overall 48% deficit of heterozygotes over Hardy-Weinberg expectations. Gene diversity is mainly explained
by the within population component. The averaged between population differentiation coefficient, F
st
, over 7 loci is only 0.13, which accounts for only 13% of the whole diversity and was contrary to allozyme analysis. The
mean genetic distance between populations was 0.12. However, a χ2 -test showed that allele frequencies were different (p < 0.05) among the populations at 5 of the 7 loci. In comparison with
the genetic variation detected by allozymes, microsatellite loci showed higher levels of genetic variation. Microsatellite
analysis revealed that population H10576 possesses the lowest genetic variation among the tested three populations, which
concur with allozyme analysis. The dendrogram generated by microsatellites agreed very well with allozymic data. Our results
suggest that natural selection may be an important factor in shaping the genetic diversity in these three local E. alaskanus populations. Possible explanations for deficit heterozygosity and incongruence between microsatellites and allozymes are discussed.
Received November 6, 2001; accepted April 24, 2002 Published online: November 14, 2002
Addresses of the authors: Genlou Sun (e-mail: Genlou.sun@STMARYS.CA), Biology Department, Saint Mary's University, Halifax.
Nova Scotia, B3H 3C3, Canada. B. Salomon, R. von Bothmer, Department of Crop Science, The Swedish University of Agricultural
Sciences, P.O. Box 44, SE-230 53, Alnarp, Sweden. 相似文献
18.
A. R. Hagen T. Sæther L. Borgen R. Elven O. E. Stabbetorp C. Brochmann 《Plant Systematics and Evolution》2002,230(3-4):203-219
The high polyploids Cerastium alpinum (8x) and C. nigrescens (12x) were investigated in a mixed population in central Norway to evaluate whether hybridisation has resulted in continuous variation
in morphology and genetic markers, a hypothesis previously proposed to account for the extensive taxonomic confusion in this
species group. Isozyme, fertility, and morphological (37 characters) variation were examined among 347, 265, and 237 plants,
respectively. A PCO analysis based on 23 quantitative morphological characters identified two main groups, corresponding to
C. alpinum and C. nigrescens. The groups were also clearly separated in isozyme markers, several qualitative morphological characters, and chromosome numbers.
Only 20 plants (8.4%) were more or less intermediate in the PCO analysis. These plants had a parental or hybrid isozyme multilocus
phenotype and typically few well-developed anthers, low pollen stainability, and no seed set. Several plants within the C. nigrescens group also had reduced pollen stainability. These results indicate that later-generation hybrids and/or backcrosses towards
C. nigrescens are formed. Thus, interspecific, interploidal gene flow probably occurs, but at rates that are insufficient to break down species integrity.
Received July 5, 2000 Accepted August 2, 2001 相似文献
19.
We investigated patterns of isozyme variation and the hierarchic structure of genetic diversity in 25 Scandinavian populations
of the lilioid herb, Anthericum liliago. Isozyme data suggest that tetraploid A. liliago has an allopolyploid origin and that A. ramosum may be one of its diploid progenitors. Two populations contained known or suspected hybrids between A. liliago and A. ramosum. Isozymes show that one population from S Sweden contains both triploid (hybrid) and tetraploid individuals whereas a putatively
hybrid Danish population represents diploid A. liliago. There is an overall northward and eastward decline in allelic richness in the tetraploid populations, with the highest numbers
of alleles in Denmark and SW Sweden. This pattern is consistent with a progressive loss of allelic variation during the species'
postglacial colonization of Scandinavia. The between-population component of genetic diversity is 4% (compared with 12% in
diploid A. ramosum), the between-region diversity component is 7% and 89% of the total diversity is stored within populations.
Received March 13, 2002; accepted September 24, 2002 Published online: December 11, 2002 相似文献
20.
From the predominantly aposporous Ranunculus cassubicus group, a subgroup of the R. auricomus complex, two species with both diploid and tetraploid cytodemes (R. cassubicifolius W. Koch and R. carpaticola Soó) were known. Nine population samples of both species have been analyzed for variation of ploidy levels and isozymes.
DNA image analysis showed that three populations of R. cassubicifolius from Bavaria and Salzburg are diploid, two from Lower Austria tetraploid. In R. carpaticola, two populations from Central Slovakia and one from Romania are diploid, one from northern Slovakia is hexaploid. The polyploid
populations had somewhat smaller C-values than expected from diploids. Ploidy levels are consistent within populations, contradicting
previous hypotheses that cycles of diploid-tetra-ploid-dihaploid apomictic individuals occur in natural populations of goldilocks.
Isozyme-allozyme analysis of nine polymorphic loci showed that individual variation and genetic measures of di-ploid and tetraploid
populations are equivalent to those of sexual taxa. Multiple allelism and unbalanced gene dosages in tetraploid R. cassubicifolius give evidence for autopolyploidy that is most probably of multiple origin. The observed excess of homozygotes and the high
diversity between populations in the diploid populations of R. cassubicifolius are most probably due to geographical isolation of population groups, that might have happened during the Würm glaciation
and might have promoted the separation of autotetraploids in the easternmost part of the distribution range. Genetic distance
values analyzed by UPGMA of all sexual populations separated the two taxa and the cytodemes within R. cassubicifolius. Multidimensional scaling of individuals (including the apomicts) based on a presence/absence matrix of alleles confirmed
this differentiation with an overlapping zone between R. cassubicifolius and R. carpaticola. The hexaploid R. carpaticola population showed reduced genotypic diversity, an increased number of heterozygotes and fixed heterozygosity as typical for
apomictic mode of reproduction. This population shared alleles of both species without any specific ones, multidimensional
scaling placed genotypes among R. cassubicifolius. Thus, the hexa-ploid apomicts might have originated from hybrids of R. cassubicifolius and R. carpaticola. In general, evolution of agamic lineages in the R. cassubicus complex might have been facilitated by autopoly-ploids, because they can provide a bridge between the reproductive systems
that are otherwise isolated by ploidy levels, and also a starting point for spontaneous origin of apomixis.
Received October 8, 2001; accepted May 10, 2002 Published online: November 7, 2002
Addresses of the authors: Elvia H?randl (E-mail: elvira.hoerandl@univie.ac.at), Department of Systematics and Evolution of
Higher Plants; Johann Greilhuber (E-mail: Johann.Greilhuber@univie. ac.at), Department of Systematic Karyology and Embryology
of Plants; both: Institute of Botany, University of Vienna, Rennweg 14, A-1030 Vienna, Austria. 相似文献