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1.
Aeschynanthus Jack, an epiphytic genus with c.160 species, is widespread in SE Asia. We selected 50 species for ITS nrDNA sequencing, to include all biogeographic areas and all infrageneric groupings, which are currently based on seed morphology. Some species were sequenced directly from PCR product; others cloned because of ITS length polymorphisms. The clone sequences were analysed individually and combined in an elision matrix. Results extend earlier findings that Aeschynanthus is divided into two clades, one occurring primarily in mainland SE Asia and the other in Malesia. This pattern is interpreted as indicating an ancient vicariance event followed by dispersal and plate fusion. Clade I has straight or clockwise spiral orientation of the testa cells and clade II anticlockwise spiral orientation. In clade I some species of section Microtrichium form a basal group with other sections being polyphyletic or paraphyletic. In clade II the monophyletic section Aeschynanthus is nested within the paraphyletic basal Microtrichium. Received February 8, 2001 Accepted June 8, 2001  相似文献   

2.
Recent studies of mitochondrial DNA sequences have indicated the requirement for substantial revisions of the morphological understanding of the phylogeny of Megachiroptera (Pteropodidae). There is disagreement between studies as to what these revisions might be. This investigation was undertaken to expand the number of studied species and to add the first data from a nuclear gene sequence. For 12S ribosomal DNA (aligned length of 405 positions), 75 Megachiroptera (50 species in 20 genera) and two outgroup species were sequenced. For the oncogene c-mos (aligned length of 488 bases), 56 Megachiroptera (42 species in 19 genera) were sequenced and three eutherians from GenBank used as outgroups.The root of the megachiropteran phylogeny cannot be determined with the present data. Nyctimene, the only studied insectivorous genus (Paranyctimene not being included), plus Notopteris, the only long-tailed megachiropteran, form the sister clade to the other genera in combined analyses. Several alternative rootings are not rejected by the data, suggesting a rapid early radiation. Generic distributions indicate that this may have occurred in Melanesia. The results confirm that the subfamily Macroglossinae is not monophyletic with the long tongued phenoptype arising at least twice and support the existence of a major clade including a monophyletic endemic African component and biogeographically neighboring genera such as Rousettus and Eonycteris. The phylogenetic position of one African genus, Eidolon, remains uncertain.A cynopterine section (excluding Nyctimene and Myonycteris) is supported, albeit weakly, as a monophyletic group. Pteropus and the related, possibly polyphyletic genus Pteralopex, are unexpectedly basal compared to previous molecular studies.  相似文献   

3.
The taxon currently known as Isothecium myosuroides var. brachythecioides (Dixon) Braithw. is reinstated as a species, I. interludens Stirt., the name originally assigned by Stirton when it was first described. The morphological characters separating I. myosuroides s.s. and I. interludens are summarised. The sporophytes of I. interludens, described here for the first time, differ in shape, and pattern of exothecial cells from those of I. myosuroides. A molecular analysis based on variation of the ITS region shows that I. holtii Kindb. and I. alopecuroides (Lam. ex Dubois) Isov. are not monophyletic, calling for a re-assessment of these species, whereas the monophyly of the other species, including I. interludens, cannot be rejected. The analysis failed, however, to yield molecular synapomorphies for I. interludens and other species within I. myosuroides s.l., which we interpret as the incomplete sorting of alleles among recently evolved species. Isothecium interludens is a European endemic with a hyperoceanic temperate distribution. Its nested position within a clade including the two Macaronesian endemics I. prolixum (Mitt.) M.Stech and I. montanum Draper, Hedenäs, M.Stech, T.Lopes & Sim-Sim is suggestive of a Macaronesian origin, in line with the idea that the European Atlantic fringe flora assembled during the course of the last interglacial from Macaronesian ancestors. Isothecium therefore offers a model of prime importance for the study of ongoing speciation in mosses.  相似文献   

4.
Evolutionary relationships among the genera of Macaronesian Sempervivoideae, Aeonium, Aichryson, Greenovia, and Monanthes, were studied using sequence variation of the chloroplast DNA trnL (UAA) - trnF (GAA) spacer and the nuclear ribosomal Internal Transcribed Spacer 2 (ITS2). Phylogenetic analysis indicates that the Moroccan Sedum sect. Monanthoidea is the sister taxon of the Macaronesian Sempervivoideae. In combination with the terminal position in the Macaronesian Sempervivoideae of the East African A. leucoblepharum, which has formerly been assumed to be the sister taxon of the other species of Macaronesian Sempervivoideae (i.e. Aichryson and Monanthes), a recent remigration to Africa is suggested. Statistical support for the terminal position of A. leucoblepharum using only spacer sequences is without homoplasy but not high since only single mutations in both the chloroplast and nuclear sequence characterize the clade containing A. leucoblepharum. A. leucoblepharum and the Canarian species with a similar growth-form share 50% of the RAPDs. Within a clade comprising woody species with yellow flowers and a herbaceous rosette, the highest genetic divergence, as determined with RAPDs, is found between A. simsii and the woody Macaronesian and African species. The extremely close genetic ties among the woody and branched (sub)shrubs indicate that, when compared to the other species of the genus, the woody, African Aeonium species are not the sister group of the Macaronesian Sempervivoideae and substantiate the view that an ancestor of A. leucoblepharum recently migrated from the Canary Islands to East Africa and Arabia through long distance dispersal, rather than being a relict of an African Aeonium flora from the Tertiary.  相似文献   

5.
The genusCheirolophus has an interesting western Mediterranean and Macaronesian distribution. Here we investigate the delimitation of the genus and its exclusion from the large genusCentaurea, the systematic position of the related genusPaleocyanus, the delimitation of some species and the phylogeny of the group. We have carried out a phylogenetic analysis of the PCR-generated sequences of the internal transcribed spacers (ITS-1 and ITS-2) of the nuclear ribosomal DNA. The results suggest that the genus, includingPaleocyanus crassifolius is monophyletic; thus, a new combination of this species underCheirolophus is proposed. The Macaronesian group of species is also monophyletic, indicating a single colonization of the archipelago. The poor resolution of microspecies in the Macaronesian group reinforces the hypothesis of a very recent differentiation of the group.  相似文献   

6.
A phylogeny of the Neotropical members of the Tribe Troidini (Lepidoptera: Papilionidae) was obtained with sequences of three protein-coding genes: two mitochondrial (COI and COII), and one nuclear (EF-1α). Parsimony and Bayesian analyses of 33 taxa resulted in very similar trees regardless of method used with the 27 troidines always forming a monophyletic clade. Within Troidini, the genus Battus is sister group to the remaining troidines, followed by a clade formed by the Paleotropical taxa (here represented by three exemplars). The genus Euryades is the next branch, and sister group of Parides. The genus Parides is monophyletic, and is divided into four main groups by Maximum Parsimony analysis, with the most basal group composed of tailed species restricted to SE Brazil. Character optimization of ecological and morphological traits over the phylogeny proposed for troidines indicated that the use of several species of Aristolochia is ancestral over the use of few or a single host-plant. For the other three characters, the ancestral states were the absence of long tails, forest as the primary habitat and oviposition solitary or in loose group of several eggs.  相似文献   

7.
Aim The angiosperm genus Cryptotaenia (family Apiaceae, tribe Oenantheae) exhibits an anomalous distribution pattern, with five of its eight species being narrow endemics geographically isolated from their presumed relatives. We examined the monophyly of the genus and ascertained the phylogenetic placements of its constituent members in order to explain their distribution patterns. Location Eastern North America, eastern Asia, the Caucasus, southern Italy, Macaronesia and Africa. Methods In total, 173 accessions were examined for nuclear rDNA ITS sequence variation, representing nearly all major lineages of Apiaceae subfamily Apioideae and seven species of Cryptotaenia. Sampling of tribes Oenantheae, Scandiceae and Pimpinelleae was comprehensive. Phylogenetic analyses included Bayesian, maximum parsimony and neighbour‐joining methods; biogeographical scenarios were inferred using dispersal–vicariance analysis (diva ). Results Cryptotaenia is polyphyletic and includes three distant lineages. (1) Cryptotaenia sensu stricto (C. canadensis, C. japonica, C. flahaultii and C. thomasii) is maintained within tribe Oenantheae; C. canadensis and C. japonica, representing an eastern North American–eastern Asian disjunction pattern, are confirmed to be sister species. (2) Cryptotaenia elegans, endemic to the Canary Islands, is placed within Scandiceae subtribe Daucinae along with two woody endemics of Madeira, Monizia edulis and Melanoselinum decipiens. The phylogeny of these Canarian and Madeiran endemics is unresolved. Either they constitute a monophyletic sister group to a clade comprising some Mediterranean and African species of Daucus and their relatives, or they are paraphyletic to this clade. The herbaceous/woody genus Tornabenea from Cape Verde, once included in Melanoselinum, is not closely related to the other Macaronesian endemics but to Daucus carota. (3) The African members of Cryptotaenia (C. africana, C. calycina and possibly C. polygama) comprise a clade with some African and Madagascan umbellifers; this entire clade is sister group to Eurasian Pimpinella. Main conclusions Elucidating the phylogeny of the biogeographically anomalous Cryptotaenia sensu lato enabled hypotheses on the biogeography of its constituent lineages. Cryptotaenia sensu stricto exhibits a holarctic distribution pattern, with its members occurring in regions that were important glacial refugia. The genus probably originated in eastern Asia and from there dispersed to Europe and North America. For the Macaronesian endemic species –C. elegans, M. edulis and M. decipiens–diva reconstructs either a single dispersal event to Macaronesia from the Mediterranean/African region, or a single dispersal followed by a back‐dispersal to the mainland. The radiation of Tornabenea from Cape Verde followed a second dispersal of Daucinae to Macaronesia. Woodiness in Melanoselinum/Monizia and Tornabenea, therefore, is a derived and independently acquired trait. The African members of Cryptotaenia are derived from an ancestor arriving from the Middle East.  相似文献   

8.
The long generation time and large effective size of widespread forest tree species can result in slow evolutionary rate and incomplete lineage sorting, complicating species delimitation. We addressed this issue with the African timber tree genus Milicia that comprises two morphologically similar and often confounded species: M. excelsa, widespread from West to East Africa, and M. regia, endemic to West Africa. We combined information from nuclear microsatellites (nSSRs), nuclear and plastid DNA sequences, and morphological systematics to identify significant evolutionary units and infer their evolutionary and biogeographical history. We detected five geographically coherent genetic clusters using nSSRs and three levels of genetic differentiation. First, one West African cluster matched perfectly with the morphospecies M. regia that formed a monophyletic clade at both DNA sequences. Second, a West African M. excelsa cluster formed a monophyletic group at plastid DNA and was more related to M. regia than to Central African M. excelsa, but shared many haplotypes with the latter at nuclear DNA. Third, three Central African clusters appeared little differentiated and shared most of their haplotypes. Although gene tree paraphyly could suggest a single species in Milicia following the phylogenetic species concept, the existence of mutual haplotypic exclusivity and nonadmixed genetic clusters in the contact area of the two taxa indicate strong reproductive isolation and, thus, two species following the biological species concept. Molecular dating of the first divergence events showed that speciation in Milicia is ancient (Tertiary), indicating that long-living tree taxa exhibiting genetic speciation may remain similar morphologically.  相似文献   

9.
10.
 Representatives of nearly all genera of the taxon-rich stem-succulent stapeliads and most of the few related, leafy genera were analyzed. Sequence data from two non-coding molecular markers (ITS region of nrDNA and trnT-L and trnL-F spacers as well as the trnL intron of cpDNA) support the traditional tribal affiliation of the genera, which form a monophyletic group. This monophylum breaks into a basal Neoschumannia/Anisotoma/Riocreuxia/Sisyranthus nk;clade, from which the core Ceropegieae are derived. The four Ceropegia species included are not monophyletic, and their relationship to Brachystelma changes depending on the marker studied. The stem succulent taxa fall in a number of well supported, but unresolved clades, the most prominent being the predominantly southern African clade comprising Orbea, Stapelia and some other genera. The most derived taxa of NE Africa, Duvaliandra and White-sloanea, are basal to this southern African clade. The other clades comprise the more basal genera of stem-succulent stapeliads, including the members of the Caralluma complex. Of the 17 genera accepted by Plowes for the Caralluma complex, seven are recognized: Caralluma, Apteranthes, Australluma, Boucerosia, Caudanthera, Desmidorchis and Monolluma. New combinations are proposed in 15 cases; Caralluma adscendens var. geniculata is raised to specific rank. Anomalluma is reinstated, and Pseudolithos mccoyi is transfered to it. A broadened concept for Orbea (incl. Angolluma and Orbeopsis) is recognized, but Orbeanthus is kept separate. The monotypic Ballyanthus, recently separated from Orbea, is nested within Duvalia. Piaranthus (incl. Huerniopsis) is monophyletic. The bitypic Notechidnopsis is reduced to the type species, N. tessellata, while N. columnaris is transferred to a new genus, Richtersveldia. Received February 25, 2002; accepted June 17, 2002 Published online: November 7, 2002 Address of the authors: Dr. Ulrich Meve (e-mail: ulrich.meve@uni-bayreuth.de) and Prof. Dr. Sigrid Liede (e-mail: sigrid.liede@uni-bayreuth.de), Universit?t Bayreuth, Lehrstuhl für Pflanzensystematik, Universit?tsstrasse 30, D-95440 Bayreuth, Germany.  相似文献   

11.
 Variation of 80 multistate morphological characters and isozymes encoded by 13 loci among 23 vetch species of the type subgenus of the genus Vicia in comparison with V. dumetorum, V. pisiformis and V. sylvatica of the subgenus Cracca is described and analyzed with cladistic parsimony and phenetic neighbour-joining methods by using two different ways of coding. Morphological analyses showed the subgenus Vicia monophyletic and revealed subgroups in a general agreement with traditionally recognized sections, except showing V. faba nested within section Narbonensis and ambiguity in the position of V. lathyroides and V. bithynica. Parsimony analysis of orthozymes as presence/absence characters revealed in the subgenus two basic monophyletic clades: 1) V. faba and three species of the section Peregrinae, V. michauxii, V. aintabensis and V. peregrina, in one subclade linked with species of the Narbonensis and Hyperchusa sections together with V. pisiformis of subgenus Cracca in a second subclade; 2) species belonging to sections Vicia, Sepium, Pseudolathyrus and Lathyroides together with V. sylvatica of the subgenus Cracca. Neighbour-joining analysis of orthozymes revealed the same two basic groups, differing only in the relative position of some species in subclusters. Both isozyme analyses showed paraphyly of the subgenera Vicia and Cracca. Parsimony analysis of orthozymes as character states of isozymes yielded a largely unresolved strict consensus cladogram of 209 most parsimonious trees, and reweighting of characters failed to produce a stable tree. Phylogenetic congruence and discordance among morphological and isozyme analyses, coding ways, homoplasy and weighting of characters are discussed. Received November 20, 2001 Accepted January 31, 2002  相似文献   

12.
A cladistic analysis based on morphological characters is presented for the Pyretophorus Series of subgenus Cellia of Anopheles. The cibarial armature was investigated for the first time since the pioneering work of Christophers (1933) , which is still used to define taxonomic series within Cellia, and for the first time ever using scanning electron microscopy. Christophers’ observations of characters of the cibarial armature were corroborated and several novel characters discovered. Despite difficulties in delimiting and encoding morphological characters at the species level, the analysis provided insights into relationships within the Pyretophorus Series. The data support the monophyly of the Series and establish the Oriental species as a monophyletic group. The Afrotropical species are basal and paraphyletic relative to the Oriental species, with Anopheles christyi placed in the most basal position. The pattern of relationships suggests that the capacity to transmit malaria is an ancestral condition subsequently lost independently in several lineages.  相似文献   

13.
Karyotypes are presented for 19 taxa of Eucharis, Caliphruria, and Urceolina, a monophyletic group of Andean Amaryllidaceae within “infrafamily” Pancratioidinae Traub. All three genera are characterized by 2n = 46, the most common somatic number occurring in the “infrafamily.” Incidences of polyploidy are low. Only two tetraploid (2n = 92) species of Eucharis are so far known, E. bouchei and E. bonplandii, the northernmost species of E. subg. Eucharis. The 2n = 68 karyotype of E. amazonica is interpreted as triploid-derived (3x – 1). Chromosomal heteromorphism is reported for C. subedentata. Karyotype data is analyzed with principal component analysis and unweighted pairgroup cluster analysis. In a number of cases, phenetic relationships among the karyotypes correlate with phenetic and cladistic relationships based on morphological data. Karyotype evolution among the three genera is discussed in the context of classical theories of karyotypic symmetry. Stability of chromosome number in Eucharis and related genera suggests that chromosomal evolution has proceeded via nonreciprocal interchanges between chromosomes and infrachromosomal structural change. In at least one case (E. bakeriana), rapid sympatric speciation may have been vectored by chromosomal change.  相似文献   

14.
The tribe Sonerileae in tropical Africa and Madagascar is a morphologically diverse lineage that consists of 239 species in 10 genera. In this study, we present the first in-depth phylogenetic analysis of African Sonerileae to test monophyly of the currently recognized genera. Phylogenetic analyses were performed using sequence data from two nuclear (nrITS and nrETS) and three plastid loci (accD-psaI, ndhF and psbK-psbL). Sampling consisted of 140 accessions including 64 African, 27 Malagasy, 46 Asian, and three neotropical Sonerileae together with a broad outgroup sampling (105 spp.). Phylogenetic relationships were inferred using maximum likelihood and Bayesian inference approaches, and a careful reassessment of morphological characters was carried out. Our results neither support the monophyly of the Old World nor African Sonerileae. The monospecific African genus Benna is partially supported as sister to Phainantha, one of the basal neotropical lineages, while African and Malagasy Medinilla are nested among the SE Asian genera. Gravesia (116 spp.), the most species-rich and morphologically diverse genus in Madagascar, is recovered as monophyletic. The African genera of Sonerileae Calvoa, Dicellandra, and Preussiella form well-supported clades. In contrast, Amphiblemma (including Amphiblemma molle) and Cincinnobotrys s.l. (including Cincinnobotrys felicis) are not monophyletic. To accommodate the caulescent C. felicis we propose reinstatement of the monospecific genus Bourdaria. For the distinctive A. molle a new genus Mendelia is described. Calvoa hirsuta is designated here as the type of genus Calvoa, lectotypes are designated for Medinilla engleri and Veprecella lutea, and a neotype is designated for Preussiella kamerunensis.  相似文献   

15.
 The phylogenetic distribution of two deletions, of about 350 and 250 bp respectively, within the chloroplast trnT–trnL intergenic spacer was examined. One deletion was found in all members of Cactaceae subfamily Cactoideae sampled, totaling 37 species, but not in taxa from other subfamilies or closely related families. The second was shared by a subset of Cactoideae comprising members of tribes Cereeae, Trichocereeae, and Browningieae (in part), as well as Harrisia. Close links among the former three South American tribes have been previously hypothesized. This distribution suggested that Browningieae, a tribe defined largely by shared primitive features, were not monophyletic, and that Harrisia may have been incorrectly placed outside the Browningieae–Cereeae–Trichocereeae group. Received June 12, 2001 Accepted October 26, 2001  相似文献   

16.
Jørgensen, A., Madsen, H., Nalugwa, A., Nyakaana, S., Rollinson, D., Stothard, J. R. & Kristensen, T. K. A molecular phylogenetic analysis of Bulinus (Gastropoda: Planorbidae) with conserved nuclear genes. —Zoologica Scripta, 40, 126–136. Mutational saturation of inspected DNA loci and topological incongruence in the phylogenetic inferences have previously confounded attempts to resolve the evolutionary relationships within the freshwater snail genus Bulinus. Traditionally, the 37 species of Bulinus are placed within the four species groups and the evolutionary divergence between groups is substantial. With an intention to shed new light on species group relationships, the present study was designed to investigate the basal divergences in the phylogeny of Bulinus using highly conserved nuclear genes. The resolved phylogeny inferred that the four species groups of Bulinus were monophyletic and Shimodaira‐Hasegawa topology tests found them to be significantly supported. The Bulinus truncatus/tropicus species complex and Bulinus wrighti (Bulinus reticulatus group) formed a well‐supported sister‐group relationship. The Bulinus africanus species group was the sister‐group to the clade (Bulinus truncatus/tropicus + B. wrighti) with the Bulinus forskalii species group as the sister‐group to these taxa. The sister‐group relationship between Indoplanorbis and Bulinus was non‐significant and the basal clade support of Bulinus improved upon exclusion of Indoplanorbis. The finding of basal long branches of Bulinus species originating from Madagascar strongly suggests the presence of additional cryptic species and an evolutionary scenario influenced by this island’s geological vicariance from the African mainland. Speciation by polyploidy was inferred to have evolved within a clade in the Bulinus truncatus/tropicus species complex. Although the monophyletic status of each species group was firmly supported, it was difficult to establish species group concepts equally across the variations and place this precisely in a specific temporal framework.  相似文献   

17.
Although the subfamily Zapodinae (Rodentia, Dipodidae) contains only five species, the phylogeny and taxonomy of these species are still being disputed. First, whether Eozapus and Napaeozapus should be treated as independent genera or subgenera of Zapus has been argued for a long period. Second, the subspecific genetic differentiation of Chinese jumping mouse (Eozapus setchuanus) has not been studied in detail, neither from morphological nor molecular aspects. In this study, the phylogenetic relationship among all the five species of Zapodinae was reconstructed using DNA sequence data from the mitochondrial cytochrome b gene and the nuclear interphotoreceptor retinoid binding protein gene. Bayesian inference, maximum parsimony and maximum likelihood analyses were conducted. The results showed that two major clades could be recognized within Zapodinae. Eozapus setchuanus, is the species endemic to China, strongly formed a monophyletic clade. In the other clade, genus Zapus received significant support in all analyses to be the sister group of the genus Napaeozapus. By comparing genetic distances among these three genera, we conclude that both Eozapus and Napaeozapus should be considered as valid genera rather than subgenera of Zapus. Furthermore, we observed that the two subspecies of E. setchuanus did not form reciprocally monophyletic groups, thus the traditional taxonomy which divided E. setchuanus into two subspecies based on only one morphological character was questionable.  相似文献   

18.
This paper presents the first phylogenetic analysis of Pachydeminae Reitter, 1902 ; one of the least known subfamilies of Melolonthidae, `leaf‐chafers' (Scarabaeoidea, Coleoptera). Some species of Pachydeminae have recently become agricultural pests in southern Spain. We analysed the phylogenetic relationships among 49 species belonging to 16 genera in the Palearctic region, based on a set of 63 morphological characters from the adult external morphology, wing anatomy, mouthparts and male and female genitalia. The last three sets of characters are described here for the first time. The phylogeny shows that the Palearctic Pachydeminae are monophyletic within the subfamily. Mouthparts and male and female genitalia provide the best synapomorphies for intergeneric relationships. In contrast, most of the external morphological characters used in the taxonomy of Pachydeminae are highly homoplastic. The phylogeny shows a basal split between the genera Hemictenius Reitter, 1897; Pachydema Castelnau, 1832, and the monospecific Peritryssus Reitter, 1918; and a second clade including the rest of genera. The remarkable Peritryssus is confirmed as a Pachydeminae, being the sister group to the monophyletic Hemictenius . Except for the position of P. rubripennis (Lucas, 1848) and P. zhora Normand, 1951, the phylogeny supports the monophyly of Pachydema but rejects the traditional division into species groups and the monophyly of the endemic Canarian species. In contrast, Tanyproctus Faldermann, 1835, must be rejected as polyphyletic. Otoclinius Brenske, 1896, is also probably polyphyletic (two new species synonymies), whereas Leptochristina Baraud and Branco, 1991 , is either mono‐ or paraphyletic. The two Mediterranean genera Ceramida Baraud, 1897, and Elaphocera Gené, 1836, form a monophyletic group, this clade being the best supported by the data set. Ceramida is clearly monophyletic, whereas Elaphocera is probably monophyletic except for E. barbara Rambur, 1843, which shares with Ceramida the character state for numerous mouthpart and genitalic characters. The phylogeny questions the generic status of the small and monospecific genera of Pachydeminae. The monotypic Alaia Petrovitz, 1980 , and Brenskiella Berg, 1898, are merged with Europtron Marseul, 1867, into one clade, whereas Atanyproctus Petrovitz, 1954, is grouped with some species of Tanyproctus , and the monotypic Pachydemocera Reitter, 1902 , is proposed as a junior synonym of Elaphocera .  相似文献   

19.
Abstract Chirita D. Don, a large genus in the subfamily Cyrtandroideae of Gesneriaceae, has been the subject of much debate whether it is a natural group or not. In addition, the highly heterogeneous Chirita has also been very problematic with regard to delimitation and subdivision. Here we used the nrDNA internal transcribed spacer and cpDNA trnL‐F for molecular phylogenetic analaysis, combined with morphological data. Our results suggest that Chirita is an artificial, polyphyletic genus. The most important character that defines Chirita, the dorso‐ventrally oblique and bilamellar stigma, has evolved convergently in different clades of diandrous Cyrtandroideae. Chirita sensu stricto only includes the species of Chirita sect. Chirita, whereas Chirita sect. Microchirita is an independent clade located at the basal node of the phylogenetic tree. Chirita sect. Liebigia is closely related to Didymocarpus with an entire stigma unlike other species of Chirita. The species of Chirita sect. Gibbosaccus, Chiritopsis, Primulina, and Wentsaiboea form a monophyletic group that is sister to a strongly supported clade comprising four monotypic genera Paralagarosolen, Calcareoboea, Petrocodon, and Tengia. We further analyzed the morphological evolution of Chirita and identified a series of morphological synapomorphies for the monophyletic groups revealed herein, and thereby provide a taxonomic treatment in this study.  相似文献   

20.
脆弱刚毛藻(Cladophora fracta)是一种大型丝状绿藻,生境分布广泛。然而,对于岩溶泉域分布的刚毛藻研究较少,它们的遗传多样性、生物地理亲缘性和生理特性都有待于深入研究。该研究对我国北方地区五个典型岩溶泉域的50个脆弱刚毛藻样本进行了形态学和分子系统学描述。主要研究目标:(1)对我国北方地区五个典型岩溶泉的刚毛藻生境进行描述;(2)根据形态学特征和分子序列对藻体进行鉴定;(3)探究生境对藻体生理特性的影响。结果表明:基于SSU和LSU序列的结果,发现所分析的50株刚毛藻个体为同一种,同时还发现了13个不同的核糖体基因型。基于SSU和LSU的系统发育树,刚毛藻属均未能形成单系分支,分布在三个不同的分支上。13个样本基因型在SSU和LSU树中的位置相似,与Cladophora vagabunda有很高的序列同源性,但是形态特征却差异很大。从显微结构结果来看,五个岩溶泉域采集到的刚毛藻在细胞直径上无显著差异,藻体的形态特征与脆弱刚毛藻相一致。但是,岩溶泉域采集的藻体细胞直径比文献报道中在湖泊和河流中采集的脆弱刚毛藻直径要大。另外,仅在两个地点(XA和ST)采集的标本中发现有假根状分枝。因此,基于形态学和分子序列的结果,将这五个泉域的刚毛藻鉴定为脆弱刚毛藻(Cladophora fracta)。  相似文献   

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