首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
蓑藓属(Macromitrium Brid.)是藓类植物中分类最困难的类群之一。先后该属记录946个种,现接受351个种。目前中美洲、亚洲、澳大利亚、新西兰等地区的蓑藓属植物基本完成了分类修订,而南美洲、非洲中部、马达加斯加等地区的蓑藓属植物尚未进行系统的分类修订。蓑藓属的属下分类系统问题众多,先后在该属下建立了10个亚属、20个组和2个亚组,目前接受的有4个亚属和8个组,但是这些类群之间的分类地位和关系仍然不清。鉴于蓑藓属种数多,种间分类问题多,分布广泛,需要开展国际间的合作才能够解决世界蓑藓属的分类修订和系统学研究。  相似文献   

2.
3.
4.
Phylogenetic reconstruction and species delimitation are often challenging in the case of recent evolutionary radiations, especially when postspeciation gene flow is present. Leopardus is a Neotropical cat genus that has a long history of recalcitrant taxonomic problems, along with both ancient and current episodes of interspecies admixture. Here, we employ genome-wide SNP data from all presently recognized Leopardus species, including several individuals from the tigrina complex (representing Leopardus guttulus and two distinct populations of Leopardus tigrinus), to investigate the evolutionary history of this genus. Our results reveal that the tigrina complex is paraphyletic, containing at least three distinct species. While one can be assigned to L. guttulus, the other two remain uncertain regarding their taxonomic assignment. Our findings indicate that the “tigrina” morphology may be plesiomorphic within this group, which has led to a longstanding taxonomic trend of lumping these poorly known felids into a single species.  相似文献   

5.
6.
The taxonomy of treeshrews (Order Scandentia) has long been complicated by ambiguous morphological species boundaries, and the treeshrews of the Palawan faunal region of the Philippines are no exception. Four named forms in the genus Tupaia Raffles, 1821, have been described from four island groups based on subtle qualitative morphological characters, and as many as three distinct species have been recognized. A recent molecular phylogenetic study of relationships among Tupaia species suggests that the two currently-recognized treeshrew species from the Palawan faunal region diverged very recently relative to other sister-species divergences within the genus and may not represent species-level taxonomic entities. Here we review the taxonomic and biogeographic histories of the Tupaia taxa from this region. We also collected craniodental data from 133 skulls of all four named forms, representing five island populations, and conducted univariate and multivariate analyses on these data. Our morphometric results are consistent with molecular results, further suggesting that there is insufficient evidence to recognize T. moellendorffi Matschie, 1898, as a separate species from T. palawanensis Thomas, 1894. Our analyses also revealed a craniodentally divergent population from the island of Balabac, which has never been considered a distinct subspecies (or species) from the population on Palawan. These results have conservation implications for the island populations in our analyses, but additional surveys and molecular evidence will be required to fully assess conservation priorities for the treeshrews of the Palawan faunal region.  相似文献   

7.
Salix L. is the largest genus in the family Salicaceae (450 species). Several classifications have been published, but taxonomic subdivision has been under continuous revision. Our goal is to establish the phylogenetic structure of the genus using molecular data on all American willows, using three DNA markers. This complete phylogeny of American willows allows us to propose a biogeographic framework for the evolution of the genus. Material was obtained for the 122 native and introduced willow species of America. Sequences were obtained from the ITS (ribosomal nuclear DNA) and two plastid regions, matK and rbcL. Phylogenetic analyses (parsimony, maximum likelihood, Bayesian inference) were performed on the data. Geographic distribution was mapped onto the tree. The species tree provides strong support for a division of the genus into two subgenera, Salix and Vetrix. Subgenus Salix comprises temperate species from the Americas and Asia, and their disjunction may result from Tertiary events. Subgenus Vetrix is composed of boreo-arctic species of the Northern Hemisphere and their radiation may coincide with the Quaternary glaciations. Sixteen species have ambiguous positions; genetic diversity is lower in subg. Vetrix. A molecular phylogeny of all species of American willows has been inferred. It needs to be tested and further resolved using other molecular data. Nonetheless, the genus clearly has two clades that have distinct biogeographic patterns.  相似文献   

8.
9.
Bythinella is a species-rich genus of spring-snails, having a wide range in Europe and Asia Minor. The genus contains several endemic species with narrow ranges, creating interest from a conservation perspective as well as their use as a model for research into biogeographical patterns and evolutionary development. Most of the species of the genus Bythinella are difficult to distinguish by traditional methods due to their similar shell morphology. In previous studies, molecular approaches often came to conclusions that contradicted those from a morphology-based approach, hence the classification of species of Bythinella has been in dispute. Bythinella pannonica has clearly distinct shell morphological features, and consequently is one of the few species of undisputed taxonomic status within this genus. As an important step towards clarifying the systematics of this genus, we have attempted to describe the structure and spatial pattern of diversity of the mitochondrial COI marker within this species, in the hope of applying these findings generally to the whole genus. Molecular results support the monophyly of B. pannonica within the genus. The largest pairwise intraspecific COI sequence difference was almost 5 %, much larger than the value of 1.5 % previously proposed as a barcoding threshold for delimitation of Bythinella species. This finding suggests that incautious application of barcoding might lead to incorrect taxonomic conclusions. Within B. pannonica there are two deeply divergent intraspecific clades, the spatial distribution of which has been shaped by fragmentation, as well as by short and long distance dispersal events. These two clades have not been found syntopically but, as a peculiar feature of this taxon, they are able to persist in nearby habitats. We have demonstrated that the patchy distribution of suitable habitats and the restricted, but non-zero gene flow amongst the populations might play a key role in maintenance of the observed genetic structure of this species.  相似文献   

10.
11.
The polymorphic genus Petaurista includes a group of diverse species and subspecies that are adapted for gliding and arboreal life. This morphological diversity has resulted in taxonomic discrepancies, and molecular phylogenetic studies have been limited by taxon sampling. To clarify this controversial taxonomy, we used the cytochrome b gene to reconstruct the phylogeny to obtain a more accurate picture of the evolutionary relationships, species differentiation and divergence pattern of Petaurista. The results revealed a significant inconsistency between taxonomic designations, phylogeny and genetic distances. When 6 recognized species were included, species delimitation revealed 15 putative species, a finding that warrants a comprehensive morphological diagnosis and a re-assessment of the species status. The validity of P. caniceps and P. marica was discussed. An estimation of the molecular divergence time demonstrated that the diversification and speciation of Petaurista began during the later Miocene and may have been affected by the uplifting of the Qinghai-Tibet plateau and subsequent climate change.  相似文献   

12.
In the past few decades, in the marine realm in particular, the use of molecular tools has led to the discovery of hidden taxonomic diversity, revealing complexes of sister species. A good example is the red algal genus Asparagopsis. The two species (A. armata and A. taxiformis) recognized in this genus have been introduced in many places around the world. Within the nominal species A. taxiformis, previous molecular analyses have uncovered several lineages, suggesting the existence of sister species or subspecies. Although the genus has been well studied in some regions (e.g., the Mediterranean Sea and Hawaii), it remains poorly investigated in others (e.g., South Pacific). Our study mainly focused on these latter areas to clarify lineages and better determine lineage status (i.e., native vs. introduced). A total of 188 specimens were collected from 61 sites, 58 of which had never been sampled before. We sequenced the DNA from samples for three markers and obtained 112 sequences for the chloroplastic RuBisCo spacer, 118 sequences for the nuclear LSU rRNA gene, and 174 for the mitochondrial spacer cox2-3. Phylogenetic analyses using all three markers suggested the existence of two cryptic sister species with the discovery of a new clade within A. armata. This clade was found only in Western Australia, Tasmania and New Zealand, and is thus restricted to a subregional biogeographic unit. We also discovered a new, fifth lineage for A. taxiformis restricted to the South Pacific and Western Australia. Except for this newly described lineage, all other lineages showed a global distribution influenced by introduction events. These results illustrate the difficulty in accurately defining cosmopolitan species. Our findings also highlight the need for targeted (i.e., in poorly studied areas) and geographically extensive sampling efforts when studying taxa that have been introduced globally and that are likely to hide species complexes.  相似文献   

13.
14.
The European bone-skippers (Diptera: Piophilidae: Thyreophorina), long considered extinct, have recently been the object of much interest by dipterists after their unexpected rediscovery. Considerable faunistic work has been done on these flies in recent years. However, some nomenclatural and taxonomic issues still require attention. A neotype is designated for Thyreophora anthropophaga Robineau-Desvoidy, 1830 (now in the genus Centrophlebomyia Hendel, 1903) to fix the identity of this nominal species. Centrophlebomyia anthropophaga is recognized as a valid species. It is described and illustrated in detail, and information on its preimaginal instars is provided for the first time. Four Palaearctic species of Centrophlebomyia are recognized and reviewed and a key is provided for their identification. Centrophlebomyia orientalis Hendel, 1907 from northern India, is removed from synonymy with Centrophlebomyia anthropophaga and recognized as a valid species of Centrophlebomyia, stat. r. The nominal genus Protothyreophora Ozerov, 1984 is considered a junior synonym of Centrophlebomyia, syn. n.  相似文献   

15.
The six species and three subspecies in the genus Chimarrogale (Soricomorpha: Soricidae) are commonly referred to as Asiatic water shrews. The Chimarrogale are the most widely distributed group of Nectogaline shrews, extending throughout the Oriental region and Japan. Because of the limited numbers of specimens available for study, the phylogenetic relationships and biogeographical history of this genus have not been comprehensively discussed. We used mitochondrial cytochrome b gene sequences to estimate phylogenetic relationships and divergence times among four Chimarrogale species, including all three subspecies of Chimarrogale himalayica. We also conducted a species delimitation analysis and tested two alternative migration scenarios in Asia through species distribution modeling and a reconstruction of the ancestral distribution. Here, we present the first proposed hypothesis regarding the Asiatic water shrew phylogeny and reveal ten putative species within the four recognized species. Distinct phylogenetic statuses of Chimarrogale phaeura, Chimarrogale platycephala, and Chimarrogale styani were confirmed. Chimarrogale himalayica was strongly supported as paraphyletic. We suggest that three subspecies of Chimarrogale himalayica should be reconsidered as distinct species. However, these suggestions must be considered with caution because only a single locus of a mtDNA gene was used. Four additional putative species, possibly distributed in central southwestern China and Taiwan, are currently undescribed; therefore, comprehensive morphological analyses are warranted to test their taxonomic statuses. The estimated molecular divergence times indicated that rapid speciation occurred during the early Pliocene, and current distribution patterns may have been affected by global cooling during the Pliocene/Pleistocene boundary. Reconstruction of the ancestral distribution and species distribution modeling for Asiatic water shrews revealed a low-latitude migration route over which ancestral Chimarrogale migrated from Europe via Central Asia to their current distribution. Our results demonstrated that Asiatic water shrews could have evolved throughout the low-latitude migration route from Europe to East and Southeast Asia.  相似文献   

16.
African Grass Rats of the genus Arvicanthis Lesson, 1842, are one of the most important groups of rodents in sub‐Saharan Africa. They are abundant in a variety of open habitats, they are major agricultural pests, and they became a popular model in physiological research because of their diurnal activity. Despite this importance, information about their taxonomy and distribution is unsatisfactory, especially in eastern Africa. In this study, we collected the most comprehensive multilocus DNA dataset to date across the geographic and taxonomic range of the genus (229 genotyped specimens from 130 localities in 16 countries belonging to all currently recognized species). We reconstructed phylogenetic relationships, mapped the distribution of major genetic clades, and used the combination of cytogenetic, nuclear, and mitochondrial markers for species delimitations and taxonomic suggestions. The genus is composed of two major evolutionary groups, called here the ANSORGEI and NILOTICUS groups. The former contains four presumed species, while the latter is more diverse and we recognized nine species. Most relationships among species are not resolved, which suggests a rapid radiation (dated to early–middle Pleistocene). Further, there is an indication of reticulate evolution in Ethiopia, that is, the region of the highest Arvicanthis diversity. The distribution of genetic diversity suggests diversification in eastern Africa, followed by repeated dispersals to the west (Sudano‐Guinean savannas) and to the south (Masai steppe). We propose nomenclatural changes for Ethiopian taxa and provide suggestions for future steps toward solving remaining taxonomic questions in the genus.  相似文献   

17.
An actinobacterial strain YIM 80766T was isolated from a soil sample collected from the eastern desert of Egypt, and its taxonomic position was investigated by a polyphasic approach. The organism was found to have a range of chemical and morphological properties consistent with its classification in the genus Dietzia. Phylogenetic analysis indicated that the levels of 16S rRNA gene sequence similarity between strain YIM 80766T and the other type strains of recognized members of the genus Dietzia were 97.0–98.9%. However, DNA–DNA hybridization values and phenotypic characteristics revealed that the strain differed from the currently recognized species of the genus Dietzia. Therefore, strain YIM 80766T represents a novel species of the genus Dietzia, for which the name Dietzia lutea sp. nov. is proposed. The type strain is YIM 80766T (=KCTC 19232T=DSM 45074T=CCTCC AA 207008T). The 16S rRNA gene sequence of strain YIM 80766T has been deposited in GenBank under the accession number EU821598.  相似文献   

18.
Twenty-seven species of the genus Coleophora Hübner (Lepidoptera, Coleophoridae) are recognized in the Korean peninsula, including seven species that are new to Korea: C. albicans Zeller, C. falkovitshella Vives, C. honshuella Baldizzone & Oku, C. japonicella Oku, C. kononenkoi Baldizzone & Savenkov, C. rectimarginalis Li, and C. vestianella (Linnaeus). For all known species, bibliographies, collecting localities, distribution, biological information, and some taxonomic notes are provided, with illustrations of the male or the female genitalia.  相似文献   

19.
Alkaloidal profiles of 21 Lupinus species indigenous to North and South America have been determined. Nineteen quinolizidine alkaloids were identified, including aphyllidine and N-methylcytisine, which have not previously been found in the genus. Two dipiperidine alkaloids were also detected. The pattern of alkaloidal distribution is related to a taxonomic classification of the genus.  相似文献   

20.
A taxonomic revision of the neotropical genusAsterogyne Hook. (Arecaceae: Arecoideae: Geonomeae) is presented. The genus is characterized by one autoapomorphic character, the separation of anther thecae by a bifid connective, and the combination of small to medium-sized stems, bifid simple leaf blades, floral pits in bud covered by a rounded upper lip that overlaps a lower lip, and pistillate flowers with staminodial lobes that are displayed in a starlike shape. Five species are recognized in this treatment: one of them (Asterogyne martiana) is widely distributed from Belize in Central America to northern Ecuador, three species (A. ramosa, A. spicata, andA. yaracuyense) are endemic to small areas in the Venezuelan Coastal Range, and one species (A. guianensis) is endemic to eastern French Guiana. The taxonomic history, morphology, reproductive biology, distribution and ecology, intrageneric relationships, and conservation status are reviewed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号