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There are over 100 species in the Order Clevelandellida distributed in many hosts. The majority is assigned to one of the five families, the Nyctotheridae. Our knowledge of clevelandellid genetic diversity is limited to species of Nyctotherus and Nyctotheroides. To increase our understanding of clevelandellid genetic diversity, species were isolated from intestines of the Australian wood‐feeding roach Panesthia cribrata Saussure, 1864 from August to October, 2008. Four morphospecies, similar to those reported in Java and Japan by Kidder [Parasitologica, 29 :163–205], were identified: Clevelandella constricta, Clevelandella nipponensis, Clevelandella parapanesthiae, and Clevelandella panesthiae. Small subunit rRNA gene sequences assigned all species to a “family” clade that was sister to the clade of species assigned to the Family Nyctotheridae in the Order Clevelandellida. Genetics and morphology were consistent for the first three Clevelandella species, but isolates assigned to C. panesthiae were assignable to three different genotypes, suggesting that this may be a cryptic species complex.  相似文献   

3.
The broadly distributed genus Hyalopterus currently comprises three formally recognized species that are highly similar morphologically and hence difficult to be identified with certainty. This group has undergone multiple revisions in the past century, but none of these has assessed species from Asia, which has hampered our understanding of the species diversity within this genus. Based on a comprehensive data set from morphological data and host-associated data, and by coalescent-based delimitation approaches, the Hyalopterus species boundaries, distribution and diversity were clarified here to further reveal the composition of the species. Two single-locus (ML-GMYC and mPTP) and two multilocus (BPP and STACEY) delimitation methods were conducted based on extensive sampling. Then, the phylogenetic relationships and morphological divergence were assessed. Our data strongly supported that the number of recognized species in Hyalopterus had likely been underestimated. The phylogenetic analyses recovered four major clades, which corresponded to distinct host-plant preferences. Also, the morphological analyses showed significant differentiation for only one of the newly recognized candidate species uncovered by the delimitation approaches, suggesting the existence of at least two independent evolutionary lineages within Hyalopterus arundiniformis, which showed different patterns of host association. Moreover, based on our data, the taxonomic misidentification of H. arundiniformis in China was corrected here. This study lays the groundwork for the thorough taxonomic revision of Hyalopterus and for future evolutionary studies and underlines the importance of an integrated framework for species determination.  相似文献   

4.
The legume family is so well represented in the Caribbean that if a preserve was needed somewhere on earth to harbor all of the primary lineages in this family, the flora of just Cuba would suffice. Molecular phylogenetic, biogeographic, and evolutionary rates analysis all suggest that legume diversity and endemism in the Caribbean are mostly of recent origin and are likely a function of the abundance of seasonally dry tropical forests (SDTFs) throughout the neotropics. Legumes have a strong ecological affinity for SDTFs, and the Caribbean basin is well covered by this forest type. Rate-variable molecular clock analysis suggests that the majority of worldwide island lineages of legumes have ages of much less than 30 Ma. Singular historical events invoking land bridges or mobile continental plates are thus not needed to explain Caribbean legume diversity and endemism. The Greater Antilles are large islands located close to the American continent. They are therefore expected to fairly represent the diverse continental lineages of legumes. Yet, they are distant enough to be dispersal limited. As such, island lineages can speciate and diversify over evolutionary time unimpeded by high rates of immigration from the mainland. Vicariance and other standard phylogenetic methods of historical biogeography are likely to be replaced by those of ecological and island biogeography. This is because model selection approaches derived from the neutral concept of isolation by distance will be able to quantify patterns of alpha and beta diversity and detect niche assembly and phylogenetic niche conservatism within and among metacommunities that are hypothesized to constrain phylogeny.  相似文献   

5.
Abstract Aims Ants (Hymenoptera: Formicidae) of the Baja California peninsula are poorly known, with information based largely on scattered museum and literature records. We provide the first comprehensive account of ant species occurring on the peninsula, we examine distribution patterns, and we assess the ‘peninsular effect’ which predicts that species richness declines from the base to the tip of a peninsula. Location Peninsula of Baja California, Mexico. Methods Data collection involved examining, identifying and recording label data from c. 2350 series of ants. These records provide a provisional, if incomplete, species list. We applied the incidence‐based estimator, Chao‐2, to our data base of specimen records to estimate the total number of ant species on the peninsula. We assessed endemism by comparing our peninsular species list to those from adjacent states. The peninsular effect was tested by comparing genus and species level richness between the two states of Baja California, and across five latitudinal blocks. Results We document 170 native ant species in thirty‐three genera, plus six non‐native species, in Baja California. It seems likely that additional species remain to be discovered: the Chao‐2 estimator of species richness, at 206.0 species, is about 20% higher than our observed species richness. About 30% of the species and 20% of the genera are restricted within Baja California to the relatively mesic California Floristic Province of north‐western Baja California. Nearly all of these species also occur in California. Forty‐seven species (27.6%) are peninsula endemics. Using our entire data set, the peninsular effect appears to be strong, with about twice as many species in the northern state of Baja California than are recorded from the southern state of Baja California Sur; the ratio of genera is 33 to 24. However, this effect becomes weak at the species level and absent at the genus level when minimizing habitat effects by omitting species restricted to the California Floristic Province. At a finer scale, across latitudinal blocks of about 1.9°, the number of species declines towards central portions of the peninsula and then increases in the Cape Region. Nine ant species display strongly disjunct distributions, and these occur in two general patterns: peninsula disjuncts and peninsula–mainland disjuncts. Main conclusions The Baja California peninsula supports a diverse and distinctive ant fauna, with the proportion of endemic species similar to that displayed by plants. Patterns of species and genus richness across the five latitudinal blocks provide poor support for the peninsular effect. Moreover, habitat diversity, especially that related to topographic relief, appears to be the most important factor affecting the gradient of ant species richness in Baja California. Additional collections are needed to develop a more complete species list and to determine the boundaries and status of many species. Nevertheless, the present data base provides a useful starting point for understanding the evolution of ant assemblages in Baja California and for comparison with peninsular patterns in other taxa.  相似文献   

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This study investigated the range-wide phylogenetics and biogeography of the Cape kurper Sandelia capensis, a primary freshwater fish endemic to and widespread within the Cape Floristic Region (CFR) of South Africa. Maximum likelihood, Bayesian phylogenetic and haplotype network analyses, based on two mitochondrial and two nuclear genes, revealed the existence of three reciprocally monophyletic, deeply divergent and allopatric clades that probably represent cryptic species. The West Coast Clade is largely confined to the Langvlei, Verlorenvlei, Berg and Diep Rivers, the Klein River Clade is endemic to the Klein River and the South Coast Clade is found everywhere else in the range of S. capensis sensu lato. It was hypothesised that divergences within S. capensis sensu lato probably occurred because of isolation of coastal drainages by persistent drainage divides or vicariance of current tributaries by the drowning of their confluences by high sea levels. The current distribution of lineages could be due to historical range expansion and gene flow via river capture or some other mode of transdivide dispersal or dispersal during periods of low sea level via palaeoriver confluences of currently isolated coastal rivers. Comparison of BEAST2 estimated divergence times with the timing of climatic, geological and geomorphological events supported long-term coastal drainage isolation, punctuated by rare transdivide dispersal events and limited palaeoriver dispersal, as the best explanation of current phylogeographic and divergence patterns in S. capensis. Hydrological barriers that block upstream passage in palaeotributaries could hypothetically explain why S. capensis failed to disperse through certain palaeoriver confluences. There were several sites where biogeographic patterns have likely been confounded by human translocation of S. capensis. Alien fish predators and water extraction may threaten the three cryptic species more severely than previously realised, due to their smaller population sizes and inhabitation of only a portion of the range previously ascribed to S. capensis sensu lato. The preponderance of cryptic diversity and endemism in the CFR suggests that additional undescribed cryptic species of obligate freshwater fishes may be found in short coastal river systems around the world, especially in regions with a history of geological stability and a narrow continental shelf.  相似文献   

8.
The morphological and molecular differentiation of the Micrasterias truncata (Corda) ex Bréb species complex was investigated. In total, 17 strains traditionally assigned to M. truncata were isolated from different European localities (Czech Republic, southwest France, Ireland), and obtained from public culture collections. In addition, strains of the morphologically similar species, M. decemdentata (Nägeli) W. Archer and M. zeylanica F. E. Fritsch, were also included. Molecular phylogenetic analysis based on trnGucc intron sequences revealed five well supported clades. Two Australian strains assigned to M. truncata var. pusilla G. S. West formed a lineage sister to M. zeylanica. This was evident from a concatenated phylogeny based on small subunit rDNA and trnGucc intron sequences. The isolated position of these strains was also illustrated by parallel landmark‐based geometric morphometric analysis of cell shapes. The strains NIES 783 and NIES 784 probably represent a separate species. Particular analysis, including additional strains, is needed to resolve the relationship inside this lineage. The second phylogenetic lineage, containing two strains of M. truncata var. semiradiata (Kützing) Wolle, was also different from other strains on the basis of morphometric data. We suggest recognizing this variety as a separate species, Micrasterias semiradiata L.A. Brébisson ex F. T. Kützing. The remaining three clades formed a firmly supported group of the ‘core’M. truncata recognized by both molecular markers. However, neither any morphological, morphometric, nor geographical pattern was detected among members of these three clades. This pattern could be caused by a relatively recent origin of these lineages that may represent a sympatric, truly cryptic species. Strains attributable to traditional morphologically defined variety M. truncata var. neodamensis were nested within the ‘core’M. truncata.  相似文献   

9.
The brown alga Lobophora (Dictyotales, Phaeophyceae) is an important macroalga in the North-eastern Atlantic archipelagos (i.e., Macaronesia). Notably in the Canaries it can dominate benthic assemblages. While the genus has been the subject of several ecological studies in the Canaries, no study has yet been conducted to assess species-level diversity of Lobophora in Macaronesia. We reassessed the diversity of Lobophora in Macaronesia, reporting the presence of seven species (L. caboverdeana sp. nov., L. canariensis, L. dagamae sp. nov., L. delicata, L. dispersa, L. littlerorum, and L. schneideri). Lobophora spp. from Macaronesia are morphologically and ecologically distinguishable. In the Canaries, L. schneideri dominates the photophilic assemblages from the intertidal to 20-30 m depth. Lobophora dagamae sp. nov. grows in less illuminated shallow habitats, and replaces L. schneideri from 30 to ~80 m. Lobophora canariensis also has a wide vertical distribution, from the intertidal to deep waters, while L. delicata, L. dispersa and L. littlerorum grow in shallow waters. The dominance of species with an upright habit versus prostrate or crustose species may be mediated by the pressure of herbivores. Four species have an amphi-Atlantic distribution: L. littlerorum, L. canariensis, L. delicata, and L. schneideri. Lobophora schneideri and L. delicata are furthermore distributed in the Mediterranean Sea. By sampling a pivotal region in the Atlantic, this study significantly improves our knowledge of Lobophora biogeography in the Atlantic Ocean. Macaronesia constitutes a species–poor region for Lobophora where no diversification events occurred, and a region of overlap between the Greater Caribbean and the Indo-Pacific.  相似文献   

10.
There has been much recent interest and progress in the characterization of community structure and community assembly processes through the application of phylogenetic methods. To date most focus has been on groups of taxa for which some relevant detail of their ecology is known, for which community composition is reasonably easily quantified and where the temporal scale is such that speciation is not likely to feature. Here, we explore how we might apply a molecular genetic approach to investigate community structure and assembly at broad taxonomic and geographical scales, where we have little knowledge of species ecology, where community composition is not easily quantified, and where speciation is likely to be of some importance. We explore these ideas using the class Collembola as a focal group. Gathering molecular evidence for cryptic diversity suggests that the ubiquity of many species of Collembola across the landscape may belie greater community complexity than would otherwise be assumed. However, this morphologically cryptic species-level diversity poses a challenge for attempts to characterize diversity both within and among local species assemblages. Recent developments in high throughput parallel sequencing technology, combined with mtDNA barcoding, provide an advance that can bring together the fields of phylogenetic and phylogeographic analysis to bear on this problem. Such an approach could be standardized for analyses at any geographical scale for a range of taxonomic groups to quantify the formation and composition of species assemblages.  相似文献   

11.
A cryptic species of the Tetrahymena pyriformis complex, Tetrahymena australis, has been known for a long time but never properly diagnosed based on taxonomic methods. The species name is thus invalid according to the International Code of Zoological Nomenclature. Recently, a population isolated from a freshwater lake in Wuhan, China was investigated using live observations, silver staining methods and gene sequence data. This organism can be separated from other described species of the T. pyriformis complex by its relatively small body size, the number of somatic kineties and differences in sequences of two genes, namely the small subunit ribosomal RNA (SSU rRNA) and the mitochondrial cytochrome c oxidase subunit I (cox1). We compared the SSU rRNA gene sequences of all available Tetrahymena species to reveal the nucleotide differences within this genus. The sequence of the Wuhan population is identical to two sequences of a previously isolated strain of T. australis (ATCC #30831). Phylogenetic analyses indicate that these three sequences (X56167, M98015, KT334373) cluster with Tetrahymena shanghaiensis (EF070256) in a polytomy. However, sequence divergence of the cox1 gene between the Wuhan population and another strain of T. australis (ATCC #30271) is 1.4%, suggesting that these may represent different subspecies.  相似文献   

12.
Measures of biodiversity are often hindered by a lack of methodological practices that distinguish cryptic or morphologically similar cohabiting species. This is particularly difficult for marine fishes where direct observations of the ecology and demography of populations are difficult. Dragonets (Foetorepus c.f. calauropomus) were collected as bycatch from research trawls deployed in waters off north-eastern Tasmania, Australia. Morphometric and genetic analyses were conducted on the 43 specimens recovered. Sequence analysis of two mitochondrial loci distinguished three genetic clusters, each having levels of dissimilarity consistent with species-level distinctions between other members of the Callionymidae. While clear morphological distinctions were observed between male and female fish, limited morphometric analyses could not differentiate between members of the three genetic groups. This finding highlights questions about the ability of genetically distinct but morphologically similar groups to occupy the same ecological niche, and points to additional and undescribed hidden biodiversity amongst cryptic species of fish.  相似文献   

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The highly conserved P3-P7 domain of the Group I intron ribozymes is known to contain essential elements, such as the binding site for the cofactor guanosine, required for conducting the splicing reaction. We investigated the domain of the Tetrahymena intron ribozyme and its variants in order to clarify the relationship between its stability and function. We found that the destabilization of the P3-P7 domain facilitates the active structure formation at high magnesium ion concentrations where the formation is retarded for the wild type. The destabilized domain also increases K(GTP)(m) although this can be compensated by increasing the concentration of Mg(2+), indicating that the stable domain is required for establishing a tight guanosine binding site. The results suggest that the stability of the domain affects the rate-limiting step in the RNA folding pathway and also regulates the efficiency of the splicing reaction.  相似文献   

15.
以ND4L和ND4基因为标记探讨黑腹果蝇种组的系统发育关系   总被引:2,自引:0,他引:2  
多年来的形态学、染色体组学以及DNA序列几个方面的研究均没有很好地阐明黑腹果蝇种组内的系统发育关系。本实验测定了33个样品的ND4和31个样品的ND4L基因序列,以D.obscuroides为外群,用最大简约法和Bayesian法分别构建进化树。结果表明两种方法构建的拓扑结构一致,而且大部分支系的支持率较高。整个黑腹果蝇种组分成三大谱系:1)montium种亚组;2)ananssae种亚组;3)Oriental种亚组(melanogaster、ficsphila、eugracilis、elegans、suzukii、takahashii)。montium是最早分化的种亚组。在第三谱系中,melanogaster分化得最早;然后依次是ficsphila,eugracilis,elegans;suzukii与takahashii为姐妹种亚组,最后分化。  相似文献   

16.
Chlorella Beijerinck (Chlorellaceae, Trebouxiophyceae) strains from the collection of the National Institute for Environmental Studies (NIES) were characterized using gene sequence data. The misidentification of a number of strains was rectified. Chlorella vulgaris Beijerinck NIES‐2173 was reclassified as C. sorokiniana Shihira et Krauss. Chlorella sp. NIES‐2171 was described as a new species in the genus Micractinium Fresinius, M. inermum Hoshina et Fujiwara. Chlorella sorokiniana NIES‐2167 and Chlorella sp. NIES‐2330 were found to be phylogenetically related to Didymogenes Schmidle. We propose these two strains be transferred to the genus Didymogenes and given new names: D. sphaerica Hoshina et Fujiwara and D. soliella Hoshina et Fujiwara. Taxonomic decisions were primarily based on small subunit‐internal transcribed spacer ribosomal DNA phylogeny for genus assignment and ITS2 sequence‐structure to determine species autonomy. Our findings suggest that this strategy is the most effective way to use the species concept among autosporic coccoids.  相似文献   

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We studied group I introns in sterile cultures of selected groups of lichen photobionts, focusing on Trebouxia species associated with Xanthoria s. lat. (including Xanthomendoza spp.; lichen‐forming ascomycetes). Group I introns were found inserted after position 798 (Escherichia coli numbering) in the large subunit (LSU) rRNA in representatives of the green algal genera Trebouxia and Asterochloris. The 798 intron was found in about 25% of Xanthoria photobionts including several reference strains obtained from algal culture collections. An alignment of LSU‐encoded rDNA intron sequences revealed high similarity of these sequences allowing their phylogenetic analysis. The 798 group I intron phylogeny was largely congruent with a phylogeny of the internal transcribed spacer region, indicating that the insertion of the intron most likely occurred in the common ancestor of the genera Trebouxia and Asterochloris. The intron was vertically inherited in some taxa, but lost in others. The high‐sequence similarity of this intron to one found in Chlorella angustoellipsoidea suggests that the 798 intron was either present in the common ancestor of Trebouxiophyceae, or that its present distribution results from more recent horizontal transfers, followed by vertical inheritance and loss. Analysis of another group I intron shared by these photobionts at small subunit position 1512 supports the hypothesis of repeated lateral transfers of this intron among some taxa, but loss among others. Our data confirm that the history of group I introns is characterized by repeated horizontal transfers, and suggests that some of these introns have ancient origins within Chlorophyta.  相似文献   

19.
The matrilineal genealogy of the genus Paramesotriton is hypothesized based on DNA sequences from mitochondrial NADH subunit two (ND2) and its flanking tRNAs (tRN^Arp and a partial tRNA^Ala). The genealogy identifies a highly divergent, unnamed lineage from Qixiling Nature Reserve, Jiangxi, China and places it as the sister taxon of P. chinensis. The newly discovered population differs from other congeners by several features of external morphology including having large clusters of dark brown conical warts on the dorsum of the head, lateral surface of the body and dorsolateral ridges. Its intermittent dorsal vertebral ridge is the same color as other parts of the dorsum and tail narrows gradually from the base to the tip. Further, the new population differs from all congeners by an uncorrected P-distance of more than 9.38% in ND2. Consequently, we describe the new species of Asian warty newt (Salamandridae) as Paramesotriton qixilingensis sp. nov.  相似文献   

20.
The fraterculus species group, composed of 34 species in the genus Anastrepha (Diptera: Tephritidae), includes the fraterculus cryptic species complex formed by eight reproductively isolated morphotypes. A previous study revealed six genetic mitochondrial types of Anastrepha obliqua, suggesting the existence of a second cryptic species complex. However, marked discrepancies between nuclear and mitochondrial loci rather suggest incomplete lineage sorting or introgression between A. obliqua and A. fraterculus. Such hybridization could nevertheless result in reproductive isolation, an outcome that could affect efficacy of area‐wide management for the most important pest of mangos in America. Two mitochondrial types occur in Mexico, and the limits of a third one, encompassing Central American populations, have not been clearly established. Here, we tested reproductive compatibility among three A. obliqua populations from the Pacific and a population from the Gulf of Mexico. No evidence of pre‐zygotic isolation was found. Flies from the Atlantic mated randomly for equal duration with individuals from three Pacific populations. Homotypic and heterotypic crosses produced similar numbers of eggs, with heterotypic crosses of Pacific males and Atlantic females hatching in lower proportions. Larvae of all cross types developed equally in mangos and exhibited no sex ratio distortion of hybrid F1. The three mitochondrial types identified in Mexico and Central America do not appear to be cryptic species and can be managed using one single strain for the sterile insect technique.  相似文献   

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