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 383 毫秒
1.
We describe a new cliff-dwelling species within Sonchus (Asteraceae): Sonchus boulosii and analyze its systematic position and evolutionary significance; in addition, we provide a key to the species of Sonchus in Morocco. Both morphological and ecological characteristics suggest a close relationship of S. boulosii with taxa of section Pustulati. However, ITS nrDNA and cpDNA matK markers indicate its uncertain position within the genus, but clear genetic differentiation from the remaining major clades. ITS phylogenetic trees show that likely evolutionary shifts to rocky habitat took place at least five times within genus Sonchus and that sect. Pustulati and S. boulosii clades have a clearly independent evolutionary origin. We postulate that the strong resemblance of S. boulosii to other rocky species reflects a phenomenon of homoplasy, probably driven by parallel evolutionary adaptations to the severe ecological constraints of its cliff face habitat. Therefore, a new section is also described, which includes S. boulosii as its sole representative: section Pulvinati. According to phylogenetic trees, the new clade may share its common ancestor with the clade comprising sections Maritimi and Arvenses, from which it is widely divergent in morphology and ecology, with the exception of Sonchus novae-zelandiae. However, the latter is a derived taxon, with high level of polyploidy unlike S. boulosii that shows 2n?=?18, basal chromosome number of the genus. Since sections Pulvinati and Pustulati seem to be quite old in Sonchus, we also hypothesize that some similarities, such as fruit morphology, may reflect the persistence of some primitive characteristics.  相似文献   

2.
3.
The genus Imbira Carbayo et al., 2013 encompasses two species, Imbira guaiana (Leal-Zanchet & Carbayo, 2001) and Imbira marcusi Carbayo et al., 2013, which occur in south Brazil, in areas originally covered by the Atlantic Forest. In the present study, we examine the genetic diversity within the genus, investigate the occurrence of molecular autapomorphies for its species and describe a new species for the genus based on an integrative approach. The Bayesian and maximum likelihood analyses based on DNA barcoding recovered the monophyly of the genus Imbira, but indicate that specimens representing I. marcusi correspond to five distinct lineages. These analyses, as well as sequence divergence data, revealed that the new species herein described is closely related to I. guaiana and that the specific status of specimens of I. marcusi available in GenBank should be reviewed. In addition, sequence analysis revealed 32 molecular autapomorphies for all independent evolutionary units within the genus. The new species described herein seems to be endemic to its type locality, a private area without legal protection.  相似文献   

4.
Ectomycorrhizas (ECM) of Inocybe species (Inocybaceae, Basidiomycota) formed by three host plant species (Populus alba, Salix rosmarinifolia and Pinus nigra) in a semiarid woody steppe of Hungary were studied. To identify the fungal partners, we performed phylogenetic analyses of nucleotide sequences for the internal transcribed spacer region of nuclear DNA (nrDNA ITS) together with sequences gained from public databases. Seven Inocybe ectomycorrhiza morphotypes were morpho-anatomically characterised. Five morphotypes were identified (I. phaeoleuca, I. psammophila, I. semifulva, I. splendens and I. subporospora), whereas two morphotypes represented unidentified Inocybe species. Differences were discernible among the morphotypes, and they showed general anatomical characteristics of Inocybe ECM, such as the slightly organised plectenchymatic mantle (types A, B and E and the gelatinous C). The ECM of I. subporospora and I. phaeoleuca were detected from the introduced Pinus nigra. These two fungi are probably native to the area but capable of forming a novel ectomycorrhizal association with the invasive host.  相似文献   

5.
6.
Identifying patterns and causes of species displacement is important from the viewpoints of ecology and evolutionary biology as this phenomenon affects community structure. Here I review the species displacement between Liriomyza trifolii (Burgess) and Liriomyza sativae Blanchard (Diptera: Agromyzidae) in Japan. These two species and Liriomyza huidobrensis (Blanchard) originated from the New World and are considered to have invaded Japan from around 1990 to the early 2000s. During this period, L. trifolii was apparently displaced by L. sativae, but the direction of displacement in Japan has been contrary to that observed between the same two species in the USA and China. While the displacement of L. sativae by L. trifolii in these two countries can be attributed to the lower insecticide susceptibility of L. trifolii there, species displacement in the opposite direction in Japan is probably due to the relatively high fecundity of L. sativae and differential effects of the introduced parasitoid Dacnusa sibirica Telenga (Hymenoptera: Braconidae) on both Liriomyza species, except in the south of the country.  相似文献   

7.
Environmental sampling yielded two yeast species belonging to Microstromatales (Exobasidiomycetes, Ustilaginomycotina). The first species was collected from a leaf phylloplane infected by the rust fungus Coleosporium plumeriae, and represents a new species in the genus Jaminaea, for which the name Jaminaea rosea sp. nov. is proposed. The second species was isolated from air on 50% glucose media and is most similar to Microstroma phylloplanum. However, our phylogenetic analyses reveal that species currently placed in Microstroma are not monophyletic, and M. phylloplanum, M. juglandis and M. albiziae are not related to the type species of this genus, M. album. Thus, Pseudomicrostroma gen. nov. is proposed to accommodate the following species: P. glucosiphilum sp. nov., P. phylloplanum comb. nov. and P. juglandis comb. nov. We also propose Parajaminaea gen. nov. to accommodate P. albizii comb. nov. and P. phylloscopi sp. nov. based on phylogenetic analyses that show these are not congeneric with Jaminaea or Microstroma. In addition, we validate the genus Jaminaea, its respective species and two species of Sympodiomycopsis and provide a new combination, Microstroma bacarum comb. nov., for the anamorphic yeast Rhodotorula bacarum. Our results illustrate non-monophyly of Quambalariaceae and Microstromataceae as currently circumscribed. Taxonomy of Microstroma and the Microstromataceae is reviewed and discussed. Finally, analyses of all available small subunit rDNA sequences for Jaminaea species show that J. angkorensis is the only known species that possess a group I intron in this locus, once considered a potential feature indicating the basal placement of this genus in Microstromatales.  相似文献   

8.
Bruguiera hainesii (Rhizophoraceae) is one of the two Critically Endangered mangrove species listed in the IUCN Red List of Threatened Species. Although the species is vulnerable to extinction, its genetic diversity and the evolutionary relationships with other Bruguiera species are not well understood. Also, intermediate morphological characters imply that the species might be of hybrid origin. To clarify the genetic relationship between B. hainesii and other Bruguiera species, we conducted molecular analyses including all six Bruguiera species using DNA sequences of two nuclear genes (CesA and UNK) and three chloroplast regions (intergenic spacer regions of trnL-trnF, trnS-trnG and atpB-rbcL). For nuclear DNA markers, all nine B. hainesii samples from five populations were heterozygous at both loci, with one allele was shared with B. cylindrica, and the other with B. gymnorhiza. For chloroplast DNA markers, the two haplotypes found in B. hainesii were shared only by B. cylindrica. These results suggested that B. hainesii is a hybrid between B. cylindrica as the maternal parent and B. gymnorhiza as the paternal one. Furthermore, chloroplast DNA haplotypes found in B. hainesii suggest that hybridization has occurred independently in regions where the distribution ranges of the parental species meet. As the IUCN Red List of Threatened Species currently excludes hybrids (except for apomictic plant hybrids), the conservation status of B. hainesii should be reconsidered.  相似文献   

9.
Phenotypic integration can influence evolutionary rate and direction by channeling variation into few dimensions. The extent to which that channeling serves as a constraint over macroevolutionary timescales is determined in part by the evolutionary lability of phenotypic integration. Evolutionary change in patterns of pleiotropy, potentially reducing that constraint, is thought to be more readily achieved when pleiotropy is structured by variation arising in parallel along different developmental pathways rather than by variation arising from direct interactions within and between those pathways. Herein we test two predictions that follow from that hypothesis: (1) that clades undergoing dramatic diversification are characterized by integration that is weakly influenced by direct interactions; and (2) that the structure of integration arising from direct interactions is more conservative than that arising from parallel variation. We examine integration of the cranidium of two Cambrian ptychoparioid trilobites, Crassifimbra walcotti and Eokochaspis nodosa, comparing them to each other and to a previously studied species, C.? metalaspis. Shape variation is decomposed into components representing variation among individuals and variation due to direct interactions. In all three species, variation among individuals was only weakly influenced by direct interactions, suggesting that integration was unlikely to have been a long-term constraint on the Cambrian diversification of ptychoparioids. Phenotypic integration of E. nodosa is no more similar than expected by chance to either Crassifimbra species, but the component due to direct interactions is more similar than expected by chance to that of C.? metalaspis. Conversely, the two Crassifimbra species are generally similar (although not identical) in phenotypic integration, but markedly differ in their structure of direct interactions. Integration arising from direct interactions was therefore not immune to restructuring over even short evolutionary timescales, and was not always more conservative than that arising from parallel variation.  相似文献   

10.
Capitulate inflorescence is a specific, strongly adaptive and rare feature in the genus Campanula. We studied morphologically eight capitulate Campanula taxa from the Balkans (1537 individuals/52 populations) and one more species from Caucasus at the molecular level (using chloroplast markers trnGUCC-trnSGCU and psbA-trnH, 130 individuals/58 populations) to assess their relations and evolutionary histories. Although all studied taxa were well circumscribed at both the morphological and molecular levels (except morphologically distinct but genetically invariable C. moesiaca which acquired its single haplotype via past cytoplasmic introgression from C. cervicaria), their relations inferred from the two datasets were incongruent possibly due to the homoplasy of morphological characters frequently reported in Campanula. Interspecific hybridization and introgression affected majority of studied species and may be more common in Campanula than previously thought. These processes, along with incomplete lineage sorting and retention of ancestral polymorphisms, hampered our phylogenetic reconstructions and prevented us to fully resolve species relations, and to support monophyletic origin of capitulate Campanula species. Nonetheless, several cryptic taxa were delineated, and C. daucoides was described as a new capitulate Campanula species. Different evolutionary histories and multiple glacial refugia were inferred for all species represented by multiple samples (except C. moesiaca). According to our dating, their speciation was in most cases triggered by various geo-historic events such as the uplift of the Alpide belt, Messinian Salinity Crisis, or desiccation of the Pannonian Sea/Pliocene Lakes from the central Balkans, while their further diversification was mainly driven by the onset of the Quaternary and cycles of glacials/interglacials.  相似文献   

11.
Climate warming is predicted to amplify drought stress. Thus, it is important to understand how coexisting plant species respond to severe droughts. Here we study how seven Mediterranean woody plant species with different evolutionary history and functional characteristics (Pinus halepensis Mill., Juniperus phoenicea L., Pistacia lentiscus L., Rhamnus lycioides L., Rosmarinus officinalis L., Genista scorpius (L.) DC., and Globularia alypum L.) responded to a severe winter drought during 2011–2012 in Spain. The study site is located in the Valcuerna valley, Monegros desert, northeastern Spain. We evaluated how the drought affected the annual growth-ring formation of the species by using dendrochronology and quantified the intensity of drought-induced defoliation and mortality and compared it between species and groups of species with different evolutionary history. Radial growth of all species was strongly reduced by the 2012 drought. The pre-Mediterranean species (P. halepensis, J. phoenicea, P. lentiscus and R. lycioides) reduced growth more than the Mediterranean species (R. officinalis, G. scorpius and G. alypum). Defoliation was significantly higher in pre-Mediterranean than in Mediterranean species. When species were analyzed separately we found that P. halepensis was the species with the highest growth reduction but J. phoenicea was defoliated more severely and showed higher mortality rates as a consequence of drought. In the case of the Mediterranean shrubs, drought-induced mortality was only noticeable in R. officinalis. Drought impacted growth of all species but this did not induce mortality in all of them. Growth reduction was dependent on evolutionary history. However, functional characteristics of the species such as leaf stomatal regulation and root architecture may be more important than evolutionary history on explaining drought-induced mortality. Indeed, species with shallow root systems such as J. phoenicea and R. officinalis were the most adversely affected by the drought.  相似文献   

12.
In several surveys in the tropical forests in Thailand, specimens that looked morphologically similar to Metarhizium martiale and Cordyceps variegata, as well as other Metarhizium species were collected and cultured in vitro. A combined phylogeny of several genes including the small (18S) and large (28S) subunits of the ribosomal DNA, elongation factor 1-α (TEF), RNA polymerase II subunits 1 and 2 (RPB1, RPB2) genes has shown these to be new taxa in the Clavicipitaceae. Nigelia is described as a new genus closely related to Metarhizium, to the scale insect pathogens Aschersonia (Hypocrella), Samuelsia and Moelleriella, and to plant pathogens in Claviceps and Balansia, and other relatives. Nigelia comprises M. martiale and a new species Nigelia aurantiaca, which has been found infecting lepidopteran larvae and which produces pseudoimmersed, obliquely arranged, obpyriform perithecia with curved or bent ostioles and with whole (non-separating) cylindric ascospores. Metarhizium chaiyaphumense, M. kalasinense, M. prachinense, M. samlanense, and M. takense are described as new species of Metarhizium. Metarhizium martiale is transferred to Nigelia, and Paecilomyces reniformis is transferred to Metarhizium.  相似文献   

13.
A large number of Crassostrea oysters are found in Asia-Pacific. While analyses of interspecific variation have helped to establish historical relationships among these species, studies on intraspecific variation are necessary to understand their recent evolutionary history and current forces driving population biology. We resequenced 18 and analyzed 31 mitogenomes of five Crassostrea species from China: Crassostrea gigas, Crassostrea angulata, Crassostrea sikamea, Crassostrea ariakensis, and Crassostrea hongkongensis. Our analysis finds abundant insertions, deletions, and single-nucleotide polymorphisms in all species. Intraspecific variation varies greatly among species with polymorphic sites ranging from 54 to 293 and nucleotide diversity ranging from 0.00106 to 0.00683. In all measurements, C. hongkongensis that has the narrowest geographic distribution exhibits the least sequence diversity; C. ariakensis that has the widest distribution shows the highest diversity, and species with intermediate distribution show intermediate levels of diversity. Low sequence diversity in C. hongkongensis may reflect recent bottlenecks that are probably exacerbated by human transplantation. High diversity in C. ariakensis is likely due to divergence of northern and southern China populations that have been separated without gene flow. The significant differences in mitogenome diversity suggest that the five sister species of Crassostrea have experienced different evolutionary forces since their divergence. The recent divergence of two C. ariakensis populations and the C. gigas/angulata species complex provides evidence for continued diversification and speciation of Crassostrea species along China’s coast, which are shaped by unknown mechanisms in a north–south divide.  相似文献   

14.
15.
Inaequalispora and Parvothecium are two myrothecium-like, closely related genera of Hypocreales. They are also morphologically similar, sharing sporodochial conidiomata, penicillate conidiophores, fusiform to ellipsoidal conidia accumulating in a green slimy drop, and hypha-like setoid extensions emerging through the conidial mass. During a revision of myrothecium-like isolates originating from rainforest areas of South America (Ecuador, Brazil) and Southeast Asia (Singapore), multilocus phylogenetic inferences (based on DNA sequence data of ITS, partial nuc 28S, and partial tef1a, rpb2 and tub2) and morphological studies concordantly revealed the occurrence of two undescribed species of Inaequalispora (I. longiseta sp. nov. and I. cylindrospora sp. nov.) and one undescribed species of Parvothecium (P. amazonensesp. nov.). Myrothecium setiramosum, M. dimorphum, and two undescribed taxa form the base of a new lineage, sister to the current Parvothecium lineage. This lineage is recognized as Digitiseta gen. nov., typified by D. setiramosa comb. nov. Digitiseta dimorpha comb. nov. is also proposed, and the new species D. parvodigitata sp. nov. and D. multidigitata sp. nov. are described.  相似文献   

16.
17.
We report here the prevalence of parasitism by water mites (Arrenurus sp.) and terrestrial mites (Leptus killingtoni) on parthenogenetic Ischnura hastata (Odonata: Coenagrionidae) from the Azores islands. Leptus killingtoni was only found on the island of Pico, and the prevalence of infestation was highly variable among the different ponds studied, ranging from 0 to 41%. Leptus killingtoni was observed on three of the four odonate species from the archipelago: I. hastata, I. pumilio, and Sympetrum fonscolombii, all of them new hosts for this species. Aquatic mites have been found parasitizing I. hastata females on the island of São Miguel. The prevalence of mite parasitism by Arrenurus sp. on I. hastata was very low, ranging from 12% (2003) to 1% (2008), and in most of the studied ponds, no mites were found attached to females. Although I. hastata coexists with a sexual congener species in the Azores (I. pumilio), they are syntopic in only a small fraction of ponds. Therefore, a comparison between I. hastata and I. pumilio was insufficient to test the predictions of the Red Queen Hypothesis, and further research on parasitism rates in both species needs to be done. In any case, the low prevalence of mite parasitism found in the Azores, coupled with the fact that most of the populations in the archipelago are almost free from competitors and predators, could explain the persistence of these I. hastata parthenogenetic populations, despite their low levels of genetic variation.  相似文献   

18.
We describe a new species and propose a new combination of Ctenitis from South America. The new species is from Peru. We named it Ctenitis megalastriformis due to the resemblance to Megalastrum. The new combination corresponds to the species known until now as C. pedicellata. This species should be called C. nervata, based on the older name Aspidium nervatum. Lectotypes are designated for A. pedicellatum and Dryopteris indecora, both considered here to be synonyms of C. nervata.  相似文献   

19.
The larch bark beetle (Ips subelongatus), which occurs in larch plantations over a vast area of eastern Asia, infects both dying and fallen trees. When its population reaches a high density, the beetle may also infect healthy trees, resulting in tree decline and, eventually, death. Leptographium spp., in both their sexual and asexual states, are mainly associated with conifer-infesting bark beetles; some species are important tree pathogens. The aims of this study were to identify the Leptographium spp. associated with I. subelongatus infestations of Larix spp. in northern China and to examine their pathogenicity towards the tree. Morphological studies and phylogenetic approaches based on multilocus DNA sequence data (ITS2- partial r28S, partial β-tubulin, and EF-1α gene regions) showed that three Leptographium species occur in association with I. subelongatus in the areas investigated: Leptographium taigense, which is recorded in China for the first time, and two new species, namely L. innermongolicum sp. nov. and L. zhangii sp. nov. Leptographium innermongolicum is closely related to L. taigense, whereas L. zhangii belongs to the Grosmannia piceaperda species complex. The pathogenicity of these Leptographium species towards mature Larix spp. was tested by stem inoculation in forests. All inoculations only resulted in small lesions on the inner bark; therefore, the three Leptographium species were not considered to be pathogenic.  相似文献   

20.
Species in Plectosphaerella are well known as pathogens of several plant species causing fruit, root and collar rot and collapse. In an investigation of endophytic fungi associated with cucurbit plants in China, we isolated 77 strains belonging to the genus Plectosphaerella. To identify the isolated strains, we collected the type or reference strains of all currently accepted species in Plectosphaerella except P. oratosquillae and conducted a phylogenetic analysis. Phylogenetic analysis of the partial 28S rDNA sequences showed that all species in Plectosphaerella were located in one clade of Plectosphaerellaceae. Based on multi-locus phylogenetic analysis of the ITS, CaM, EF1, TUB and morphological characteristics, all species in Plectosphaerella were well separated. Three endophytic strains from stems of Cucurbita moschata, Citrullus lanatus and Cucumis melo from North China were assigned to a new species described as P. sinensis in this paper. The new species differs morphologically from other Plectosphaerella species by irregular chlamydospores, and the dimensions of phialides and conidia. The other endophytic strains from several cucurbit plants were identified as P. cucumerina.  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