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 31 毫秒
1.
2.
The three surviving ‘brush-tailed’ bettong species—Bettongia gaimardi (Tasmania), B. tropica (Queensland) and B. penicillata (Western Australia), are all classified as threatened or endangered. These macropodids are prolific diggers and are recognised as important ‘ecosystem engineers’ that improve soil quality and increase seed germination success. However, a combination of introduced predators, habitat loss and disease has seen populations become increasingly fragmented and census numbers decline. Robust phylogenies are vital to conservation management, but the extent of extirpation and fragmentation in brush-tailed bettongs is such that a phylogeny based upon modern samples alone may provide a misleading picture of former connectivity, genetic diversity and species boundaries. Using ancient DNA isolated from fossil bones and museum skins, we genotyped two mitochondrial DNA (mtDNA) genes: cytochrome b (266 bp) and control region (356 bp). These ancient DNA data were combined with a pre-existing modern DNA data set on the historically broadly distributed brush-tailed bettongs (~300 samples total), to investigate their phylogenetic relationships. Molecular dating estimates the most recent common ancestor of these bettongs occurred c. 2.5 Ma (million years ago), which suggests that increasing aridity likely shaped their modern-day distribution. Analyses of the concatenated mtDNA sequences of all brush-tailed bettongs generated five distinct and well-supported clades including: a highly divergent Nullarbor form (Clade I), B. tropica (Clade II), B. penicillata (Clades III and V), and B. gaimardi (Clade IV). The generated phylogeny does not reflect current taxonomy and the question remains outstanding of whether the brush-tailed bettongs consisted of several species, or a single widespread species. The use of nuclear DNA markers (single nucleotide polymorphisms and/or short tandem repeats) will be needed to better inform decisions about historical connectivity and the appropriateness of ongoing conservation measures such as translocations and captive breeding.  相似文献   

3.
The extremely high diversity of spined loach biotypes in the Lower Danube has been detected by biochemical genetic investigation and cytometric analysis of 358 specimens collected in the riverbed and shallow channels. Along with two diploid species (C. elongatoides and C. “tanaitica”), six hybrid forms were revealed, namely, diploid C. elongatoides-“tanaitica”; triploid C. 2 elongatoides-“tanaitica,” C. elongatoides-2 “tanaitica,” and C. 2 elongatoides-species-1; and tetraploid C. 3 elongatoides-“tanaitica” and C. elongatoides-species-2-2 “tanaitica.” In addition, specimens with recombinant genotypes were also found. In spite of the apomictic mode of reproduction, the polyploids did not possess clonal structure, but according to the level of polymorphism and the genotype distribution, they were isomorphous to parental diploid species. Thus, in contrast to the polyploidy in Cobitids of the Dnieper, which have appeared in the basin due to the expansion, the polyploids of the Lower Danube are autochthonous and were derived by crossing with local diploid species. The process is apparently proceeds without any limitations.  相似文献   

4.
The Persian dwarf snake Eirenis (Pseudocyclophis) persicus (Anderson, 1872) has a wide distribution range in south‐western Asia. This species group was comprehensively studied here using traditional biometry, geometric morphometrics, ecological niche modelling, and genetics. Our analyses revealed that E. persicus is split into two clades. A western clade, bearing at least two different species: E. persicus, distributed in south‐western Iran, and an undescribed species from south‐eastern Turkey and western Iran. The eastern clade consists of at least three species: Eirenis nigrofasciatus, distributed across north‐eastern Iraq, and western and southern Iran; Eirenis walteri, distributed across eastern Iran, southern Turkmenistan, and western and southern Pakistan, and Eirenis angusticeps, distributed in north‐eastern Pakistan. Ecological niche modelling revealed that the distribution of the species in the western clade are mainly affected by winter precipitation, and those in the eastern clade are mainly affected by the minimum temperature of the coldest month. A molecular clock analysis revealed that the divergence and diversification of the E. persicus species group mainly correspond to Eocene to Pliocene orogeny events subsequent to the Arabia–Eurasia collision. This study confirms that specimens with the unique morphology of having 13 dorsal scale rows on the anterior dorsum, occurring in the Suleiman Mountains in central Pakistan, can be referred to Eirenis mcmahoni (Wall, 1911). However, at this moment we have insufficient data to evaluate the taxonomy of this species.  相似文献   

5.
DNA sequences of Capitotricha bicolor from Quercus, Fagus sylvatica, Alnus alnobetula, and Nothofagus, and C. rubi from Rubus idaeus were obtained from apothecia to establish whether specimens from different hosts belong to separate species. The obtained ITS1–5.8S–ITS2 rDNA sequences were examined with Bayesian and parsimony phylogenetic analyses. Intra- and interspecific variation was also investigated based on molecular distances in the ITS region. The phylogenetic analyses supported the specific distinctness of Capitotricha rubi and the Capitotricha from Nothofagus, but also suggest specific distinctness between samples from Quercus, Fagus, and Alnus. The interspecific distances were larger than intraspecific distances for all examined units. The smallest distance was found between the “Alnus alnobetula” and “Fagus sylvatica” units. Two new sequences of Brunnipila are published. Capitotricha, Lachnum, and Erioscyphella are compared to each other based on hair and excipulum characteristics.  相似文献   

6.
This study evaluated the phylogenetic relationship among samples of “Chantransia” stage of the Batrachospermales and Thoreales from several regions of the world based on sequences of two genes—the plastid‐encoded RUBISCO LSU gene (rbcL) and the nuclear SSU ribosomal DNA gene (SSU rDNA). All sequences of “Chantransia macrospora” were shown to belong to Batrachospermum macrosporum based on both molecular markers, confirming evidence from previous studies. In contrast, nine species are now associated with “Chantransia pygmaea,” including seven species of the Batrachospermales and two of the Thoreales. Therefore, the presence of “C. macrospora” in a stream can be considered reliable evidence that it belongs to B. macrosporum, whereas the occurrence of “C. pygmaea” does not allow the recognition of any particular species, since it is associated with at least nine species. Affinities of “Chantransia” stages to particular taxa were congruent for 70.5% of the samples comparing the rbcL and SSU analyses, which were associated with the same or closely related species for both markers. Sequence divergences have been reported in the “Chantransia” stage in comparison to the respective gametophyte, and this matter deserves further attention.  相似文献   

7.
8.
The genus Calogaya (Teloschistaceae, Xanthorioideae) was established to accommodate mainly epilithic lichens with lobate thalli, previously regarded as the “Caloplaca saxicola group.” Data supporting the recognition of this new genus came from European lichens, and although the genus is soundly based, we have found in Asia numerous epiphytic lineages and lineages with reduced, non-lobate thallus in dry continental areas. The taxonomic and functional diversity of Calogaya is distinctly higher in steppe and desert areas of Asia than in the less arid regions of Europe. We sampled 238 specimens, mostly from arid regions of north-western China, Iran, southern Siberia and Turkey. Three nuclear DNA loci were analysed separately and jointly by Bayesian inference, maximum likelihood and *BEAST approaches. Delimitations of 28 putative species were tested by BP&P multispecies coalescent model with joint analysis of species delimitation and species-tree estimation. Finally, we recognised 22 taxonomic units: 16 are at species rank, 3 are treated as subspecies and 3 are complexes, treated here as a single entity, but in reality probably including more than one species. Calogaya altynis, C. biatorina subsp. asiatica, C. decipiens subsp. esorediata, C. haloxylonis, C. orientalis, C. xanthoriella and C. xinjiangis are newly described. Caloplaca zoroasteriorum is combined into Calogaya, and Calogaya persica is reduced to a subspecies. The taxonomic status of Calogaya saxicola is unclear, and the name is employed here “sensu lato” for several non-monophyletic epilithic lineages with short-lobed thalli. Calogaya biatorina and C. ferrugineoides are the two other heterogeneous taxonomic units probably including more species.  相似文献   

9.
The Persian Horned Viper (Pseudocerastes persicus) is distributed from northeast Iraq through the Iranian Plateau to western Pakistan with isolated populations in the Hajar Mountains of south-eastern Arabia. Like the other members of the genus Pseudocerastes, P. persicus is a sit-and-wait ambush feeder with low vagility, a characteristic that often results in high levels of population differentiation. In order to clarify the level of genetic variability, phylogenetic relationships, and biogeography of the Arabian populations of P. persicus we sequenced 597 base pairs of the mitochondrial cytochrome b of four individuals from the Hajar Mountains in south-eastern Arabia and inferred their phylogenetic relationships including 10 samples of P. persicus from Iran and Pakistan, four P. urarachnoides and one P. fieldi downloaded from GenBank. The four Arabian samples are genetically very similar in the gene fragment analysed and are phylogenetically very closely related to populations of P. persicus from coastal south Iran. Biogeographically, it appears that colonisation of the Hajar Mountains by P. persicus took place from Iran very recently, most probably during the last glaciation, when most of the Persian Gulf was above sea level and did not represent a barrier for dispersal.  相似文献   

10.
Human activity and land use changes in the past decades have led to landscape homogenization and small-scale fragmentation of grassland habitats in most regions of central Europe. As a result, populations of many grassland species are small and strongly fragmented, facing extinction due to genetic depauperation and local maladaptation in remnant habitats. In this study, remaining populations of the strongly endangered grassland species Dianthus seguieri ssp. glaber (“Ragged Pink”) in Bavaria were investigated in order to evaluate the environmental factors influencing its genetic variation and performance. We first evaluated habitat, vegetation and population structure. Species performance was then studied by assessing the number of generative shoots, flowers and fertile capsules; and evaluating seed weight and seed viability. Finally, genetic variation was analyzed using molecular markers (AFLPs). Our analyses revealed that population size and land use abandonment have the strongest impact on genetic variation and species’ performance. Large and extended populations were most variable. 72 % of overall genetic variability of Dianthus seguieri ssp. glaber was found to be within populations, whereas 28 % remained between populations. Increased vegetation height and coverage, and a high proportion of gramineous species resulting from the lack of land use, reduced genetic variation, effective fruit and seed set. Our study shows that both population size and land use abandonment need to be considered to ensure the long term protection of endangered plant species. Maintaining an open habitat structure and adequate soil nutrient conditions through targeted annual mowing regime, over-storey vegetation trimming and green waste removal and the establishment of vegetation buffer strips will allow this species’ persistence and continuous recruitment.  相似文献   

11.
Genetic diversity among 43 petroleum hydrocarbon-degrading Pseudomonas belonging to four different species and the type strain Pseudomonas aeruginosa MTCC1034 was assessed by using restriction fragment length polymorphism (RFLP) of polymerase chain reaction (PCR)-amplified 16S–23S rDNA intergenic spacer regions (ISRs) polymorphism. PCR amplification from all Pseudomonas species yielded almost identical ISR amplicons of “?” 800 bp and in nested PCR of “?” 550 bp. The RFLP analysis with MboI and AluI revealed considerable intraspecific variations within the Pseudomonas species. The dendrogram constructed on the basis of the PCR-RFLP patterns of 16S–23S rDNA intergenic spacer regions differentiated all the species into seven different clusters.  相似文献   

12.
《Biological Control》2005,32(1):70-77
Climatic matching and pre-release performance evaluation were useful predictors of parasitoid establishment in a retrospective analysis of a classical biological control program against Bemisia tabaci biotype “B” in the USA. Laboratory evaluation of 19 imported and two indigenous parasitoid species in quarantine on B. tabaci showed that the Old World Eretmocerus spp, had the highest attack rate. The climate matching program CLIMEX was used to analyze the establishment patterns of five Old World Eretmocerus spp. introduced to the Western USA. The top matches ±10% for the climate of the area of introduction and origin of the introduced parasitoids always included the species that established. The Old World Eretmocerus spp. came from regions characterized by many separate biotypes of B. tabaci other than “B,” but are considered specialists of the B. tabaci complex as compared to the indigenous North American oligophagous Eretmocerus spp. This narrower host range and high attack rate combined with climatic adaptation may account for their establishment in the USA. A set of predictive tools and guidelines were used to select the best candidate for importation and possible release into Australia that has been recently invaded by the “B” biotype. The establishment patterns of the introduced Eretmocerus spp. and a comparison of climates of their respective locations in the USA were compared with the affected area in Australia. The best climatic match was the Lower Rio Grande Valley of Texas suggesting its dominant parasitoid, E. hayati ex. Pakistan be considered as the first candidate for evaluation as a biological control agent.  相似文献   

13.
In flora of Turkey, there are six species of Carthamus L: Carthamus dentatus (Forssk.) Vahl., C. glaucus M. Bieb. subsp. glaucus, C. lanatus L., C. tenuis (Boiss. & Blanche) Bornm., C. persicus Desf. ex Willd. and C. tinctorius L. Within these species, C. tinctorius L. is an alien species for the Turkish flora. The pollen grains belonging to six taxa collected from different locations of Anatolia and examined both under light microscope (LM) and under scanning electron microscope (SEM). As a result of these examinations and measurements, pollen grains of taxa are radially symmetrical, isopolar, oblate-spheroid, spheroid, tricolporate rarely tetracolporate, echinate. There are high similarities among taxa but some differences are recorded in size and spin length. According to cluster analyses of Carthamus species’ pollens, C. glaucus and C. tenuis have the most similar pollens. C. dentatus grouped with these two. C. persicus placed as the closest relative of C. tinctorius in the dendrogram.  相似文献   

14.
Non‐biting midges (Diptera: Chironomidae) adapt to species‐specific environmental conditions and hence are promising bioindicators for aquatic and ecotoxicological monitoring. Although their utility for these purposes was historically limited by difficulties in their morphological identification, DNA barcoding offers a possible solution. Here, eight Japanese species of the genus Chironomus, which is characterized by its worldwide distribution and abundance among Chironomidae, were subjected to DNA barcoding using cytochromec oxidase subunit I (COI). To examine whether this DNA barcode is a useful indicator for Japanese species of Chironomus, we calculated genetic distances within and between the COI sequences of Chironomus species both from this study and worldwide and constructed phylogenetic trees. Based on 415 bp COI sequences and the Kimura two‐parameter model, the average genetic distances within 37 species and between 72 species were 2.6% and 17.2%, respectively. Although the ranges of genetic distances within and between species overlapped from 0.8% to 17.3%, 99.7% of average genetic distances between species were >3.0%. Some of this overlap is attributable to distances within species that were “too large” as well as those between species that were “too small”. Of eight Japanese species examined, two showed genetic distances between species that were below a 3.0% threshold, and four had distances within species that were greater than 3.0%. These results suggest a possible reclassification of these species and the need for further sampling to unveil biogeographic variations among different countries and regions.  相似文献   

15.
The genus Pythium, with slightly over 280 described species has been classified traditionally with other filamentous, coenocytic, sporangia-producing fungi as “Phycomycetes”. However, with recent advances in chemical, ultrastructural and molecular studies Pythium spp. are now considered as “fungus-like organisms” or “pseudo-fungi” and are placed in the kingdom Chromista or kingdom Straminopila, distinct from the true fungi or the kingdom Fungi. Little is known about the biodiversity of Pythium in Iran. This paper attempts to assess the position of the genus Pythium and provides details of the historical development of the study of Pythium in Iran. The survey list contains 33 species, 4 species groups and 1 unknown species of Pythium.  相似文献   

16.
A rich association of calcareous algae is described from the Lower Cretaceous (Barremian–? Lower Aptian) deposits of the Taft Formation, located south of Aliabad (in the vicinity of Yazd, central Iran). The association mainly consists of dasycladaleans and bryopsidales (udoteaceans and gymnocodiaceans); additionally, rare “solenoporaceans” and cyanophyceans are present. Three new species are described: two are dasycladaleans (Pseudoactinoporella? iranica and Holosporella farsica) and one is an udoteacean (Boueina minima). Many of the described and illustrated algae are mentioned for the first time from Iran.  相似文献   

17.
18.
Peach belongs to the genus Prunus, which includes Prunus persica and its relative species, P. mira, P. davidiana, P. kansuensis, and P. ferganensis. Of these, P. ferganensis have been classified as a species, subspecies, or geographical population of P. persica. To explore the genetic difference between P. ferganensis and P. persica, high-throughput sequencing was used in different peach accessions belonging to different species. First, low-depth sequencing data of peach accessions belonging to four categories revealed that similarity between P. ferganensis and P. persica was similar to that between P. persica accessions from different geographical populations. Then, to further detect the genomic variation in P. ferganensis, the P. ferganensis accession “Xinjiang Pan Tao 1” and the P. persica accession “Xia Miao 1” were sequenced with high depth, and sequence reads were assembled. The results showed that the collinearity of “Xinjiang Pan Tao 1” with the reference genome “Lovell” was higher than that of “Xia Miao 1” and “Lovell” peach. Additionally, the number of genetic variants, including single nucleotide polymorphisms (SNPs), structural variations (SVs), and the specific genes annotated from unmapped sequence in “Xia Miao 1” was higher than that in “Xinjiang Pan Tao 1” peach. The data showed that there was a close distance between “Xinjiang Pan Tao 1” (P. ferganensis) and reference genome which belong to P. persica, comparing “Xia Miao 1” (P. persica) and reference ones. The results accompany with phylogenetic tree and structure analysis confirmed that P. ferganensis should be considered as a geographic population of P. persica rather than a subspecies or a distinct species. Furthermore, gene ontology analysis was performed using the gene comprising large-effect variation to understand the phenotypic difference between two accessions. The result revealed that the pathways of gene function affected by SVs but SNPs and insertion-deletions markedly differed between the two peach accessions.  相似文献   

19.
Climate change refugia are areas that are relatively buffered from contemporary climate change and may be important safe havens for wildlife and plants under anthropogenic climate change. Topographic variation is an important driver of thermal heterogeneity, but it is limited in relatively flat landscapes, such as the boreal plain and prairie regions of western Canada. Topographic variation within this region is mostly restricted to river valleys and hill systems, and their effects on local climates are not well documented. We sought to quantify thermal heterogeneity as a function of topography and vegetation cover within major valleys and hill systems across the boreal–grassland transition zone.Using iButton data loggers, we monitored local temperature at four hills and 12 river valley systems that comprised a wide range of habitats and ecosystems in Alberta, Canada (N = 240), between 2014 and 2020. We then modeled monthly temperature by season as a function of topography and different vegetation cover types using general linear mixed effect models.Summer maximum temperatures (T max) varied nearly 6°C across the elevation gradient sampled. Local summer mean (T mean) and maximum (T max) temperatures on steep, north‐facing slopes (i.e., low levels of potential solar radiation) were up to 0.70°C and 2.90°C cooler than highly exposed areas, respectively. T max in incised valleys was between 0.26 and 0.28°C cooler than other landforms, whereas areas with greater terrain roughness experienced maximum temperatures that were up to 1.62°C cooler. We also found that forest cover buffered temperatures locally, with coniferous and mixedwood forests decreasing summer T mean from 0.23 to 0.72°C and increasing winter T min by up to 2°C, relative to non‐forested areas.Spatial predictions of temperatures from iButton data loggers were similar to a gridded climate product (ClimateNA), but the difference between them increased with potential solar radiation, vegetation cover, and terrain roughness.Species that can track their climate niche may be able to compensate for regional climate warming through local migrations to cooler microsites. Topographic and vegetation characteristics that are related to cooler local climates should be considered in the evaluation of future climate change impacts and to identify potential refugia from climate change.  相似文献   

20.
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