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 540 毫秒
1.
We used species distribution modeling to investigate the potential effects of climate change on 24 species of Neotropical anurans of the genus Melanophryniscus. These toads are small, have limited mobility, and a high percentage are endangered or present restricted geographical distributions. We looked at the changes in the size of suitable climatic regions and in the numbers of known occurrence sites within the distribution limits of all species. We used the MaxEnt algorithm to project current and future suitable climatic areas (a consensus of IPCC scenarios A2a and B2a for 2020 and 2080) for each species. 40% of the species may lose over 50% of their potential distribution area by 2080, whereas 28% of species may lose less than 10%. Four species had over 40% of the currently known occurrence sites outside the predicted 2080 areas. The effect of climate change (decrease in climatic suitable areas) did not differ according to the present distribution area, major habitat type or phylogenetic group of the studied species. We used the estimated decrease in specific suitable climatic range to set a conservation priority rank for Melanophryniscus species. Four species were set to high conservation priority: M. montevidensis, (100% of its original suitable range and all known occurrence points potentially lost by 2080), M. sp.2, M. cambaraensis, and M. tumifrons. Three species (M. spectabilis, M. stelzneri, and M. sp.3) were set between high to intermediate priority (more than 60% decrease in area predicted by 2080); nine species were ranked as intermediate priority, while eight species were ranked as low conservation priority. We suggest that monitoring and conservation actions should be focused primarily on those species and populations that are likely to lose the largest area of suitable climate and the largest number of known populations in the short-term.  相似文献   

2.
Melanophryniscus is a genus of small toads inhabiting the southern portion of South America. This genus is considered basal within the family Bufonidae. Data on larval chondrocranial morphology do not exist for the genus and larval internal oral anatomy has only been described for a single species. Here, we describe chondrocranial and internal oral morphology in Melanophryniscus montevidensis , M. orejasmirandai and M. sanmartini . Chondrocranial morphology is similar among the species examined. Comparisons with other bufonids and with outgroup taxa suggest that the following chondrocranial characters may represent synapomorphies for the Bufonidae: free (or absent) ceratobranchial IV, a reduced or absent larval crista parotica, the lack of a larval otic process, and late development of thin, poorly chondrified orbital cartilages. The presence of an elongated processus anterior dorsalis of the suprarostral alae and the absence of a chondrified commissura quadratoorbitalis appear to be unique in Melanophryniscus among bufonids. Internal oral anatomy is conserved in Melanophryniscus , and among bufonids in general.  相似文献   

3.
We present a comprehensive review of larval morphology in the Neotropical toad genus Melanophryniscus. The taxa studied included 23 species with representatives of recognized phenetic groups and different larval ecomorphological guilds: pond, stream, and phytotelm‐dwelling tadpoles. Their external morphology variation is congruent with current phenetic arrangement based on adult features, but also reflects the habitat where larvae develop. Lotic tadpoles (i.e. M. tumifrons group and M. krauczuki) in general exhibit a more depressed body, a longer tail with lower fins, and larger oral discs than lentic forms (i.e. M. stelzneri group, M. moreirae, M. sanmartini, and M. langonei). Despite their peculiar, confined microhabitat, phytotelm larvae do not diverge markedly from non‐arboreal species. The distinctive features of all species are the presence of a pineal end organ and the placement of the intestinal reversal point at the left of the abdomen in typical larval stages. The buccal cavity and musculoskeletal anatomy are quite conserved between species, yet some characteristics differ from those of other bufonids. The presence of one pair of subhyoid muscles is apparently an exclusive trait of Melanophryniscus among Bufonidae. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 417–441.  相似文献   

4.
The genus Amphictene is reported for the first time from Mexico. Previous records for America are restricted to Brazil (Amphictene catharinensis) (Grube, 1870), and Guatemala (Amphictene guatemalensis) (Nilsson, 1928). In this paper we describe a new species, Amphictene helenae sp. n., characterized by the presence of three pairs of tentacular cirri, while other species have only two pairs. The new species is closely similar to Amphictene catharinensis, and can be distinguished by the presence of a circular group of glandular papillae inserted between the lines of glandular cirri present from the second segment. Amphictene guatemalensis is redescribed based on type material; it differs from the new species in the presence of two pairs of tentacular cirri on segments 1 and 2, six pairs of glandular cirri on the third segment, and four glandular lobes fused in pairs on the fourth segment.  相似文献   

5.
Nine species of terrestrial isopods are reported for the Polynesian island of Rapa Nui (Easter Island) based upon museum materials and recent collections from field sampling. Most of these animals are non-native species, but two are new to science: Styloniscus manuvaka sp. n. and Hawaiioscia rapui sp. n. Of these, the former is believed to be a Polynesian endemic as it has been recorded from Rapa Iti, Austral Islands, while the latter is identified as a Rapa Nui island endemic. Both of these new species are considered ‘disturbance relicts’ and appear restricted to the cave environment on Rapa Nui. A short key to all the oniscidean species presently recorded from Rapa Nui is provided. We also offered conservation and management recommendations for the two new isopod species.  相似文献   

6.
A new species of Hisonotus is described from the headwaters of the rio Xingu. The new species is distinguished from its congeners by having a functional V-shaped spinelet, odontodes not forming longitudinal aligned rows on the head and trunk, lower counts of the lateral and median series of abdominal figs, presence of a single rostral fig at the tip of the snout, absence of the unpaired figlets at typical adipose fin position, yellowish-tipped teeth, absence of conspicuous dark saddles and stripe on the body and higher number of teeth on the premaxillary and dentary. The new species, Hisonotus acuen, is restricted to headwaters of the rio Xingu basin, and is the first species of the genus Hisonotus described from the rio Xingu basin. Hisonotus acuen is highly variable in aspects of external body proportions, including body depth, snout length, and abdomen length. This variation is partly distributed within and among populations, and is not strongly correlated with body size. PCA of 83 adult specimens from six allopatric populations indicates the presence of continuous variation. Therefore, the available morphological data suggest that the individuals inhabiting the six localities of rio Xingu represent different populations of a single species. Low intraspecific variation in mitochondrial Cytochrome oxidase subunit I (COI) provides corroborative evidence.  相似文献   

7.
The Fascinating World of RNA Interference   总被引:1,自引:0,他引:1       下载免费PDF全文
Micro- and short-interfering RNAs represent small RNA family that are recognized as critical regulatory species across the eukaryotes. Recent high-throughput sequencing have revealed two more hidden players of the cellular small RNA pool. Reported in mammals and Caenorhabditis elegans respectively, these new small RNAs are named piwi-interacting RNAs (piRNAs) and 21U-RNAs. Moreover, small RNAs including miRNAs have been identified in unicellular alga Chlamydomonas reinhardtii, redefining the earlier concept of multi-cellularity restricted presence of these molecules. The discovery of these species of small RNAs has allowed us to understand better the usage of genome and the number of genes present but also have complicated the situation in terms of biochemical attributes and functional genesis of these molecules. Nonetheless, these new pools of knowledge have opened up avenues for unraveling the finer details of the small RNA mediated pathways.  相似文献   

8.
Several evolutionary hypotheses help explain why only some species adapt readily to new conditions and expand distributions beyond borders, but there is limited evidence testing these hypotheses. In this study, we consider patterns of neutral (microsatellite) and quantitative genetic variation in traits in three species of Drosophila from the montium species group in eastern Australia. We found little support for restricted or asymmetrical gene flow in any species. In rainforest-restricted Drosophila birchii, there was evidence of selection for increased desiccation and starvation resistance towards the southern border, and a reduction in genetic diversity in desiccation resistance at this border. No such patterns existed for Drosophila bunnanda, which has an even more restricted distribution. In the habitat generalist Drosophila serrata, there was evidence for geographic selection for wing size and development time, although clinal patterns for increased cold and starvation resistance towards the southern border could not be differentiated from neutral expectations. These findings suggest that borders in these species are not limited by low overall genetic variation but instead in two of the species reflect patterns of selection and genetic variability in key traits limiting borders.  相似文献   

9.
Current taxonomy of the Etheostoma asprigene species group recognizes four species, two of which (Etheostoma ditrema Ramsey and Suttkus and Etheostoma nuchale Howell and Caldwell) are restricted to isolated springs and spring-fed stream systems above the Fall Line of the Mobile Basin of Alabama, Georgia, and Tennessee. Previous studies of morphological and biochemical variation between disjunct populations of E. ditrema support the presence of multiple independent lineages. Unfortunately, the lack of phylogenetic methodology has made it impossible to distinguish historically differentiated non-sister taxa from currently intergrading sister lineages.The current study examines members of the E. asprigene species group, particularly E. ditrema and E. nuchale, from throughout their respective ranges for products of 44 presumptive gene loci. Highly significant levels of genetic subdivision (FIT) and genetic differentiation (FST) are observed both within and between species of this group, supporting the presence of previously unrecognized diversity within this clade. Phylogenetic evaluation of polyallelic loci supports the specific recognition of E. nuchale and three taxa currently under the name E. ditrema: nominal E. ditrema (upper Coosa River system), E. sp. cf. E. ditrema (Coldwater Spring), and E. sp. cf. E. ditrema (central Coosa River system) based on either fixed allelic products or significant allele frequency differences. The Gulf darter, Etheostoma swaini, is also identified as a composite of at least three diagnosable evolutionary species, two of which (Black Warrior River system above and Cahaba River system below the Fall Line) are more closely related to E. nuchale and species of the E. ditrema complex than to remaining E. swaini. It is recommended that future conservation efforts with these highly geographically restricted and imperiled species incorporate these patterns of genetic subdivision into management and recovery plans.  相似文献   

10.
Deep-sea bivalves of the Xylophagaidae, a poorly known group, are obligate wood-borers. Deployment of wood in three submarine canyons off the Iberian coast, the Blanes and La Fonera Canyons (Mediterranean Sea) and the Avilés Canyon (Cantabric Sea, Bay of Biscay), lead to the discovery of four xylophagaid species in our samples. Xylophaga dorsalis (the dominant species), X. atlantica, X. cf. anselli and the new species X. brava, were identified on the basis of morphological data, and supported by a phylogenetic reconstruction based on the nuclear genes 18S rDNA and 28S rDNA and including several genus of Xylophagaidae. Genetic divergence between species of Xylophaga varied between genes, ranging from 0.5 to 4.0% for the 18SrDNA and from 4.1 to 16.6% for the 28SrDNA. Xylophaga brava sp. nov. appeared to be restricted to the Mediterranean and morphologically resembled the closely related X. cf. anselli from the Cantabrian Sea. However, they clearly diverged in two well-supported clades. Low levels of intraspecific variability and higher interspecific divergence between species also supported the existence of these two different species. Morphologically they differ in the number of cirri at the siphon openings, in the shape of the posterior shell and in the size of prodissoconch II. The new species is characterized by having weak, poorly mineralized mesoplax and siphons united throughout, covered by a periostracal, non-calcified tube; distinct proximal and distal siphons, the former translucent and soft, the latter muscular, with concentric rings. Xylophaga atlantica, previously known only from the western Atlantic, is reported for the first time in the Mediterranean Sea. Whether its presence in the Mediterranean indicates its natural distribution or reflects its recent introduction is unknown. Although xylophagaids have been previously reported to recruit heavily to wood deposited on the seabed, these four species colonized wood suspended 30 m above the seafloor.  相似文献   

11.
The genus Rhophitulus Ducke, 1907 is a large and complex group of bees of the tribe Protandrenini comprising small, slender, mostly black ground-nesting species that are restricted to South America. We describe a new species of Rhophitulus from Parque Nacional São Joaquim, Urubici, state of Santa Catarina, Brazil. Rophitulus ater sp. nov. is distinctive and easily distinguished from other species of the genus by a unique combination of morphological characters in both sexes, but especially by the following: dull black body, coarsely and densely punctate integument, basal area of metapostnotum depressed and areolate rugose, posterior margin of hind tibia and pygidial fimbria of female with blackish pilosity, and characters of the male genitalia with hidden sterna. The new species is closely associated with Blumenbachia catharinensis (Loasaceae), which is restricted to cloud forest of the southeastern rim of Serra Geral. Flowers of B. catharinensis are pollen and nectar resources and mating sites for the new species.  相似文献   

12.
One of the basal Glyptodontidae groups is represented by the Propalaehoplophorinae (late Oligocene — middle Miocene), whose genera (Propalaehoplophorus, Eucinepeltus, Metopotoxus, Cochlops, andAsterostemma) were initially recognized in Argentinian Patagonia. Among these,Asterostemma was characterized by its wide latitudinal distribution, ranging from southernmost (Patagonia) to northernmost (Colombia, Venezuela) South America. However, the generic assignation of the Miocene species from Colombia and Venezuela (A.? acostae, A. gigantea, andA. venezolensis) was contested by some authors, who explicitly accepted the possibility that these species could correspond to a new genus, different from those recognized in southern areas. A new comparative study of taxa from Argentinian Patagonia, Colombia and Venezuela (together with the recognition of a new genus and species for the Pliocene of the latter country) indicates that the species in northern South America are not Propalaehoplophorinae, but represent the first stages in the cladogenesis of the Glyptodontinae glyptodontids, the history of which was heretofore restricted to the late Miocene — early Holocene of southernmost South America. Accordingly, we propose the recognition of the new genusBoreostemma for the species from northern South America and the restriction ofAsterostemma to the Miocene of Patagonia. Thus, the available data indicate that the Glyptodontinae would in fact have arisen in the northernmost regions of this continent. Their arrival to more southerly areas coincides with the acme of the “Age of Southern Plains”. The Propalaehoplophorinae are geographically restricted to Patagonia.  相似文献   

13.
A new species, Neolepidapedon smithi, is described from the fish Mora moro in the north-eastern Atlantic Ocean and is distinguished from other members of the genus. It differs from its congeners in the extension of the vitellarium into the forebody and/or the body shape. The genus Neolepidapedon is reviewed and a key to species given. The genus has previously contained up to 20 species, but is here restricted to eight species, which possess a very thick male duct wall within the cirrus-sac, a narrow internal seminal vesicle, an excretory vesicle restricted to the hindbody and no eye-spots. The remaining nominal species with a relatively thin-walled internal male duct, a globular internal seminal vesicle, an excretory system which reaches into the forebody and eye-spots are considered to belong to a separate group which is related to Opechona. Some of these species were included by Yamaguti (1971) in his new subgenus Neolepidapedon (Neolepidapedoides), which is raised to full generic status. Eight new combinations are made: Neolepidapedoides belizensis (Fischthal, 1977), N. dollfusi (Durio & Manter, 1968), N. equilatum (Siddiqi & Cable, 1960), N. hypoplectri (Nahhas & Cable, 1964), N. israelense (Fischthal, 1980), N. macrum (Overstreet, 1969), N. medialunae (Montgomery, 1957) and N. mycteropercae (Siddiqi & Cable, 1960).  相似文献   

14.
Fungi from the genus Geosmithia (Ascomycota: Hypocreales) are associated with bark beetles (Coleoptera: Scolytinae), though little is known about ecology, diversity, and distribution of these fungi across beetle and its host tree species. This study surveyed the diversity, distribution and vector affinity of Geosmithia isolated from subcortical insects that colonized trees from the family Pinaceae in Central and Northeastern Europe. Twelve Geosmithia species were isolated from 85 plant samples associated with 23 subcortical insect species (including 14 bark beetle species). Geosmithia community composition was similar across different localities and vector species; although the fungal communities associated with insects that colonized Pinus differed from that colonizing other tree species (Abies, Larix, and Picea). Ten Geosmithia species from four independent phylogenetic lineages were not reported previously from vectors feeding on other plant families and seem to be restricted to the vectors from Pinaceae only. We conclude that presence of such substrate specificity suggests a long and stable association between Geosmithia and bark beetles.  相似文献   

15.
柳叶蕨属为分布于石灰岩区域的一类较特别的植物。文献资料和野外调查表明,广东有柳叶蕨属植物共4种,其中3种为广东省分布新记录,即峨眉柳叶蕨、镰羽柳叶蕨和柳叶蕨,建议将这几种植物列为国家重点保护植物。  相似文献   

16.
African clawed frogs, genus Xenopus, are extraordinary among vertebrates in the diversity of their polyploid species and the high number of independent polyploidization events that occurred during their diversification. Here we update current understanding of the evolutionary history of this group and describe six new species from west and central sub-Saharan Africa, including four tetraploids and two dodecaploids. We provide information on molecular variation, morphology, karyotypes, vocalizations, and estimated geographic ranges, which support the distinctiveness of these new species. We resurrect Xenopus calcaratus from synonymy of Xenopus tropicalis and refer populations from Bioko Island and coastal Cameroon (near Mt. Cameroon) to this species. To facilitate comparisons to the new species, we also provide comments on the type specimens, morphology, and distributions of X. epitropicalis, X. tropicalis, and X. fraseri. This includes significantly restricted application of the names X. fraseri and X. epitropicalis, the first of which we argue is known definitively only from type specimens and possibly one other specimen. Inferring the evolutionary histories of these new species allows refinement of species groups within Xenopus and leads to our recognition of two subgenera (Xenopus and Silurana) and three species groups within the subgenus Xenopus (amieti, laevis, and muelleri species groups).  相似文献   

17.
18.
The amphipod genus Epimeria is very speciose in Antarctic waters. Although their brooding biology, massive and heavily calcified body predict low dispersal capabilities, many Epimeria species are documented to have circum-Antarctic distributions. However, these distribution records are inevitably dependent on the morphological species definition. Yet, recent DNA evidence suggests that some of these Epimeria species may be complexes of species with restricted distributions. Mitochondrial COI and nuclear 28S rDNA sequence data were used to infer evolutionary relationships among 16 nominal Epimeria species from the Antarctic Peninsula, the eastern Weddell Sea and the Adélie Coast. Based on this phylogenetic framework, we used morphology and the DNA-based methods GMYC, bPTP and BPP to investigate species boundaries, in order to revise the diversity and distribution patterns within the genus. Most of the studied species appeared to be complexes of pseudocryptic species, presenting small and previously overlooked morphological differences. Altogether, 25 lineages were identified as putative new species, increasing twofold the actual number of Antarctic Epimeria species. Whereas most of the species may be geographically restricted to one of the three studied regions, some still have very wide distribution ranges, hence suggesting a potential for large-scale dispersal.  相似文献   

19.
We review the systematics of the Hypsiboas calcaratus species complex, a group of widely distributed Amazonian hylid frogs. A comprehensive analysis of genetic, morphological, and bioacoustic datasets uncovered the existence of eleven candidate species, six of which are confirmed. Two of them correspond to Hypsiboas fasciatus and Hypsiboas calcaratus and the remaining four are new species that we describe here. Hypsiboas fasciatus sensu stricto has a geographic range restricted to the eastern Andean foothills of southern Ecuador while Hypsiboas calcaratus sensu stricto has a wide distribution in the Amazon basin. Hypsiboas almendarizae sp. n. occurs at elevations between 500 and 1950 m in central and northern Ecuador; the other new species (H. maculateralis sp. n., H. alfaroi sp. n., and H. tetete sp. n.) occur at elevations below 500 m in Amazonian Ecuador and Peru. The new species differ from H. calcaratus and H. fasciatus in morphology, advertisement calls, and mitochondrial and nuclear DNA sequences. Five candidate species from the Guianan region, Peru, and Bolivia are left as unconfirmed. Examination of the type material of Hyla steinbachi, from Bolivia, shows that it is not conspecific with H. fasciatus and thus is removed from its synonymy.  相似文献   

20.
A new species of Noblella is described from the humid montane forest of the Región Cusco in Peru. Specimens were collected at 2330–2370 m elevation in Madre Selva, near Santa Ana, in the province of La Convención. The new species is readily distinguished from all other species of Noblella by having a broad, irregularly shaped, white mark on black background on chest and belly. The new species further differs from known Peruvian species of Noblella by the combination of the following characters: tympanic membrane absent, small tubercles on the upper eyelid and on dorsum, tarsal tubercles or folds absent, tips of digits not expanded, no circumferential grooves on digits, dark brown facial mask and lateral band extending from the tip of the snout to the inguinal region. The new species has a snout-to-vent length of 15.6 mm in one adult male and 17.6 mm in one adult female. Like other recently described species in the genus, this new Noblella inhabits high-elevation forests in the Andes and likely has a restricted geographic distribution.  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