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1.
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Abstract Identification of biodiversity hotspots is essential to conservation strategies aimed at minimizing the possibility of losing half of the world's species in the next 50 years. The aims of the present study were: (i) to locate and designate zones of endemism in the temperate forest of South America; and (ii) to compare the distribution of these areas with the distribution of existing protected areas in this habitat type. Endemism areas were determined by using parsimonious analysis of endemism, which identified zones of endemism on the basis of sets of endemic species that were restricted to two or more study areas. We used distribution information for five unrelated taxa (ferns, trees, reptiles, birds and mammals) to provide more reliable results and patterns than would work with only a single taxon or related taxa. The northern part of this region has high endemism for all of the taxa considered in this study. We demonstrate that although the temperate forest of South America has more than 30% of its area under some type of protection, correlation between protected areas and the areas of endemism is remarkably low. In fact, less than 10% of protected areas are situated in areas that have the greatest value for conservation (i.e. high endemism). Under the current strategy, biodiversity within South America's temperate forest is in danger despite the large amount of protected area for this forest type.  相似文献   

3.
Animals destined for meat production are usually exposed to many stressful conditions during production and particularly during preslaughter operations. Handling animals on farm, loading into and unloading from vehicles, transportation, passing through livestock markets, fasting, lairage and stunning can all affect their welfare. How badly welfare can be affected will depend on both the intrinsic factors of the specific type of animal involved and the extrinsic factors of the environment where those animals live or are being handled, including the animal handlers. In South America (SA), it has been part of a strategy for improving animal welfare (AW) to address not only ethical aspects, but to emphasize the close relationship existing between handling ruminants preslaughter and the quantity and quality of the meat they produce. This has resulted not only in improvements in AW, but has also brought economic rewards to producers which in turn can lead to higher incomes for them and hence better human welfare. For producers with a high number of animals, considering AW during production and preslaughter operations can determine the possibility of exporting and/or getting better prices for their products. At smallfarmer level, particularly in some less developed countries, where human welfare is impaired, using this strategy together with education has also been relevant. It is important that education and training in AW are done not only considering global knowledge, but also including specific geographical and climatic characteristics of each country and the cultural, religious and socio-economical characteristics of its people; therefore, research within the context of each country or region becomes relevant. The aim of this review was to show the results of research dealing with AW of ruminant livestock in Chile and some other SA countries. Some of the main problems encountered are related to lack of proper infrastructure to handle animals; long distance transport with high stocking densities in the larger countries; long fasting times due to animals passing through livestock markets and dealers; bad handling of animals by untrained personnel in these and other premises; and finally the lack of knowledge and skills by operators in charge of stunning procedures. Interventions at these stages have considered training animal handlers and transporters by showing them the consequences of bad handling with audiovisual material prepared on site. Research results have helped to improve AW and support the development of new legislation or to make changes in the existent legislation related to AW.  相似文献   

4.
Oxalis jiayinensis, sp. nov., is described from the Late Cretaceous (TuronianSenonian) in Jiayin County, Heilongjiang Province, northeastern China. The seed is about 1 mm long, less than 1 mm in diameter, crescentic with obtuse apices and 9~10 transverse ribs. The seed wall is composed of equiaxial, strongly thickened sclereids. The fossil repre-sents the oldest occurrence of the family Oxalidaceae in the world.  相似文献   

5.
本文描述了发现于中国黑龙江省嘉荫县晚白垩世(土仑期至赛诺期)的酢酱草科酢酱草属新种 Oxalis jiayinensis Feng,Liu,Song et Ma;炭化种子长约1 mm,宽不足1mm;新月形,两端钝;表面具9 ~10条横脊;种皮石细胞等轴、细胞壁明显加厚。该化石种是酢酱草科在地质时期迄今最早的代表。  相似文献   

6.
The first steps in the history of South American mammals took place ca. 130 Ma., when the South American plate, still connected to the Antarctic Peninsula, began to drift away from the African-Indian plate. Most of the Mesozoic history of South American mammals is still unknown, and we only have a few enigmatic taxa (i.e., a Jurassic Australosphenida and an Early Cretaceous Prototribosphenida) that pose more evolutionary and biogeographic questions than answers. The best-known Mesozoic, South American land-mammal fossils are from Late Cretaceous Patagonian beds. These fossils represent the last survivors of non- and pre-tribosphenic Pangaean lineages, all of them with varying endemic features: some with few advanced features (e.g., ?Eutriconodonta and “Symmetrodonta”), some very diversified as endemic groups (e.g., ?Docodonta Reigitheriidae), and others representing vicariant types of well known Laurasian Mesozoic lineages (e.g., Gondwanatheria as vicariant of Multituberculata). These endemic mammals lived as relicts (although advanced) of pangeic lineages when a primordial South American continent was still connected to the Antarctic Peninsula and, at the northern extreme, near the North American Plate. By the beginning of the Late Cretaceous, the volcanic and diastrophic processes that finally led to the differentiation of the Caribbean region and Central America built up transient geographic connections that permitted the initiation of an overland inter-American exchange that included, for example, dinosaurian titanosaurs from South America and hadrosaurs from North America. The immigration of other vertebrates followed the same route, for example, polydolopimorphian marsupials. These marsupials were assumed to have differentiated in South America prior to new discoveries from the North American Late Cretaceous. The complete extinction of endemic South American Mesozoic mammals by the Late Cretaceous-Early Paleocene, and the subsequent and in part coetaneous immigration of North American therians, respectively, represent two major moments in the history of South American mammals: a Gondwanan Episode and a South American Episode. The Gondwanan Episode was characterized by non- and pre-tribosphenic mammal lineages that descended from the Pangeic South American stage (but already with a pronounced Gondwanan accent, and wholly extinguished during the Late Cretaceous-Early Paleocene span). The South American Episode, in turn, was characterized only by therian mammals, mostly emigrated from the North American continent and already with a South American accent obtained through isolation. The southernmost extreme of South America (Patagonia) remained connected to the present Antarctic Peninsula at least up until about 30 Ma., and both provided the substratum where the primordial cladogenesis of “South American” mammals occurred. The resulting cladogenesis of South American therian mammals followed Gould's motto: early experimentation, later standardization. That is to say, early cladogenesis engendered a great variety of taxa with scarce morphological differentiation. After this early cladogenesis (Late Eocene-Early Oligocene), the variety of taxa became reduced, but each lineage became clearly recognizable distinctive by a constant morphologic pattern. At the same time, those mammals that underwent the “early experimentation” were part of communities dominated by archaic lineages (e.g., brachydont types among the native “ungulates”), whereas the subsequent communities were dominated by mammals of markedly “modern” stamp (e.g., protohypsodont types among the native “ungulates”). The Gondwanan and South American Episodes were separated by a critical latest Cretaceous-earliest Paleocene hiatus, it is as unknown as it is important in which South American land-mammal communities must have experienced extinction of the Gondwanan mammals and the arrival and radiation of the North American marsupials and placentals (with the probable exception of the xenarthrans, whose biogeographic origin is still unclear).  相似文献   

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We have analysed the genetic diversity of South and Central American (SCA) goats by partially sequencing the mitochondrial control region of 93 individuals with a wide geographical distribution. Nucleotide and haplotype diversities reached values of 0.020 ± 0.00081 and 0.963 ± 0.0012 respectively. We have also observed a rather weak phylogeographic structure, with almost 69% of genetic variation included in the within-breed variance component. The topology of a median-joining network analysis including 286 European, Iberian, Atlantic and SCA mitochondrial sequences was very complex, with most of the haplotypes forming part of independent small clusters. SCA sequences showed a scattered distribution throughout the network, and clustering with Spanish and Portuguese sequences occurred only occasionally, not allowing the distinguishing of a clear Iberian signature. Conversely, we found a prominent cluster including Canarian, Chilean, Argentinian and Bolivian mitochondrial haplotypes. This result was independently confirmed by constructing a Bayesian phylogenetic tree (posterior probability of 0.97). Sharing of mitochondrial haplotypes by SCA and Canarian goats suggests that goat populations from the Atlantic archipelagos, where Spanish and Portuguese ships en route to the New World used to stow food and supplies, participated in the foundation of SCA caprine breeds.  相似文献   

9.
South America is home to one of the most culturally diverse present-day native populations. However, the dispersion pattern, genetic substructure, and demographic complexity within South America are still poorly understood. Based on genome-wide data of 58 native populations, we provide a comprehensive scenario of South American indigenous groups considering the genomic, environmental, and linguistic data. Clear patterns of genetic structure were inferred among the South American natives, presenting at least four primary genetic clusters in the Amazonian and savanna regions and three clusters in the Andes and Pacific coast. We detected a cline of genetic variation along a west-east axis, contradicting a hard Andes-Amazon divide. This longitudinal genetic variation seemed to have been shaped by both serial population bottlenecks and isolation by distance. Results indicated that present-day South American substructures recapitulate ancient macroregional ancestries and western Amazonia groups show genetic evidence of cultural exchanges that led to language replacement in precontact times. Finally, demographic inferences pointed to a higher resilience of the western South American groups regarding population collapses caused by the European invasion and indicated precontact population reductions and demic expansions in South America.  相似文献   

10.
Freshwater copepods were sampled in the La Plata River basin to identify the processes that affect beta diversity and to determine the main factors influencing their geographical distribution and patterns of endemism. Beta diversity patterns exhibited strong dissimilarity between locations; the turnover process was predominant and indicated a replacement of species along the basin. Redundancy analysis indicated the presence of two large sets of species separated geographically by a boundary zone, with several associated variables. Northern species were associated with water transparency and temperature, mean air temperature, mean air temperature during winter and minimum air temperature of coldest month, indicating that these species are not tolerant to low temperatures and are abundant in reservoirs that are common in the upper stretch of the Paraná River basin. Southern species were related with amplitude of air temperature, turbidity, total phosphorus and total suspended matter, indicating that these species are polythermic and have adapted to live in river stretches. From 20 environmental variables analyzed in our study, partial least squares analysis indicated four variables with increased retention of effects on copepod abundance: air temperature, minimum temperature of coldest month, turbidity and transparency. Because almost all of the species found in this study occurred across a wide range of habitat types, the cause of the separation between river and reservoir species could be considered to be more anthropogenic than natural, and it primarily affected species abundance. For certain members of the northern group of copepod species, distribution was dependent on high temperatures, whereas the distribution of the southern group indicated that the species were polythermic.  相似文献   

11.
Phytotelmata, or plant-held waters, are considered to be good model systems for the study of community ecology. The fauna of these natural container habitats, particularly the mosquitoes, have been extensively investigated in tropical regions, but there is little known about them in temperate South America. We assessed the structure of immature mosquito communities in leaf axils, tree holes, and bamboo stumps from a temperate wetland of Argentina. A total of 4,330 immature mosquitoes were collected among the 2,606 phytotelmata inspected. Leaf axils of eight plant species and tree holes were larval habitats for nine mosquito species belonging to the genus Culex, Wyeomyia, Isostomyia, and Toxorhynchites. The mosquito communities showed richness ranging from one to four species. Marked differences were detected in the plant specificity for the species collected. Some of them were exclusively found in one plant species (Isostomyia paranensis in Scirpus giganteus), whereas others were collected in up to five plant species but belonging to the same phytotelm class, the leaf axils. Those from tree holes are well-known dwellers of artificial containers and ground water habitats, such as Culex pipiens. Our results support the idea of low mosquito richness in phytotelmata from temperate regions in comparison with tropical areas, but the observed specificity patterns echo the findings of tropical forests.  相似文献   

12.
Cladistic and biogeographic analyses of the genus Farrodes are presented. Two species groups are delineated within Farrodes: F. caribbianus and F. bimaculatus. Three species formerly placed in other genera– Thraulus caribbianus Traver, Thraulus roundsi Traver and Homothraulus maculatus (Needham & Murphy)–are transferred to Farrodes. The species of the F. caribbianus species group are revised. Three new species are described: F. savagei from Venezuela, F. maya and F. mexicanus from Mexico. Keys to separate the two species groups of Farrodes and the species of the F caribbianus species group are provided. Successive cladistic analyses were carried out on both adult and nymphal characters using Hennig86 and CLADOS. The matrix was composed of all available data (nymphal characters were missing for some species), from nymphal and adult stages separately and on taxa represented by both adult and nymphal characters. Species of the genera Simothraulopsis and Homothraulus (components of the Farrodes lineage) were included in the analyses, and Ecuaphkbia was used as the outgroup. Results of the four analyses are compatible. The historical biogeography of Farrodes , with a distribution from nordiern Argentina to southern Texas, is analysed using the program COMPONENT. Areas of endemism are established, and some of their relationships compared with those of other groups available in the literature.  相似文献   

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Phylogenetic relationships based on 801 base pairs (bp) of the mitochondrial cytochrome b gene are examined for eight genera and 28 species of the akodontine tribe of South American murid rodents. The akodontine tribe comprises some 35% of the total diversity of the subfamily Sigmodontinae, but the current taxonomy at virtually all levels is uncertain because of inadequate generic diagnoses and assessments of variation and trends in traditional morphological characters. Monophyly of the tribe cannot be resolved by the sequence data, based on comparisons to outgroup taxa in three other tribes (Oryzomyini, Phyllotini, and Thomasomyini). However, highly corroborated monophyletic units within the group are obtained in a variety of both parsimony and distance analyses. These include a redefined and numerically dominant genus Akodon (with Microxus and Hypsimys as synonyms), Bolomys, Lenoxus, Oxymycterus, and a strongly supported assemblage that includes the central Andean Chroeomys and 'Akodon' andinus and the southern Abrothrix, 'Akodon' olivaceus, and the long-clawed mice of the genera Notiomys, Geoxus, and Chelemys. Sequence divergence within species is typically less than 5%, although levels can reach 10% for some highly polytypic forms. Divergence among genera within the tribe reaches 35% in corrected estimates, a level that is as great as that among representatives of different tribes. Changes in the current classification of akodontines are suggested based on these data, and the timing and place of origin of the tribe and its radiation is discussed.  相似文献   

15.
Reproduction is a key factor for the successful establishment and spread of introduced species. Oxalis pes‐caprae is a tristylous species with a self‐ and morph‐incompatibility sexual system that, in the invaded range of the western Mediterranean Basin, has been found to reproduce asexually because only the pentaploid, short‐styled morph (5x S‐morph) was introduced. The objective of this study was to test the ability of the 5x S‐morph of O. pes‐caprae to produce viable offspring in the absence of compatible mates, exploring the hypothesis that new morphs could have emerged by sexual reproduction events of the initially introduced morph. Pollen germination, pollen tube development, fruit and seed production, seed germination and offspring ploidy levels were analysed after controlled hand‐pollinations to assess self‐ and morph‐incompatibility and production of viable gametes by the 5x S‐morph. The self‐incompatibility system is still operating, but a partial breakdown in the morph‐incompatibility system combined with the production of viable gametes was observed, allowing sexual reproduction of the 5x S‐morph in the invaded range. The ability of the 5x S‐morph to reproduce sexually may have major consequences for the dynamics of invasive populations of O. pes‐caprae and could be one of the factors involved in the occurrence of new floral morphs in this invaded range.  相似文献   

16.
The first extensive and stratigraphically detailed taxonomic study of the Middle to Late Eocene Bryozoa of the St Vincent Basin has identified more than 200 species of Cheilostomata and 50 species of Cyclostomata. There are three biogeographic groups: basin endemic, Australian and global. Two-thirds (116) of the cheilostome species and seven genera are currently considered endemic to this basin. Most species are endemic to Australia and similar to those found in the Oligo-Miocene of Victoria. The Cellariidae are a common component of most Australian Cainozoic deposits, but the species are highly dissimilar, with 13 of the 17 species here being new. The global component indicates that biogeographic links with regions outside Australia still existed in the Eocene. The cyclostome genus Reticrescis is only known from the Australian and Antarctic Eocene. Ten genera have their first occurrence in the Eocene St Vincent Basin. The Phidoloporidae and Smittinidae represent the most diverse and ubiquitous groups at a geological time close to their time of origination. Contemporaneous sediments in Antarctica, eastern Europe and North America also have a diverse fauna of this family, pointing to a strong Tethyan link. Rhamphosmittina lateralis (MacGillivray) is still extant in New Zealand, having an exceptionally long time range of 40 million years. Overall, the fauna has a distinct Late Cretaceous character. A new genus of Onychocellidae appears similar to genera that were common in Cretaceous Tethyan faunas but rare during the Cainozoic. This similarity ends in the Oligocene, after which the Australian bryozoan became endemic  相似文献   

17.
Abstract Species of Trillium have a disjunct distribution occurring in both North America and eastern Asia. In North America all 36 species are diploid. The 11 species of eastern Asia, however, include only a single diploid with all the other species being polyploids. Why do different patterns of speciation develop in North America and in eastern Asia? The breeding systems of populations in the North American T. erectum, T. grandiflorum and T. ovatum , and in Asian T. kamtschaticum were investigated by estimating the inbreeding coefficient from cold-induced banding patterns which reveal homozygotes and heterozygotes. From the analyses of the inbreeding coefficients, T. erectum, T. grandiflorum and the Pacific coastal species, T. ovatum are predominantly inbreeding species. T. ovatum populations from the Rocky Mountain region are outbreeders. However the Japanese species, T. kamtschaticum has a mixture of outbreeding and inbreeding among populations. The development of polyploid systems in Asia is possibly the result of the diversity of the breeding systems among the populations. The shift from outbreeding to inbreeding appears to be an important key step in the occurrence of poliploids by hybridization between the different species.  相似文献   

18.
For the first time, the structures of the female genital field are described and compared among ten species of Venezuelan diaptomids. A nomenclature for these structures is suggested, and there is a preliminary report on the interspecific differences observed in one of these structures, the genital operculum.  相似文献   

19.
  • 1 Most aquatic mammals have high dispersal potential, and there are often severe conservation concerns related to their legal or illegal harvesting. Therefore, economic, social and forensic factors often arise in decisions relating to their population management. Molecular markers are essential tools in modern conservation genetics, revealing previously unknown aspects of aquatic mammal behaviour, natural history, population structure and demography. Molecular markers also have been used to define management units, to recognize taxonomic units, to conduct forensic analyses and to control illegal wildlife trade, providing valuable information for decision‐making in wildlife conservation and management.
  • 2 We review studies published in peer‐reviewed journals between 1993 and 2010, in which genetic approaches have been applied to conservation‐related issues involving natural populations of 25 species of aquatic mammals in South America. These studies cover just 34% of the 70 aquatic mammal species recorded in South America.
  • 3 Most of the studies are related to population structure, phylogeography, gene flow and dispersal movements. In addition, recent findings relate to evolutionarily significant units, management units, forensics and conservation policy.
  • 4 Finally, we look to the future and, based on numbers of studies and conservation concerns, suggest which species, geographic areas and genetic studies should be prioritized. Moreover, we discuss constraints on research and suggest collaborative works that would provide critical information towards the effective conservation and management of aquatic mammals in South America.
  相似文献   

20.
An evaluation of the first inventory of South American wetlands   总被引:1,自引:0,他引:1  
L. G. Naranjo 《Plant Ecology》1995,118(1-2):125-129
Thanks to the efforts of the International Waterfowl Research Bureau, during 1982–1984, geographic and biotic data from 368 wetlands across South America were gathered. However, the conservation impact of this inventory has not been as striking as expected because of two reasons. First, since most contributors did not work for governmental agencies, the major points stressed in the document have been overlooked by local authorities. Second, because of logistic limitations of the inventory, large wetlands (i.e. those across the Amazon basin), were not inventoried using the IWRB criteria and thus considered as one large wetland. A critical, comparative, review of the results of the inventory revealed that in addition, the reliability of the inventory is questionable because of the differential effort put into the compilation of the information. Several countries appear to contain only a small percentage of South American wetlands, while in fact they have as many wetlands of international importance as countries that have many times their estimated area of wetlands.  相似文献   

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