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1.
The Beni savannas (locally referred to as pampas) is composed of two clearly differentiated ecoregions, the Llanos de Moxos (or Moxos) and the Beni Cerrado. Both tropical savannas are shaped to a greater (Moxos) or lesser (Beni Cerrado) by cycles of drought and flood and the labor of generation of farmers. It contains floristic elements of four biogeographic regions (Amazonian, Chaco, Cerrado and Chiquitana). However, in spite of their biological richness, they are little represented in the National System of Protected Areas (SNAP, in Spanish). By employing an ecoregion and sub-ecoregion approach, we examined the representation of both savanna-type ecoregions in the Departmental System of Protected Areas (SDAP, in Spanish), which includes national, departmental, municipal, and private protected areas. The study also enabled us to compare Bolivia’s newest ecoregion/vegetation zones maps as applied to the both savannas and to produce a sub-ecoregion map for the Beni department (northeastern Bolivia). Our results show that the Llanos de Moxos and the Beni Cerrado are found in protected areas of departmental and municipal level. Although they are still under-represented (mainly the Beni Cerrado), they have nonetheless important extensions inside these protected areas. A better representation of these zones would guarantee improved levels of protection of these unique ecosystems. On the other hand, our study shows the importance of the conservation-representation target relationships (sensu Rodrigues et al. 2004). This is the first time that this approach is used to examine gaps of floristic representativeness of savanna-type ecoregions showing that the traditional 10% minimal conservation target should be used with caution.  相似文献   

2.
The not yet uploaded Trichoptera World Checklist (TWC) [], as at July 2006, recorded 12,627 species, 610 genera and 46 families of extant and in addition 488 species, 78 genera and 7 families of fossil Trichoptera. An analysis of the 2001 TWC list of present-day Trichoptera diversity at species, generic/subgeneric and family level along the selected Afrotropical, Neotropical, Australian, Oriental, Nearctic and Palaearctic (as a unit or assessed as Eastern and Western) regions reveals uneven distribution patterns. The Oriental and Neotropical are the two most species diverse with 47–77% of the species in widespread genera being recorded in these two regions. Five Trichoptera families comprise 55% of the world’s species and 19 families contain fewer than 30 species per family. Ten out of 620 genera contain 29% of the world’s known species. Considerable underestimates of Trichoptera diversity for certain regions are recognised. Historical processes in Trichoptera evolution dating back to the middle and late Triassic reveal that the major phylogenetic differentiation in Trichoptera had occurred during the Jurrasic and early Cretaceous. The breakup of Gondwana in the Cretaceous led to further isolation and diversification of Trichoptera. High species endemism is noted to be in tropical or mountainous regions correlated with humid or high rainfall conditions. Repetitive patterns of shared taxa between biogeographical regions suggest possible centres of origin, vicariant events or distribution routes. Related taxa associations between different regions suggest that an alternative biogeographical map reflecting Trichoptera distribution patterns different from the Wallace (The Geographical Distribution of Animals: With a Study of the Relations of Living and Extinct Faunas as Elucidating the Past Changes of the Earth’s Surface, Vol. 1, 503 pp., Vol. 2, 607 pp., Macmillan, London, 1876) proposed biogeography patterns should be considered. Anthropogenic development threatens biodiversity and the value of Trichoptera as important functional components of aquatic ecosystems, indicator species of deteriorating conditions and custodians of environmental protection are realised.  相似文献   

3.
The goal of biodiversity hotspots is to identify regions around the world where conservation priorities should be focused. We undertake a geographic information system and remote sensing analysis to identify the rarest and least protected forests in biodiversity hotspots. World Wildlife Fund ecoregions with terrestrial forest were subset from 34 biodiversity hotspots and forest cover calculated from GlobCover data at a 300?m pixel resolution. There were 276 ecoregions in 32 biodiversity hotspots classified as containing terrestrial forests. When the first quartile of forest ecoregions was subset based on smallest extent of forest cover in protected areas, there were 69 rare forests identified within 20 biodiversity hotspots. Most rare forest ecoregions (45) occurred on islands or island archipelagos and 47 rare forest ecoregions contained less than 10?% forest cover in protected areas. San Félix-San Ambrosio Islands Temperate Forests, Tubuai Tropical Moist Forests, Maldives-Lakshadweep-Chagos Archipelago Tropical Moist Forests, and Yap Tropical Dry Forests were identified as the least protected and possibly most vulnerable forests within biodiversity hotspots. These ecoregions cover less than 500?km2, forest cover is less than 50?km2, and there are no protected areas. There is a need to update classifications and boundaries of protected areas, insure that islands are included in global land cover datasets, and identify levels of endemism and endangerment within forest ecoregions. This should improve our ability to compare, prioritize, and monitor forests in biodiversity hotspots.  相似文献   

4.
North western Argentina, the southernmost portion of the tropical Andes, contains one of the main areas of endemism within the Southern Cone, as well as one of the main diversity hotspots of the country. Historically its reserve area systems have been located in the richest ecoregion of the area; the Southern Andean Yungas. We evaluated the effectiveness of the current protected areas in preserving the endemic flora of the region. The distributions of 505 endemic species were either modeled or included as observed data to determine endemism hotspots in each ecoregion. The endemic species were mainly found in arid ecoregions such as the High Monte and the Central Andean Puna, as well as in the transition zones between these regions and the Southern Andean Yungas. We found that more than 1/3 of the endemic species are unprotected in their entire ranges by the current system, while nearly half of the species are protected in only 5 % of their distribution ranges. New priority areas were chosen to increase the effectiveness based on the irreplaceability concept. We show that adding 251 new cells of 100 km2 each would improve the protection values and convert the system to effective. The present paper highlights that priorities set on the basis of species richness may not successfully conserve areas of high plant endemism. However, zoologist would have to realize similar assessments in the endemic fauna in order to find the optimal designed of protected areas system to conserve both the endemic flora and fauna in the Southern Central Andes.  相似文献   

5.
In Bolivia, the plant families Araceae and Bromeliaceae offer numerous non-timber products, including ornamental plants, medicines, foods, and fibers. The economic potential for the utilization of these resources depends critically on the distribution of potentially useful species in different ecoregions in Bolivia. We conducted both a bibliographical revision of uses and ecological field work at 43 sites in the Bolivian Andes and lowlands to assess the potential for sustainable use as suggested by the Rapid Vulnerability Assessment method. The ecological criteria used for the evaluation were abundance (frequency), life form, geographical distribution, and habitat preference. We found that Bolivia has a striking number of potentially useful species of both families but that their potential use differs among ecoregions. Araceae were most species-rich and frequent in the humid lowland and montane forests. In these ecoregions, this family has a particular local importance mainly as traditional medicines and a great potential as ornamental plants. In contrast, economically useful bromeliads are best represented in seasonally dry forest habitats, especially for the production of fibres. Many species of bromeliads, which also occur in humid montane forests, although rare, are potentially important for commercialisation as ornamental species. This study shows that the uses of Araceae and Bromeliaceae are manifold and could be greatly increased through efficient management, although with different strategies according to the different ecoregions.  相似文献   

6.
Aim To test predictions of the vicariance model, to define basic biogeographical units for Cerrado squamates, and to discuss previous biogeographical hypotheses. Location Cerrado; South American savannas south of the Amazon, extending across central Brazil, with marginal areas in Bolivia and Paraguay and isolated relictual enclaves in adjacent regions. Methods We compiled species occurrence records via field sampling and revision of museum specimens and taxonomic literature. All species were mapped according to georeferenced locality records, and classified as (1) endemic or non‐endemic, (2) typical of plateaus or depressions, and (3) typical of open or forested habitats. We tested predictions of the vicariance model using biotic element analysis, searching for non‐random clusters of species ranges. Spatial congruence of biotic elements was compared with putative areas of endemism revealed by sympatric restricted‐range species. Effects of topographical and vegetational mosaics on distribution patterns were studied according to species composition in biotic elements and areas of endemism. Results We recorded 267 Cerrado squamates, of which 103 (39%) are endemics, including 20 amphisbaenians (61% endemism), 32 lizards (42%) and 51 snakes (32%). Distribution patterns corroborated predictions of the vicariance model, revealing groups of species with significantly clustered ranges. An analysis of endemic species recovered seven biotic elements, corroborating results including non‐endemics. Sympatric restricted‐range taxa delimited 10 putative areas of endemism, largely coincident with core areas of biotic elements detected with endemic taxa. Distribution patterns were associated with major topographical and vegetational divisions of the Cerrado. Endemism prevailed in open, elevated plateaus, whereas faunal interchange, mostly associated with forest habitats, was more common in peripheral depressions. Main conclusions Our results indicate that vicariant speciation has strongly shaped Cerrado squamate diversity, in contrast to earlier studies emphasizing faunal interchange and low endemism in the Cerrado vertebrate fauna. Levels of squamate endemism are higher than in any other Cerrado vertebrate group. The high number of recovered endemics revealed previously undetected areas of evolutionary relevance, indicating that biogeographical patterns in the Cerrado were poorly represented in previous analyses. Although still largely undocumented, effects of vicariant speciation may be prevalent in a large fraction of Cerrado and Neotropical biodiversity.  相似文献   

7.
Aim We present a biogeographical analysis of the areas of endemism and areas of diversification in the Muscidae. This analysis searched for geographical patterns in the Muscidae to reconstruct elements of the evolutionary biogeographical history of this insect family. Location Andean and Neotropical regions. Method We constructed a geographic database of 728 species from the literature and museum specimens. Areas of endemism were established by parsimony analysis of endemicity (PAE) based on grids of two different sizes: 5° (550 × 550 km) and 2° (220 × 220 km). Areas of diversification were delimited by track analysis that also included phylogenetic information. This process was independently applied to 11 genera. For each genus, we plotted generalized tracks generated by sister species on a map. When these generalized tracks supported inter‐generic nodes they were manually contoured and inferred to be areas of diversification for the Muscidae. Results Thirteen endemic areas were found using the 5° grid, and eight endemic areas resulted from the 2° grid. Ten areas were in agreement with previous studies, and 11 were new. Amazonian and Atlantic areas of diversification agreed with previous areas for the genus Polietina, and new areas of diversification were found in Panama and in central Chile. Main conclusions Six spatial patterns in the Muscidae were identified: (1) areas of endemism in both Pampa and Puna provinces were established with species whose distributions had not previously been analysed; (2) a new area of endemism was established in extreme southern South America, in Tierra del Fuego; (3) two new areas of diversification, which include Panama and central Chile, were identified; (4) a spatial association was identified between the separation of Chiloe Island from the continent and the diversification in Andean species; (5) a north–south track axis and latitudinal node intervals were identified, interpreted as spatial responses to glaciation or glacial retreat in the Andes; and (6) a spatial coincidence of areas of endemism, of diversification and high species richness in the Muscidae was discovered. The analysis of a complete database and the recognition of areas of diversification are extremely important in elucidating novel biogeographical patterns, which will in turn contribute to a better understanding of the geographical patterns of evolution in the Muscidae.  相似文献   

8.
The recognition of areas of endemism (AEs) is important for conservation biology and biogeographical regionalization. Our objective was to quantitatively identify AEs and distributional congruence patterns of native rodents at the tropical/temperate transition in the central Andes. We analysed 6200 geo‐referenced distributional records of 80 species in north‐western Argentina using NDM/VNDM software. We found 20 AEs defined by 22 endemic species (27% of the total rodent fauna) and 34 patterns of distributional congruence in non‐endemic rodents. Geographical range congruence follows two main patterns running parallel along the Andes. One is related to the humid eastern slopes of the Andes (Argentinean Yungas forest) and the other to the high Andes (Argentinean Puna plateau). Endemism was mainly restricted to the southernmost part of the Yungas forest and adjacent dryer valleys (Monte desert). Species diversity was highest in the northern sector of the Argentinean Yungas forest, where several species reach their southern distributional range. This incongruence among hotspots of diversity and endemism has also been also noted in diversity studies at continental and global scales. Our results provide a starting point for conservation planning in the southernmost Central Andes, which combines the taper of tropical diversity and range‐restricted species endemic to the tropical–temperate transition. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 163–179.  相似文献   

9.
With only five protected areas dedicated to the conservation of biodiversity (two national parks, one strict nature reserve and two faunal reserves), Guinea has one of the smallest protected area networks in West Africa. As a result, two of the five ecoregions of the country and six of the 14 globally threatened large and medium-sized mammals occurring in Guinea are not found in the national protected area network. To identify areas with high biodiversity that could be included in the national protected area network, we used the Key Biodiversity Areas (KBA) methodology. We devised a scoring system to rank the identified KBAs according to their relative conservation significance. We identified a total of 16 KBAs throughout the country. Their proclamation as protected areas would result in the protection of all ecoregions and all but one of Guinea’s globally threatened large and medium-sized mammals. Twelve of the 16 KBAs have the legal status of classified forest, a status that should facilitate the change into formal biodiversity protected areas (IUCN category I–IV). Our analysis indicates that even if only the two areas with the highest conservation significance score, the Ziama and Diécké forests, become formal protected areas, this would provide protection to both the western Guinean lowland forests, one of the most threatened ecoregions in Africa, and to 11 of the 14 threatened large and medium-sized mammals occurring in Guinea.  相似文献   

10.
Delineating biogeographical regions is a critical step towards the establishment and evaluation of conservation priorities. In the present study, we analysed the distribution patterns of the freshwater fish of an understudied European biodiversity hotspot, the Balkan Peninsula. Based on the most extensive available database of native freshwater fish species distributions, we performed a hierarchical clustering analysis to identify the major biogeographical regions of the Balkan Peninsula. We also highlighted the ‘hottest hotspots’ of freshwater fish diversity across the delimited biogeographical regions by describing the patterns of species richness, endemic and vulnerable species; indicator species were also determined. The bioregionalisation scheme consisted of eight groups of drainage basins that correspond to distinct regions of the Balkan Peninsula. Overall, the delineated biogeographical regions varied in terms of species richness, endemism, vulnerability (i.e. extinction threats) and indicator species composition. From a conservation perspective, this study emphasises the prioritisation of areas characterised by high levels of irreplaceability (endemism) and vulnerability (i.e. the Attikobeotia region, Ionian Sea and Prespa Lakes) and stresses the necessity of implementing a network of protected freshwater areas across the Balkan Peninsula.  相似文献   

11.
The hope among policy-makers and scientists alike is that conservation strategies designed to protect biodiversity also provide direct benefits to people by protecting other vital ecosystem services. The few studies that have examined the delivery of ecosystem services by existing conservation efforts have concentrated on large, ‘wilderness’-style biodiversity reserves. However, such reserves are not realistic options for densely populated regions. Here, we provide the first analyses that compare representation of biodiversity and three other ecosystem services across several contrasting conservation strategies in a human-dominated landscape (England). We show that small protected areas and protected landscapes (restrictive zoning) deliver high carbon storage and biodiversity, while existing incentive payment (agri-environment) schemes target areas that offer little advantage over other parts of England in terms of biodiversity, carbon storage and agricultural production. A fourth ecosystem service—recreation—is under-represented by all three strategies. Our findings are encouraging as they illustrate that restrictive zoning can play a major role in protecting natural capital assets in densely populated regions. However, trade-offs exist even among the four ecosystem services we considered, suggesting that a portfolio of conservation and sustainability investments will be needed to deliver both biodiversity and the other ecosystem services demanded by society.  相似文献   

12.
Aim Twelve per cent of the Earth’s terrestrial surface is covered by protected areas, but neither these areas nor the biodiversity they contain are evenly distributed spatially. To guide future establishment of protected areas, it is important to understand the factors that have shaped the spatial arrangement of the current protected area system. We used an information‐theoretic approach to assess the ability of vertebrate biodiversity measures, resource consumption and agricultural potential to explain the global coverage pattern of protected areas. Location Global. Methods For each of 762 World Wildlife Fund terrestrial ecoregions of the world, we measured protected area coverage, resource consumption, terrestrial vertebrate species richness, number of endemic species, number of threatened species, net primary production, elevation and topographic heterogeneity. We combined these variables into 39 a priori models to describe protected area coverage at the global scale, and for six biogeographical realms. Using the Akaike information criterion and Akaike weights, we identified the relative importance and influence of each variable in describing protected area coverage. Results Globally, the number of endemic species was the best variable describing protected area coverage, followed by the number of threatened species. Species richness and resource consumption were of moderate importance and agricultural potential had weak support for describing protected area coverage at a global scale. Yet, the relative importance of these factors varied among biogeographical realms. Measures of vertebrate biodiversity (species richness, endemism and threatened species) were among the most important variables in all realms, except the Indo‐Malayan, but had a wide range of relative importance and influence. Resource consumption was inversely related to protected area coverage across all but one realm (the Palearctic), most strongly in the Nearctic realm. Agricultural potential, despite having little support in describing protected area coverage globally, was strongly and positively related to protection in the Palearctic and Neotropical realms, as well as in the Indo‐Malayan realm. The Afrotropical, Indo‐Malayan and Australasian realms showed no clear, strong relationships between protected area coverage and the independent variables. Main conclusions Globally, the existing protected area network is more strongly related to biodiversity measures than to patterns of resource consumption or agricultural potential. However, the relative importance of these factors varies widely among the world’s biogeographical realms. Understanding the biases of the current protected area system may help to correct for them as future protected areas are added to the global network.  相似文献   

13.
Our aims were to quantify and map the plant ecoregions of the Atlantic Forest, a biodiversity hotspot that covers ca 150 million ha in eastern South America. We used a data set on the distribution of 4378 shrub and tree species across 711 localities. Plant ecoregions were identified using analyses of species turnover for both species occurrences and relative abundances. We interpolated NMDS axes of compositional variation over the entire the Atlantic Forest extent, and then classified the compositional dissimilarity according to the number of biogeographical ecoregions previously identified through K‐means analyses. We assessed the ability of environmental, historical vegetation stability and the current human footprint to explain the occurrence of the identified ecoregions through multinomial logistic regression models. We identified 21 spatially cohesive occurrence and 14 abundance ecoregions. Aridity, soil and historical biome stability were retained in the best model explaining both occurrence and abundance ecoregions. Broad compositional zones were identified through UPGMA cluster analysis of ecoregions, and formed north and south compositional blocks. Our work confirms the existence of a broad north–south divide within the Atlantic Forest, previously suggested based on climatic and amphibious data. Differences between the occurrence and abundance maps suggest the location of transition zones to neighbouring domains and endemism centres. Due to the aggregate nature of our analyses, site‐level disturbance degree was not considered, implying that human impacts could be broader then we could detect. There was limited overlap between our results and previous Atlantic Forest regionalization efforts, indicating that multi‐taxa, physiognomic and environmental regionalization schemes based on expert opinion or vegetation maps are poor proxies for compositional ecoregions.  相似文献   

14.
In conservation planning, species richness and species endemism are the most often used metrics for describing the biodiversity importance of areas. However, when it comes to prioritizing regions for conservation actions these measures alone are insufficient because they do not reveal how similar or different the actual composition of species may be from one area to another. For comparative analysis an additional useful metric would be one that indicates the degree to which the species assemblage in one area is also represented in—or is distinct from—species assemblages of other areas. Here we describe a method for quantifying the compositional representativeness of species assemblages among geographic regions. The method generates asymmetric pairwise similarity coefficients that are then used to calculate separate measures for the representativeness and the distinctiveness of species assemblages in the regions being compared. We demonstrate the method by comparing fish communities among freshwater ecoregions of the Mississippi Basin, and then among smaller hydrological units within two individual freshwater ecoregions. At both scales of analysis, our measures of representativeness and distinctiveness reveal patterns of fish species composition that differ from patterns of species richness. This information can enhance conservation planning processes by ensuring that priority-setting explicitly consider the most representative and distinctive species assemblages.  相似文献   

15.
The protected areas of Bolivia cover 10.2% of its territory, but only 60% of this surface is considered to be of conservation value. Protected areas are unevenly distributed over the eight phyto-geographic regions of Bolivia. The Pantanal is not represented in any conservation unit. Inventories and basic information are usually lacking as plant surveys have been carried out mostly outside protected areas.  相似文献   

16.
Stream fish assemblages are structured by biogeographical, physical and biological factors acting on different spatial scales. We determined how physical factors, geomorphology and stream habitat, influenced fish species composition (presence–absence) in eastern Oklahoma, USA relative to the ecoregion and biogeographic effects previously reported. We sampled fish assemblages and surveyed geomorphology and habitat at 107 stream sites in the Boston Mountains, Ouachita Mountains, and Ozark Highlands ecoregions in eastern Oklahoma. Partial canonical correspondence analyses (pCCAs) and variance partitioning showed that patterns of endemism related to drainage basins and ecoregions explained important variation in fish species composition in all streams, but stream size and local channel morphology explained more variation overall. Stream size effects were most important in explaining variability in fish species composition in both northeastern and southeastern Oklahoma streams. Local channel morphology and substrate characteristics were secondarily important. Variables typically considered important as fish habitat (aquatic vegetation, etc.) had little effect on fish species composition.  相似文献   

17.
Aim  To examine current biogeographical patterns of Aphodiinae dung beetles (Coleoptera: Scarabaeoidea: Scarabaeidae) in order to reveal relationships among regions and their potential impact on the diversification of this group.
Location  Worldwide.
Methods  Information about all Aphodiinae genera was obtained from the literature. An occurrence matrix was built for the six worldwide biogeographical regions, and their faunas were characterized through simple statistics. Regional variations and similarities were further explored using co-occurrence and nestedness analyses, sequential agglomerative, hierarchical and nested clustering (SAHN), and a parsimony analysis of endemicity (PAE). Mantel tests were also employed to assess the relationships between several characteristics of the regions and their faunas.
Results  The Palaearctic and Palaeotropical regions showed the highest total numbers of Aphodiinae genera and the greatest generic endemism. Both these regions and the Oriental also showed higher numbers of genera than would be expected according to their size. Co-occurrence and nestedness analyses confirmed the non-randomness of the distribution of genera. Clustering and PAE showed that the Palaearctic and Oriental regions are the most similar, followed by the Palaeotropical region. Regional dissimilarity in genera composition was related to biological and historical traits, but not to ecoregions.
Main conclusions  A structured geographical pattern for Aphodiinae was confirmed. Land continuity and proximity in the long term could have played a unifying role in regional faunas. We suggest that the different biogeographical regions have acted as either macroevolutionary sources (basically the Palaearctic and the Palaeotropical regions) or sink regions, according to their role as diversification centres. We review the processes and events that could account for current patterns of Aphodiinae diversity.  相似文献   

18.

Background

Monitoring land change at multiple spatial scales is essential for identifying hotspots of change, and for developing and implementing policies for conserving biodiversity and habitats. In the high diversity country of Colombia, these types of analyses are difficult because there is no consistent wall-to-wall, multi-temporal dataset for land-use and land-cover change.

Methodology/Principal Findings

To address this problem, we mapped annual land-use and land-cover from 2001 to 2010 in Colombia using MODIS (250 m) products coupled with reference data from high spatial resolution imagery (QuickBird) in Google Earth. We used QuickBird imagery to visually interpret percent cover of eight land cover classes used for classifier training and accuracy assessment. Based on these maps we evaluated land cover change at four spatial scales country, biome, ecoregion, and municipality. Of the 1,117 municipalities, 820 had a net gain in woody vegetation (28,092 km2) while 264 had a net loss (11,129 km2), which resulted in a net gain of 16,963 km2 in woody vegetation at the national scale. Woody regrowth mainly occurred in areas previously classified as mixed woody/plantation rather than agriculture/herbaceous. The majority of this gain occurred in the Moist Forest biome, within the montane forest ecoregions, while the greatest loss of woody vegetation occurred in the Llanos and Apure-Villavicencio ecoregions.

Conclusions

The unexpected forest recovery trend, particularly in the Andes, provides an opportunity to expand current protected areas and to promote habitat connectivity. Furthermore, ecoregions with intense land conversion (e.g. Northern Andean Páramo) and ecoregions under-represented in the protected area network (e.g. Llanos, Apure-Villavicencio Dry forest, and Magdalena-Urabá Moist forest ecoregions) should be considered for new protected areas.  相似文献   

19.
The concepts of biogeographical regions and areas of endemism are briefly reviewed prior to a discussion of what constitutes a natural biogeographical unit. It is concluded that a natural biogeographical unit comprises a group of endemic species that share a geological history. These natural biogeographical units are termed Wallacean biogeographical units in honour of the biogeographer A.R. Wallace. Models of the geological development of Indonesia and the Philippines are outlined. Areas of endemism within Wallacea are identified by distributional data, and their relationship to each other and to the adjacent continental regions are evaluated using molecular phylogenies from the literature. The boundaries of these areas of endemism are in broad agreement with earlier works, but it is argued that the Tanimbar Islands are biologically part of south Maluku, rather than the Lesser Sundas, and that Timor (plus Savu, Roti, Wetar, Damar, and Babar) and the western Lesser Sundas form areas of endemism in their own right. Wallacean biogeographical units within Wallacea are identified by congruence between areas of endemism and geological history. It is concluded that although Wallacea as a whole is not a natural biogeographical region, neither is it completely artificial as it is formed from a complex of predominantly Australasian exotic fragments linked by geological processes within a complex collision zone. The Philippines are argued to be an integral part of Wallacea, as originally intended. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 193–212.  相似文献   

20.
The Guianas are one of the most diverse regions of the Neotropics, hosting a particularly high rate of freshwater fish endemism. The present distributional patterns of freshwater fish species in the major catchments of the Guianas (comprising Guyana, Suriname and French Guiana) were analysed to reveal the faunal relationships between rivers, evaluate different hypotheses concerning biogeographical units, and redefine the boundaries of the Guianese freshwater ecoregions. A parsimony analysis of endemicity was performed using a data partitioning strategy to alleviate some drawbacks inherent to the method (e.g. long branch attraction artefact, heterotachy), and take into account alternative parsimony models assigning different constraints on state changes for the different species. A strong spatial element was present in the data with a structuring of species along a west–east gradient. Two main biogeographical units were highlighted: one to the west, ranging from the Essequibo to the Commewijne rivers and including the Proto Berbice and Surinamese regions, and one to the east ranging from the Maroni to the Oyapock rivers and including the Western, Central and Eastern French Guiana regions. Each ecoregion possessed distinctive fish assemblages, and three to four potential zones of faunal exchanges between Amazonian and Guianese rivers have been confirmed.  相似文献   

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