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1.
There is an increasing need for protected areas to conserve biodiversity efficiently. The Anura of sub-equatorial Africa have received little attention, but we quantitatively analyse a database containing presence-only data for anurans of sub-equatorial Africa to determine patterns of distribution and species richness, and discuss the roles of present and past environmental conditions in shaping these patterns. We consider the distribution of areas rich in endemic, range-restricted and Red Data Book (RDB) species to identify areas of significance to conservation. The Eastern Highlands of Zimbabwe and adjacent area in Mozambique, southeastern Malawi and the northern coast of KwaZulu/Natal are particularly species rich, whereas the southwestern Cape of South Africa and northwestern Zambia exhibit high degrees of endemism. Four major biogeographical sub-regions are identified, which can be further subdivided into provinces. All statistically significant, current environmental factors together account for 52.6% of species richness. Annual maximum rainfall, soil type variation, minimum temperature and range of elevation were all positively correlated with species richness. Thus, both habitat influences and history appear to have influenced patterns of anuran richness in the region. Generally, areas of high species richness coincide with those high in range-restricted, endemic and RDB species. In South Africa, the northeastern coast and southwestern Cape are hypothesised to have been both refugia and centres of speciation. Results suggest that the current reserve system in sub-equatorial Africa is inadequate for the conservation of the full complement of anuran species in the region.  相似文献   

2.
Input data, analytical methods and biogeography of Elegia (Restionaceae)   总被引:1,自引:0,他引:1  
Aim The aim of this paper is to determine the optimal methods for delimiting areas of endemism for Elegia L. (Restionaceae), an endemic genus of the Cape Floristic Region. We assess two methods of scoring the data (presence–absence in regular grids, or in irregular eco‐geographical regions) and three methods for locating biogeographical centres or areas of endemism, and evaluate one method for locating biotic elements. Location The Cape Floristic Region (CFR), South Africa. Methods The distribution of all 48 species of Elegia was mapped as presence–absence data on a quarter‐degree grid and on broad habitat units (eco‐geographical areas). Three methods to delimit areas of endemism were applied: parsimony analysis of endemism (PAE), phenetic cluster analysis, and NDM (‘end em ism’). In addition, we used presence–absence clustering (‘Prabclus’) to delimit biotic elements. The performances of these methods in elucidating the geographical patterns in Elegia were compared, for both types of input data, by evaluating their efficacy in maximizing the proportion of endemics and the number of areas of endemism. Results Eco‐geographical areas perform better than quarter‐degree grids. The eco‐geographical areas are potentially more likely to track the distribution of species. The phenetic approach performed best in terms of its ability to delimit areas of endemism in the study area. The species richness and the richness of range‐restricted species are each highest in the south‐western part of the CFR, decreasing to the north and east. The phytogeographical centres identified in the present study are the northern mountains, the southern mountains (inclusive of the Riviersonderend Mountains and the Cape Peninsula), the Langeberg range, the south coast, the Cape flats, and the west coast. Main conclusions This study demonstrates that (1) eco‐geographical areas should be preferred over a grid overlay in the study of biogeographical patterns, (2) phenetic clustering is the most suitable analytical method for finding areas of endemism, and (3) delimiting biotic elements does not contribute to an understanding of the biogeographical pattern in Elegia. The areas of endemism in Elegia are largely similar to those described in other studies, but there are many detailed differences.  相似文献   

3.
Aim To examine how current and historical environmental gradients affect patterns of millipede (Diplopoda) endemism and species turnover in a global hotspot of floristic diversity, and to identify regions of high endemism and taxonomic distinctness for conservation management. Location South‐western Australia. Methods Museum database records of millipedes (subclasses Pentazonia and Helminthomorpha), supplemented with extensive fieldwork, were used to map species richness, species turnover (β‐diversity), weighted endemism, average taxonomic distinctness and variation in taxonomic distinctness in half‐degree grid squares (c. 2500 km2). Generalized linear models were used to examine relationships between these parameters with rainfall (present day and historical), topography and human disturbance (clearing for agriculture and urbanization). Results Millipede species richness, particularly within the order Spirostreptida, and millipede endemism were positively associated with large within‐cell differences in elevation (mountainous regions). Large variation in taxonomic distinctness (unevenness in the taxonomic tree) in higher‐rainfall areas was mainly due to speciation within the Spirostreptida genus Atelomastix. Hotspots of millipede endemism and taxonomic distinctness were identified within three categories of importance: primary (Stirling Range East, Cape Le Grand, Cape Arid, Walpole, Porongurups), secondary (Mount Manypeaks, Bremer Bay, Stirling Range West, Duke of Orleans Bay, Ravensthorpe, Albany, Busselton) and tertiary (Nornalup). A species turnover boundary was positively associated with rainfall, broadly located in the transition zone of 300–600 mm year?1. Main conclusions The current lack of knowledge on the endemism of invertebrates hampers their incorporation into conservation planning. With this knowledge we can identify global biodiversity hotspots and, at a smaller scale, significant conservation areas within a region. Here we have shown that weighted endemism and taxonomic distinctness are useful tools in identifying centres of high endemism and speciation for millipedes within the south‐west Australian hotspot. Moreover, it is unlikely that either vertebrates or vascular plants will be useful surrogates for identifying significant areas for invertebrate conservation. While other workers have shown that vascular plants, mammals and frogs have different centres of endemism within south‐west Australia, our results show that centres of endemism for millipedes encompass all of these plus other areas.  相似文献   

4.
Aim To investigate the distribution of Australian species of Sauropus. The information obtained is used to (1) identify areas of highest richness and centres of endemism, (2) investigate latitudinal gradients of richness and range size, (3) determine the types of rarity shown, and (4) provide hypotheses on historical biogeography of the genus within Australia. Location Australia. Methods Specimens from 17 herbaria and field searches were examined and label and field information collated on distribution, habit and habitat. Distribution information was used to map all species within 784 grid cells of 1° × 1° and within the 97 Australian ‘ecological regions’. Morphometric cluster analysis of species was conducted using Kulczynski association and flexible UPGMA on 23 character states. Simple regression was used to correlate species richness, density and range size to changes in latitude. CLIMEX is used to match the climate of the region of highest richness in Australia with other areas of the world. Results Species richness was highest within the tropical north of Australia, and most species were associated with tropical savanna woodlands. Two areas were identified as centres of endemism and these corresponded closely to areas of high species richness. Four morphological groups were identified. One species (Sauropus trachyspermus) was found to be widespread, however all other species had small geographical ranges. Species richness and range size were significantly correlated with changes in latitude. Ten species were found to be of the rarest type, warranting conservation initiatives. Main conclusions Two regions of high richness and endemism of Sauropus occur, Thailand and Australia. Within Australia, the Kakadu‐Alligator River and the Cairns‐Townsville areas were identified as centres of endemism and high species richness for Sauropus. Australian Sauropus in general occur in similar communities and climates as other members of the genus elsewhere. Ten of the 27 species of Australian endemic Sauropus are extremely rare and warrant conservation initiatives. Correlations of latitude to species richness are potentially due to Sauropus radiating from the climatically stable top end of Australia. Increasing range size in more southern latitudes may also be due to stability of climates in the top end or because there is more available land area at these latitudes. Sauropus micranthus, the only non‐endemic species, is probably a more recent invader from the Tertiary period when tropical rain forests where more extensive and congruent with those of New Guinea.  相似文献   

5.
Biodiversity and biogeography of southern temperate and polar bryozoans   总被引:2,自引:0,他引:2  
Aim To describe the distribution of biodiversity and endemism of bryozoans in southern temperate and polar waters. We hypothesized that we would find: (1) no strong latitudinal richness gradient; (2) striking contrasts in richness and endemism between clades and between regions; and (3) that faunal similarity of regions would cluster geographically around each southern continent. Location South Atlantic, Indian and Pacific Oceans and the Southern Ocean. Methods We constructed a data base from known literature, regional data bases and recent finds. We regionalized each southern continent, calculated levels of richness and endemism for each region and continent, and used primer 5 to perform multivariate statistical analysis. Results A third (1681) of global bryozoan species described occur south of 30° S, of which c. 87% were cheilostomes. In richness we found no latitudinal cline and change across longitude was stronger. New Zealand was richest and had the most (60%) endemic species, followed by Antarctica at 57%. There were striking contrasts in regional richness and endemism between clades but the highest levels of between‐region similarity were around Antarctica. The timing of past continent connectivity was reflected. Main conclusions Bryozoans show strong hemispherical asymmetry in richness and, like molluscs and corals, decrease away from Australasia rather than with latitude. Species endemism is much lower in Antarctic bryozoans than previously thought, and as this taxon is not particularly dispersive and is now amongst the best studied regionally, maybe Antarctic endemism in general is lower and Antarctica less cut‐off to species dispersal than previously thought. However, Antarctic generic endemism is double the level previously calculated and regional faunal similarities are much higher than around other continents – both reflecting long‐term isolation. Bryozoans, in contrast to the paradigm of Antarctic fauna, may be fairly robust to predicted climate change. Paradoxically, they may also be one of the best taxa to monitor to sensitively detect marine benthic responses.  相似文献   

6.
We investigate the relative importance of stochastic and environmental/topographic effects on the occurrence of avian centres of endemism, evaluating their potential historical importance for broad‐scale patterns in species richness across Sub‐Saharan Africa. Because species‐rich areas are more likely to be centres of endemism by chance alone, we test two null models: Model 1 calculates expected patterns of endemism using a random draw from the occurrence records of the continental assemblage, whereas Model 2 additionally implements the potential role of geometric constraints. Since Model 1 yields better quantitative predictions we use it to identify centres of endemism controlled for richness. Altitudinal range and low seasonality emerge as core environmental predictors for these areas, which contain unusually high species richness compared to other parts of sub‐Saharan Africa, even when controlled for environmental differences. This result supports the idea that centres of endemism may represent areas of special evolutionary history, probably as centres of diversification.  相似文献   

7.
Plant species richness and range-size rarity in Africa south of the Sahara is concentrated in centres of plant diversity and endemism. Distribution patterns of plants mapped in the Distributiones Plantarum Africanum series and selected taxonomic monographs are analysed using the computer programme WORLDMAP. The plants are divided into four groups: herbaceous geophytes, mesophytic herbs, light-demanding shrubs and woody genera. Each group has peaks of species richness and range-size rarity at locations different to the other groups. Herbaceous geophytes and mesophytic herbs have their peaks of species richness and range-size rarity in the same location, the western Cape for geophytes and the Crystal Mountain for mesophytic herbs, whereas light-demanding shrubs and woody genera have peaks in different places. The results are discussed in relation to possible factors determining species richness and endemism and their likely conservation significance.  相似文献   

8.
Aim This study aimed to detect distribution patterns and identify diversity hotspots for Chinese endemic woody seed plant species (CEWSPS). Location China. Methods Presence of 6885 CEWSPS throughout China was mapped by taking the Chinese administrative county as the basic spatial analysis unit. The diversity was measured with five indices: endemic richness (ER), weighted endemism (WE), phylogenetic diversity (PD), phylogenetic endemism (PE) and biogeographically weighted evolutionary distinctiveness (BED). Three levels of area (i.e. 1, 5 and 10% of China’s total land area) were used to identify hotspots, but the 5% level was preferred when both the total area of the hotspots identified and the diversity of CEWSPS reached by the hotspots were considered. Results Distribution patterns of CEWSPS calculated with the five indices are consistent with each other over the national extent. However, the hotspots do not show a high degree of consistency among the results derived from the five indices. Those identified with ER and PD are very similar, and so are those with WE and BED. In total, 20 hotspots covering 7.9% of China’s total land area were identified, among which 11 were identified with all the five indices, including the Hengduan Mountains, Xishuangbanna Region, Hainan Island, and eight mountainous areas located in east Chongqing and west Hubei, in east Yunnan and west Guangxi, in north Guangxi, south‐east Guizhou and south‐west Hunan, in north Guangdong and south Hunan, in south‐east Tibet, and in south‐east Hubei and north‐west Jiangxi. Taiwan Island was also identified as a major hotspot with WE, PE and BED. Main conclusions Hotspots of CEWSPS were identified with five indices considering both distributional and phylogenetic information. They cover most of the key areas of biodiversity defined by previous researchers using other approaches. This further verifies the importance of these areas for China’s biodiversity conservation.  相似文献   

9.
Aim  The study aimed to identify areas of endemism for aphids in the Qinghai-Tibetan Plateau and the Himalayas (QTPH), and to test congruence between patterns of endemism and patterns of overall species richness identified in a previous study.
Location  The QTPH.
Methods  A distribution data base of 326 endemic aphids in the QTPH was compiled. The study area was divided into a grid of 2°× 2° operative geographical units. Parsimony analysis of endemicity (PAE) was used to identify areas of endemism, and the diversity patterns of endemic species were then mapped using GIS.
Results  We identified 326 endemic species belonging to 138 genera within Adelgidae and 14 subfamilies of Aphididae. Five areas of endemism were found using PAE analysis: the eastern Himalayas, the western Himalayas, north-western Yunnan, southern Tibet and the eastern QTPH. Maps of patterns of endemism identified four major centres for endemic aphids, namely the western Himalayas, the eastern Himalayas (or Sikkim-Assam Himalayas), north-western Hengduan Mountains and the mountains of southern Gansu Province, and three minor centres, southern Tibet, south-eastern Tibet and the eastern Qinghai Province in the north-eastern QTPH.
Main conclusions  Our study identifies major centres of aphid endemism. Furthermore, there is a noticeable congruence between patterns of endemism and patterns of species richness. The patterns of endemism were most likely influenced by the recent uplift of the QTPH.  相似文献   

10.
Abstract We examined broad scale patterns of diversity and distribution of lotic Chironomidae (Diptera) within the Wet Tropics bioregion of northern Queensland, Australia. Field surveys across broad latitudinal and altitudinal gradients within the Wet Tropics revealed a fauna of 87 species‐level taxa in 49 genera comprising three main elements: a small genuinely tropical fraction, and larger cosmopolitan and Gondwanan components. The latter group originated when Australia, as part of the ancient Gondwana supercontinent, was situated over Antarctic latitudes with a cooler, wetter climate than today. In the Wet Tropics, cool Gondwanan taxa occurred predominantly in upland and shaded lowland sites, but no species appeared narrowly temperature restricted, and there was no faunal zonation with altitude. Most chironomid species occurred at all latitudes within the Wet Tropics, with no evidence for an enduring effect of the historical rainforest contractions on current‐day distribution patterns. These findings contrast with those for aquatic faunas elsewhere in the world and for the terrestrial Wet Tropics fauna. We relate this to the generally broad environmental tolerances of Australian chironomids, and comment on why the latitudinal diversity gradient does not apply to the Australian chironomid fauna.  相似文献   

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