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1.
Aim The genus Kniphofia contains 71 species with an African–Malagasy distribution, including one species from Yemen. The genus has a general Afromontane distribution. Here we explore whether Kniphofia is a floristic indicator of the Afromontane centre of endemism and diversity. The South Africa Centre of diversity and endemism was explored in greater detail to understand biogeographical patterns. Location Africa, Afromontane Region, southern Africa, Madagascar and Yemen. Methods Diversity and endemism for the genus were examined at the continental scale using a chorological approach. Biogeographical patterns and endemism in the South Africa Centre were examined in greater detail using chorology, phenetics, parsimony analysis of endemicity (PAE) and mapping of range‐restricted taxa. Results Six centres of diversity were recovered, five of which are also centres of endemism. Eight subcentres of diversity are proposed, of which only two are considered subcentres of endemism. The South Africa Centre is the most species‐rich region and the largest centre of endemism for Kniphofia. The phenetic analysis of the South Africa Centre at the full degree square scale recovered three biogeographical areas that correspond with the subcentres obtained from the chorological analysis. The PAE (at the full degree square scale) and the mapping of range‐restricted taxa recovered two and six areas of endemism (AOEs), respectively. These latter two approaches produced results of limited value, possibly as a result of inadequate collecting of Kniphofia species. Only two AOEs were identified by PAE and these are embedded within two of the six AOEs recovered by the mapping of range‐restricted taxa. All the above AOEs are within the three subcentres found by chorological and phenetic analysis (at the full degree square scale) for the South Africa Centre. Main conclusions The centres for Kniphofia broadly correspond to the Afromontane regional mountain systems, but with some notable differences. We regard Kniphofia as a floristic indicator of the Afromontane Region sensu lato. In southern Africa, the phenetic approach at the full‐degree scale retrieved areas that correlate well with those obtained by the chorological approach.  相似文献   

2.
Sponges play a key role in Antarctic marine benthic community structure and dynamics and are often a dominant component of many Southern Ocean benthic communities. Understanding the drivers of sponge distribution in Antarctica enables us to understand many of general benthic biodiversity patterns in the region. The sponges of the Antarctic and neighbouring oceanographic regions were assessed for species richness and biogeographic patterns using over 8,800 distribution records. Species-rich regions include the Antarctic Peninsula, South Shetland Islands, South Georgia, Eastern Weddell Sea, Kerguelen Plateau, Falkland Islands and north New Zealand. Sampling intensity varied greatly within the study area, with sampling hotspots found at the Antarctic Peninsula, South Georgia, north New Zealand and Tierra del Fuego, with limited sampling in the Bellingshausen and Amundsen seas in the Southern Ocean. In contrast to previous studies we found that eurybathy and circumpolar distributions are important but not dominant characteristics in Antarctic sponges. Overall Antarctic sponge species endemism is ~43%, with a higher level for the class Hexactinellida (68%). Endemism levels are lower than previous estimates, but still indicate the importance of the Polar Front in isolating the Southern Ocean fauna. Nineteen distinct sponge distribution patterns were found, ranging from regional endemics to cosmopolitan species. A single, distinct Antarctic demosponge fauna is found to encompass all areas within the Polar Front, and the sub-Antarctic regions of the Kerguelen Plateau and Macquarie Island. Biogeographical analyses indicate stronger faunal links between Antarctica and South America, with little evidence of links between Antarctica and South Africa, Southern Australia or New Zealand. We conclude that the biogeographic and species distribution patterns observed are largely driven by the Antarctic Circumpolar Current and the timing of past continent connectivity.  相似文献   

3.
Aim In this study we evaluate patterns of endemism for benthic polychaete species along the southeastern Pacific coast of Chile. Our goals were (1) to describe latitudinal gradients of endemism and identify areas of high endemism, (2) to evaluate the effect of biogeographical limits on endemism patterns, and (3) to evaluate indirectly the role played by evolutionary dynamics on patterns of endemism. Location South‐eastern Pacific coast of Chile, ranging from Arica (18° S) to Cape Horn (56° S). Methods We used a list of 178 species of endemic, shallow benthic polychaetes to evaluate patterns of endemism. Parsimony analysis of endemicity (PAE) and the endemism index (EI) were used to evaluate hierarchical relationships of endemism between different latitudinal bands, and to identify areas with high degrees of endemism and differences in endemism. We evaluated the effect of biogeographical limits on endemic polychaete fauna by testing for the existence of geometric constraints (mid‐domain effect). The role of evolutionary dynamics on latitudinal patterns of endemism was evaluated with nestedness analysis (NA) using the temperature index. Results The PAE analysis indicated two large, separate areas of endemism: (1) the northern area between 18° S and 38° S, and (2) the southern area between 39° S and 56° S. The endemism index showed a maximum value (32 species) around 39°–41° S. Species‐richness curves of each 3° band of latitude showed a clear mid‐domain effect (69%), but the two maximum points of species richness at mid‐latitudes (36° S to 38° S and 39° S to 41° S) did not correspond to the mid‐domain peak in species richness, presenting a greater number of species than expected by the mid‐domain effect. The nestedness analysis showed that the number of genera reaches a maximum of 70 at mid‐latitudes (36°–41° S), decreasing towards both the northern and southern areas. The spatial distribution of the entire data set of endemic species showed a nested pattern (T° = 24.5°, P < 0.0001). Main conclusions Our results strongly support the existence of a latitudinal gradient of endemism for benthic polychaete species along the Chilean coast. The shape of this gradient is clearly non‐linear, with a marked peak of endemism occurring at mid‐latitudes (36°–41° S, endemism hotspot), which also corresponds to a peak in species richness. Furthermore, this hotspot is the midpoint separating two distinct areas of endemism to the north and south. We suggest that the observed pattern of endemism for benthic polychaete taxa of the Chilean coast can be explained by a combination of geometric constraints and historical mechanisms, such as the processes that affected the Chilean coast during the Neogene (e.g. ENSO, oxygen minimum zone, glaciations).  相似文献   

4.
Willi Hennig's (Beitr. Ent. 1960, 10, 15) Die Dipteren-Fauna von Neuseeland als systematisches und tiergeographisches Problem applied a phylogenetic approach to examine the distributional patterns exhibited by the Diptera of New Zealand. Hennig showed how phylogenetic trees may be used to infer dispersal, based on the progression and deviation rules, and also discussed the existence of vicariance patterns. The most important author who applied Hennig's phylogenetic biogeography was Lars Brundin, when analysing the phylogenetic relationships of two taxa of Chironomidae (Diptera) and using them to examine the biogeographic relationships of Australia, New Zealand, South America and South Africa. The relevance of Brundin's contribution was noted by several authors, as it began the cladistic or vicariance approach to biogeography, that implies the discovery of vicariance events shared by different monophyletic groups. Both phylogenetic and cladistic biogeography have a place in contemporary biogeography, the former for analysing taxon biogeography and the latter when addressing Earth or biota biogeography. The recent use of the term “phylogenetic biogeography” to refer to a posteriori methods of cladistic biogeography is erroneous and should be avoided.  相似文献   

5.
The Scotia Arc is the only shallow-water and island bridge linking nowadays Patagonia and the Antarctic. The Antarctic Circumpolar Current as an oceanographic peculiarity makes this region an interesting biogeographic transition zone, because this frontal system traditionally is said to isolate the Antarctic fauna from that of the adjacent northern ecosystems. Based on benthos samples from three expeditions onboard R/V Polarstern, we studied distribution patterns of 200 polychaete species and 34 major benthic taxa in order to evaluate the role of polychaetes in the benthic realm of this part of the Southern Ocean. ANOSIM test distinguished three station groups: the central eastern Scotia Sea, the continental shelf off South America and stations at the tip of the Antarctic Peninsula. These station groups differed in organism densities and diversities with stations at the tip of the Antarctic Peninsula hosting the most diverse and dense community. The polychaete diversity patterns in the three assemblages evidenced closer connectivity between the tip of the Antarctic Peninsula and the central eastern Scotia Sea than between the continental shelf off South America with either the stations off the tip of the Peninsula or the central eastern Scotia Sea. This is probably supported by the Polar Front, which divides the island chain into two branches. Species distribution and community patterns of polychaetes appear to be associated with oceanographic and sediment conditions in this region. Most of the shared species showed the capability to tolerate differences in hydrostatic pressure. We suggest that the islands of the Scotia Sea may constitute a bridge for exchange of benthic species, particularly for polychaetes with eurybathic distribution and high dispersal capabilities.  相似文献   

6.
Orthoglymma Liebherr, Marris, Emberson, Syrett & Roig‐Juñent gen.n. (Coleoptera: Carabidae: Broscini) is described to accommodate the single type species Orthoglymma wangapeka Liebherr, Marris, Emberson, Syrett & Roig‐Juñent sp.n., known from the Wangapeka Track, Kahurangi National Park, north‐western South Island, New Zealand. Orthoglymma wangapeka sp.n. is analysed cladistically along with a comprehensive array of 42 other broscine generic terminals and four out‐group taxa, using information obtained from 73 morphological characters, and placed as adelphotaxon to the remainder of subtribe Nothobroscina, a clade distributed in New Zealand, southern South America and Australia. Based on fossil evidence for Carabidae, the occurrence of Orthoglymma wangapeka sp.n. on the Buller Terrane, a geological feature once situated on the eastern margin of Gondwana, and early cladistic divergence of Orthoglymma from the remaining Nothobroscina, Orthoglymma wangapeka sp.n. is interpreted as a Gondwanan relict. The New Zealand arthropod fauna is reviewed to identify other taxa in existence at the time of Cretaceous vicariance of New Zealand and Australia. These candidate Gondwanan taxa, all of which are specified using fossil data or molecular divergence‐based estimates, are analysed biogeographically. Where phylogenetic hypotheses are available, primordial distributions are optimized using event‐based, dispersal‐vicariance (DIVA) analysis. The hypothesized Gondwanan‐aged taxa demonstrate inordinate fidelity to the Gondwanan‐aged geological terranes that constitute the western portions of New Zealand, especially in the South Island. Persistence of these relicts through a hypothesized ‘Oligocene drowning’ event is the most parsimonious explanation for the concentration of Gondwanan relicts in the Nelson, Buller and Fiordland districts of the South Island. Geographic patterns of Gondwanan‐aged taxa are compared with distributions of taxa hypothesized to have colonized New Zealand across the Tasman Sea from Australia and New Caledonia, subsequent to Cretaceous vicariance. These post‐Gondwanan taxa exhibit very different patterns of distribution and diversification in New Zealand, including: (i) abundant endemism in Northland, and the islands and peninsulas of the North Island; (ii) species geographically restricted to areas underlain by the youngest Rakaia and Pahau geological terranes; and (iii) species exhibiting exceedingly widespread geographic distributions spanning geological terranes of disparate ages.
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7.
The Southern Hemisphere has traditionally been considered as having a fundamentally vicariant history. The common trans-Pacific disjunctions are usually explained by the sequential breakup of the supercontinent Gondwana during the last 165 million years, causing successive division of an ancestral biota. However, recent biogeographic studies, based on molecular estimates and more accurate paleogeographic reconstructions, indicate that dispersal may have been more important than traditionally assumed. We examined the relative roles played by vicariance and dispersal in shaping Southern Hemisphere biotas by analyzing a large data set of 54 animal and 19 plant phylogenies, including marsupials, ratites, and southern beeches (1,393 terminals). Parsimony-based tree fitting in conjunction with permutation tests was used to examine to what extent Southern Hemisphere biogeographic patterns fit the breakup sequence of Gondwana and to identify concordant dispersal patterns. Consistent with other studies, the animal data are congruent with the geological sequence of Gondwana breakup: (Africa(New Zealand(southern South America, Australia))). Trans-Antarctic dispersal (Australia <--> southern South America) is also significantly more frequent than any other dispersal event in animals, which may be explained by the long period of geological contact between Australia and South America via Antarctica. In contrast, the dominant pattern in plants, (southern South America(Australia, New Zealand)), is better explained by dispersal, particularly the prevalence of trans-Tasman dispersal between New Zealand and Australia. Our results also confirm the hybrid origin of the South American biota: there has been surprisingly little biotic exchange between the northern tropical and the southern temperate regions of South America, especially for animals.  相似文献   

8.
Molecular phylogenetic studies have become a major area of interest in plant systematics, and their impacts on historical biogeographic hypotheses are not to be disregarded. In Brazil, most historical biogeographic studies have relied on animal phylogenies, whereas plant biogeographic studies have largely lacked a phylogenetic component, having a limited utility for historical biogeography. That country, however, is of great importance for most biogeographic studies of lowland tropical South America, and it includes areas from a number of biogeographic regions of the continent. Important biogeographic reports have been published as part of phylogenetic studies, taxonomic monographs, and regional accounts for small areas or phytogeographic domains, but the available information is subsequently scattered and sometimes hard to find. In this paper we review some relevant angiosperm biogeographic studies in Brazil. Initially we briefly discuss the importance of other continents as source areas for the South American flora. Then we present a subdivision of Brazil into phytogeographic domains, and we cite studies that have explored the detection of biogeographic units (areas of endemism) and how they are historically related among those domains. Examples of plant taxa that could be used to test some biogeographic hypotheses are provided throughout, as well as taxa that exemplify several patterns of endemism and disjunction in the Brazilian angiosperm flora.  相似文献   

9.
The analysis of regional scale patterns of diversity allows insights into the processes that have shaped modern biodiversity at the macro‐scale. Previous analyses studying biogeographic regionalisation across different high‐level taxa have shown similar trends at a global scale. However, incorporating phylogenetic methods when comparing biogeographic regionalisation between subgroups facilitates identification of mechanisms leading to the biogeographic distribution of specific taxa. We analysed the spatial trends of phylogenetic diversity and phylogenetic endemism of 325 species of New World bats, using updated range maps of the modern distributions. These analyses showed phylogeographic signals that reflect the different evolutionary histories of these families. Zoogeographical zones were detected based on range‐weighted phylogenetic turnover. Values of high phylogenetic diversity and endemism were distributed differently across families, suggesting niche conservatism, but a general latitudinal trend of diversity was evident across taxa. Overall, two main bioregions were shared across New World bat taxa (Nearctic and Neotropical), with two additional subregions (Andean and La Platan). We found strong support for an additional transitional zone in the Pacific coast of South America for Emballonuridae and Molossidae. Differences in regionalisation across families indicate that niche conservatism, in situ diversification and dispersal ability are major drivers for the regionalisation of New World bats, within a dual‐centre of diversification scenario. We also found strong inter‐familial support for an independent Caribbean biogeographic region.  相似文献   

10.
Aim We test hypotheses regarding the origin of diversity and patterns of species richness in and around the New Zealand Southern Alps with 25 species of Chionochloa (Poaceae, Danthonioideae). Location New Zealand. Methods We inferred a well‐resolved and mostly robustly supported chloroplast phylogeny based on multiple DNA sequence markers (trnT–L–F, rpl16, trnD–psbM, atpB–rbcL, matK and ndhF), sampling 92% of the recognized species and 82% of the subspecific taxa. Nuclear ribosomal internal transcribed spacer sequences were also sampled, but proved uninformative. Biogeographic reconstruction and character optimization were done using both parsimony and likelihood approaches, and molecular dating used relaxed clock approaches. Results Most of the species diversity in Chionochloa stemmed from a common ancestor in the southern South Island with subsequent dispersal between areas. One clade of apparently cryptic taxa diversified within the central South Island ‘endemism gap’, persisting there throughout at least the latter half of the Pleistocene. Exclusively alpine and other habitat specialist species originated independently, the former relatively recently (between 7.6 Ma and the present). Main conclusions The phylogeny of Chionochloa and other published phylogenies of New Zealand plant groups demonstrate that the higher degree of endemism in the north and south of the New Zealand South Island relative to a central endemism gap cannot be explained by Alpine Fault displacement. Furthermore, our results suggest that if extinctions resulting from glaciations played a role in the origin of the central endemism gap, their impact was less than might be presumed on the basis of the distribution of taxa as they are currently defined. The diversification of Chionochloa and a number of New Zealand plant groups, such as Ranunculus, was contemporaneous with the initiation of the uplift of the Southern Alps. In contrast to patterns of diversifications within the alpine regions typical of the hyperdiverse Andes, exclusively alpine species in New Zealand arose independently from ancestors distributed in more lowland areas. Similarly, habitat specialists in Chionochloa arose independently from more generalist ancestors. Thus, although diversification in these groups may have been stimulated by mountain building and Pleistocene climatic oscillations, cladogenesis did not occur within the high alpine habitat itself.  相似文献   

11.
Aim To discover the pattern of relationships of areas of endemism for Australian genera in the plant family Rhamnaceae tribe Pomaderreae for comparison with other taxa and interpretation of biogeographical history. Location Australian mainland, Tasmania and New Zealand. Methods A molecular phylogeny and geographic distribution of species within four clades of Pomaderreae are used as a basis for recognition of areas of endemism and analysis of area relationships using paralogy‐free subtrees. The taxon phylogeny is the strict consensus tree from a parsimony analysis of 54 taxa, in four clades, and sequence data for the internal transcribed spacer regions of ribosomal DNA (ITS1‐5.8S‐ITS2) and the plastid DNA region trnL‐F. Results The biogeographical analysis identified five subtrees, which, after parsimony analysis, resulted in a minimal tree with 100% consistency and seven resolved nodes. Three sets of area relationships were identified: the areas of Arnhem and Kimberley in tropical north Australia are related based on the phylogeny of taxa within Cryptandra; the moister South‐west of Western Australia, its sister area the coastal Geraldton Sandplains, the semi‐arid Interzone region and arid Western Desert are related, based on taxa within Cryptandra, Spyridium, Trymalium and Pomaderris; and the eastern regions of Queensland, McPherson‐Macleay, south‐eastern New South Wales (NSW), Victoria, southern Australia, Tasmania and New Zealand are related based on Cryptandra, Pomaderris and Spyridium. Tasmania and NSW are related based entirely on Cryptandra, but the position of New Zealand relative to the other south‐eastern Australian regions is unresolved. Main conclusions The method of paralogy‐free subtrees identified a general pattern of geographic area relationships based on Australian Pomaderreae. The widespread distribution of clades, the high level of endemicity and the age of fossils for the family, suggest that the Pomaderreae are an old group among the Australian flora. Their biogeographical history may date to the early Palaeogene with subsequent changes through to the Pleistocene.  相似文献   

12.
Parsimony Analysis of Endemicity (PAE) has been compared with other methods regarding its performance to identify areas of endemism. It is frequently compared with the Analysis of Endemicity (AE), which seems to perform better than PAE to identify these areas. Here I compare PAE and AE considering the sympatric taxa diagnosed as endemic, being as strictly close as possible to sympatry, and using previously published data of Sciobius (Coleoptera: Curculionidae). AE identified more candidate areas of endemism than PAE, but the number of highly restricted endemic taxa to these areas was insufficient to support them as areas of endemism. Considering strictly sympatry (homopatry), PAE performed better than AE; however, both methods may identify areas with some grade of sympatry, but the recognition of which areas constitute real areas of endemism in the strict sense depends on the interpretation of the researcher.  相似文献   

13.
Aim The ectomycorrhizal (ECM) mushroom family Inocybaceae is widespread in north temperate regions, but more than 150 species are encountered in the tropics and the Southern Hemisphere. The relative roles of recent and ancient biogeographical processes, relationships with plant hosts, and the timing of divergences that have shaped the current geographic distribution of the family are investigated. Location Africa, Australia, Neotropics, New Zealand, north temperate zone, Palaeotropics, Southeast Asia, South America, south temperate zone. Methods We reconstruct a phylogeny of the Inocybaceae with a geological timeline using a relaxed molecular clock. Divergence dates of lineages are estimated statistically to test vicariance‐based hypotheses concerning relatedness of disjunct ECM taxa. A series of internal maximum time constraints is used to evaluate two different calibrations. Ancestral state reconstruction is used to infer ancestral areas and ancestral plant partners of the family. Results The Palaeotropics are unique in containing representatives of all major clades of Inocybaceae. Six of the seven major clades diversified initially during the Cretaceous, with subsequent radiations probably during the early Palaeogene. Vicariance patterns cannot be rejected that involve area relationships for Africa–Australia, Africa–India and southern South America–Australia. Northern and southern South America, Australia and New Zealand are primarily the recipients of immigrant taxa during the Palaeogene or later. Angiosperms were the earliest hosts of Inocybaceae. Transitions to conifers probably occurred no earlier than 65 Ma. Main conclusions The Inocybaceae initially diversified no later than the Cretaceous in Palaeotropical settings, in association with angiosperms. Diversification within major clades of the family accelerated during the Palaeogene in north and south temperate regions, whereas several relictual lineages persisted in the tropics. Both vicariance and dispersal patterns are detected. Species from Neotropical and south temperate regions are largely derived from immigrant ancestors from north temperate or Palaeotropical regions. Transitions to conifer hosts occurred later, probably during the Palaeogene.  相似文献   

14.
Nested areas of endemism analysis   总被引:1,自引:0,他引:1  
Aim  To develop and evaluate a nested clade approach to aid in the determination of areas of endemism (AoE) in biogeographical studies.
Methods  We adapted the nested clade analysis (NCA) to studies of areas of endemism. For this purpose we adapted several of the programs currently in use. Two data sets were examined using this approach – one involving Sciobius in southern Africa and the other involving terrestrial mammals in Mexico.
Results  Nested clade analysis as applied to areas of endemism produced results similar to those of previous analyses of Sciobus in southern Africa. An analysis of terrestrial mammals in Mexico supports the designation of some biogeographical provinces as areas of endemism while suggesting that other provinces may comprise composite distributions that should be subdivided.
Main conclusions  The nested clade analysis approach utilized primarily in genetic analysis of phylogeographical patterns in population biology studies can be adapted to understanding AoE in the realm of biogeography. This approach offers a statistical paradigm to evaluate AoE suggested by parsimony analysis of endemicity (PAE) trees.  相似文献   

15.
Abstract

Panbiogeographic track analysis is applied to the distribution of several groups of mosses which occur in the New Zealand region. The analysis highlights areas of biogeographic interest (nodes) in the New Zealand region as follows: 1. New Guinea, 2. New Caledonia, 3. New South Wales/Queensland border in Australia, 4. northern New Zealand, 5. Rapa Island, 6. subantarctic New Zealand.

New Zealand is connected to these nodes by the following standard tracks: 1. New Guinea—New South Wales/Queensland border—Tasmania—subantarctic New Zealand, 2. New Guinea—New Caledonia—New Zealand—subantarctic New Zealand, 3. a central Tasman Sea transversal track; New South Wales/Queensland border—New Caledonia. Rapa Island is connected to the Tasman region by northern New Zealand and New Caledonia.  相似文献   

16.
Aim To use published distributional and taxonomic information on Neotropical birds in a cladistic analysis of distributions and endemism (CADE) to generate a testable hypothesis of area‐relationships for the arid areas of endemism, particularly those of Central South America (the ‘arid diagonal’), and to clarify the different methodologies commonly associated with parsimony analysis of endemicity (PAE). Location South America. Methods Cladistic analysis of distributions and endemism. Results We obtain a tree where the relationships of most areas are resolved, and we find support for an exclusive clade of Central South American areas, with the Caatinga as sister to both the Chaco and Cerrado. Main conclusions There is a substantial amount of historical signal in avian distributions, when large numbers of taxa and multiple taxonomic levels are considered. Ecological noise and historical information are more easily distinguished in CADE analyses than they would be in PAE analyses. Based on our results we predict that among aridland birds, the Cerrado and Chaco species will be more closely related to each other than to Caatinga species.  相似文献   

17.
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   

18.
Towards a generalized biogeography of the Southern Ocean benthos   总被引:1,自引:0,他引:1  
Aim To investigate whether the biogeographical regions proposed by J. W. Hedgpeth and widely adopted by other authors hold true, are an oversimplification or with further data might show a unified Antarctic province. Location Southern Hemisphere. Methods The distributions of 1318 species of bivalves, 4656 species of gastropods, 1465 species of cheilostome and 167 species of cyclostome bryozoans were analysed for 29 regions in the Southern Hemisphere, including South American, South African, Tasmanian, New Zealand, sub‐Antarctic and Antarctic regions. We present data on species richness, rates of endemism, patterns of radiation, faunal similarities and multivariate biogeographical analyses. Results The most striking pattern to emerge from our data set of species counts per region was a strong east–west hemispheric asymmetry, with high species numbers in New Zealand, Tasmania and South Africa and low numbers in South America. In contrast, no difference was found in richness between the east and west parts of the Southern Ocean. We compared findings in our model taxa with published data on ascidians, cephalopods and pycnogonids. Further evidence of strong faunal links between the Antarctic and South America is reported in this study, although we found little evidence for a biogeographical relationship between the Antarctic or South America and New Zealand/Tasmania. Strong evidence exists for a long‐term influence of the Antarctic Circumpolar Current upon the distribution of Southern Ocean benthos. This is demonstrated by the reduced prevalence of South American species in the Antarctic and sub‐Antarctic with increasing distance from South America in the direction of the current. Three of our four study taxa (bivalves, cheilostomes and cyclostomes) show the Southern Ocean as a ‘single functional unit’ with no evidence for a biogeographical split between east and west. Main conclusions Unlike the biogeographical schemes previously proposed, we show that biogeographical regions in the Southern Ocean differ depending upon the class of animals being considered. Despite this we suggest that some general rules are viable, including species endemism rates of around 50%, a single Antarctic province and a definite distinction between the sub‐Antarctic islands influenced by South America and those of New Zealand.  相似文献   

19.
Aim Biogeographers have long been intrigued by New Zealand’s biota due to its unique combination of typical ‘continental’ and ‘island’ characteristics. The New Zealand plateau rifted from the former supercontinent Gondwana c. 80 Ma, and has been isolated from other land masses ever since. Therefore, the flora and fauna of New Zealand include lineages that are Gondwanan in origin, but also include a very large number of endemics. In this study, we analyse the evolutionary relationships of three genera of mite harvestmen (Arachnida, Opiliones, Cyphophthalmi) endemic to New Zealand, both to each other and to their temperate Gondwanan relatives found in Australia, Chile, Sri Lanka and South Africa. Location New Zealand (North Island, South Island and Stewart Island). Methods A total of 94 specimens of the family Pettalidae in the suborder Cyphophthalmi were studied, representing 31 species and subspecies belonging to three endemic genera from New Zealand (Aoraki, Neopurcellia and Rakaia) plus six other members of the family from Chile, South Africa, Sri Lanka and Australia. The phylogeny of these taxa was constructed using morphological and molecular data from five nuclear and mitochondrial genes (18S rRNA, 28S rRNA, 16S rRNA, cytochrome c oxidase subunit I and histone H3, totalling c. 5 kb), which were analysed using dynamic as well as static homology under a variety of optimality criteria. Results The results showed that each of the three New Zealand cyphophthalmid genera is monophyletic, and occupies a distinct geographical region within the archipelago, grossly corresponding to palaeogeographical regions. All three genera of New Zealand mite harvestmen fall within the family Pettalidae with a classic temperate Gondwanan distribution, but they do not render any other genera paraphyletic. Main conclusions Our study shows that New Zealand’s three genera of mite harvestmen are unequivocally related to other members of the temperate Gondwanan family Pettalidae. Monophyly of each genus contradicts the idea of recent dispersal to New Zealand. Within New Zealand, striking biogeographical patterns are apparent in this group of short‐range endemics, particularly in the South Island. These patterns are interpreted in the light of New Zealand’s turbulent geological history and present‐day patterns of forest cover.  相似文献   

20.
The phylogeny and biogeography of Thamnochortus (Restionaceae)   总被引:1,自引:0,他引:1  
Parsimony analysis of morphological data was used to demonstrate the existence of five groups in Thamnochortus (Restionaceae). Although the most parsimonious trees have a resolved relationship among these groups, there appears to be little support for this resolution. The composition of the terminal groups, and the relationships among the species making up these groups, is more robust. The distribution patterns of Thamnochortus differ only in detail from the general patterns ascribed to the Cape Flora (southern South Africa). Within the Cape Floristic Region four centres can be recognized, and more than half of the Thamnochortus species are endemic to these centres. Embedded in these centres (or phytochoria) are small centres of endemism: in the Cedarberg, Bokkeveld mountains, Cape Peninsula, Overberg, Bredasdorp plain and the Langeberg. These centres are best demonstrated by mapping the distributions of range-restricted species, rather than using parsimony analysis of endemicity. There are two major patterns within the phytogeographical elements: an arid group, which ranges from the West Coast to the Klein Swartberg, and a mesic coastal group. The coastal group can be further subdivided. A cladistic biogeographic analysis indicates that the first division follows the divide between all-year rainfall and summer drought, and the second division suggests greater aridity. This implies that geographical differentiation within the genus has followed climatic patterns, suggesting that some of the speciation may be a consequence of climatic change in southern Africa. Curiously, centres of endemism appear to be defined too narrowly for effective cladistic biogeographic analysis, and more success is obtained using wider areas.  相似文献   

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