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1.
Aim To investigate the biogeographical structure and affinities of the Australian marine demersal ichthyofauna at the scale of provinces and bathomes for the purposes of regional marine planning. Location Australia. Methods Patterns of distribution in the Australian fish fauna, at both intra‐regional and global scales, were examined using a science‐based, management framework dividing Australia’s marine biodiversity into 16 province‐level biogeographical units. Occurrences of 3734 species in eight depth‐stratified bathomes (from the coast to the mid‐continental slope) within each province were analysed to determine the structure and local affinities of their assemblages and their association with faunas of nearby regions and oceans basins. Results Strong geographic and depth‐related structure was evident. Fish assemblages in each province, and in each bathome of each province, were distinct, with the shelf‐break bathome more similar to the adjacent continental shelf bathome than to the upper slope bathome. Data based only on endemic species performed well as a surrogate of the entire dataset, yielding comparable patterns of similarity between provinces and bathomes. Tropical and temperate elements were better discriminated than elements of the Pacific and Indian oceans, with the central western province more similar to the tropical provinces (including those in the east), and the eastern province closer to southern temperate provinces. The fauna shares the closest regional affinities with those of the adjacent south‐west Pacific, western Pacific Rim, and elements of wide‐ranging Indo‐Pacific components. Elements unique to the Pacific and Indian oceans are poorly represented. Main conclusions The complex nature of Australia’s marine ichthyofauna is confirmed. A hierarchy of provinces and bathomes, used to ensure that Australia’s developing marine reserve network is both representative and comprehensive, is equally robust when based on all known Australian fish species or on only those species endemic to this continent. Latitude and depth are more important than oceanic influences on the composition of this fauna at these scales.  相似文献   

2.
Pinder  Adrian 《Hydrobiologia》2001,463(1-3):49-64
This paper provides a summary of the diversity and distribution of Australian naidid and phreodrilid oligochaetes. As for other continents, the Australian naidid fauna consists mostly of cosmopolitan species, although there are indications of greater endemicity than currently recognised. While some naidids are widespread in Australia, others have a northern or a southern bias to their distribution, but few have been recorded in Tasmania. Many new records and species of Phreodrilidae have been documented since the review by Pinder & Brinkhurst (1997a) and these have allowed notions of phreodrilid zoogeography to be refined. The family is still considered particularly diverse in some temperate areas (Tasmania and the far south-west of Western Australia), but surprisingly few species are known from the temperate south-east mainland. Increasingly, new phreodrilid species are being collected from seasonal habitats on granite outcrops in the south-west and from refugial habitats (caves, groundwater and permanent river pools) in drier regions. A complete picture of oligochaete distributions will require much more work and patterns suggested by current data are presented here as hypotheses.  相似文献   

3.
中国长臂虾总科的动物地理学特点   总被引:14,自引:0,他引:14  
本文讨论了长臂虾总科在中国分布的3个科,即拟贝隐虾科、叶颚虾科和长臂虾科的属、种在中国的分布情况及区系特点。拟贝隐虾科和叶颚虾科种类较少,分布于热带海域,我国分别在南沙群岛和西沙群岛发现1属1种和3属3种,均为广布的常见种。长臂虾科是本总科中种类最多、分布最广、十分常见的科,包括2亚科102属,世界性分布,海洋、淡水均有,我国大量分布。其起源中心应在印度-西太平洋暖水区,一部分浅海沿岸种经河口进入淡水水域, 大量发展,很少种可分布至温带区边缘;另一部分在热带珊瑚礁环境大量发展,并与许多动物类群共栖或共生。长臂虾亚科基本上是浅海-淡水自由生活类群,我国已记录9属61种,主要分布于南部,多数为东洋界热带和亚热带种,分别属东洋界(淡水)和印度-西太平洋区(海水、半咸水);而极少数种分布至北方,温带性的淡水种有2种白虾,1种小长臂虾和仅见于东北部的条纹长臂虾,属于古北界区系(淡水),海水种有黄、东海的敖氏长臂虾及细指长臂虾,属于北太平洋温带区系(海水、半咸水)。隐虾亚科全部为海洋种,主要分布在热带、亚热带海域,以珊瑚礁为主要栖息地,大部分分布于印度-西太平洋海域,80%以上的种类或多或少与其他海洋生物共栖,自由生活的种很少。根据推论,隐虾类的起源中心应在印度-西太平洋热带水域的珊瑚礁环境, 并在这一水域得到了充分的分化与发展,分别适应与腔肠动物、双壳类软体动物、海绵动物、棘皮动物和海鞘类被囊动物共栖生活;而热带美洲的类群则是在隐虾类演化到可与石珊瑚类共栖时由印度-西太平洋水域扩散过去的, 共栖宿主仅涉及腔肠动物和棘皮动物。我国南海水域已发现31属96种,极少数种也分布到东海,属于印度-西太平洋热带水域珊瑚礁区系。  相似文献   

4.
Aim Since the opening of the Suez Canal in 1869, many tropical taxa from the Indo‐West Pacific (IWP) realm have entered the Mediterranean Sea, which is experiencing rising temperatures. My aims are: (1) to compare biogeographically this tropical transformation of the Mediterranean biota with the tropical faunas of the Mediterranean and adjacent southern European and West African seas during the Late Oligocene to Pliocene interval; (2) to infer the relative contributions of the tropical eastern Atlantic and IWP to the tropical component of the marine biota in southern Europe; and (3) to understand why West Africa is not now a major source of warm‐water species. Location Southern Europe, including the Mediterranean Sea, and the coast of tropical West Africa. Methods I surveyed the literature on fossil and living shell‐bearing molluscs to infer the sources and fates of tropical subgenus‐level taxa living in southern Europe and West Africa during the Late Oligocene to Pliocene interval. Results Ninety‐four taxa disappeared from the tropical eastern Atlantic (including the Mediterranean) but persisted elsewhere in the tropics, mainly in the IWP (81 taxa, 86%) and to a lesser extent in tropical America (36 taxa, 38%). Nine taxa inferred to have arrived in the tropical eastern Atlantic from the west after the Pliocene did not enter the Mediterranean. The modern West African fauna is today isolated from that of other parts of the marine tropics. Main conclusions Taxa now entering the Mediterranean through the Suez Canal are re‐establishing a link with the IWP that last existed 16 million years ago. This IWP element, which evolved under oligotrophic conditions and under a regime of intense anti‐predatory selection, will continue to expand in the increasingly warm and increasingly oligotrophic Mediterranean. The IWP source fauna contrasts with the tropical West African biota, which evolved under productive conditions and in a regime of less anti‐predatory specialization. Until now, the post‐Pliocene West African source area has been isolated from the Mediterranean by cold upwelling. If further warming should reduce this barrier, as occurred during the productive and warm Early Pliocene, the Mediterranean could become a meeting place for two tropical faunas of contrasting source conditions.  相似文献   

5.
Aim To describe the biogeography of the ascidian fauna of southern Africa, to compare the results obtained with those reported for other fauna and flora of the same region, and to speculate about the origin of ascidians in the region. Location Southern Africa extending over 4000 km from Mossâmedes (15° S–12° E) to Inhaca Island (26°30′ S–33° E), including Vema Seamount (31°40′ S–8 °20′ E), Amsterdam‐Saint Paul Islands (38° S–77°30′ E) and the Tristan‐Gough Islands (38° S–12°20′ W). Methods We constructed a presence/absence matrix of 168 species for 26 biogeographical divisions, 21 classical biogeographical regions described by Briggs (Marine zoogeography, McGraw‐Hill, New York, 1974) and five provinces within the southern African region. We considered the following limits and divisions into provinces for the southern African region: Namibia, Namaqua, Agulhas and Natal as proposed by Branch et al. (Two oceans. A guide to the marine life of southern Africa, David Philip Publishers, 1994), and the West Wind Drift Islands province (WWD) according to Briggs (Global biogeography, Elsevier Health Sciences, Amsterdam, 1995). To examine the biogeographical structure, species and divisions were classified using cluster analysis (based on UPGMA as the aggregation algorithm) with the Bray–Curtis index of similarity. This classification was combined with MDS ordination. Main conclusions Four main groups were obtained from the analysis of affinities among species: (1) species present in the WWD, separated by a high percentage of endemisms and a low number of species with a southern African distribution. Moreover, in the light of the species distribution and the results of further analysis, which revealed that they are completely separated and not at all related to the southern African region, it appears that there are no close relationships among the different islands and seamounts of the West Wind Drift Island province. This province was therefore removed from the remaining analyses; (2) species with a wide distribution; (3) species of colder waters present in Namaqua and Agulhas provinces, a transitional temperate area in which gradual mixing and replacement of species negate previous hypotheses on the existence of a marked distributional break at Cape of Good Hope; (4) species of warmer waters related to Natal province. The classification into biogeographical components was dominated by the endemic (47%), Indo‐Pacific (25%) and cosmopolitan (13%) components. The analysis of affinities among biogeographical areas separated Namibia from the rest of the southern African provinces and showed that it was related to some extent to the Antarctic region because of the cold‐temperate character of the province and the low sampling effort; Namaqua, Agulhas and Natal were grouped together and found to be closely related to the Indo‐West Pacific region. In general, our results were consistent with those obtained for other southern African marine invertebrates. The frequency distribution of solitary/colonial strategies among provinces confirmed the domination of colonial organisms in tropical regions and solitary organisms in colder regions. Finally, we speculate that the southern African ascidian fauna mainly comprises Indo‐Pacific, Antarctic and eastern Atlantic ascidians.  相似文献   

6.
The major biogeographic structure and affinities of the Australian chondrichthyan fauna were investigated at both interregional and intraregional scales and comparisons made with adjacent bioregions. Faunal lists were compiled from six geographical regions with species from these regions assigned to distributional classes and broad habitat categories. Australian species were further classified on provincial and bathomic structure following bioregionalization outputs from regional marine planning. About 40% of the world's chondrichthyan fauna occurs in Indo-Australasia (482 species) of which 323 species are found in Australian seas. The tropical Australian component, of which c. 46% of taxa are regional endemics, is most similar to faunas of Indonesia, New Guinea and New Caledonia. The temperate Australian component is most similar to New Zealand and Antarctica with about half of its species endemic. Highest levels of Australian endemism exist in bathomes of the outer continental shelf and upper slope. A relatively high proportion of regional endemism (57% of species) on the slope in the poorly surveyed but species-rich Solanderian unit is probably due to high levels of large-scale habitat complexity in the Coral Sea. The richness of demersal assemblages on the continental shelf and slope appears to be largely related to the spatial complexity of the region and the level of exploration. Much lower diversity off Antarctica is consistent with the pattern in teleosts. The complex chondrichthyan fauna of Australia is confirmed as being amongst the richest of the mega-diverse Indo-West Pacific Ocean. Species-level compositions of regional faunas across Indo-Australasia differ markedly because of moderate to high levels of intraregional speciation. Faunal assemblages in Australian marine provinces and bathomes differ from each other, supporting a broader pattern for fishes that underpins a marine planning framework for the region.  相似文献   

7.
西双版纳热带雨林蚁科昆虫区系分析   总被引:9,自引:1,他引:8  
徐正会 《动物学研究》1999,20(5):379-384
在西双版纳热带雨林已鉴定蚊科昆虫9亚科76属267种。西双版纳地区的蚂蚁区系以热带至亚热带分布的东洋界成分最为丰富。在属级水平上,与马来西亚界关系最为密切。与澳洲界关系较密切;与非洲界和马拉加西界的关系知中。与新北界,新热带界和古北界的关系最为疏远。可见西双版纳的蚂蚁区系具有典型的热带亚洲起源特征,同时与澳洲和非洲的热带区系有一定的渊源关系。  相似文献   

8.
We synthesize the evolutionary implications of recent advances in the fields of phylogeography, biogeography and palaeogeography for shallow‐water marine species, focusing on marine speciation and the relationships among the biogeographic regions and provinces of the world. A recent revision of biogeographic provinces has resulted in the recognition of several new provinces and a re‐evaluation of provincial relationships. These changes, and the information that led to them, make possible a clarification of distributional dynamics and evolutionary consequences. Most of the new conclusions pertain to biodiversity hotspots in the tropical Atlantic, tropical Indo‐West Pacific, cold‐temperate North Pacific, and the cold Southern Ocean. The emphasis is on the fish fauna, although comparative information on invertebrates is utilized when possible. Although marine biogeographic provinces are characterized by endemism and thus demonstrate evolutionary innovation, dominant species appear to arise within smaller centres of high species diversity and maximum interspecies competition. Species continually disperse from such centres of origin and are readily accommodated in less diverse areas. Thus, the diversity centres increase or maintain species diversity within their areas of influence, and are part of a global system responsible for the maintenance of biodiversity over much of the marine world.  相似文献   

9.
The influence of pelagic larval duration (PLD) and egg type dispersal capabilities of 35 demersal and pelagic-spawning tropical fish species is examined in relation to their abundance on the temperate coasts of Japan. The PLDs of pelagic spawners were significantly longer than those of demersal spawners, and a high occurrence of pelagic spawners on the temperate coasts suggests that these fishes are more easily transported to temperate coasts than demersal spawners. For demersal spawners, the common species on the temperate coasts had significantly longer PLDs than the rare species; this suggests that PLD is a major factor influencing the distribution patterns of tropical demersal spawners on temperate coasts. Moreover, a negative correlation between PLD and the abundance of some species of pelagic and demersal spawners suggests the presence of reproductively active fishes in northern subtropical and even in temperate waters.  相似文献   

10.
The three species of flying fishes—Indo-Pacific Cypselurus poecilopterus, Central Pacific C. simus, and Eastern Pacific C. callopterus form a particular species group within the subgenus Poecilocypselurus. These species rather weakly differ in the body height, number of predorsal scales and number of gill rakers. The sculls of these three species are very much alike; there are just very small differences in the proportions of some bones and the number of skull lateral line canals and pores. It could be imagined that C. poecilopterus has appeared in the Indo-Malayan Archipelago area and thence extended in all directions (up to the coasts of the Eastern Africa, Northern and Eastern Australia, New Guinea and adjacent islands, the western islands of Polynesia and the waters of Japan). C. callopterus inhabiting warm waters of the Eastern Pacific and C. simus whose area is situated in the central part of the Pacific Ocean are seemingly derived from this species.  相似文献   

11.
The present study aimed to assess the consequences of tectonic events and temperature regime on the diversification of Indo‐West Pacific (IWP) turban shell species. Bayesian and parsimony methods were used to construct a phylogenetic hypothesis using sequence data from three genes for the turban shell genus Turbo and for a larger data set including representatives of all known genera in the subfamily Turbininae. Phylogenetic analyses indicate that all IWP Turbo species form a single clade approximately 68 Myr in age, predating the closure of the Tethys Sea and therefore predating the physical separation of the IWP from other biogeographical regions. All but one of the IWP subgenera tested in Turbo also predate the closure of the Tethys Sea. Fossil evidence for Marmarostoma, the largest subgenus, confirms that at least some Turbo lineages currently restricted to the IWP were previously more widespread. The combination of the phylogeny with the fossil evidence suggests that present day diversity in IWP Turbo is the result of the evolutionary persistence within the IWP of several, morphologically distinct lineages, some of which were more widespread in the Oligocene. Some IWP lineages show significant increases in diversification in the early Miocene, probably as a result of the increased availability of both shallow‐water habitats due to tectonic plate movements and increased carbonate platforms in the central IWP resulting from coincident diversification of zooxanthellate corals. The IWP is therefore behaving as both a cradle of diversity (with new species originating in situ) and a museum of diversity (with lineages that predate its isolation also being maintained). Bayesian and parsimony analyses of the subfamily recovered five clades and mapping the temperature regime (tropical or temperate) of each species onto the molecular tree using parsimony suggested that temperate habitat is an ancestral character in at least four of the clades. This result was also supported by Bayesian reconstruction of ancestral states. Astralium (the fifth clade) may also prove to have a temperate origin, but this could not be determined with certainty given the available data. The origin of diversity in tropical regions is of particular interest because it has been suggested that the tropics are the source of many evolutionary novelties and have provided a species pool, from which temperate regions were populated. The present study suggests that Turbininae may be an exception to this rule. The tree shape also suggests that temperature has had an effect on speciation rates; temperate Turbininae are apparently evolving more slowly or suffering more extinction than their tropical sister clades, which show greater diversity. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92 , 573–592.  相似文献   

12.
Aim Our aims were: (1) to reconstruct a molecular phylogeny of the cephalaspidean opisthobranch genus Bulla, an inhabitant of shallow sedimentary environments; (2) to test if divergence times are consistent with Miocene and later vicariance among the four tropical marine biogeographical provinces; (3) to examine the phylogenetic status of possible Tethyan relict species; and (4) to infer the timing and causes of speciation events. Location Tropical and warm‐temperate regions of the Atlantic, Indo‐West Pacific, Australasia and eastern Pacific. Methods Ten of the 12 nominal species of Bulla were sampled, in a total sample of 65 individuals, together with cephalaspidean outgroups. Phylogenetic relationships were inferred by Bayesian analysis of partial sequences of the mitochondrial cytochrome c oxidase I (COI) and 16S rRNA and nuclear 28S rRNA genes. Divergence times and rates of evolution were estimated using uncorrelated relaxed‐clock Bayesian methods with fossil calibrations (based on literature review and examination of fossil specimens), implemented in beast . The geographical pattern of speciation was assessed by estimating the degree of overlap between sister lineages. Results Four clades were supported: Indo‐West Pacific (four species), Australasia (one species), Atlantic plus eastern Pacific (three species) and Atlantic (two species), with estimated mean ages of 35–46 Ma. Nominal species were monophyletic, but deep divergences were found within one Indo‐West Pacific and one West Atlantic species. Species‐level divergences occurred in the Miocene or earlier. The age of a sister relationship across the Isthmus of Panama was estimated at 7.9–32.1 Ma, and the divergence of a pair of sister species on either side of the Atlantic Ocean occurred 20.4–27.2 Ma. Main conclusions Fossils suggest that Bulla originated in the Tethys realm during the Middle Eocene. Average ages of the four main clades fall in the Eocene, and far pre‐date the 18–19 Ma closure of the Tethys Seaway. This discrepancy could indicate earlier vicariant events, selective extinction or errors of calibration. Similarly, the transisthmian divergence estimate far pre‐dates the uplift of the Panamanian Isthmus at about 3 Ma. Speciation events occurred in the Miocene, consistent with tectonic events in the central Indo‐West Pacific, isolation of the Arabian Sea by upwelling and westward trans‐Atlantic dispersal. Differences in habitat between sister species suggest that ecological speciation may also have played a role. The basal position of the Australasian species supports its interpretation as a Tethyan relict.  相似文献   

13.
The genus Asparagopsis was studied using 25 Falkenbergia tetrasporophyte strains collected worldwide. Plastid (cp) DNA RFLP revealed three groups of isolates, which differed in their small subunit rRNA gene sequences, temperature responses, and tetrasporophytic morphology (cell sizes). Strains from Australia, Chile, San Diego, and Atlantic and Mediterranean Europe were identifiable as A. armata Harvey, the gametophyte of which has distinctive barbed spines. This species is believed to be endemic to cold‐temperate waters of Australia and New Zealand and was introduced into Europe in the 1920s. All isolates showed identical cpDNA RFLPs, consistent with a recent introduction from Australia. Asparagopsis taxiformis (Delile) Trevisan, the type and only other recognized species, which lacks spines, is cosmopolitan in warm‐temperate to tropical waters. Two clades differed morphologically and ecophysiologically and in the future could be recognized as sibling species or subspecies. A Pacific/Italian clade had 4–8° C lower survival minima and included a genetically distinct apomictic isolate from Western Australia that corresponded to the form of A. taxiformis originally described as A. sanfordiana Harvey. The second clade, from the Caribbean and the Canaries, is stenothermal (subtropical to tropical) with some ecotypic variation. The genus Asparagopsis consists of two or possibly three species, but a definitive taxonomic treatment of the two A. taxiformis clades requires study of field‐collected gametophytes.  相似文献   

14.
The European earwig, Forficula auricularia, is a cosmopolitan insect endemic to Europe, West Asia and North Africa, which has invaded many temperate regions of the world including Australia and New Zealand. F. auricularia has been shown to be a complex of morphologically identical, reproductively isolated lineages that possess two distinct clades of mitochondrial DNA. Entomological collection data, historical literature and further field collections were used to develop a greater understanding of Australian F. auricularia’s invasion biology and its current distribution. Genetic analysis of F. auricularia collected from Australia and New Zealand using two mitochondrial genes (COI and a fragment overlapping parts of the COI -COII genes) was also undertaken. To identify the possible source populations of the Australasian invasion these sequences were compared to those from 16 locations within Britain and continental Europe. All Australasian populations were shown to be of the clade B lineage. Tasmanian and New Zealand populations consist of a single subclade comprised of only 4 and 1 haplotypes respectively. The Australian mainland populations also contained a second subclade consisting of up to 11 haplotypes indicating that multiple introductions possibly occurred on the Australian mainland. Comparison of mitochondrial genomes from Australasian and European populations showed the Australian mainland subclade to be most closely related to Portuguese haplotypes, and the Tasmanian and New Zealand clade closely related to those in Brittany, France. No European haplotypes perfectly matched the Australasian sequences. Therefore, the original source populations are still to be identified with harbours on the Iberian Peninsula’s western coast and those on the English Channel likely candidate areas.  相似文献   

15.
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   

16.
Seven species are recognized, of whichStenotaphrum helferi, native to forested streambanks in southeastern Asia, is considered the most primitive. Four species are restricted to tropical islands and coasts of the western Indian Ocean ; one of these, 5.dimidiatum, may have had its range within the region expanded by planting as a pasture grass during the early colonial period.Stenotaphrum micranthum is a naturally wide-ranging beach pioneer in both the tropical Pacific and Indian Oceans, particularly on small, remote islands. The last species,S. secundatum, includes fertile diploids and sterile polyploids. The common diploid race has been found since the early days of botanical exploration as a seashore pioneer on both sides of the Atlantic; in West Africa it is strictly tropical, but in the New World it ranges from the Carolinas and Bermuda to Argentina; early Pacific expeditions also found it in Hawaii and the Australian region ; this race has been taken inland as a lawn grass and spread locally as a weed. A triploid clone of this species, originally confined to the Cape of Good Hope region, has recently been planted and naturalized in Australia, various Pacific islands, and North America; another aberrant Southern Hemisphere race has become naturalized in the Mediterranean region.  相似文献   

17.
Revision of material from Australian waters previously assigned to Herdmania momus ( Savigny, 1816 ) has resulted in the recognition of five species (including two new indigenous species). A tropical Indo-West Pacific range is recorded for the type species ( H. momus ), although it is not recorded from Western Australia. A circum-continental range for the third and largest species, H. grandis ( Heller, 1878 ) is confirmed. Herdmania pallida (Heller, 1878), with a wide range in the western Pacific and Indian Ocean including the north-eastern and north-western coasts of Australia, is a different species from the Atlantic Ocean species (formerly thought to be conspecific). Herdmania fimbriae , a new species with a geographical range from southern to north-eastern Australia, is distinct from H. mentula , also a new species, from the north-western coast. The structure of the gonads and their ducts and accessory membranes and the arrangement and number of body wall muscles distinguish the species. Species differences are supported by the maximum size of individuals, nature of their test, number of branchial folds, number of internal longitudinal vessels on the folds and between the dorsal lamina and dorsal fold, the size and form of the dorsal tubercle and dorsal lamina, and the shape of the ciliated opening of the neural duct, although these characters are affected to some extent by growth. A variety of accessory membranes associated with both male and female gonoducal apertures are found in the majority of species in this genus. © 2002 The Linnean Society of London. Zoological Journal of the Linnean Society , 134 , 359–374.  相似文献   

18.
About 43Cladophora species inhabit the coasts of the northern Atlantic Ocean. These can be subdivided into seven distribution groups: (a) the tropical western Atlantic group (16 species); (b) the warm temperate Mediterranean-Atlantic group (9 species); (c) the warm temperate North American group (1 species); (d) the Arctic group (1 species); (e) the amphiatlantic tropical to warm temperature group (7 species); (f) the amphiatlantic tropical to temperate group (4 species), and (g) the amphiatlantic temperate group (5 species). These groups agree with general phytogeographic patterns. Thus, the high numbers of species restricted to the tropical western Atlantic region and the warm temperate Mediteranean-Atlantic region are in agreement with the richness and high degree of endemism of these regions. The fact that all species occurring in northeast America also occur in Europe agrees with the high floristic similarity of the boreal areas in America and Europe. The sediment coasts of the Carolinas are an efficient barrier to the south-north dispersal of benthic algae. The temperature bound phytogeographic limits are set in most cases by the species ability to survive adverse temperatures; for “northern” species to survive a high summer temperature in the south, and for “southern” species to survive a low winter temperature in the north. The limits in the Arctic region are all set by the species ability for sufficient growth and reproduction in summer. Conversely, only few northern species have a southern limit which is set by a winter temperature that is not too high for sufficient growth and reproduction. Most species of this group are winter-annuals at their southern limit, and summer-annuals at their northern limit. A comparatively small number of species with a tropical-to-warm temperate distribution have a northern limit at temperate latitudes which is set by a sufficiently high summer temperature for growth and reproduction. A high proportion of this group are lagoonal or quiet water species, which profit by higher summer temperatures in sheltered waters.C. vagabunda is an example.C. rupestris andC. sericea have an amphiboreal distribution and also occur in the southern temperate belt. They probably used a Pleistocene temperature drop to disperse, through the Atlantic along the African coast, from one hemisphere to the other. In the Pacific temperatures were not sufficiently low for this dispersal; and hence these two species reached the Pacific probably by way of the Bering Strait.  相似文献   

19.
Understanding species distribution and behavior is essential for conservation programs of migratory species with recovering populations. The critically endangered Antarctic blue whale (Balaenoptera musculus intermedia) was heavily exploited during the whaling era. Because of their low numbers, highly migratory behavior, and occurrence in remote areas, their distribution and range are not fully understood, particularly in the southwest Pacific Ocean. This is the first Antarctic blue whale study covering the southwest Pacific Ocean region from temperate to tropical waters (32°S to 15°S). Passive acoustic data were recorded between 2010 and 2011 across the southwest Pacific (SWPO) and southeast Indian (SEIO) oceans. We detected Antarctic blue whale calls in previously undocumented SWPO locations off eastern Australia (32°S, 152°E) and within the Lau Basin (20°S, 176°W and 15°S, 173°W), and SEIO off northwest Australia (19°S, 115°E).In temperate waters, adjacent ocean basins had similar seasonal occurrence, in that calling Antarctic blue whales were present for long periods, almost year round in some areas. In northern tropical waters, calling whales were mostly present during the austral winter. Clarifying the occurrence and distribution of critically endangered species is fundamental for monitoring population recovery, marine protected area planning, and in mitigating anthropogenic threats.  相似文献   

20.
西北干旱荒漠区种子植物科的区系分析   总被引:25,自引:4,他引:21  
西北干旱荒漠区分布有种子植物82科、484属、1704种,优势现象明显,优势科11个,它们是菊科、豆科、禾本科、藜科,十字花科、蓼科,莎草科、毛莨科、蔷薇科、唇形科和百合科;表征科8个,它们是香蒲科,麻黄科,柽柳科、蒺藜科,胡颓子科、藜科、眼子菜科和蓼科。地理成分多样,其中以世界广布成分为主,共37科,占总科数的45.12%,其次为温带成分(包括热带至温带,亚热带至温带,温带,温带至寒带),共有31科,占总科数的37.80%,热带成分,热带致亚热带成分较少,共14科,占总科数的17.07%。这些反映出植物的分布与本地区气候相适应的特点。  相似文献   

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