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1.
Aim To infer the phylogenetic relationships within the freshwater shrimp genus Paratya Miers, 1882 (Atyidae) and to use these data to answer biogeographical questions about the location, timing and form of evolution of this genus in the South Pacific. Location Paratya are spread throughout various freshwater habitats in the western Pacific, with a disjunct northern range in the North Pacific (Japan, Korea, Ryukyu Islands, Siberia) and South Pacific (Australia, New Zealand, New Caledonia, Lord Howe, Norfolk Island). Methods Specimens were obtained from throughout its range. Mitochondrial sequences of cytochrome oxidase subunit I and 16S ribosomal DNA were analysed using phylogenetic techniques to identify whether landmasses are monophyletic and what the relationships are between landmasses. Molecular clock dating methods were used to date divergences between taxa. Results Each landmass was recovered as monophyletic. Japan/Ryukyu Islands is the most basal group, followed by New Zealand. Australian specimens form a sister group to a clade made up of two groups (New Caledonia and Lord Howe/Norfolk Island). The oldest divergence within the genus (between North and South Pacific) took place 12–19 Ma. Main conclusions The geographical origin of the genus (either Gondwana or Laurasia) is unclear. Dispersal occurred between the North and South Pacific long after the split up of Gondwana. Dispersal likely explains the presence of Paratya on each landmass in the South Pacific, from continent to isolated oceanic island. This dispersal is conjectured to have taken place through oceanic currents because of the amphidromous life cycle of some taxa of Paratya, given that amphyidromy is plesiomorphic in atyid shrimp.  相似文献   

2.
There are substantial differences among taxonomic groups in their capacity to reach remote oceanic islands via long-distance overwater dispersal from mainland regions. Due to their permeable skin and intolerance of saltwater, amphibians generally require human-assisted dispersal to reach oceanic islands. Several Litoria frog species have been introduced to remote islands throughout the Pacific Ocean region. Lord Howe Island (LHI) is an oceanic island that lies approximately 600 km east of the Australian mainland and has a diverse, endemic biota. The bleating tree frog (Litoria dentata) is native to mainland eastern Australia, but was accidentally introduced to LHI in the 1990s, yet its ecology and potential impact on LHI has remained unstudied. We used a mitochondrial phylogeographical approach to determine that L. dentata was introduced from the Ballina region in northeastern New South Wales. The founding population was likely accidentally introduced with cargo shipped from the mainland. We also completed the first detailed investigation of the distribution, ecology and habitat use of L. dentata on LHI. The species is widespread on LHI and is prevalent in human habitat, cattle pasture and undisturbed forest. We discuss the potential impact of introduced Litoria species on Pacific islands and outline what biosecurity protocols could be implemented to prevent the introduction of further amphibian species to the ecologically sensitive oceanic area.  相似文献   

3.
We use approximately 1900bp of mitochondrial (ND2) and nuclear (c-mos and Rag-1) DNA sequence data to recover phylogenetic relationships among 58 species and 26 genera of Eugongylus group scincid lizards from New Caledonia, Lord Howe Island, New Zealand, Australia and New Guinea. Taxon sampling for New Caledonian forms was nearly complete. We find that the endemic skink genera occurring on New Caledonia, New Zealand and Lord Howe Island, which make up the Gondwanan continental block Tasmantis, form a monophyletic group. Within this group New Zealand and New Zealand+Lord Howe Island form monophyletic clades. These clades are nested within the radiation of skinks in New Caledonia. All of the New Caledonian genera are monophyletic, except Lioscincus. The Australian and New Guinean species form a largely unresolved polytomy with the Tasmantis clade. New Caledonian representatives of the more widespread genera Emoia and Cryptoblepharus are more closely related to the non-Tasmantis taxa than to the endemic New Caledonian genera. Using ND2 sequences and the calibration estimated for the agamid Laudakia, we estimate that the diversification of the Tasmantis lineage began at least 12.7 million years ago. However, using combined ND2 and c-mos data and the calibration estimated for pygopod lizards suggests the lineage is 35.4-40.74 million years old. Our results support the hypothesis that skinks colonized Tasmantis by over-water dispersal initially to New Caledonia, then to Lord Howe Island, and finally to New Zealand.  相似文献   

4.
The asterinid sea star Parvulastra exigua (Lamarck) is a common member of temperate intertidal marine communities from geographically widespread sites around the southern hemisphere. Individuals from Australian populations lay benthic egg masses (through orally directed gonopores) from which nonplanktonic offspring hatch and metamorphose without a dispersing planktonic larval phase. Scattered reports in the taxonomic literature refer to a similar form in southern Africa with aborally directed gonopores (and possibly broadcast spawning of planktonic eggs and larvae); such differences would be consistent with cryptic species variation. Surveys of morphology and mtDNA sequences have revealed cryptic species diversity in other asterinid genera. Here we summarize the taxonomic history of Lamarck's "Astérie exigu?" and survey morphological variation (the location of the gonopores) for evidence that some P. exigua populations include cryptic species with a different mode of reproduction. We found strong evidence for multiple species in the form of two phenotypes and modes of reproduction (oral and aboral gonopore locations) in populations from southern Africa and islands in the Atlantic and Indian oceans. Both modes of reproduction have broad geographic ranges. These results are consistent with previously published genetic data that indicate multiple species in African and island (but not Australian) populations.  相似文献   

5.
Anguilla reinhardtii, hitherto known from eastern Australia, New Caledonia, Norfolk Island, and Lord Howe Island, has recently been discovered in rivers of northern New Zealand. Identification, based on morphological and genetic characteristics, is unequivocal; eight consecutive year classes have been found. The only reasonable explanation of this occurrence is transoceanic dispersal to New Zealand, probably from subtropical oceanic spawning grounds north of New Zealand. This corroborates past hypotheses that the strongly diadromous freshwater fish fauna of New Zealand is derived by transoceanic dispersal of known marine life intervals. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

6.
Cenozoic Tawera Marwick, 1927 from the Southern Hemisphere exhibits a pattern of disjunt distribution around the southern oceans. A single species, Tawera gayi (Hupé in [Gay, C. (1854). Historia Física y Política de Chile, Zoología 8. Paris.]) is confined to southern South America. Taking into account the occurrence of Tawera in the fossil record, taxonomy based on shell morphology, and available information on extant species of Tawera, it is plausible that the genus appeared first in southern Australia during the Early Miocene, and then expanded and radiated to New Zealand. It also appears that Tawera first crossed from Australasia to South America during the Early Pleistocene. This picture can be better explained if Tawera was able to achieve circumglobal range by means of the Antarctic Circumpolar Current. Thus, different potential factors of dispersal (i.e., larval dispersal, drifting, kelp rafting and Pleistocene cooling) are considered and discussed.

Shell morphology and overall appearance of Tawera gayi is very similar to Tawera philomela (Smith, 1885) from South Africa and Tawera mawsoni (Hedley, 1916) from Macquarie Island, suggesting these taxa have a close relationship. One postulated explanation, which should be confirmed by means of a phylogenetic study, is a subsequent migration of Tawera from South America arriving first to the Southern African Region (via the West Wind Drift Islands Province), and then probably coming back again to Australasia. It could have been mediated via the same current during the Late Pleistocene and much later during the Holocene.  相似文献   


7.
Aim The aim is to use DNA sequence data to test between vicariance and long range dispersal (by floating seed-pods) explanations for the origin and range of the Edwardsia species of Sophora (Sophoreae: Papilionoideae: Leguminosae). Location This group is widely distributed around the South Pacific and into the South Atlantic on both continental fragments and oceanic islands. Methods DNA sequences from an intergene region (atpB-rbcL) of the chloroplast were determined for twelve taxa (including outgroups) and used to test these hypotheses. Sophora fossils were used to calibrate the evolutionary tree. Results The Edwardsia group of Sophora appears monophyletic and is well differentiated from other Sophora. However, the genetic difference between species within the South Pacific and to the South Atlantic is very low. Main conclusionsThe results eliminate vicariance explanations for this section of Sophora and strongly support an origin from other (non-Edwardsia) Sophora in the north-west Pacific. Dispersal appears initially to be to Tuvalu, Lord Howe Island, New Zealand, and subsequently across the South Pacific, probably within the last 2–5 million years. Dispersal of buoyant Sophora seeds to oceanic islands is the most likely explanation of its distributions. Fossil pollen dates in New Zealand are consistent with the conclusion.  相似文献   

8.
The red seaweed Asparagopsis taxiformis embodies five cryptic mitochondrial lineages (lineage 1–5) introduced worldwide as a consequence of human mediated transport and climate change. We compared globally collected mitochondrial cox2‐3 intergenic spacer sequences with sequences produced from multiple Australian locations and South Korea to identify Asparagopsis lineages and to reveal cryptic introductions. We report A. taxiformis lineage 4 from Cocos (Keeling) Islands, Australia, and the highly invasive Indo‐Pacific Mediterranean lineage 2 from South Korea and Lord Howe Island, Australia. Phylogeographic analysis showed a clear haplotype and geographic separation between western Australian and Great Barrier Reef (GBR) isolates belonging to the recently described lineage 5. The same lineage, however, was characterized by a substantial genetic and geographic break between the majority of Australian specimens and Asparagopsis collections from South Solitary Island, Southern GBR, Lord Howe Island, Kermadec Islands, Norfolk Island, New Caledonia and French Polynesia. The disjunct geographic distribution and sequence divergence between these two groups supports the recognition of a sixth cryptic A. taxiformis mitochondrial lineage. As climatic changes accelerate the relocation of biota and offer novel niches for colonization, periodic surveys for early detection of cryptic invasive seaweeds will be critical in determining whether eradication or effective containment of the aliens are feasible.  相似文献   

9.
Aim To test whether marine biogeographical patterns observed at the community level are also important within species. It is postulated that historical hydrogeographic barriers have driven in situ diversification. Location The intertidal and shallow subtidal zones of southern Australia, New Zealand and nearby islands. Australia's temperate marine communities are characterized by a high degree of endemism and show strong biogeographical structure along an east–west axis. Methods Phylogeographical analysis of the widespread asteriid sea‐star Coscinasterias muricata Verrill across southern Australia and New Zealand. Forty‐two samples from 27 locations were included in phylogenetic analyses of mitochondrial (CO1; control region) and nuclear (ITS2) DNA sequences. Results Analysis of mtDNA revealed a deep phylogenetic split within Australian C. muricata, strongly correlated with latitude. ‘Northern’ haplotypes (latitude ≤ 37.6° S, nine sites, 15 samples) were 7.3–9.4% divergent from ‘southern’ haplotypes (latitude ≥ 37.6° S, 19 sites, 27 samples), consistent with late Pliocene separation. Eastern and western representatives of the ‘northern’ clade were 0.5–1.0% divergent, probably reflecting Pleistocene isolation. The ‘southern’ clade of Australia is also represented in New Zealand, indicating Pleistocene oceanic dispersal. Nuclear DNA (ITS2) sequences yielded relatively little phylogenetic resolution, but were generally congruent with mtDNA‐based groupings. Main conclusions The phylogeographical pattern detected within Australian C. muricata closely resembles marine biogeographical groupings proposed on the basis of community and species distributions. Recurring evolutionary patterns may have been driven by the hydrographic history of southern Australia. Specifically, we suggest that Plio‐Pleistocene temperature change and the repeated opening and closure of Bass Strait promoted allopatric divergence and perhaps cryptic speciation in C. muricata.  相似文献   

10.
While the genetic impact of Pleistocene climate change on temperate species has been well characterized, especially in Europe and North America, an effect on the diversification of species on oceanic islands has been less well studied. This is perhaps a surprising observation given the traditional and continuing contribution of island species (e.g. Darwin's finches, Partula snails, Lord Howe Island palms) to understand speciation. Here, we combine mitochondrial and microsatellite data from the ground-living and arboreal Mandarina snails of the oceanic, subtropical Hahajima archipelago (Ogasawara, colloquially 'Galápagos of the Orient') to enable a comparative approach to understand the impact of the Pleistocene glaciations on their phylogeography. Prior work suggested that several narrowly divergent, ground-living species pairs of Mandarina populations on the outlying islands, as well as the low-lying southern and central parts of Hahajima, probably underwent bottlenecks and subsequent expansions during the recent Pleistocene. Here, the most striking finding is that largely arboreal species have deeply divergent, geographically restricted mitochondrial lineages, in contrast to a census size that is at least an order of magnitude lower than ground-living snails. As populations of both types are highly polymorphic at microsatellite loci, the systematic difference at the mitochondrial locus probably indicates a contrasting effect of the Pleistocene climate cycles on the two groups. We speculate that this may have partly come about owing to a reduced efficacy of natural selection on the more greatly structured populations of arboreal snails. If so, then a prediction is that the genome of other snails, or other species with limited mobility, will show a similar response to the Pleistocene climate cycles.  相似文献   

11.
Both mtDNA variation and allozyme data demonstrate that geographic groupings of different color morphs of the starfish Linckia laevigata are congruent with a genetic discontinuity between the Indian and Pacific Oceans. Populations of L. laevigata sampled from Thailand and South Africa, where an orange color morph predominates, were surveyed using seven polymorphic enzyme loci and restriction fragment analysis of a portion of the mtDNA including the control region. Both allozyme and DNA data demonstrated that these populations were significantly genetically differentiated from each other and to a greater degree from 23 populations throughout the West Pacific Ocean, where a blue color morph is predominant. The genetic structure observed in L. laevigata is consistent with traditional ideas of a biogeographic boundary between the Indian and Pacific Oceans except that populations several hundreds kilometers off the coast of north Western Australia (Indian Ocean) were genetically similar to and had the same color morphs as Pacific populations. It is suggested that gene flow may have continued (possibly at a reduced rate) between these offshore reefs in Western Australia and the West Pacific during Pleistocene falls in sea level, but at the same time gene flow was restricted between these Western Australian populations and those in both Thailand and South Africa, possibly by upwellings. The molecular data in this study suggest that vicariant events have played an important role in shaping the broadscale genetic structure of L. laevigata. Additionally, greater genetic structure was observed among Indian Ocean populations than among Pacific Ocean populations, probably because there are fewer reefs and island archipelagos in the Indian Ocean than in the Pacific, and because present-day surface ocean currents do not facilitate long-distance dispersal.  相似文献   

12.
Porina howeanasp. nov.,P. mariaesp. nov. andP. ocellatoidessp. nov. are described from shaded basalt on Lord Howe Island, New South Wales, Australia.  相似文献   

13.
Aim and location New Zealand began to separate from Gondwana c. 85 Ma, and has been isolated from the nearest large landmass, Australia, by some 2000 km of the Tasman Sea since c. 60 Ma. Given New Zealand's long geographical isolation, there has been considerable interest in explaining the origins of its different biotic elements. Here we investigate the biogeography of the fern genus Polystichum from temperate Australasia. Six species are found in New Zealand, four in Australia, and two on Lord Howe Island. Methods The evolutionary relationships between the twelve Polystichum species found in temperate Australasia were inferred from phylogenetic analyses of two molecular data sets: DNA sequence from the chloroplast rps4–trnS spacer locus; and AFLP DNA‐fingerprinting. The timing of the separation between Australian and New Zealand Polystichum was estimated by using the fossil record to temporally calibrate the rbcL sequence differentiation between representative species from these regions. Results Species of Polystichum from New Zealand appear to comprise a monophyletic group. This suggests that Polystichum crossed the Tasman only once. Temporal calibration of the rbcL sequence differentiation between Australian and New Zealand Polystichum indicates that a vicariant explanation for their separation can be rejected in favour of trans‐oceanic dispersal. Main conclusions The extant diversity within New Zealand Polystichum appears to have been derived from a single, trans‐oceanic dispersal event (within the last c. 20 Myr), followed by a relatively extensive in situ ecological radiation.  相似文献   

14.
Speciation on islands, and particularly the divergence of species in situ, has long been debated. Here, we present one of the first, complete assessments of the geographic modes of speciation for the flora of a small oceanic island. Cocos Island (Costa Rica) is pristine; it is located 550 km off the Pacific coast of Central America. It harbors 189 native plant species, 33 of which are endemic. Using phylogenetic data from insular and mainland congeneric species, we show that all of the endemic species are derived from independent colonization events rather than in situ speciation. This is in sharp contrast to the results of a study carried out in a comparable system, Lord Howe Island (Australia), where as much as 8.2% of the plant species were the product of sympatric speciation. Differences in physiography and age between the islands may be responsible for the contrasting patterns of speciation observed. Importantly, comparing phylogenetic assessments of the modes of speciation with taxonomy‐based measures shows that widely used island biogeography approaches overestimate rates of in situ speciation.  相似文献   

15.
Lycium comprises approximately 70 species and is disjunctly distributed in temperate to subtropical regions in South America, North America, southern Africa, Eurasia, and Australia. Among them, only Lycium sandwicense A. Gray sporadically occurs widely on oceanic islands in the Pacific Ocean. To investigate phylogenetic and biogeographic relationships of the genus with emphasis on L. sandwicense, the coding region of matK, the two intergenic spacers trnT (UGU)-trnL (UAA) and trnL (UAA)-trnF (GAA), and the trnL (UAA) intron of chloroplast DNA (cpDNA) were sequenced. A strict consensus tree resulting from the phylogenetic analysis indicates the following: (1) New World species comprise a potentially paraphyletic assemblage; (2) southern African, Australian, and Eurasian species together are monophyletic; (3) southern African species are a paraphyletic assemblage; and (4) L. sandwicense is in a clade with certain New World species. The estimated biogeographic events based on the cpDNA analysis indicate that (1) Lycium originated in the New World, (2) all southern African, Australian, and Eurasian species have a common ancestor from the New World, (3) Australian and Eurasian species originated once from a southern African progenitor, and (4) L. sandwicense differentiated from the New World species.  相似文献   

16.
Abstract Phylogeographical disjunctions in high-dispersal marine taxa are variously ascribed to palaeogeographical conditions or contemporary ecological factors. Associated biogeographical studies, however, seldom incorporate the sampling design required to confidently discriminate among such competing hypotheses. In the current study, over 7800 gastropod specimens were examined for operculum colour, and 129 specimens genetically, to test ecological and historical biogeographical hypotheses relating to biogeographical disjunction in the Southern Hemisphere, and to southern Australia in particular. Mitochondrial DNA sequence analysis of the high-dispersal intertidal gastropod Nerita atramentosa in southern Australia (88 specimens; 18 localities) revealed an east-west phylogeographical split involving two highly divergent clades (26.0 +/- 1.9%) exhibiting minimal geographical overlap in the southeast. The eastern clade of Nerita atramentosa is also widespread in northern New Zealand (43 specimens, 10 localities), but no significant genetic differentiation is explained by the Tasman Sea, a 2000-km-wide oceanic barrier. Spatial genetic structure was not detected within either clade, consistent with the species' dispersive planktotrophic phase lasting for 5-6 months. Digital analysis of operculum colouration revealed substantial differences between eastern (tan) and western (black) specimens. Genetic analysis and visual inspection of 88 Australian specimens revealed a completely nonrandom association between mtDNA data and operculum colouration. Independent examination of a further 7822 specimens from 14 sites in southern Australia revealed both colour morphs at all localities, but reinforced the phylogeographical data by indicating a marked turnover in colour morph abundance associated with a palaeogeographical barrier: Wilsons Promontory. This sharp biogeographical disjunction is in marked contrast to the species' high dispersal abilities. The genetic similarity of Nerita morio (Easter Island) and the eastern Australian + New Zealand lineage (1.1 +/- 0.3%) provides further evidence of long-distance dispersal in southern Nerita. Phylogenetic relationships of nine species (four genera) of Neritidae, an almost exclusively tropical gastropod family, are consistent with the hypothesis that southern temperate black nerites comprise a monophyletic radiation.  相似文献   

17.
Pocsia mucronataP. M. McCarthy sp. nov. (incert. sed.) is described from Lord Howe Island, New South Wales, Australia. This foliicolous lichen inhabits leaves of the endemic palm,Howea forsteriana.  相似文献   

18.
Sardines (Sardinops spp.) occupy temperate upwelling zones in the coastal regions of the Indian and Pacific Oceans, including locations in Japan, California, Chile, Australia, and South Africa. East and West Pacific populations are separated by vast expanses of open ocean, and northern and southern hemisphere populations are separated by tropical waters which are lethal to sardines. The relative importance of these barriers has been the focus of a longstanding debate between vicariance and dispersal schools in biogeography. Comparisons of a 500 bp fragment of the mitochondrial (mt) DNA control region reveal strong geographic structuring of mtDNA lineages but shallow divergence both within and between regional populations. Regional populations are related to one another in a stepping-stone pattern, the apparent result of a series of Pleistocene dispersal events around the continental margins of the Indian-Pacific Basin. These mtDNA data, combined with an electrophoretic survey of variability at 34 nuclear loci (Grant and Leslie 1996), indicate that the five regional forms of Sardinops (considered separate taxa by most authorities) probably diverged within 500,000 years BP, a much shorter timeframe than predicted by vicariance models based on plate tectonics. High mtDNA haplotype diversity, coupled with an excess of rare alleles in the protein electrophoretic dataset, may indicate exponential growth from a small ancestral population. The mtDNA and allozyme data are concordant with climate records and fossil evidence in portraying regional populations as recent, unstable, and ephemeral. Regional populations of sardines have probably been extinguished and recolonized over short evolutionary timescales in response to changes in climate and the oceanography of coastal upwelling zones.  相似文献   

19.
Duration of the pelagic phase of benthic marine fishes has been related to dispersal distance, with longer pelagic larval duration (PLD) expected to result in greater dispersal potential. Here, we examine PLDs of 2 species of coral-reef butterflyfish (Chaetodon auriga and C. flavirostris) across latitudes (14°S–37°S) along the Great Barrier Reef into south-eastern Australia; we predict that PLD will be higher for fish collected below the breeding latitudes of 24°S. For C. auriga, apart from significantly longer PLDs at Lord Howe Island and Jervis Bay (means of 54 and 52 days, respectively), all locations had similar PLDs (mean 41 days). For C. flavirostris, there was no significant location effect on PLD (mean 41.5 days); however, PLD at Lord Howe Island was 58 days with high variance precluding significance. Also, there was no significant variation in PLD among years for either species despite considerable variation in East Australian Current strength.  相似文献   

20.
Aim This paper describes the biogeographical setting of the Falkland Islands, in the context of the relationships of the islands’ biota to other sub‐Antarctic/cold temperate lands. Location The analysis focuses primarily on the Falklands biota, and explores its relationships to those of Patagonian South America and South Africa, other southern lands and the islands of the sub‐Antarctic Pacific, Indian and Atlantic Oceans. Methods The study derives largely from literature sources on the biota and geological history of the Falkland Islands. Results The animals and plants known from the Falkland Islands exhibit strong affinities with those of Patagonian South America, and especially Tierra del Fuego; additional affinities are with various remote islands of the sub‐Antarctic, as well as New Zealand and to a lesser extent Australia; often these are shared with Patagonia. While the biotic affinities might be interpreted, by some, as indicating a former Gondwanan/South American geological connection of the Falklands, geological evidence points to the Falklands formerly having a land connection to south‐eastern South Africa. Only faint hints of a South African biotic connection remain. The historical biotic and geological connections of the Falklands thus conflict. Moreover, the Falklands biota is so strongly Patagonian that derivation of that biota is best seen as resulting from dispersal, much of it probably recent. This dispersal biota appears to have replaced, and perhaps displaced, the South African biota present on the islands as they detached from South Africa and drifted across the south Atlantic Ocean, as it opened up as South America and Africa drifted apart.  相似文献   

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