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Howe Island (howe + island)

Distribution by Scientific Domains
Life Sciences100%

Kinds of Howe Island

  • lord howe island
    		•

    Selected Abstracts

    Climate change, genotypic diversity and gene flow in reef-building corals

    ECOLOGY LETTERS, Issue 4 2004
    David J. Ayre
    Abstract In the ocean, large-scale dispersal and replenishment by larvae is a key process underlying biological changes associated with global warming. On tropical reefs, coral bleaching, degradation of habitat and declining adult stocks are also likely to change contemporary patterns of dispersal and gene flow and may lead to range contractions or expansions. On the Great Barrier Reef, where adjacent reefs form a highly interconnected system, we use allozyme surveys of c. 3000 coral colonies to show that populations are genetically diverse, and rates of gene flow for a suite of five species range from modest to high among reefs up to 1200 km apart. In contrast, 700 km further south on Lord Howe Island, genetic diversity is markedly lower and populations are genetically isolated. The virtual absence of long-distance dispersal of corals to geographically isolated, oceanic reefs renders them extremely vulnerable to global warming, even where local threats are minimal. [source]

    Case studies and mathematical models of ecological speciation.

    MOLECULAR ECOLOGY, Issue 14 2007

    Abstract A recent study of a pair of sympatric species of palms on the Lord Howe Island is viewed as providing probably one of the most convincing examples of sympatric speciation to date. Here we describe and study a stochastic, individual-based, explicit genetic model tailored for this palms system. Overall, our results show that relatively rapid (< 50 000 generations) colonization of a new ecological niche, and sympatric or parapatric speciation via local adaptation and divergence in flowering periods are theoretically plausible if (i) the number of loci controlling the ecological and flowering period traits is small; (ii) the strength of selection for local adaptation is intermediate; and (iii) an acceleration of flowering by a direct environmental effect associated with the new ecological niche is present. We discuss patterns and time-scales of ecological speciation identified by our model, and we highlight important parameters and features that need to be studied empirically in order to provide information that can be used to improve the biological realism and power of mathematical models of ecological speciation. [source]

    Hydroclathrus (Scytosiphonaceae, Phaeophyceae): Conspectus of the genus and proposal of new species from Australia and Hawaii

    PHYCOLOGICAL RESEARCH, Issue 4 2003
    Gerald T. Kraft
    SUMMARY Representatives of the two current species of Hydroclathrus, Hydroclathrus clathratus (C. Agardh) Howe (the generitype) and Hydroclathrus tenuis Tseng et Lu, are compared to recent collections of the genus from isolated localities in the central and south Pacific: Necker Island and Lord Howe Island, respectively. Although published descriptions of the virtually pan-tropical/warm-temperate H. clathratus portray a species highly variable in the habits and soral distribution patterns of the macro-phases of its life history, our observations support the hypothesis that the newly discovered Pacific island populations represent new species. Hydroclathrus steph-anosorus Kraft, sp. nov., from Lord Howe Island, differs from seemingly typical H. clathratus by the low-domed profiles of its surface cortical cells, aggregates of moniliform hair primordia that are almost always associated with plurangial sori, and particularly by the configurations of the sori themselves, which form discrete, nearly circular rings around the central hair tufts. Hydroclathrus tumulis Kraft et Abbott, sp. nov., from two deep-water localities in the northwestern Hawaiian Islands, has subacutely papillate cortical cells, scattered single, paired or laxly aggregated hair primordia of distinctive obcuneate morphology, and discrete, angular plurangial sori with no predetermined relationship to hairs, the plurangia being relatively laxly aggregated by virtue of their often arising on pedicels formed by the peaked crests of the cortical bearing cells. H. tenuis, although making the most striking visual impression of any of the species because of its exceedingly narrow, fibrous membranes, seems otherwise closest to H. clathratus in cortical cell, hair and soral features, absolute morphological boundaries between the two species being perhaps difficult to draw at times. [source]

    Biogeographical and ecological context for managing threats to coral and rocky reef communities in the Lord Howe Island Marine Park, south-western Pacific

    AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2010
    Graham J. Edgar
    Abstract 1.Quantitative subtidal surveys of fishes, macro-invertebrates and sessile organisms at 33 sites within the Lord Howe Island Marine Park revealed a rich fauna and flora, including 164 fishes, 40 mobile invertebrate taxa, 53 coral and other sessile invertebrate taxa, 32 algal taxa, and two seagrasses. The biota in this newly-zoned marine park was overwhelmingly tropical when species lists were tabulated; however, species with distributions centred on temperate coasts of eastern Australia and New Zealand occurred in disproportionately high densities compared with the tropical species. 2.Lord Howe Island reefs were generally in good condition. Virtually no bleached coral was observed (0.2% of the reef surface; 0.8% of total hard coral cover). Living scleractinian coral comprised the predominant group of organisms growing on reef surfaces, with 25.5% cover overall. Other major taxa observed were brown algae (18.8% cover) and red algae (16.9% cover). 3.Three distinctive community types were identified within the marine park,coral reefs, macroalgal beds and an offshore/open coast community. The distribution of these community types was strongly related to wave exposure, as indicated by an extremely high correlation with the first principal coordinates axis for biotic data (R2=0.80). 4.The close (<3,km) proximity of tropical coral and temperate macroalgal community types off Lord Howe Island is highly unusual, with localized patterns of nutrient enrichment suggested as the primary cause. The macroalgal community type is only known from a small area off the south-western coast that is not protected from fishing. This community is considered highly susceptible to threats because of potential impacts of global warming and the possibility of expansion of sea urchin barrens. Coral bleaching and ocean acidification associated with global climate change also threaten the coral reef community, which includes relatively high numbers of endemic and near endemic fish species. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Long-distance dispersal and local retention of larvae as mechanisms of recruitment in an island population of a coral reef fish

    AUSTRAL ECOLOGY, Issue 2 2007
    HEATHER M. PATTERSON
    Abstract Although recruitment of pelagic larvae is a fundamental and well-documented process in the dynamics of benthic marine populations, identifying the sources of recruitment, or the degree to which populations are connected via dispersal of larvae, has remained elusive for most marine taxa. In this study we used natural environmental markers (trace elements) recorded in fish otoliths (ear stones) as tags of natal origin. Specifically, we used the otolith core and edge chemistries of a locally endemic wrasse (Coris bulbifrons) from Lord Howe Island (LHI), Australia, and a widely distributed species (Coris picta) from three potential mainland source regions, to determine the likely sources of recruitment to C. picta populations on LHI. The use of a local endemic species, which is by definition self-recruiting, is a novel approach for ground-truthing the dispersal history of non-endemic coral reef fish. Discriminant function analyses were able to separate LHI from mainland fish, using both edge and core signatures, with a high degree of accuracy, suggesting at least some of the C. picta collected on LHI were of local origin. This result was corroborated when half of the C. bulbifrons and LHI C. picta were introduced as unknowns into a discriminant function analysis using the remaining C. bulbifrons, LHI C. picta, and the mainland C. picta as a training data set. Overall, our findings suggest that both long distance dispersal and local retention are important sources of recruitment to populations of C. picta on LHI and that otolith chemistry of endemic species could be a useful benchmark for determining the prevalence of self-recruitment in insular populations of other widespread species. [source]

    Revision of the genus Menippus Clark in Australia (Coleoptera: Chrysomelidae: Galerucinae)

    AUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 2 2008
    Chris A M Reid
    Abstract, The genus Menippus is revised for Australia, with six species, three of which are new: M. cynicus Clark, M. darcyisp. nov., M. ewanisp. nov., M. fugitivus (Lea), M. sufisp. nov. and M. yulensis (Jacoby) comb. nov. (from Diorhabda Weise). Menippus yulensis was described from New Guinea. This species and M. darcyi were formerly confused in Australia with M. fugitivus, which is now considered endemic to Lord Howe Island. The species formerly considered M. fugitivus and protected under the Threatened Species Conservation Act, New South Wales, is now named M. darcyi. A key is provided for the Australian species of Menippus and a lectotype designated for M. yulensis. The composition of Menippus is discussed and three non-Australian species are transferred to this genus: M. inconspicua (Jacoby) comb. nov. (from Diorhabda Weise); M. laterimaculata (Jacoby) comb. nov.; and M. marginipennis (Jacoby) comb. nov. (from Galerucella Crotch). A revised checklist of Menippus species is given. The recorded foodplants of Menippus are species of Celtis (Ulmaceae). [source]