浮遊性カイアシ類の両極および反赤道分布について(<特集>中〜高緯度の両極性分布を持つ生物から見た地球史)

概要

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Bipolar and antitropical distributions of planktonic copepods are reviewed from the previous data. Some particle-feeding copepods show an antitropical distribution in the oceanic regions without tropical submergence in the deep waters. A molecular phylogenetic analysis has revealed that four closely related species of the genus Neocalanus consist of a sister group which clearly exhibits an antitropical distribution: three species in the subarctic seas and a single one in the subantarctic seas. Their origins and evolutionary processes are inferred on the basis of synapomorphies, habitats and life cycles of these copepods and the oceanic topography. Upwelling regions off the western coasts of the American continents could have been a corridor for the dispersal of the ancestor from one hemisphere to another. As for the neritic Labidocera pectinata species group the Wallacea and its neighboring areas were supposedly related to the formation of the antitropical distribution of the components during the Pleistocene. Some deep-sea species show a bipolar distribution, only one of which, Spinocalanus antarcticus, is exclusively distributed in the Arctic and Southern Oceans. Ecological characteristics of polar copepods are also compared.
2009-03-31