amazonian fish fauna accumulated increments period tens millions years principally means allopatric speciation arena extending area tropical south america albert reis words unlike well known insular faunas galapagos finches hawaiian drosophilid flies african rift lake cichlids species rich amazonian ichthyofauna result recent adaptive radiations ref name lovejoy n r pp lovejoy n r c willis j albert molecular signatures neogene biogeographic events amazon fish fauna pp
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