allopatric speciation animal arctic ocean asia australia before present bering sea biological classification biology letters channel islands of california columbian mammoth continental shelf corsica crete cyclades cyclops cyprus delos digital object identifier dorothea bate europe flores fossil holocene hugh falconer insular dwarfism kyrenia kythnos kyuss malta mammal mammoth milos naxos island palaeoloxodon pleistocene proboscidea proby cautley pygmy mammoth rhodes sardinia serifos sicily skeleton stegodon straight-tusked elephant sulawesi tilos timor wallacea woolly mammoth wrangel island