Chapter 1 - The Dusky Dolphins' Place in the Delphinid Family Tree

Abstract

Perhaps no group of cetaceans epitomizes the confused state of cetacean taxonomy at the end of the nineteenth century more than the genus Lagenorhynchus. There are currently six recognized species, all of which are distributed in temperate to cool waters in the North Pacific, North Atlantic, and Southern Pacific and Indian Oceans. All species of the genus share a general body plan defined by a relatively short rostrum, a prominent falcate dorsal fin, a stocky robust body shape, and a complex pattern of body coloration, dominated by bands, stripes, and flares of multiple hues. It is clear from the molecular phylogeography that regional dusky dolphin populations are genetically isolated from each other, and for management purposes should be considered as different stocks, if not different subspecies. Prior to the Darwinian revolution, species were considered static, unchangeable entities, and it was the goal of the taxonomist to identify, name, and organize this diversity. After Darwin published his theory of Natural Selection in 1859, it was no longer satisfactory to simply group species according to similarity of features—it became important that organisms be classified into “natural groups” to reflect their shared evolutionary history.