Macroevolutionary Transition of Cetaceans Back to the Sea
Today, one of the best known examples of macroevolution is that which can be speculated upon and observed in relation to marine mammals. Wales, porpoises and dolphins, members of the Catacean order, share a number of distinctions in the marine ecosystem, not the least of which is their high intelligence. Additionally, that these species are mammals that must ascend to the surface for respiration has underscored long-standing zoological speculation as to their origins. As the question of macroevolution suggests, these origins may well denote that the species in question originated on land.
According to the research by Bajpai et al. (2009), the speculative nature of the macroevolutionary theory was given some of its strongest evidence to date by fossil finds in the Indian and Pakistan region. These have suggested that whales in particular can be shown to have evolved into aquatic creatures from an array of land-dwelling prehistoric species. The research by Bajpai et al. indicates that "the first steps of whale evolution, i.e. The transition from a land mammal to obligate marine predators, documented by the Eocene cetacean families of the Indian subcontinent: Pakicetidae, Ambulocetidae, Remingtonocetidae, Protocetidae, and Basilosauridae, as well as their artiodactyl sister group, the Raoellidae. We also discuss the influence that the excellent fossil record has on the study of the evolution of organ systems, in particular the locomotor and hearing systems." (Bajpai et al., p. 673)
Perhaps more telling than these organ, locomotor and hearing systems are the vestigial hind flippers that are observable on cetaceans. These, our research denotes, point directly to a feature descendent from the order's ungulate origins and implies that at early points in its evolution, these hind flippers had been hind legs.
2. Explain the process of phylogenetic reconstruction including types of data and analyses.
Understanding the process of evolution for a single species or of an array of related species requires a mode of inquiry that combines both fossil evidence and speculative evaluation in order to devise the likeliest sequence of evolutionary steps and correlations. This mode of evaluation is called phylogenetic reconstruction and employs a wide array of variables relating the phylogenetic...
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