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Phylogenetics

Biological classification systems and unique names are important for several reasons:

  1. They are aids to memory and precise communication.
  2. They improve the ability to infer relationships among organisms, and are also useful for predictions in scientific investigations.

Below are several examples of how biological classification helped propel scientific research:

CortisoneThe discovery of precursors of cortisone in some yam species of the genus Dioscorea stimulated a successful search for higher concentrations of the drug in other species of Dioscorea.
Phylogeny

Studies of fresh water characiform fishes illustrate how phylogenetic analyses can help determine when lineages split. The 1,400 species of these freshwater fishes vary greatly in size, shape, and diet. Closely related species have been found on both sides of the Atlantic Ocean. Genetic differences in the rRNA of both groups are great enough to be consistent with a split caused by the separation of Africa from South America, about 90 million years ago.

A plausible phylogeny enables biologists to answer a variety of questions about the history of the group. For example, molecular and geological data have been used to reconstruct a phylogeny of Lake Victoria’s cichlid fishes. Initially, the radiation that produced more than 500 species was assumed to have occurred over a period of about 750,000 years. Recent geological evidence suggests, however, that the lake dried up completely between 15,600 and 14,700 years ago.

Biologists determined that the hundreds of diverse cichlids could not have evolved in such a short time. A new phylogeny of the cichlids of Lake Victoria and other lakes in the region was developed using 300 mtDNA sequences. This phylogeny suggested that the ancestors of the Lake Victoria cichlids came from the much older lake Kivu. The phylogeny also indicated that some of the cichlid lineages found only in Lake Victoria split at least 100,000 years ago, suggesting that the lake did not completely dry up about 15,000 years ago.

HumannessMay 20, 2003 — Chimpanzees share 99.4 percent of functionally important DNA with humans and belong in our genus, Homo, according to a recent study published in the Proceedings of the National Academy of Sciences. Previous studies put the genetic similarity between humans and chimps at 95 to 99 percent, so the new figure suggests chimps and humans are even more closely related than previously thought. Scientists analyzed 97 functionally important human genes, along with comparable sequences from chimps, gorillas, orangutans and Old World monkeys (i.e., baboons and macaques). They determined that humans and chimps shared a common ancestor between 4 and 7 million years ago. That ancestor diverged from gorillas 6 to 7 million years ago.
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