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A phylogenetic tree of life

A phylogenetic tree of life - lineages of organisms appear...

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A phylogenetic tree of life Biologists are interested in how organisms are related to one another and have as a general goal the  construction of a  tree of life  in which the evolutionary relationships of all organisms are traced  through time much as genealogists trace human family histories. In biology the study of  developmental history and evolutionary relationships is called  phylogeny . It is possible to trace  phylogenies  because  Organisms have  heredity;  parents transmit genetic information to their offspring  through the renowned molecule,  DNA  (  deoxyribonucleic acid ).  Organisms change over time; they  evolve  to meet changing environmental  conditions. The changes gradually become encoded in the DNA and separate 
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Unformatted text preview: lineages of organisms appear. The sequence of base pairs in individual molecules of DNA and RNA are used to track relationships. Organisms with similar sequences are assumed to have had a common ancestor, and the more alike the strings of base pairs, the closer is the relationship. By combining molecular data with the information already known about organisms, biologists construct phylogenetic trees like that shown in Figure 1 . Most, but not all, biologists agree that at present this is the best way to arrange the branches, but new data undoubtedly will require new interpretations and, perhaps, different phylogenetic trees....
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