The Coming of Age of Molecular Systematics

For decades, taxonomists examined the insides and outsides of organisms to gain clues about their evolutionary relationships. Recently, molecular biology has provided a new set of characteristics for examination--gene sequences. But constructing evolutionary trees by comparing the sequences of the most commonly used gene, a gene for ribosomal RNA, is not trivial. In their commentary, Maley and Marshall outline the problems encountered in using this method of studying the ancient origins of animals.