| Popis: |
Many evolutionary biologists seek to learn about genealogy among life forms. Toward this end, researchers have sought out informative systems or characters from fields as disparate as behavior, morphology, physiology, biogeography, and molecular genetics. DNA sequences in particular appear promising for resolving evolutionary questions, due in part to the fact that they constitute the physical material of inheritance in its most particulate form. However, the promise of DNA rests on the assumption that historical change in nucleotide sequences can be inferred unambiguously from sequences of extant (or recently extinct) forms, and this task remains as a challenge. It is important to recognize that the pursuits of molecular systematics (history of descent among organisms) and molecular evolution (history of change among and within molecules) are mutually informing. Molecular systematic studies have been instrumental in studies of molecular evolution because patterns of sequence change over thousands and millions of years can be inferred only by comparing sequences among taxa whose divergences span |
