TIME AND BIOSEQUENCES

In this paper we discuss and demonstrate the importance of several fac tors relative to the relationship between time and evolution of bioseq uences. In both quantitative and qualitative measurements of the genet ic distances, the compositional constraints of the nucleotide sequence s play a very important role. We demonstrate that when homologous sequ ences significantly differ in base composition we get erratic branchin g order and/or wrong evaluation of the evolutionary rates. We must con sider that every gene may have a different evolutionary dynamic along its sequence, generally linked to its functional constraints; this too can seriously affect its clocklike behavior. We report some cases sho wing how these factors can affect the quantitative measurements of the genetic distances of biosequences.