Chapter 1 - Molecules and Morphology in Studies of Fish Evolution

Abstract

This chapter discusses the evolution of fishes, which is the most diverse group of living vertebrates, with more than 24,600 extant species currently known. Morphological studies have been especially successful in defining species and in organizing these species into genera. These groupings have usually been confirmed when examined with molecular approaches. Both morphological and molecular studies have had particular difficulty discerning higher-level relationships. This chapter traces the history of an increasingly sophisticated realm of techniques that have been developed. Allozyme studies, mitochondrial DNA, polymerase chain reaction and DNA sequencing, nuclear DNA sequences, and some other nuclear techniques are explained. The controversies of these techniques over analytical methods are also focussed on. Morphologists have generally rejected distance approaches. Molecular systematists appear relatively flexible in the approaches taken to recover phylogenetic relationships from their data and have found that the evolution of sequences is often most easily modeled with distance methods.