12 - Molecular Systematics and Evolution of Arthropods

Abstract

Systematics is the study of phylogeny and taxonomy. Taxonomy is into descriptive taxonomy and identification. Deoxyribonucleic acid (DNA) is suitable for systematics studies because it provides the most direct analysis of a genetic material possible and is unlikely to be confounded by life stage or environmentally induced variability. Molecular techniques commonly used include analyses of isozymes, molecular cytogenetics, restriction analyses of DNA sequences, and DNA sequencing. Each method has virtues and limitations in the amount and type of information provided, their technical difficulties, and their costs. There have been several significant controversies associated with the use of molecular techniques to study systematics and evolution. These include debates over the relative importance of molecular versus morphological data, the constancy of a molecular clock for evaluating time of divergence of taxa, the proper use of the terms “homology” and “similarity”, and the neutrality of a DNA sequence variation. Another issue of how to resolve incongruencies between molecular- and morphology-based phylogenies is discussed in the chapter. The immense diversity of insects and their long evolutionary history provide a challenge, but the use of molecular data provides new opportunities to discern the long and diverse evolutionary histories of arthropods and their relatives. With the use of molecular methods, systematists and population geneticists have started to use common approaches to study both intraspecific and interspecific genetic diversity.