Abstract
Understanding physiological tasks may start by a good understanding of evolutionary traits in a given protein gene family. The successful completion of various genome projects is a key step forward for comparative analysis of similar and/or orthologous genes between species, measuring genetic relatednesses, studying evolutionary changes among different behaviors, helping to identify specifically conserved genes or genes that are variable enough to determine a new strain or organism. How evolutionary data can improve the understanding of a protein gene family is exploited here in the case of the insect Chemosensory Proteins (CSPs) as a guidance model. In this chapter, Diptera are presented not only as a huge diversity of appearances (phenotypes), behaviors and lifestyles, but also as major differences that are gene copy numbers, gene family members, polymorphisms and evolutionary rate variations, without any a priori assumption about the origin and function of the sampled gene family.
