Chapter 13 - Insect Population Ecology and Molecular Genetics

Abstract

Molecular genetic techniques provide powerful tools for the study of insect biology, ecology, and population genetics in both natural and laboratory populations. Analysis of proteins, nuclear or mitochondrial DNA and messenger RNA can be used to answer ecological questions at the individual, population, or ecosystem level. Analysis of proteins by electrophoresis has been useful with many insects, but some taxa with low levels of detectable genetic variation cannot be studied unless more-sensitive DNA markers are used. DNA analyses can identify biotypes, sibling species, determine paternity or whether hybridization or introgression occurs, and provide information on founder effects, population genetic structure, gene flow, inbreeding, genetic bottlenecks, dispersal, predation, and selection intensity. Large amounts of genetic variation can be sampled rapidly and inexpensively in large numbers of individuals by the RAPD-PCR method or by restriction-enzyme digests of DNA amplified by the PCR (RFLP-PCR) or by the AFLP-PCR method. Although technically more challenging and expensive, DNA fingerprinting using microsatellite DNA, heteroduplex analysis, or double-strand conformation polymorphism (DSCP) provide information on genetic variation at the individual and population level. The use of DNA microarray (DNA chip) analysis has allowed researchers to evaluate the responses of plants to insect attack; microarray analysis could answer other important ecological questions in insects.