13 - Insect Population Ecology and Molecular Genetics

Abstract

Molecular genetic techniques provide powerful tools to study insect biology, ecology, and population genetics in both natural and laboratory populations. Analysis of proteins, nuclear or mitochondrial deoxyribonucleic acid (DNA), and messenger ribonucleic acid (mRNA) can be used to answer ecological questions. Analysis of proteins by electrophoresis is 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 or sibling species, determine paternity, resolve whether hybridization or introgression occurs, and provide information on founder effects, population genetic structure, gene flow, inbreeding, genetic bottlenecks, dispersal, and selection intensity. The polymerase chain reaction (PCR) is often used to reduce costs and allow large numbers of specimens to be sampled. Large amounts of genetic variation can be sampled rapidly and inexpensively in large numbers of individuals by random amplified polymorphic DNA (RAPD) method of PCR, restriction enzyme digests of DNA amplified by PCR restriction fragment length poly-morphisms (RFLP-PCR), or amplified fragment length poly-morphism (AFLP-PCR) method. Although technically more challenging and expensive, techniques such as DNA fingerprinting using microsatellite DNA, heteroduplex analysis, or double-strand conformation polymorphism (DSCP) provide information on genetic variation at individual and population levels. Recently, the use of DNA microarray (DNAchip) analysis has allowed researchers to evaluate the responses of plants to insect attack, and it shows promise of answering other important ecological questions as well.