Comparative environmental genomics in non-model species: using heterologous hybridization to DNA-based microarrays

The emerging field of comparative environmental genomics involves the cross-species comparison of broad-scale patterns of gene expression. Often, the goal is to elucidate the evolutionary basis or ecological implications of genomic responses to environmental stimuli. DNA-based microarrays represent powerful means with which to investigate gene expression, and the application of genomic tools to studies on non-model species is becoming increasingly feasible. The use of a microarray generated from one species to probe gene expression in another, a method termed 'heterologous hybridization', eliminates the need to fabricate novel microarray platforms for every new species of interest. In this review, recent advances in heterologous hybridization are reviewed, and the technical caveats of this approach are discussed.