Scientists have used microarrays to look at the broad genetic changes that accompany reproductive declines in inbred populations. Their study, published in Conservation Biology, is the first to look at genome-wide gene expression differences in inbred populations, small populations of closely related plants or animals that are likely to suffer from low reproductive success. Using six lines of fruit flies that had been inbred, they found that "significant amount of inbreeding depression is due to a few key genes that affect the expression of other genes," says University of Illinois at Urbana-Champaign's Ken Paige at Medical News Today. Of the 46 differentially expressed genes, those most important were involved in metabolism, stress, and defense. This is a surprising finding, Paige says, "because we think of inbreeding as a random process."