Digging Deeper: Exploring the Genetic Architecture of Mammalian Behavior

Recent years have witnessed an explosion in the number of phenotypic adaptations that have been mapped to genomic loci across the entire tree of life.  While the taxonomic breadth of these studies is steadily expanding, the variety in phenotypes has been rather more limited, with the preponderance of studies (especially in metazoans) focusing on coloration and physical dimensions of all or part of the adult organism.

Evolution of behavior, on the other hand, has received less attention, likely due to the paucity of heritable, stereotyped behaviors which can be precisely and repeatably measured.  To better understand the similarities and differences between genetic architectures of morphological and behavioral traits, we have developed a several

robust, quantitative assays of a heritable, innate burrowing behavior which shows extensive phenotypic evolution in mice of the genus Peromyscus.  We have mapped behavioral modules responsible for different aspects of burrow construction to a small set of genomic loci, and preliminary results suggest that the observed changes in this behavior may have their mechanistic roots in large-magnitude shifts in motivation and resource allocation, which is conceptually congruent with the small-number/large-effect trend observed in many studies of recent morphological adaptation.