Behavioral Genetics

Genetic architecture and evolution of behavior

We are interested in the genetic basis of naturally occurring behaviors. Presently we are focusing our investigations on three primary behaviors: burrowing behavior, climbing behavior and mate choice/mating system. First, we are studying the genetic basis of mate choice and mating system in Peromyscus using a forward genetics approach (i.e., genetic crosses of species that vary in behaviors). Using a similar approach, we are exploring the genetics of innate burrow-building between two sister species of Peromyscus that differ in their burrow design. In both of these projects, we are characterizing the genetic architecture of behavior. We ask the following questions: How many and which genes contribute to behavioral adaptation? Do adaptive behaviors and morphologies have similar genetic architectures? Do adaptive behaviors have a large genetic component? Is behavioral variation controlled by changes in gene regulation?

 

To better understand the evolutionary dynamics of behavioral evolution, we are also investigating:

(1) the prevalence and causes of behavioral variation in nature

(2) the evolution of behaviorial traits among closely related species of Peromyscus.

Evolution of burrowing

Different species of Peromyscus build dramatically different burrows in the wild, and these burrow structures are important for both survival and reproduction. In particular, the burrows of the oldfield mouse (P. polionotus) are eminently large and complex compared to the short, simple burrows of their sister species, the deer mouse (P. maniculatus). Strikingly, the oldfield mouse excavates a second “escape tunnel,” which radiates up from the nest chamber to just below the soil surface. This secret escape hatch is derived and unique to P. polionotus, and thus represents an evolutionary innovation. (Figure by Hillery Metz, Harvard)

Hoekstra and Mice Since burrowing behavior leaves behind an “extended phenotype,” we are able to study the “morphology” of the burrows themselves, in addition to the digging behavior of the mice. We have shown that these burrowing behaviors are largely innate, and are recapitulated by mice raised under controlled laboratory conditions, allowing us to study the genetic basis of this species-specific behavior. Current research on burrowing is focused on

(1) identifying the genes that contribute to differences in burrow architecture,

(2) uncovering the genetic basis of differences in digging activity in recordings of mice burrowing in “antfarms,” and

(3) studying the neurobiological basis of differences in burrowing behavior through pharmacology, neural activity, and candidate gene approaches.

 

Evolution of climbing behavior

Hoekstra and Mice Peromyscus maniculatus live in a wide variety of habitats across North America, from the ancient forests of the Pacific Northwest to the flat prairies of the Midwest. These different habitats offer varied opportunities for arboreal movement; correspondingly, forest mice have a number of morphological and behavioral adaptations that allow them to take advantage of the vertical nature of forest habitats. In addition to longer feet and tails, forest mice have evolved an innate preference for higher perches and are more adept at crossing horizontal branches than their prairie counterparts. We test climbing ability and preference with laboratory assays and then use genetic mapping techniques to understand the genetic mechanisms underlying the interplay between behavioral and morphological adaptations. (Photo credit: Evan Kingsley, Harvard)

 

 

Evolution of social behavior

Hoekstra and MicePeromyscus species differ in their mating system, ranging from strong monogamy and biparental care to promiscuity with mostly maternal care. We are examining the genetic and neuronal bases of social behaviors between closely related species of Peromyscus that differ in mating system. (Photo credit: Rowan Barrett, Harvard)