Genetics of neural and behavioral evolution
Dramatic differences in behavior can occur between closely related species and contribute to speciation, as in sticklebacks. However, we know very little about the genetic and neural mechanisms that have given rise to the diversity of behaviors found in nature.
Although many predicted that identifying the genetic basis of behavioral evolution would be intractable, we have demonstrated that it is possible to use genetic approaches to identify loci that contribute to behavioral differences between natural populations. Most recently, we have focused our studies of the genetics of behavior to social grouping behavior. The formation of social groups is prevalent across the animal kingdom, but can vary dramatically among different species, within species, and even across the lifetime of an individual. One dramatic example of social grouping behavior is found in shoals and schools of fish. My laboratory has developed novel assays and analytical methods to study the genetic basis of shoaling and schooling in sticklebacks. We have used our “model school assay” to demonstrate that there are heritable differences in schooling behavior between stickleback populations adapted to different habitats. These populations differ in both of the key components of schooling behavior: tendency to school and coordination of body position when schooling. These two components of schooling behavior are controlled by distinct genetic modules, providing new insights into the evolution of complex behaviors. Using transgenic methods, we have demonstrated that variation in the Eda gene contributes to variation in both the lateral line neurosensory system and the ability of sticklebacks to school. Together, these experiments have provided mechanistic insight into how and why fish form schools and identified one of the first genes known to shape behavior in an evolutionary context.
Ongoing research directions
Our results suggest that the Eda gene has pleiotropic effects on skeletal morphology, neurosensory systems, and behavior. We are currently combining developmental and molecular studies in the lab with genomic studies in the field to determine whether selection on this locus is due to tight linkage of multiple genetic changes or to pleiotropic effects of a single genetic change. These studies will allow us to connect genetic variation, phenotypic variation and fitness in the wild; such studies are essential to obtain a holistic view of the evolutionary process.
Greenwood AK, Mills MG, Wark AR, Archambeault SL, Peichel CL (2016) Evolution of schooling behavior in sticklebacks is shaped by the Eda gene. Genetics 203: 677-681. 10.1534/genetics.116.188342
Greenwood AK, Ardekani R, McCann SR, Dubin ME, Sullivan A, Bensussen S, Tavaré S, Peichel CL (2015) Genetic mapping of natural variation in schooling tendency in stickleback. G3: Genes, Genomes, Genetics 5: 761-769. 10.1534/g3.114.016519
Mills MG, Greenwood AK, Peichel CL (2014) Pleiotropic effects of a single gene on skeletal development and sensory system patterning in sticklebacks. EvoDevo 5: 5. 10.1186/2041-9139-5-5
Greenwood AK*, Wark AR*, Yoshida K, Peichel CL (2013) Genetic and neural modularity underlie the evolution of schooling behavior in threespine sticklebacks. Current Biology 23: 1884-1888. 10.1016/j.cub.2013.07.058
Wark AR, Mills MG, Dang L, Chan YF, Jones FC, Brady SD, Absher DM, Grimwood J, Schmutz J, Myers RM, Kingsley DM, Peichel CL (2012) Genetic architecture of variation in the lateral line sensory system of threespine sticklebacks. G3: Genes, Genomes, Genetics 2: 1047-1056. 10.1534/g3.112.003079
Wark AR*, Greenwood AK*, Taylor EM, Yoshida K, Peichel CL (2011) Heritable differences in schooling behavior among threespine stickleback populations revealed by a novel assay. PLoS ONE 6: e18316. 10.1371/journal.pone.0018316
Wark AR, Peichel CL (2010) Lateral line diversity among ecologically divergent threespine stickleback populations. Journal of Experimental Biology 213: 108-117. 10.1242/jeb.031625