Sarah Kocher
Associate Research Scholar, Lewis-Sigler Institute for Integrative Genomics

Department|Program:
  • Lewis-Sigler Institute for Integrative Genomics

skocher@princeton.edu
143 Carl Icahn Lab
Scholar
Website

Social species are often wildly successful in nature, but group living is difficult to achieve and maintain. My lab is interested in understanding how and why social behavior evolves. We study systems that have extensive variation in social behavior, and use complementary approaches from population and quantitative genetics through field ecology and mathematical modeling to understand how genes and ecology interact to shape social traits.

Halictid bees.  Halictid bees exhibit remarkable diversity in social behavior, both within and between species. Within this family, social behavior has evolved independently 2-3 times. There have also been many replicated losses of sociality in this group, making halictids some of the most behaviorally diverse social insects on the planet.

Some halictids are socially polymorphic and capable of producing either eusocial or solitary nests. In one such species, (Lasioglossum albipes), this variation occurs among different populations, and a common garden experiment has demonstrated that this behavioral variation is likely to have a genetic underpinning. My group has developed the genomic tools needed to bring L. albipes online as a model system, and we are now beginning to probe the genetic and physiological underpinnings of this behavioral polylmorphism.

In addition to this work, we are also taking a comparative approach to identify key molecular changes associated with the evolution of social behavior in halictids. We have recently sequenced the genomes of 18 species that span all of the known gains and losses of eusociality in this family. Through these genomic comparisons, we can ask if selection has acted on the same or similar molecular pathways to shape social traits in this group.

Treehoppers. Similar to halictid bees, treehoppers exhibit extreme diversity in a number of additional morphological, behavioral, and ecological traits. And like halictids, there is also extensive variation in some of these traits within species, opening the door to quantitative and population genetic approaches. We are actively developing this system as a model for studying the evolution of maternal care and other behavioral traits.