Genetic Regulation and Divergence of Developmental Plasticity in Pristionchus nematodes

Indiana University, Bloomington IN

Investigators

Abstract

"Developmental plasticity" is the ability of creatures with identical genes to vary in response to cues from the environment. This plasticity is thought to allow evolution to occur faster because it allows a species to have multiple traits. We don't yet know of many genes that allow some creatures to have this plasticity. This project will study a set of genes that create plasticity in the nematode worm Pristionchus pacificus. This worm has different mouth structures and behaviors depending on crowding and availability of food. The research will determine the function of these genes and how they interact, and it will reconstruct how these genes have evolved in related species that don't have developmental plasticity. The results of the research will show how developmental plasticity operates and changes at the level of individual genes. In addition, the investigators will train undergraduate, graduate, and postdoctoral students in biological research spanning the fields of genetics, developmental biology, and evolution. The research will augment two successful science outreach programs established at Indiana University: a) the PI will host and mentor underrepresented minority high-school students in their own research project, collect data, and present findings at an annual poster conference; b), the PI will help high-school teachers to develop and implement projects, experiments, and activities as classroom resources to improve the teaching and learning of state life science standards. This project will build a functional genetic understanding of how development responds to diverse environmental settings, specifically through the production of discrete, alternative phenotypes (i.e., polyphenism). The objectives of the research are twofold. First, it will characterize the genetic factors and pathway that constitute a developmental switch for a polyphenism in the model nematode Pristionchus pacificus, by means of: (i) cloning and determining the spatial expression of genes that act downstream of a known polyphenism switch gene (eud-1), and; (ii) empirically determining how the interactions between their products form an environmentally responsive switch. Second, the research will determine how these factors change or assume new functions with the divergence of polyphenism regulation. Specifically, the research will reconstruct the evolutionary history of these factors via: (i) inferring patterns of sequence evolution and identifying potential functional variants, and; (ii) using reverse genetics in other species to perform comparative functional tests of those factors. Through analysis of a genetic pathway forming a developmental switch and the evolutionary divergence of its components, this research project will pioneer a functional genetic analysis of how developmental plasticity - specifically, a polyphenism - responds to environmental inputs, and how its regulation changes over evolutionary time.