Archambeault Lab – Genetics and development of adaptation

Welcome to the Archambeault Lab in the Biology Department at the University of San Francisco!

We study the genetic and developmental basis of adaptation using the threespine stickleback fish as a model system.

Overview

One driver of organismal diversity and speciation is adaptation to new environments. In order for organisms to adapt to new environments, there must be phenotypic variation and natural selection. First, there must be heritable variation

Marine stickleback (center) have repeatedly adapted to freshwater environments (outside), which has resulted in repeated phenotypic evolution — Marine stickleback (center) have repeatedly adapted to freshwater environments (outside), resulting in repeated phenotypic evolution such as loss of bony armor (Bell & Foster, 1994).

in traits (phenotypic variation) between individuals. Second, natural selection must act on this variation- individuals with certain phenotypes are better able to survive and reproduce. Over time, the population will adapt: more individuals in the population will inherit and display the phenotypes that make them better suited to the environment.

Research in my lab is focused on understanding the genetic and developmental basis of adaptation. First, we want to identify the genes and mutations that underlie heritable variation in traits within and between natural populations. Second, we want to understand how these mutations and genes affect developmental processes in order to produce new phenotypes. And third, we want to identify the selective forces that act on these heritable phenotypes.

Female (top) and male (bottom) stickleback fish from Mercer Slough, WA. — Female (top) and male (bottom) stickleback fish from Mercer Slough, Lake Washington, WA.

The threespine stickleback (Gasterosteus aculeatus) is an excellent model for studying adaptive evolution because marine sticklebacks have repeatedly invaded and adapted to freshwater environments since the end of the last ice age about 12,000 years ago. As glaciers receded, marine stickleback moved into and adapted to the newly created rivers, ponds, lakes, and streams. This repeated adaptation to freshwater resulted in similar phenotypes evolving across hundreds of populations worldwide, leaving us with a wonderful natural experiment in which to study the genetic and developmental basis of adaptation.