Ecological systems biology: disentangling the molecular mechanisms of parallel evolution

A desire to understand species diversity is a common motivating force in biology.

This typically involves identifying genes responsible for specific traits, especially those allowing an organism to adapt to specific environments.

Since genes function in a network of interactions, discerning the molecular mechanism of adaptive traits can be difficult.

However, examining repeated occurrences of adaptation (parallel evolution) can be a powerful tool for understanding how species evolve at the molecular level.In this project, we will examine the marine snail, Littorina saxatilis, which has ecotypes that have evolved repeatedly in Sweden, United Kingdom and Spain.

We will examine gene expression from ecotype replicates to discover differentially expressed genes and gene co-expression modules involved in adaptation.

Then, we will rear snails in a common environment to determine if the gene expression observed in the wild is due to plastic or genetic changes.

To see if parallel phenotypes are the result of different regulatory mutations, we will examine the regulatory architecture by sequencing open chromatin regions of the DNA of the different ecotypes. We will conduct an expression QTL analysis to link expression variation to regulatory regions. These results will be will be validated using CRISPR/Cas9.

Altogether, these experiments will identify genes, interactions among genes, and the regulatory network responsible for ecotype differentiation in Littorina saxatilis.