Variable levels of drift in tunicate cardiopharyngeal gene regulatory elements.

Background: Mutations in gene regulatory networks often lead to genetic divergence without impacting gene expression or developmental patterning. The rules governing this process of developmental systems drift, including the variable impact of selective constraints on different nodes in a gene regulatory network, remain poorly delineated.

Results: Here we examine developmental systems drift within the cardiopharyngeal gene regulatory networks of two tunicate species, and Cross-species analysis of regulatory elements suggests that -regulatory architecture is largely conserved between these highly divergent species.