Deciphering the cis-regulatory 'logic' of gene regulation is one of the biggest challenges genomics faces today. Understanding the functional constraints of regulatory elements across species has been the focus of much 'evo-devo' research, leading to many exciting insights, such as the preservation of CRM function without a base-to-base preservation of sequence [9-11] and the impact of protein-protein interactions [45]. Variation across individuals presents a snapshot of 'evolution in action', giving access to potentially suboptimal alleles without having to resort to artificial perturbation, and are a promising resource for population functional genomics studies as well as more formal association analyses. Such 'pop-fun' approaches will complement the insights obtained from 'evo-devo' studies.
