ZFIN ID: ZDB-PUB-141010-6
The evolution of cichlid fish egg-spots is linked with a cis-regulatory change
Santos, M.E., Braasch, I., Boileau, N., Meyer, B.S., Sauteur, L., Böhne, A., Belting, H.G., Affolter, M., Salzburger, W.
Date: 2014
Source: Nature communications   5: 5149 (Journal)
Registered Authors: Affolter, Markus, Belting, Heinz-Georg Paul (Henry), Braasch, Ingo, Salzburger, Walter, Santos, Emilia
Keywords: none
MeSH Terms:
  • Animals
  • Base Sequence
  • Cichlids
  • Evolution, Molecular
  • Gene Expression Regulation
  • LIM Domain Proteins/genetics*
  • Molecular Sequence Data
  • Ovum/metabolism*
  • Pigmentation/genetics*
  • Zebrafish
PubMed: 25296686 Full text @ Nat. Commun.
The origin of novel phenotypic characters is a key component in organismal diversification; yet, the mechanisms underlying the emergence of such evolutionary novelties are largely unknown. Here we examine the origin of egg-spots, an evolutionary innovation of the most species-rich group of cichlids, the haplochromines, where these conspicuous male fin colour markings are involved in mating. Applying a combination of RNAseq, comparative genomics and functional experiments, we identify two novel pigmentation genes, fhl2a and fhl2b, and show that especially the more rapidly evolving b-paralog is associated with egg-spot formation. We further find that egg-spot bearing haplochromines, but not other cichlids, feature a transposable element in the cis-regulatory region of fhl2b. Using transgenic zebrafish, we finally demonstrate that this region shows specific enhancer activities in iridophores, a type of pigment cells found in egg-spots, suggesting that a cis-regulatory change is causally linked to the gain of expression in egg-spot bearing haplochromines.