Unraveling the complex evolution of color patterns is published in Nature Ecology & Evolution

02/07/ 2017

One of the major goals in evolutionary biology is to understand what type of changes in the DNA makes individuals different from each other. In contemporary science this is addressed by studying how an organism’s genotype (genetic variation in the genome) influences the phenotype (observed characteristics such as color in a butterfly’s wing). A study led by Van Belleghem and Papa recently published in the journal Nature Ecology & Evolution sequenced 116 individual genomes to characterize the changes driving the variety in wing colorations in the Neotropical Heliconius butterflies.

Heliconius wing patterns are adaptive traits important for signaling toxicity to potential predators and for partner selection during mate choice. In the past few years the same team and other group of researchers have revealed the identity of the molecules controlling the different colors, and defined a toolkit of four developmental genes. These genes are: 1) the eye transcription factor optix = red, 2) the signaling ligand WntA and the transcription factor vvl = black, 3) the cell-cycle regulator cortex = yellow. However, after these discoveries a question buzzed scientist: how is it possible that only four genes can control 30+ distinct wing color patterns? Papa and Van Belleghem from the University of Puerto Rico, Rio Piedras together with Owen McMillan at the Smithsonian Tropical Research Institute in Panama and Brian Counterman at the Mississippi State University were able to answer such question in the manuscript titled “Complex modular architecture around a simple toolkit of wing pattern genes”.

Prof.Brian Counterman

Prof. Riccardo Papa

Prof. Owen McMillan

Dr.Van Belleghem

In their study, Van Belleghem and an international group of researchers from 10 distinct universities representing north, central and south America, Europe and Australia, suggest that a very tiny portion of the genome (0,02%) is actually responsible for such drastic changes in morphologies. In contrast, they illustrate how rapid evolution of novel morphologies is achieved by a complex regulatory genetic architecture around very few developmental genes. These non-coding regulatory DNA regions (modules) are the functional elements that contain the instructions to coordinate the spatial expression of the patterning genes in discrete areas of the developing wing. Van Belleghem and collaborators elegantly show that exchange of existing modules between differently colored races can explain a large fraction of the extreme diversification observed in Heliconius. Overall, this work provides a novel clue in the genetic mechanism controlling similar morphological changes that inspired Darwin to postulate his law of natural selection. The authors suggest that what they discovered might actually well be a common hallmark of rapid morphological diversification in adaptive radiations. Concluding, Van Belleghem and his international collaborators provide a first in-depth view of the molecular mechanisms that generates what Darwin called “endless forms most beautiful”.

Van Belleghem S.M., Rastas P., Papanicolaou A., Martin S.H., Arias C.F., Supple M.A., Hanly J.J., Mallet J., Lewis J.J., Hines H.M., Ruiz M., Salazar C., Linares M., Moreira G.R.P., Jiggins C.D., Counterman B.A., McMillan W.O. & Papa R., 2017 Complex modular architecture around a simple toolkit of wing pattern genesNature Ecology & Evolution1:0052.