Project description:Aposematic color pattern mimicry in Heliconius butterflies provides a well-known example of adaptation via selection on a few genes of large effect. To understand how selection at individual genes can drive the evolution of complex traits, we functionally characterized five novel enhancers of the color pattern gene, optix. In Heliconius erato we found that wing pattern enhancers are largely ancestral, pleiotropic, functionally interdependent, and introgressed between populations. Remarkably, many of these enhancers are also associated with regional pattern variation in the distantly related co-mimics Heliconius melpomene and Heliconius timareta. Our findings provide a case study of how parallel co-evolution of ancient, multifunctional regulatory elements can facilitate the rapid diversification of complex phenotypes, and provide a counterpoint to many widespread assumptions of cis-regulatory evolution.
Project description:Aposematic color pattern mimicry in Heliconius butterflies provides a well-known example of adaptation via selection on a few genes of large effect. To understand how selection at individual genes can drive the evolution of complex traits, we functionally characterized five novel enhancers of the color pattern gene, optix. In Heliconius erato we found that wing pattern enhancers are largely ancestral, pleiotropic, functionally interdependent, and introgressed between populations. Remarkably, many of these enhancers are also associated with regional pattern variation in the distantly related co-mimics Heliconius melpomene and Heliconius timareta. Our findings provide a case study of how parallel co-evolution of ancient, multifunctional regulatory elements can facilitate the rapid diversification of complex phenotypes, and provide a counterpoint to many widespread assumptions of cis-regulatory evolution.
Project description:Aposematic color pattern mimicry in Heliconius butterflies provides a well-known example of adaptation via selection on a few genes of large effect. To understand how selection at individual genes can drive the evolution of complex traits, we functionally characterized five novel enhancers of the color pattern gene, optix. In Heliconius erato we found that wing pattern enhancers are largely ancestral, pleiotropic, functionally interdependent, and introgressed between populations. Remarkably, many of these enhancers are also associated with regional pattern variation in the distantly related co-mimics Heliconius melpomene and Heliconius timareta. Our findings provide a case study of how parallel co-evolution of ancient, multifunctional regulatory elements can facilitate the rapid diversification of complex phenotypes, and provide a counterpoint to many widespread assumptions of cis-regulatory evolution.
Project description:Butterfly wing patterns are an important model for studying the genetic basis of morphological evolution. Here we used RNA-seq expression profiling in the butterfly Vanessa cardui to characterize the transcriptional basis of wing pigmentation. This approach identified numerous candidate genes including known and suspected components of the insect melanin and ommochrome biosynthetic pathways.
Project description:We investigated gene expression levels in Heliconius erato butterflies with divergent wing patterns across a 656KB genomic interval linked to the red color pattern wing polymorphism. This included comparison of expression between two H. erato color pattern populations (H. e. petiverana and a H.e. etylus x H. himera hybrid) across three sections of the forewing that differed in pigmentation (the basal, mid, and distal wing sections) and five different stages of pupal development (Day 1, 3, 5 pupae and ommochrome and melanin pigmentation stages). These results allowed us to determine whether certain genes in this interval were differentially expressed between the wing pattern elements, and, therefore, potentially responsible for adaptive color pattern variation in these butterflies.
Project description:Heliconius butterfly wing pattern diversity offers a unique opportunity to investigate how natural genetic variation can drive the evolution of complex adaptive phenotypes. Here we took a large-scale transcriptomic approach to identify the network of genes involved in Heliconius wing pattern development and variation. This included applying 147 microarrays representing the Heliconius transcriptome to assay shifts in gene expression across pupal development among several wing pattern morphs of Heliconius erato. We focused in particular on genes differentially expressed relative to the gene optix, which controls red pattern elements in wings. We combined expression results from three hindwing morphs from Peru and from dissected basal to apical wing elements in two forewing morphs to uncover two main classes of genes. First we looked for candidate upstream regulators of optix by determining transcripts expressed differently across basal to apical sections of the forewing prior to optix expression. Second, we assessed how optix regulates downstream gene expression by targeting transcripts with differential expression similar to optix, where expression differs among red wing pattern elements of both the forewing and hindwing.
