What Can We Learn About Adaptation from the Wing Pattern Genetics of Heliconius Butterflies?

Abstract

Heliconius wing patterns are an adaptive trait under strong selection in the wild. They are also amenable to genetic studies and have been the focus of evolutionary genetic analysis for many years. Early genetic studies characterised a large number of Mendelian loci with large effects on wing pattern elements in crossing experiments. The recent application of molecular genetic markers has consolidated these studies and led to recognition that a huge range of allelic variation at just a few major loci controls patterns across most of the Heliconius radiation. Some of these loci consist of tightly linked components that control different aspects of the phenotype and can be separated by occasional recombination. More recent quantitative analyses have also identified minor-effect loci that influence the expression of these major loci.Studies of a single locus polymorphism in Heliconius numata provide an example of a 'supergene', in which a single major locus controls segregation of a variable phenotype. This supports 'Turner's Sieve' hypothesis for the evolution of supergenes, whereby sequential linked mutations arise at the same locus. In addition, inversion polymorphisms are associated with wing pattern variation in wild populations, which reduce recombination across the supergene locus. This provides direct evidence that the architecture and organisation of genomes can be shaped by natural selection. There is also evidence that patterns of dominance of the alleles at this locus have also been shaped by natural selection. Mimicry therefore provides a case study of how natural selection shapes the genetic control of adaptive variation.Keywords Mimicry • Heliconius • Convergent evolution • Input-output gene • Developmental pathway • Adaptive radiation A major research effort in evolutionary biology is devoted to determining the molecular changes in DNA sequences that control adaptive phenotypic changes. By identifying the number and identity of genes controlling traits, and the relative

Haplotype tagging reveals parallel formation of hybrid races in two butterfly species

“…3 and SI Appendix, SI Materials and Methods). The strongest divergence peaks are found at four major loci, namely WntA (Chromosome 10) (23), vvl (Chr13), cortex (Chr15) (32,33), and optix (Chr18) (17,22,34), and they are highly correlated between the two species, highlighting the fine-scale parallelism at these loci (Fig. 3 B and C and SI Appendix, Fig.…”

“…Heliconius butterflies have diversified into many species and subspecies (or "races") across South and Central America and represent a classic example of adaptive radiation (17). They are toxic and advertise their unpalatability with bright warning coloration.…”

“…18). The striking variety notwithstanding, the genetics of these color patterns is remarkably simple, involving only a few loci of large effect (17,(21)(22)(23)(24)(25)(26).…”

“…Here, we focus on two distantly related Heliconius species, Heliconius erato and Heliconius melpomene (diverged 12 million years ago) (27), which feature many distinct color patterns and mimic each other (and other species) whenever they overlap (17). In the Pastaza valley of eastern Ecuador, a highland race of each species meets and forms a hybrid zone with a distinct lowland race (Fig.…”

High-quality haploid genomes corroborate 29 chromosomes and highly conserved synteny of genes inHyleshawkmoths (Lepidoptera: Sphingidae)

“…The invariance found at and close to optix was expected, as optix and surrounding genes are highly conserved within Lepidoptera [52]. In contrast, the high percentage of InDels found in the alignment downstream of optix between the genomes of H.…”