Contribution of Distal-less to quantitative variation in butterfly eyespots.

The colour patterns decorating butterfly wings provide ideal material to study the reciprocal interactions between evolution and development. They are visually compelling products of selection, often with a clear adaptive value, and are amenable to a detailed developmental characterization. Research on wing-pattern evolution and development has focused on the eyespots of the tropical butterfly Bicyclus anynana. There is quantitative variation for several features of eyespot morphology but the actual genes contributing to such variation are unknown. On the other hand, studies of gene expression patterns in wing primordia have implicated different developmental pathways in eyespot formation. To link these two sets of information we need to identify which genes within the implicated pathways contribute to the quantitative variation accessible to natural selection. Here we begin to bridge this gap by demonstrating linkage between DNA polymorphisms in the candidate gene Distal-less (Dll) and eyespot size in B. anynana.

Beldade P ，Brakefield PM ，Long AD 《NATURE》

Developmental and genetic mechanisms for evolutionary diversification of serial repeats: eyespot size in Bicyclus anynana butterflies.

Serially repeated pattern elements on butterfly wings offer the opportunity for integrating genetic, developmental, and functional aspects towards understanding morphological diversification and the evolution of individuality. We use captive populations of Bicyclus anynana butterflies, an emerging model in evolutionary developmental biology, to explore the genetic and developmental basis of compartmentalized changes in eyespot patterns. There is much variation for different aspects of eyespot morphology, and knowledge about the genetic pathways and developmental processes involved in eyespot formation. Also, despite the strong correlations across all eyespots in one butterfly, B. anynana shows great potential for independent changes in the size of individual eyespots. It is, however, unclear to what extent the genetic and developmental processes underlying eyespot formation change in a localized manner to enable such individualization. We use micromanipulations of developing wings to dissect the contribution of different components of eyespot development to quantitative differences in eyespot size on one wing surface. Reciprocal transplants of presumptive eyespot foci between artificial selection lines and controls suggest that while localized antagonistic changes in eyespot size rely mostly on localized changes in focal signal strength, concerted changes depend greatly on epidermal response sensitivities. This potentially reflects differences between the signal-response components of eyespot formation in the degrees of compartmentalization and/or the temporal pattern of selection. We also report on the phenotypic analysis of a number of mutant stocks demonstrating how single alleles can affect different eyespots in concert or independently, and thus contribute to the individualization of serially repeated traits.

Beldade P ，French V ，Brakefield PM 《-》

Structure of a character and the evolution of butterfly eyespot patterns.

All butterfly eyespots appear to be formed by a similar developmental mechanism. Thus the great diversity of patterns observed across different species of butterfly has evolved through changes in the genetic modulation of this mechanism. Our descriptions of both the development of eyespots and the genetic variation for eyespot traits in an African butterfly, Bicyclus anynana, are used here to discuss the most appropriate ways of applying the character concept to the evolution of butterfly eyespot patterns. J. Exp. Zool. (Mol. Dev. Evol.) 291:93-104, 2001.

Brakefield PM 《-》

Development, plasticity and evolution of butterfly eyespot patterns.

The developmental and genetic bases for the formation, plasticity and diversity of eyespot patterns in butterflies are examined. Eyespot pattern mutants, regulatory gene expression, and transplants of the eyespot developmental organizer demonstrate that eyespot position, number, size and colour are determined progressively in a developmental pathway largely uncoupled from those regulating other wing-pattern elements and body structures. Species comparisons and selection experiments suggest that the evolution of eyespot patterns can occur rapidly through modulation of different stages of this pathway, and requires only single, or very few, changes in regulatory genes.

Brakefield PM ，Gates J ，Keys D ，Kesbeke F ，Wijngaarden PJ ，Monteiro A ，French V ，Carroll SB ... -  《NATURE》

Focus on butterfly eyespot development.

The beautiful eyespot patterns on the wings of butterflies help them to evade predators, but they also present biologists with a unique opportunity to investigate the reciprocal interactions of development and evolution.

Nijhout HF 《NATURE》