Elsevier

Developmental Biology

Volume 395, Issue 2, 15 November 2014, Pages 367-378
Developmental Biology

Evolution of Developmental Control Mechanisms
Wnt signaling underlies evolution and development of the butterfly wing pattern symmetry systems

https://doi.org/10.1016/j.ydbio.2014.08.031Get rights and content
Under an Elsevier user license
open archive

Highlights

  • Many butterfly wing patterns are symmetrical and have linear organizing centers.

  • These “symmetry systems” are thought to underlie most wing pattern diversity.

  • Gene expression and pharmacology implicate Wnt signaling in symmetry systems.

  • Previous genetic mapping work further supports Wnt model.

  • Cross-species Wnt comparisons illustrate homologies of complex pattern elements.

Abstract

Most butterfly wing patterns are proposed to be derived from a set of conserved pattern elements known as symmetry systems. Symmetry systems are so-named because they are often associated with parallel color stripes mirrored around linear organizing centers that run between the anterior and posterior wing margins. Even though the symmetry systems are the most prominent and diverse wing pattern elements, their study has been confounded by a lack of knowledge regarding the molecular basis of their development, as well as the difficulty of drawing pattern homologies across species with highly derived wing patterns. Here we present the first molecular characterization of symmetry system development by showing that WntA expression is consistently associated with the major basal, discal, central, and external symmetry system patterns of nymphalid butterflies. Pharmacological manipulations of signaling gradients using heparin and dextran sulfate showed that pattern organizing centers correspond precisely with WntA, wingless, Wnt6, and Wnt10 expression patterns, thus suggesting a role for Wnt signaling in color pattern induction. Importantly, this model is supported by recent genetic and population genomic work identifying WntA as the causative locus underlying wing pattern variation within several butterfly species. By comparing the expression of WntA between nymphalid butterflies representing a range of prototypical symmetry systems, slightly deviated symmetry systems, and highly derived wing patterns, we were able to infer symmetry system homologies in several challenging cases. Our work illustrates how highly divergent morphologies can be derived from modifications to a common ground plan across both micro- and macro-evolutionary time scales.

Keywords

Wnt pathway
Nymphalid ground plan
Symmetry systems
Euphydryas
Junonia
Vanessa
Agraulis

Cited by (0)