Forewing color pattern in Micropterigidae (Insecta: Lepidoptera): homologies between contrast boundaries, and a revised hypothesis for the origin of symmetry systems

Sandra R Schachat,Richard L Brown

doi:10.1186/s12862-016-0687-z

Sandra R Schachat, Richard L Brown

Open Access

https://doi.org/10.1186/s12862-016-0687-z

Copy DOI

Abstract

BackgroundDespite the great importance of lepidopteran wing patterns in various biological disciplines, homologies between wing pattern elements in different moth and butterfly lineages are still not understood. Among other reasons, this may be due to an incomplete understanding of the relationship between color pattern and wing venation; many individual wing pattern elements have a known relationship with venation, but a framework to unite all wing pattern elements with venation is lacking. Though plesiomorphic wing veins are known to influence color patterning even when not expressed in the adult wing, most studies of wing pattern evolution have focused on derived taxa with a reduced suite of wing veins.ResultsThe present study aims to address this gap through an examination of Micropterigidae, a very early-diverged moth family in which all known plesiomorphic lepidopteran veins are expressed in the adult wing. The relationship between wing pattern and venation was examined in 66 species belonging to 9 genera. The relationship between venation and pattern element location, predicted based on moths in the family Tortricidae, holds for Sabatinca just as it does for Micropterix. However, the pattern elements that are lightly colored in Micropterix are dark in Sabatinca, and vice-versa. When plotted onto a hypothetical nymphalid wing in accordance with the relationship between pattern and venation discussed here, the wing pattern of Sabatinca doroxena very closely resembles the nymphalid groundplan.ConclusionsThe color difference in pattern elements between Micropterix and Sabatinca indicates that homologies exist among the contrast boundaries that divide wing pattern elements, and that color itself is not a reliable indicator of homology. The similarity between the wing pattern of Sabatinca doroxena and the nymphalid groundplan suggests that the nymphalid groundplan may have originated from a Sabatinca-like wing pattern subjected to changes in wing shape and reduced expression of venation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0687-z) contains supplementary material, which is available to authorized users.

Highlights

Despite the great importance of lepidopteran wing patterns in various biological disciplines, homologies between wing pattern elements in different moth and butterfly lineages are still not understood
Because micropterigid and nymphalid wings are so different in size, shape, and venation, the wing pattern of Sabatinca doroxena could be projected onto a nymphalid wing in any number of ways
In Sabatinca doroxena, the basal half of the nearly-split band that straddles the humeral vein is comprised of a single color, the apical half is bisected by a lighter color, and one more band – again, bisected by a lighter color – reaches the margin of the wing basal to the terminal branch of the subcostal vein

Summary

Introduction

Despite the great importance of lepidopteran wing patterns in various biological disciplines, homologies between wing pattern elements in different moth and butterfly lineages are still not understood. A disproportionate number of studies of Lepidoptera – such as those cited far – have focused on butterflies; the evolutionary history of wing pattern in microlepidoptera is still poorly known. A recent examination of wing pattern in Micropterix, another genus within the Micropterigidae, showed a consistent relationship between wing venation and color pattern [12] This relationship with wing venation has the potential to facilitate comparisons of wing pattern in various lepidopteran lineages, as homologies among wing veins are far better understood

Methods

Results

Discussion

Conclusion