@article{c820c48b74b34020b3c57c609cee183b,
title = "Phenotypic variation in Heliconius erato crosses shows that iridescent structural colour is sex-linked and controlled by multiple genes",
abstract = " Bright, highly reflective iridescent colours can be seen across nature and are produced by the scattering of light from nanostructures. Heliconius butterflies have been widely studied for their diversity and mimicry of wing colour patterns. Despite iridescence evolving multiple times in this genus, little is known about the genetic basis of the colour and the development of the structures which produce it. Heliconius erato can be found across Central and South America, but only races found in western Ecuador and Colombia have developed blue iridescent colour. Here, we use crosses between iridescent and non-iridescent races of H. erato to study phenotypic variation in the resulting F 2 generation. Using measurements of blue colour from photographs, we find that iridescent structural colour is a quantitative trait controlled by multiple genes, with strong evidence for loci on the Z sex chromosome. Iridescence is not linked to the Mendelian colour pattern locus that also segregates in these crosses (controlled by the gene cortex). Small-angle X-ray scattering data show that spacing between longitudinal ridges on the scales, which affects the intensity of the blue reflectance, also varies quantitatively in F 2 crosses. ",
author = "Brien, {Melanie N.} and Juan Enciso-Romero and Parnell, {Andrew J.} and Salazar, {Patricio A.} and Carlos Morochz and Darwin Chal{\'a} and Bainbridge, {Hannah E.} and Thomas Zinn and Curran, {Emma V.} and Nadeau, {Nicola J.}",
note = "Funding Information: Data accessibility. SAXS data (doi:10.15131/shef.data.6839315) and accompanying code (doi:10.15131/shef.data.6837905) have been uploaded to an online repository. Colour measurements, repeatability measurements and cross pedigree information can be found as part of the electronic supplementary material. Authors{\textquoteright} contributions. M.N.B. collected the colour data, performed the genetic analysis and wrote the manuscript. J.E.R. analysed the SAXS data under the supervision of A.J.P. A.J.P. coordinated collection of the SAXS data. The crosses were performed by P.A.S., C.M., D.C., M.N.B., N.J.N. and E.V.C. The SAXS data were collected by A.J.P., T.Z., E.V.C., N.J.N. and M.N.B. Wing size and red band measurements were performed by H.E.B. The study was devised and coordinated by N.J.N. All authors read and commented on the manuscript. Competing interests. We declare we have no competing interests. Funding. This work was funded by the UK Natural Environment Research Council (NERC) through an Independent Research Fellowship (NE/K008498/1) to N.J.N. M.N.B. and E.V.C. are funded by the NERC doctoral training partnership, ACCE. J.E.R. is funded through the Leverhulme Centre for Advanced Biological Modelling as well as scholarships from Universidad del Rosario and the University of Sheffield. Acknowledgements. We thank the governments of Ecuador and Panama for permission to collect butterflies. Thanks to Juan L{\'o}pez and Gab-riela Iraz{\'a}bal for their assistance with the crosses. We are grateful to the European Synchrotron Radiation Facility for provision of X-ray beamtime under proposal LS2720 and to Andrew Dennison for assistance with SAXS data collection. Publisher Copyright: {\textcopyright} 2018 The Author(s) Published by the Royal Society. All rights reserved. Copyright: Copyright 2019 Elsevier B.V., All rights reserved.",
year = "2019",
month = feb,
day = "6",
doi = "10.1098/rsfs.2018.0047",
language = "English (US)",
volume = "9",
journal = "Interface Focus",
issn = "2042-8898",
publisher = "Royal Society Publishing",
number = "1",
}