White Rose University Consortium logo
University of Leeds logo University of Sheffield logo York University logo

The genetics and evolution of iridescent structural colour in Heliconius butterflies

Brien, Melanie N. (2019) The genetics and evolution of iridescent structural colour in Heliconius butterflies. PhD thesis, University of Sheffield.

[img]
Preview
Text
THESIS_MNB.pdf
Available under License Creative Commons Attribution-Noncommercial-No Derivative Works 2.0 UK: England & Wales.

Download (6Mb) | Preview

Abstract

The study of colouration has been essential in developing key concepts in evolutionary biology. The Heliconius butterflies are well-studied for their diverse aposematic and mimetic colour patterns, and these pigment colour patterns are largely controlled by a small number of homologous genes. Some Heliconius species also produce bright, highly reflective structural colours, but unlike pigment colour, little is known about the genetic basis of structural colouration in any species. In this thesis, I aim to explore the genetic basis of iridescent structural colour in two mimetic species, and investigate its adaptive function. Using experimental crosses between iridescent and non-iridescent subspecies of Heliconius erato and Heliconius melpomene, I show that iridescent colour is a quantitative trait by measuring colour variation in offspring. I then use a Quantitative Trait Locus (QTL) mapping approach to identify loci controlling the trait in the co-mimics, finding that the genetic basis is not the same in the two species. In H. erato, the colour is strongly sex-linked, while in H. melpomene, we find a large effect locus on chromosome 3, plus a number of putative small effect loci in each species. Therefore, iridescence in Heliconius is not an example of repeated gene reuse. I then show that both iridescent colour and pigment colour are sexually dimorphic in H. erato and H. sara, pointing to differing selection pressures on the sexes. Structural colour, and to a lesser extent pigment colour, are condition dependent, suggesting the trait could be used as a signal of condition in mate choice. Together this work provides an understanding of the evolution of structural colour in Heliconius, in terms of its genetic control and its function as a signal and mimetic warning pattern.

Item Type: Thesis (PhD)
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > Animal and Plant Sciences (Sheffield)
Identification Number/EthosID: uk.bl.ethos.798098
Depositing User: Melanie Brien
Date Deposited: 11 Feb 2020 10:28
Last Modified: 01 Mar 2020 10:53
URI: http://etheses.whiterose.ac.uk/id/eprint/25794

You do not need to contact us to get a copy of this thesis. Please use the 'Download' link(s) above to get a copy.
You can contact us about this thesis. If you need to make a general enquiry, please see the Contact us page.

Actions (repository staff only: login required)