[HELICONIUS] Recent papers of interest

[James Mallet]

Martin A, Papa R, Nadeau NJ, Hill RI, Counterman BA, Halder G, Jiggins 
CD, Kronforst MR, Long AD, McMillan WO, Reed RD. 2012. Diversification 
of complex butterfly wing patterns by repeated regulatory evolution of a 
Wnt ligand. Proceedings of the National Academy of Sciences, USA 109: 
12632-12637.
(request from individual labs)
Abstract: Although animals display a rich variety of shapes and 
patterns, the genetic changes that explain how complex forms arise are 
still unclear. Here we take advantage of the extensive diversity of 
Heliconius butterflies to identify a gene that causes adaptive variation 
of black wing patterns within and between species. Linkage mapping in 
two species groups, gene-expression analysis in seven species, and 
pharmacological treatments all indicate that cis-regulatory evolution of 
the WntA ligand underpins discrete changes in color pattern features 
across the Heliconius genus. These results illustrate how the direct 
modulation of morphogen sources can generate a wide array of unique 
morphologies, thus providing a link between natural genetic variation, 
pattern formation, and adaptation.

Hines HM, Papa R, Ruiz M, Papanicolau A, Wang C, Nijhout HF, McMillan 
WO, Reed RD. 2012. Transcriptome analysis reveals novel patterning and 
pigmentation genes underlying Heliconius butterfly wing pattern 
variation. BMC Genomics 13: 288.
http://www.biomedcentral.com/1471-2164/13/288/abstract
Background
Heliconius butterfly wing pattern diversity offers a unique opportunity 
to investigate how natural genetic variation can drive the evolution of 
complex adaptive phenotypes. Positional cloning and candidate gene 
studies have identified a handful of regulatory and pigmentation genes 
implicated in Heliconius wing pattern variation, but little is known 
about the greater developmental networks within which these genes 
interact to pattern a wing. Here we took a large-scale transcriptomic 
approach to identify the network of genes involved in Heliconius wing 
pattern development and variation. This included applying over 140 
transcriptome microarrays to assay gene expression in dissected wing 
pattern elements across a range of developmental stages and wing pattern 
morphs of Heliconius erato.
Results
We identified a number of putative early prepattern genes with 
color-pattern related expression domains. We also identified 51 genes 
differentially expressed in association with natural color pattern 
variation. Of these, the previously identified color pattern "switch 
gene" optix was recovered as the first transcript to show color-specific 
differential expression. Most differentially expressed genes were 
transcribed late in pupal development and have roles in cuticle 
formation or pigment synthesis. These include previously undescribed 
transporter genes associated with ommochrome pigmentation. Furthermore, 
we observed upregulation of melanin-repressing genes such as ebony and 
Dat1 in non-melanic patterns.
Conclusions
This study identifies many new genes implicated in butterfly wing 
pattern development and provides a glimpse into the number and types of 
genes affected by variation in genes that drive color pattern evolution.

-- 
James Mallet
OEB & GEE Depts
Harvard University & University College London
Cambridge, MA 02138 and LONDON WC1E 6BT
USA tel: +(1)617-496-5350
www.ucl.ac.uk/taxome/jim