title: Nymphalid eyespots are co-opted to novel wing locations following a similar pattern in independent lineages.
abstract: BACKGROUND
  Variation in the number of repeated traits, or serial homologs, has contributed greatly to animal body plan diversity. Eyespot color patterns of nymphalid butterflies, like arthropod and vertebrate limbs, are an example of serial homologs. These eyespot color patterns originated in a small number of wing sectors on the ventral hindwing surface and later appeared in novel wing sectors, novel wings, and novel wing surfaces. However, the details of how eyespots were co-opted to these novel wing locations are currently unknown.
  
  
  RESULTS
  We used a large data matrix of eyespot/presence absence data, previously assembled from photographs of contemporary species, to perform a phylogenetic investigation of eyespot origins in nine independent nymphalid lineages. To determine how the eyespot gene regulatory network acquired novel positional information, we used phylogenetic correlation analyses to test for non-independence in the origination of eyespots. We found consistent patterns of eyespot gene network redeployment in the nine lineages, where eyespots first redeployed from the ventral hindwing to the ventral forewing, then to new sectors within the ventral wing surface, and finally to the dorsal wing surface. Eyespots that appeared in novel wing sectors modified the positional information of their serial homolog ancestors in one of two ways: by changing the wing or surface identity while retaining sector identity, or by changing the sector identity while retaining wing and surface identity.
  
  
  CONCLUSIONS
  Eyespot redeployment to novel sectors, wings, and surfaces happened multiple times in different nymphalid subfamilies following a similar pattern. This indicates that parallel mutations altering expression of the eyespot gene regulatory network led to its co-option to novel wing locations over time.
authors.affiliation: Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State, MS, 39762, USA. schachatsr@si.edu.|Department of Paleobiology, Smithsonian Institution, Washington, DC, 20013, USA. schachatsr@si.edu.
authors.forename: Sandra R
authors.initials: SR
authors.lastname: Schachat
authors.affiliation: Department of Integrative Biology, Oregon State University, Corvallis, OR, 97331, USA. Jeffrey.Oliver@science.oregonstate.edu.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Oliver
authors.affiliation: Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT, 06520, USA. antonia.monteiro@nus.edu.sg.|Department of Biological Sciences, National University of Singapore, 117543, Singapore, Singapore. antonia.monteiro@nus.edu.sg.|Yale-NUS College, 138614, Singapore, Singapore. antonia.monteiro@nus.edu.sg.
authors.forename: Antónia
authors.initials: A
authors.lastname: Monteiro
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002080:Butterflies / Q000033:anatomy & histology* / Q000145:classification / Q000235:genetics*; D053263:Gene Regulatory Networks; D009154:Mutation; D010802:Phylogeny; D010858:Pigmentation; D014921:Wings, Animal / Q000033:anatomy & histology*