title: Molecular shifts in limb identity underlie development of feathered feet in two domestic avian species.
abstract: Birds display remarkable diversity in the distribution and morphology of scales and feathers on their feet, yet the genetic and developmental mechanisms governing this diversity remain unknown. Domestic pigeons have striking variation in foot feathering within a single species, providing a tractable model to investigate the molecular basis of skin appendage differences. We found that feathered feet in pigeons result from a partial transformation from hindlimb to forelimb identity mediated by cis-regulatory changes in the genes encoding the hindlimb-specific transcription factor Pitx1 and forelimb-specific transcription factor Tbx5. We also found that ectopic expression of Tbx5 is associated with foot feathers in chickens, suggesting similar molecular pathways underlie phenotypic convergence between these two species. These results show how changes in expression of regional patterning genes can generate localized changes in organ fate and morphology, and provide viable molecular mechanisms for diversity in hindlimb scale and feather distribution.
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, United States.
authors.forename: Eric T
authors.initials: ET
authors.lastname: Domyan
authors.affiliation: Department of Human Genetics, University of Utah, Salt Lake City, United States.
authors.forename: Zev
authors.initials: Z
authors.lastname: Kronenberg
authors.affiliation: Department of Genetics, University of Georgia, Athens, United States.
authors.forename: Carlos R
authors.initials: CR
authors.lastname: Infante
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, United States.
authors.forename: Anna I
authors.initials: AI
authors.lastname: Vickrey
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, United States.
authors.forename: Sydney A
authors.initials: SA
authors.lastname: Stringham
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, United States.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Bruders
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, United States.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Guernsey
authors.affiliation: Department of Genetics, University of Georgia, Athens, United States.
authors.forename: Sungdae
authors.initials: S
authors.lastname: Park
authors.affiliation: Poultry Science Department, University of Georgia, Athens, United States.
authors.forename: Jason
authors.initials: J
authors.lastname: Payne
authors.affiliation: Poultry Science Department, University of Georgia, Athens, United States.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Beckstead
authors.affiliation: Department of Human Genetics, University of Utah, Salt Lake City, United States.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Kardon
authors.affiliation: Department of Genetics, University of Georgia, Athens, United States.
authors.forename: Douglas B
authors.identifier: http://orcid.org/0000-0002-7109-1451
authors.initials: DB
authors.lastname: Menke
authors.affiliation: Department of Human Genetics, University of Utah, Salt Lake City, United States.|Utah Center for Genetic Discovery, University of Utah, Salt Lake City, United States.
authors.forename: Mark
authors.initials: M
authors.lastname: Yandell
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, United States.
authors.forename: Michael D
authors.identifier: http://orcid.org/0000-0003-2900-4331
authors.initials: MD
authors.lastname: Shapiro
mesh_terms: D000818:Animals; D002645:Chickens / Q000033:anatomy & histology* / Q000235:genetics; D010856:Columbidae / Q000033:anatomy & histology* / Q000235:genetics; D005241:Feathers; D005552:Forelimb / Q000033:anatomy & histology*; D005786:Gene Expression Regulation; D006614:Hindlimb / Q000033:anatomy & histology*; D014157:Transcription Factors / Q000235:genetics
chemical_list: D014157:Transcription Factors
keywords: chicken; developmental biology; dinosaur; evolutionary biology; feathers; genomics; limb; pigeon; pitx1; stem cells; tbx5