title: Isotopic niches support the resource breadth hypothesis.
abstract: Because a broad spectrum of resource use allows species to persist in a wide range of habitat types, and thus permits them to occupy large geographical areas, and because broadly distributed species have access to more diverse resource bases, the resource breadth hypothesis posits that the diversity of resources used by organisms should be positively related with the extent of their geographic ranges. We investigated isotopic niche width in a small radiation of South American birds in the genus Cinclodes. We analysed feathers of 12 species of Cinclodes to test the isotopic version of the resource breadth hypothesis and to examine the correlation between isotopic niche breadth and morphology. We found a positive correlation between the widths of hydrogen and oxygen isotopic niches (which estimate breadth of elevational range) and widths of the carbon and nitrogen isotopic niches (which estimates the diversity of resources consumed, and hence of habitats used). We also found a positive correlation between broad isotopic niches and wing morphology. Our study not only supports the resource breadth hypothesis but it also highlights the usefulness of stable isotope analyses as tools in the exploration of ecological niches. It is an example of a macroecological application of stable isotopes. It also illustrates the importance of scientific collections in ecological studies.
authors.affiliation: Department of Zoology and Physiology, University of Wyoming, Laramie, WY, 82071, USA.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Rader
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA.
authors.forename: Seth D
authors.initials: SD
authors.lastname: Newsome
authors.affiliation: Departamento de Ciencias Ecologicas, Universidad de Chile, Santiago, Chile.|Center of Applied Ecology and Sustainability (CAPES), Santiago, Chile.
authors.forename: Pablo
authors.initials: P
authors.lastname: Sabat
authors.affiliation: USGS Patuxent Wildlife Research Center, National Museum of Natural History, Smithsonian Institution, Washington, DC, 20013, USA.
authors.forename: R Terry
authors.initials: RT
authors.lastname: Chesser
authors.affiliation: Department of Zoology and Physiology, University of Wyoming, Laramie, WY, 82071, USA.|Program in Ecology, University of Wyoming, Laramie, WY, 82071, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Dillon
authors.affiliation: Department of Zoology and Physiology, University of Wyoming, Laramie, WY, 82071, USA.|Program in Ecology, University of Wyoming, Laramie, WY, 82071, USA.|Biodiversity Institute, University of Wyoming, Laramie, WY, 82071, USA.
authors.forename: Carlos
authors.initials: C
authors.lastname: Martínez Del Rio
mesh_terms: D000818:Animals; D002247:Carbon Isotopes / Q000032:analysis; D003903:Deuterium / Q000032:analysis; D017753:Ecosystem; D005241:Feathers / Q000737:chemistry; D046109:Passeriformes / Q000033:anatomy & histology* / Q000502:physiology*; D013020:South America
chemical_list: D002247:Carbon Isotopes; D003903:Deuterium
keywords: 
  Cinclodes
  ; Furnariidae; isotopic niche; niche evolution; resource breadth hypothesis; stable isotope analysis