Meeting Abstract

16.5  Saturday, Jan. 4 11:15  Delineating ecological niches and their evolution from stable isotopes and museum specimens RADER, J. A.*; DILLON, M. E. ; MARTINEZ DEL RIO, C.; University of Wyoming; University of Wyoming; University of Wyoming rader@raderstudios.com

The niche is a fundamental concept in ecology, but is often difficult to operationalize and quantify. We used stable isotopes to explore the evolution of the ecological niche in 12 species of Cinclodes ovenbirds. We analyzed the carbon, nitrogen, hydrogen, and oxygen isotopic composition of feathers from 254 museum specimens. Carbon and nitrogen isotopes defined three conditions in isotopic space: reliance on marine resources, reliance on terrestrial resources and reliance on island resources subsidized by marine organisms. Hydrogen and oxygen were tightly correlated, and were negatively correlated with the elevation of the site at which specimens were collected. We used the area of the 95% confidence ellipse in either C/N or O/H space to assess the breadth of the isotopic niche in resource use and elevational range, respectively. Phylogenetically independent contrasts analyses showed that the evolution of niche breadth in C/N isotopic space was positively correlated with than in O/H space. Species that evolved broad elevational ranges seem to have evolved wide resource use as well. In general, broad isotopic niches were phylogenetically derived relative to narrow niches. The marine and island habits each evolved once, respectively, in the clade. Broad niches appear to have evolved twice in the genus, and concurrently with long halluces and relatively convex wings. The evolution of a marine habit was correlated with the evolution of concentrating kidneys. The well-resolved Cinclodes phylogeny and isotopic values with unambiguous interpretation made possible this first study characterizing the evolution of isotopic niches. Stable isotopes are a promising tool in the study of ecological niches and their evolution.