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Chapter 12: Ecogeographic Variation in Cinnamon Teal (Anas Cyanoptera) Along Elevational and Latitudinal Gradients - Variación Ecogeográfica en Anas cyanoptera en Gradientes de Altitud y Latitud
Robert E. Wilson, Thomas H. Valqui and Kevin G. McCracken
Vol. 67, No. 1 (April 2010), pp. 141-161
Published by: American Ornithological Society
Stable URL: http://www.jstor.org/stable/10.1525/om.2010.67.1.141
Page Count: 21
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Abstract The Cinnamon Teal (Anas cyanoptera) comprises five subspecies that inhabit a variety of habitats along an elevational gradient at temperate and tropical latitudes. North American and South American subspecies differ in their migratory behavior, which may have contributed to differences in body size. We measured body size of the five recognized subspecies (A. c. cyanoptera, A. c. orinomus, A. c. borreroi, A. c. tropica, and A. c. septentrionalium) throughout their ranges and evaluated morphometric differentiation in relation to Bergmann's rule. Subspecies and geographic regions differed significantly, with the largest subspecies and the largest individuals found at high elevations in the central Andes (A. c. orinomus) and at high latitudes in southern Patagonia (A. c. cyanoptera). Smaller-bodied individuals (A. c. cyanoptera) were found at the northern and southern limits of the Altiplano, where intermixing between subspecies with different body sizes might occur. However, there is no direct evidence of A. c. cyanoptera breeding at high elevations (>3,500 m). In contrast to patterns within South America, the migratory subspecies in North America (A. c. septentrionalium) showed few significant correlations with elevation and no relationship between latitude and body size. Morphological diversity within Cinnamon Teal appears to have arisen from spatial and temporal heterogeneity in selection pressures resulting in adaptations to their local environments.
Ornithological Monographs © 2010 American Ornithologists' Union