Down Feather Structure Varies Between High And Low Elevation Male Andean Torrent Ducks (Merganetta armata)

Cheek, R. G.; Alza, L.

doi:10.1101/207555

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bioRxiv · 10.1101/207555

Down Feather Structure Varies Between High And Low Elevation Male Andean Torrent Ducks (Merganetta armata)

Cheek, R. G.·Alza, L.

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Abstract

Feathers are one of the defining characteristics of birds and serve a critical role in thermal insulation and physical protection against the environment. Feather structure is known to vary among individuals, and it has been suggested that populations exposed to different environmental conditions may exhibit different patterns in feather structure. We examined both down and contour feathers from two populations of male Torrent Ducks (Merganetta armata) from Lima, Peru, including one high-altitude population from the Chancay-Huaral River at approximately 3500 meters (m) elevation and one low-altitude population from the Chillon River at approximately 1500 m. Down feather structure differed significantly between the two populations. Ducks from the high-altitude population had longer, denser down compared with low-altitude individuals. Contour feather structure varied greatly among individuals but showed no significant difference between populations. These results suggest that the innermost, insulative layer of plumage (the down), may have developed in response to lower ambient temperatures at high elevations. The lack of observable differences in the contour feathers may be due to the general constraints of the waterproofing capability of this outer plumage layer.\n\nResumenEl plumaje es una caracteristica que define a las aves y cumple roles criticos en el aislamiento termico y proteccion fisica del ambiente. Se sabe que la estructura de las plumas varia ente individuos, y se ha sugerido que poblaciones expuestas a diferentes condiciones ambientales pueden exhibir diferentes patrones en la estructura de las plumas. En este estudio se examinaron tanto el plumon como las plumas de contorno de machos adultos del Pato de los Torrentes (Merganetta armata) de dos poblaciones, una en el rio Chancay-Huaral a 3,500 msnm y otra en el rio Chillon a 1,500 msnm, ubicadas en Lima, Peru. La estructura de los plumones difiere significativamente entre las dos poblaciones. Los patos de la poblacion a grandes elevaciones tienen plumones largos, y densos comparados con los individuos de las partes bajas. La estructura de las plumas de contorno varia ampliamente entre individuos pero no muestra diferencias significativas entre poblaciones. Estos resultados sugieren que las diferencias entre las capas interiores de aislamiento del plumaje (plumon), haberse desarrollado como respuesta en ambientes de bajas temperaturas a grandes elevaciones. En cambio la falta de detectables diferencias en las plumas de contorno puede ser debido a la constante seleccion en la capacidad impermeable de la capa de plumas exteriores.

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Cheek, R. G., Alza, L.. 2017-10-23. Down Feather Structure Varies Between High And Low Elevation Male Andean Torrent Ducks (Merganetta armata). https://doi.org/10.1101/207555

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