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MOLECULAR SYSTEMATICS AND THE ROLE OF THE “VÁRZEA”–“TERRA-FIRME” ECOTONE IN THE DIVERSIFICATION OF XIPHORHYNCHUS WOODCREEPERS (AVES: DENDROCOLAPTIDAE)

[ "Department of Biological Sciences, and Museum of Natural Science, Louisiana State University, 119 Foster Hall, Baton Rouge, Louisiana 70803, USA"]; [ ""]
The Auk (Impact Factor: 2.4). 01/2009; DOI: 10.1642/0004-8038(2002)119[0621:MSATRO]2.0.CO;2

ABSTRACT Se reconstruyó la filogenia de todas las especies conocidas y de muchas de las subespecies de Xiphorhynchus (Dendrocolaptidae) para evaluar los límites de las especies en este género taxonómicamente complejo y para investigar el rol del ecotono entre “várzea” (bosque de inundación) y “terra-firme” (bosque de tierras altas) del Amazonas en su diversificación. Las filogenias fueron inferidas a partir de 2,430 pares de bases de los genes de ADN mitocondrial ND2, ND3 y citocromo b. Todas las estimaciones filogenéticas avalaron la monofilia de todas las especies vivientes de Xiphorhynchus, con excepción del par de especies hermanas X. picus y X. kienerii. Se encontró fuerte respaldo para incluir a Lepidocolaptes fuscus en Xiphorhynchus, confirmando estudios moleculares y anatómicos previos. Los niveles de divergencia en las secuencias entre algunas subespecies de X. guttatus, X. ocellatus y X. spixii alcanzaron o excedieron aquellos encontrados entre especies biológicas cercanamente emparentadas de Xiphorhynchus. Los altos niveles de diferenciación en las secuencias y la parafilia de algunas especies de Xiphorhynchus indicaron que los siguientes taxones deberían ser reconocidos como especies: X. guttatoides, X. chunchotambo y X. elegans. Todas las especies de Xiphorhynchus restringidas a las áreas de bosque de terra-firme de las tierras bajas del Amazonas formaron un grupo monofilético fuertemente respaldado, mientras que las especies restringidas a bosques de várzea aparecieron en la base del clado que contenía a aquellas encontradas en una amplia variedad de hábitats (X. obsoletus) o pertenecieron a un linaje separado que probablemente pueda ser considerado como un género separado (X. kienerii). Estos resultados falsifican la relación de hermandad esperada entre las especies de várzea y terra-firme que se esperaría si el ecotono de várzea y terra-firme hubiera jugado un rol importante en la diferenciación entre poblaciones y en la especiación de Xiphorhynchus. En cambio, las estimaciones filogenéticas sugirieron que la especialización de hábitat de várzea y terra-firme evolucionó temprano en la historia evolutiva de Xiphorhynchus y que las diferenciaciones subsecuentes ocurrieron principalmente en el hábitat de terra-firme.

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