Introduction

Cinclodes fuscus is a widespread and common terrestrial species of ovenbird (Furnariidae) that breeds, primarily in and along the Andes, from Tierra del Fuego to northern Colombia and Venezuela (Remsen, 2003). C. fuscus has traditionally been considered a single species (Sclater, 1890; Cory & Hellmayr, 1925; Peters, 1951), and nine subspecies are currently recognized based on morphology (Remsen, 2003).

A recent molecular study on the systematics of the genus Cinclodes (Chesser, 2004) placed C. fuscus as sister species of C. antarcticus, a marine species from extreme southern Argentina and Chile. The two C. fuscus samples used in this study formed a monophyletic group. However, paraphyly has been reported in up to 16.7% of bird species (Funk and Omland, 2003), and both individuals in the previous study were from the nominate subspecies C. f. fuscus. The long and narrow range of C. fuscus may cause restricted gene flow among populations, which may promote differentiation and be reflected in the phylogeny of a more geographically diverse sample.

Here, we use sequences from two mitochondrial genes to infer relationships among individuals of C. fuscus, to address the following questions: (1) Does C. fuscus show substantial genetic variation across its range? (2) Do all C. fuscus individuals form a monophyletic group? (3) If so, do genetic breaks correspond to biogeographic barriers known to affect other Andean species? (4) If not, to what other species are the various groups of C. fuscus related?.

Materials and Methods

Tissue samples of 32 individuals of Cinclodes fuscus were obtained from six frozen tissue collections. DNA was isolated from these samples and two mitochondrial regions (ND3 and COII) were amplified by standard polymerase chain reaction (PCR), and then sequenced. Collaborators at Louisiana State University sequenced five samples that were included into our dataset for a total of 37 individuals. Maximum Parsimony (MP) and Maximum Likelihood (ML) analyses and MP bootstraps were performed, using PAUP *4.0 (Swofford, 2003), for all C. fuscus individuals, with C. pabsti as outgroup. In additiion, all unique haplotypes of C. fuscus were added to the Cinclodes dataset of Chesser (2004) and this combined dataset was analyzed using MP and MP bootstrap algorithms . The distances among and within the subsequently identified groups of individuals were calculated using the Maximum Composite Likelihood Model in MEGA 4.0 (Tamura, et al, 2007).

Results and Discussion

Complete sequences (1035 bp) where obtained for 37 individuals. The MP and ML analysis of these individuals consistently showed three distinct reciprocally monophyletic groups. Group 1 consisted of birds from Ecuador and northern Peru; Group 2 of birds from central-southern Peru, Bolivia and northwestern Argentina; and Group 3 of birds from central and southern Argentina and Chile. The genetic distances among these groups were an order of magnitude greater than the distances between individuals within each group.

Surprisingly, the three groups of C. fuscus formed well-supported clades with other Cinclodes species rather than with each other, when analyzed with sequences from all species in the genus. Paraphyly in this case could be due to imperfections in the taxonomy, where cryptic species are not recognized as such (Funk and Omland, 2003). This is clear for group 3; however a better resolved tree is needed to make any definite conclusion regarding groups 1 and 2. If groups 1 and 2 are in fact sister groups, then differentiation between these groups may be maintained by the geographical barrier of the north-Peruvian low.

We also found C. oustaleti to be paraphyletic in our analysis: two individuals of C. fuscus grouped with the two C. oustaleti from Chesser (2004). This pattern is consistent with incomplete lineage sorting or hybridization between the two species (Funk and Omland, 2003) Additional samples of C. oustaleti are needed to form a clearer idea of this relationship.

Acknowledgments

We thank the Research Training Program of the National Museum of Natural History and the Robert Fri Internship Endowment for their support of this project. The project received additional financial support from the National Museum of Natural History, Smithsonian Institution; we thank Hans Sues and Wendy Wiswall of the office of the ADRC and Richard Vari of the Department of Vertebrate Zoology for providing funding for the molecular labwork. We are grateful to Robert Fleischer for providing access to the laboratory facilities at the Genetics Lab of the National Zoological Park, Smithsonian Institution; and to Nancy Rotzel, Sarah Haas, Jesus Maldonado and Emily Latch for their assistance and advice in the laboratory. We thank the following for contributing tissue samples or sequences to this project: Darío Lijtmaer and Pablo Tubaro, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires; James Maley and Robb Brumfield, Museum of Natural Science, Louisiana State University, Baton Rouge; John Bates and David Willard, Field Museum of Natural History, Chicago; Sharon Birks, Burke Museum, University of Washington, Seattle; Nate Rice, Academy of Natural Sciences, Philadelphia. All the pictures in this poster are copyright by Arthur Grosset.

Literature Cited

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