title: Molecular systematics of the new world screech-owls (Megascops: Aves, Strigidae): biogeographic and taxonomic implications.
abstract: Megascops screech-owls are endemic to the New World and range from southern Canada to the southern cone of South America. The 22 currently recognized Megascops species occupy a wide range of habitats and elevations, from desert to humid montane forest, and from sea level to the Andean tree line. Species and subspecies diagnoses of Megascops are notoriously difficult due to subtle plumage differences among taxa with frequent plumage polymorphism. Using three mitochondrial and three nuclear genes we estimated a phylogeny for all but one Megascops species. Phylogenies were estimated with Maximum Likelihood and Bayesian Inference, and a Bayesian chronogram was reconstructed to assess the spatio-temporal context of Megascops diversification. Megascops was paraphyletic in the recovered tree topologies if the Puerto Rican endemic M. nudipes is included in the genus. However, the remaining taxa are monophyletic and form three major clades: (1) M. choliba, M. koepckeae, M. albogularis, M. clarkii, and M. trichopsis; (2) M. petersoni, M. marshalli, M. hoyi, M. ingens, and M. colombianus; and (3) M. asio, M. kennicottii, M. cooperi, M. barbarus, M. sanctaecatarinae, M. roboratus, M. watsonii, M. atricapilla, M. guatemalae, and M. vermiculatus. Megascops watsonii is paraphyletic with some individuals more closely related to M. atricapilla than to other members in that polytypic species. Also, allopatric populations of some other Megascops species were highly divergent, with levels of genetic differentiation greater than between some recognized species-pairs. Diversification within the genus is hypothesized to have taken place during the last 8 million years, with a likely origin in Central America. The genus later expanded over much of the Americas and then diversified via multiple dispersal events from the Andes into the Neotropical lowlands.
authors.affiliation: Curso de Pós-graduação em Zoologia, Universidade Federal do Pará/Museu Paraense Emilio Goeldi, Av. Perimetral, 1901, 66077-530 Belém, PA, Brazil. Electronic address: smdantas@yahoo.com.
authors.forename: Sidnei M
authors.initials: SM
authors.lastname: Dantas
authors.affiliation: Integrative Research Center, Field Museum of Natural History, 1400 S Lake Shore Drive, Chicago, IL 60605, USA.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Weckstein
authors.affiliation: Integrative Research Center, Field Museum of Natural History, 1400 S Lake Shore Drive, Chicago, IL 60605, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Bates
authors.affiliation: Vertebrate Department of the Zoological Museum, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark.
authors.forename: Niels K
authors.initials: NK
authors.lastname: Krabbe
authors.affiliation: Departamento de Ciencias Biológicas, Universidad de los Andes, Cra 1 N˚ 18A-12, Bogotá, Colombia.
authors.forename: Carlos Daniel
authors.initials: CD
authors.lastname: Cadena
authors.affiliation: University of Kansas Biodiversity Research Institute, 1345 Jayhawk Boulevard, Lawrence, KS 66045, USA.
authors.forename: Mark B
authors.initials: MB
authors.lastname: Robbins
authors.affiliation: Departamento de Ciencias Biológicas, Universidad de los Andes, Cra 1 N˚ 18A-12, Bogotá, Colombia.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Valderrama
authors.affiliation: Coordenação de Zoologia, Museu Paraense Emílio Goeldi, Campus de Pesquisa. Av. Perimetral, 1901, 66077-530 Belém, PA, Brazil.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Aleixo
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D002170:Canada; D002489:Central America; D004272:DNA, Mitochondrial / Q000235:genetics*; D017753:Ecosystem; D014644:Genetic Variation; D016013:Likelihood Functions; D010802:Phylogeny; D013020:South America; D020305:Strigiformes / Q000145:classification* / Q000235:genetics
chemical_list: D004272:DNA, Mitochondrial
keywords: Amazonia; Ancestral area reconstruction; Andes; Central America; Diversification; Neotropics