DOI: 10.5061/dryad.dfn2z34zn
title: Data from: Extensive hybridization between two Andean warbler species with shallow divergence in mtDNA

description: Studying processes acting on differentiated populations upon secondary
 contact, such as hybridization, is important to comprehensively understand
 how species are formed and maintained over time. However, avian speciation
 studies in the tropical Andes have largely focused on the role of
 topographic and ecological barriers promoting divergence in allopatry,
 seldom examining hybridization and introgression. We describe a hybrid
 zone involving 2 closely related Andean warblers (Parulidae), the
 Golden-fronted Redstart (Myioborus ornatus) and the Spectacled Redstart
 (Myioborus melanocephalus). Geographic ranges of these species abut near
 the Colombia-Ecuador border and many specimens from the region exhibit
 intermediate phenotypes, but a formal description of phenotypic variation
 in the contact zone were heretofore lacking. We collected specimens across
 a transect encompassing the area where ranges abut and areas where only
 “pure” parental phenotypes of M. ornatus chrysops and M. melanocephalus
 ruficoronatus occur. We described variation in plumage traits including
 patterns of head and ventral coloration and tail markings based on 321
 specimens. To describe genetic variation in the contact zone and over a
 broader phylogeographic context, we used sequences of the mitochondrial
 ND2 gene for 219 individuals across the transect and the entire range of
 both species, including all subspecies, from Venezuela to Bolivia. We
 documented a hybrid zone ~200 km wide based on head coloration, where
 intermediate plumage phenotypes are most common and “pure” forms do not
 overlap geographically, consistent with extensive hybridization. Across
 the range of the M. ornatus–M. melanocephalus complex, mitochondrial
 genetic structure was shallow, with genetic breaks only coinciding clearly
 with one topographic feature. Such low genetic structure is striking given
 the high diversity in plumage phenotypes and current taxonomy of the
 group. Our phenotypic data suggest that barriers to hybridization are not
 strong, and allow us to postulate hypotheses to be tested using
 forthcoming genomic data.
description: The dataset was collected from museum specimens collected in our
 study and previously available in museum collections. Specimen information
 is on Supplementary Table 1 and Supplementary Table 2.
 The head coloration data was obtained by using the scoring system
 described in the Table 1 of the paper. Was entered on Excel, and then
 processed on R. The data table included here was exported from
 R. The underpart coloration data was obtained by using
 a reflectance spectrometer. Then, the colorimetric variables were
 calculated on R, using functions implemented in the package
 <i>pavo</i>. The data table included here was exported from
 R. The tail coloration data was entered on Excel and
 then processed in R. Data table included here was exported from
 R.
description: - Additional specimen information is also available in
 Supplementary Table 1 and Supplementary Table 3. - In
 all cases, “NA” refer to missing data. - All data
 tables are in a tab delimited format (.txt) and can be directly imported
 in R without previous modifications. - Detailed
 explanation of all data tables included in the repository is in the readme
 file.