Summary of subspecies and their clades based on [21].

<p>Birds from western Colombia are presumed to be within the Chocó clade pending further evidence.</p

Summary of vocal traits for three populations of WBWWs.

<p>Vocal trait values are presented as mean +/- standard deviation.</p

Percent of individuals approaching the speaker in each experiment.

<p>Responses to the Amazon experiment are on the left and responses to the Chocó experiment are on the right. Note that sympatric trials serve as positive controls (wrens approached the speaker in all sympatric trials).</p

Spectrograms showing representative song phrases from White-breasted Wood-Wren populations.

<p>(A) Central American (Costa Rica, ML3922); (B) Amazon (ML46962); and (C) Chocó (XC17276).</p

Range map of the White-breasted Wood-Wren.

<p>This map illustrates the distributions of four deeply divergent mitochondrial clades (A = Central American, B = Darién, C = Chocó, D = Amazon; the precise distribution of the Darién clade is unknown and marked in dashed lines). The location of La Selva Biological Station in the Caribbean lowlands of Costa Rica, where fieldwork for this study was completed, is marked by a star. Map from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0144949#pone.0144949.ref023" target="_blank">23</a>].</p

Loading scores for the first two principal components (PC1 and PC2, which explained 47% and 19% of variation, respectively) from the vocal trait analysis.

<p>Loading scores for the first two principal components (PC1 and PC2, which explained 47% and 19% of variation, respectively) from the vocal trait analysis.</p

Behavioral response to playback experiments.

<p>Responses to the Amazon experiment are on the left and responses to the Chocó experiment are on the right. Latency to approach (A), closest approach to speaker (B), total number of songs (C) and latency to vocalize (D). Boxplots illustrate median (horizontal black bar), first and third quartiles (boxes), and minimum and maximum values (points and dotted lines). Raw data are plotted as points in front of the boxplots, with points offset slightly to better display values. Sympatric treatments elicited aggressive responses (fast approaches, close approaches, many songs, low latency to vocalize) in both experiments. Allopatric treatments elicited asymmetric responses: individuals typically responded aggressively to playback of Chocó songs but not to playback of Amazonian songs.</p

PCA plot of acoustic space.

<p>Larger values on PC1 represent songs that are longer, that have more notes (that are shorter) and that cover a wider range of frequencies. Larger values on PC2 represent songs with faster note rates and smaller frequency ranges. Populations, shown in yellow (Costa Rica), red (Amazon) and blue (Chocó), are somewhat differentiated in acoustic space.</p