Data from: Divergence in vocalizations indicates cryptic speciation in Camptostoma tyrannulets

The tyrant flycatcher genus Camptostoma currently comprises two visually
similar species: the Northern Beardless-Tyrannulet (C. imberbe), ranging
from the southern United States to Costa Rica, and the Southern
Beardless-Tyrannulet (C. obsoletum), found from Costa Rica to Uruguay.
Vocal and genetic differences suggest that the Southern
Beardless-Tyrannulet may include multiple species, but no analysis of
acoustic trait variation has been conducted within the genus. We analyzed
a geographically comprehensive sample of sound recordings to measure
geographic variation in vocalizations across the genus, testing the
hypothesis that the Southern Beardless-Tyrannulet includes multiple
species. We find that Camptostoma comprises eight vocally distinct
populations, two within the Northern and six within the Southern
Beardless-Tyrannulet. These populations exhibit diagnostic differences in
multiple different vocalizations, including vocalization types that are
typically species-specific in the Tyrannidae. Their range limits and
contact zones largely corresponded with known dispersal barriers,
ecotones, and suture zones, with little evidence of gene flow between
adjacent populations. Our results strongly suggest that Camptostoma
comprises as many as eight vocally distinct biological species,
underscoring the underestimated diversity of species in birds with
conservative plumage evolution.

坎普霸鹟属（Camptostoma）目前包含两个形态相似的物种：北方无须霸鹟（C. imberbe），分布范围从美国南部至哥斯达黎加；以及南方无须霸鹟（C. obsoletum），见于哥斯达黎加至乌拉圭。鸣声与遗传差异表明，南方无须霸鹟可能包含多个物种，但此前尚未对该属内的声学特征变异展开分析。我们通过分析地理覆盖全面的录音样本，测量了整个属鸣声的地理变异，以验证南方无须霸鹟包含多个物种的假设。结果显示，坎普霸鹟属包含8个鸣声独特的种群，其中北方无须霸鹟内有2个，南方无须霸鹟内有6个。这些种群在多种鸣声特征上存在鉴别性差异，包括霸鹟科（Tyrannidae）中通常具有物种特异性的鸣声类型。它们的分布范围边界与接触带大致对应已知的扩散屏障、生态交错带及缝合带，且相邻种群间几乎无基因流的证据。我们的结果强烈表明，坎普霸鹟属包含多达8个鸣声独特的生物种，凸显了羽色演化保守的鸟类中被低估的物种多样性。