https://orcid.org/0000-0002-5583-3902
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Rafael Dantas Lima, Ruan Vieira Vaz, Divergence in vocalizations indicates cryptic speciation in Camptostoma tyrannulets, Ornithology, 2024;, ukae058, https://doi.org/10.1093/ornithology/ukae058
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ABSTRACT
The tyrant flycatcher genus Camptostoma currently comprises 2 visually similar species: C. imberbe (Northern Beardless-Tyrannulet), ranging from the southern United States to Costa Rica, and C. obsoletum (Southern Beardless-Tyrannulet), found from Costa Rica to Uruguay. Vocal and genetic differences have suggested that C. obsoletum 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 C. obsoletum includes multiple species. We find that Camptostoma comprises 8 vocally distinct populations, 2 within C. imberbe and 6 within C. obsoletum. 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 correspond 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 8 vocally distinct biological species, underscoring the underestimated diversity of species in birds with conservative plumage evolution.
RESUMEN
El género de atrapamoscas tiranos Camptostoma actualmente comprende dos especies visualmente similares: C. imberbe, que se encuentra desde el sur de los Estados Unidos hasta Costa Rica, y C. obsoletum, que se distribuye desde Costa Rica hasta Uruguay. Diferencias vocales y genéticas sugieren que C. obsoletum podría incluir múltiples especies, pero no se ha realizado un análisis de variación de rasgos acústicos dentro del género. Analizamos una muestra geográficamente completa de grabaciones de sonido para medir la variación geográfica en las vocalizaciones del género, poniendo a prueba la hipótesis de que C. obsoletum incluye múltiples especies. Encontramos que Camptostoma comprende 8 poblaciones vocalmente distintas, 2 dentro de C. imberbe y 6 dentro de C. obsoletum. Estas poblaciones presentan diferencias diagnósticas en varias vocalizaciones, incluidos tipos de vocalización que son típicamente específicos de especies en la familia Tyrannidae. Sus límites de distribución y las zonas de contacto correspondieron en gran medida con barreras de dispersión conocidas, ecotonos y zonas de sutura, con poca evidencia de flujo génico entre poblaciones adyacentes. Nuestros resultados sugieren fuertemente que Camptostoma comprende hasta 8 especies biológicas vocalmente distintas, subrayando la diversidad subestimada de especies en aves con una evolución conservadora del plumaje.
Lay Summary
• The avian genus Camptostoma is currently classified into 2 widespread species, but fragmentary vocal and genetic evidence suggests it may include more.
• Analysis of acoustic trait variation reveals 8 vocally distinct Camptostoma populations with abutting geographic ranges and limited gene flow.
• Significant differences in vocalizations suggest that Camptostoma comprises as many as 8 biological species.
