Exploring the diversification of a Neotropical songbird

Study highlights needs for extensive sampling while providing new perspective on the biogeography of the black-billed thrush

Data resources used via GBIF : 12,209 species occurrences
Turdus ignobilis
Black-billed thrush (Turdus ignobilis) by Christian Daniel Martinez Rodriguez via iNaturalist. Photo (levels adjusted slightly) licensed under CC BY-NC 4.0.

Studies describing biogeographic patterns and evolutionary processes require thorough geographic and taxonomic sampling, especially if drawing conclusions that affect classification. In the Neotropical region, answers to the most interesting evolutionary questions involve taxa with wide distributions reaching far beyond existing political boundaries.

The present study explores diversification of a common and widely distributed songbird, the black-billed thrush (Turdus ignobilis), found in northwestern South America. The authors describe the distribution of the species using a combination of GBIF-mediated occurrences and recordings of vocalizations from Xento-Canto, showing wider ranges than previously described across foothill and lowland areas east of the Andes.

Adding to the equation combined mitochondrial and nuclear gene sequencing of 76 individual birds including all named T. ignobilis subspecies, they restruct a phylogeny revealing novel biogeographic interplay between populations.

Based on these observations, the authors suggest a new taxonomic treatment recognizing two distinct biological species in the group, highlighting the importance of cross-border collaborations to obtain sufficient level of sampling neeeded for studies of Neotropical biogeography.

Avendaño JE, Arbeláez-Cortés E and Cadena CD (2017) On the importance of geographic and taxonomic sampling in phylogeography: A reevaluation of diversification and species limits in a Neotropical thrush (Aves, Turdidae). Molecular Phylogenetics and Evolution. Elsevier BV 111: 87–97. Available at: https://doi.org/10.1016/j.ympev.2017.03.020.