Hidden endemism, deep polyphyly, and repeated dispersal across the Isthmus of Tehuantepec: Diversification of the White‐collared Seedeater complex (Thraupidae: Sporophila torqueola). Issue 3 (12th January 2018)

• Record Type: Journal Article
• Authors: Mason, Nicholas A.; Olvera‐Vital, Arturo; Lovette, Irby J.; Navarro‐Sigüenza, Adolfo G.
• Is Part Of: Ecology and evolution. Volume 8:Issue 3(2018)
• Page Start: 1867
• Page End: 1881
• Publication Date: 2018-01-12
• Subjects: bird -- endemism -- Mesoamerica -- phylogeography -- taxonomy; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.3799
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Phenotypic and genetic variation are present in all species, but lineages differ in how variation is partitioned among populations. Examining phenotypic clustering and genetic structure within a phylogeographic framework can clarify which biological processes have contributed to extant biodiversity in a given lineage. Here, we investigate genetic and phenotypic variation among populations and subspecies within a Neotropical songbird complex, the White‐collared Seedeater ( Sporophila torqueola ) of Central America and Mexico. We combine measurements of morphology and plumage patterning with thousands of nuclear loci derived from ultraconserved elements (UCEs) and mitochondrial DNA to evaluate population differentiation. We find deep levels of molecular divergence between two S. torqueola lineages that are phenotypically diagnosable: One corresponds to S. t. torqueola along the Pacific coast of Mexico, and the other includes S. t. morelleti and S. t. sharpei from the Gulf Coast of Mexico and Central America. Surprisingly, these two lineages are strongly differentiated in both nuclear and mitochondrial markers, and each is more closely related to other Sporophila species than to one another. We infer low levels of gene flow between these two groups based on demographic models, suggesting multiple independent evolutionary lineages within S. torqueola have been obscured by coarse‐scale similarity in plumage patterning. These findings improve our understanding of the biogeographic history of this lineage, which includes multiple dispersal events out of South America and across the Isthmus of Tehuantepec into Mesoamerica. Finally, the phenotypic and genetic distinctiveness of the range‐restricted S. t. torqueola highlights the Pacific Coast of Mexico as an important region of endemism and conservation priority. Abstract : We examined phenotypic and genomic differentiation within a widespread Neotropical songbird. We found deep molecular divergence between two subspecies groups: One restricted to western Mexico, and the other in eastern Mexico and Central America. We find that these two lineages are not sister species, suggesting a revised biogeographic history of repeated dispersal out of South America and hidden endemism in western Mexico.