Amazonian speciation in a ring: Phylogeographic history of the Channel-billed and White-throated toucans
JENNIE LEE
Junior Biological Sciences major at The University of Chicago
REU Mentors: Dr. John Bates (Curator, Zoology, Birds) and Dr. Jason Weckstein (Staff Scientist, Zoology, Birds)
Symposium Presentation Title: Amazonian Speciation in a Ring: Phylogeographic History of the Channel-billed and White-throated Toucans
Symposium Presentation Abstract: Toucans are among the most prominent symbols of New World tropical forests and have attracted the attention of biologists for centuries, notably for their gaudy plumage coloration patterns and large bills. The Amazonian Ramphastos toucan species are a particularly interesting system for several reasons. First, throughout Amazonia two species of Ramphastos, one in the smaller-bodied Channel-billed Toucan complex (Ramphastos vitellinus) and the other in the larger-bodied White-throated Toucan complex (Ramphastos tucanus), overlap in geographic range. Second, each of these toucan species complexes includes multiple morphologically differentiated subspecies, and these subspecies hybridize to produce populations bearing intermediate or novel coloration patterns. This study focuses on uncovering the patterns of introgression (movement of different classes of genes between these differentiated populations) across these two overlapping hybrid zones. Using standard laboratory techniques and tissue samples from specimens obtained from toucan populations across the Amazon, I collected sequence data from two mitochondrial loci, cytochrome-b (cyt-b) and cytochrome oxidase I (COI) to reconstruct patterns of phylogeographic history. Phylogeographic analyses were performed on the resulting nucleotide alignments with the goal of comparing and contrasting patterns of hybridization and introgression in these two co-distributed toucan species. Future work in this system will include nuclear loci to form a more complete picture of gene flow and hybridization in these species complexes across evolutionary time.
Original Project Description: Toucans are among the most prominent symbols of New World tropical forests and have attracted the attention of biologists for centuries. They are particularly well known for their gaudy plumage coloration patterns and large bills. Several conspicuous characteristics make the Amazonian Ramphastos toucan species particularly interesting. First, at all localities in Amazonia two species of Ramphastos are found, and one is from the smaller-bodied Channel-billed Toucan complex (Ramphastos vitellinus) and the other is from the larger bodied White-throated Toucan complex (Ramphastos tucanus). Second, each of these toucan species complexes include multiple morphologically differentiated subspecies and these subspecies hybridize producing populations with novel or intermediate coloration patterns. We are using DNA sequence data (both mitochondrial and nuclear DNA) to study patterns of introgression (movement of different classes of genes between these differentiated populations) across these two overlapping hybrid zones to understand whether both species complexes show similar patterns of gene flow and hybridization. The central question of this work is whether similar evolutionary events have affected patterns of hybridization and introgression in these two co-distributed toucan species. We will use specimens collected from toucan populations across the Amazon and standard laboratory techniques to collect DNA sequence data for this study.
Research methods and techniques: The intern on this project will receive training in DNA extraction, PCR, and sequencing in the Museum’s core genetics facility, the Pritzker Laboratory and the DNA Discovery Center and will also learn to analyze DNA sequence data including phylogeographic and population genetic analytical methods.
