Diversification of avifauna in the Darién Highland region: Ecological Niche modeling, Phylogeography and Morphology to explore speciation in the montane species Myadestes coloratus, Chlorospingus tacarcunae and Margarornis bellulus.

Author

Jorge L. Garzon Vasquez Mrs, Virginia Commonwealth UniversityFollow

DOI

https://doi.org/10.25772/BTN2-RX55

Author ORCID Identifier

https://orcid.org/0000-0003-2151-0520

Defense Date

2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Integrative Life Sciences

First Advisor

Rodney Dyer

Second Advisor

Catherine Viverette

Third Advisor

Lesley Bulluck

Fourth Advisor

Michael Rosenberg

Fifth Advisor

Luis Fernando De León

Abstract

Montane regions in the Neotropics are hotspots of endemism and biodiversity, yet their species are especially vulnerable to the impacts of climate change and geographic isolation. This thesis investigates the evolutionary and ecological dynamics of three bird species endemic to the Darién Highlands of eastern Panama: Myadestes coloratus, Chlorospingus tacarcunae, and Margarornis bellulus. Through an integrative approach combining ecological niche modeling, morphometric analysis, and genomic data from ultraconserved elements (UCEs) and mitochondrial DNA, the study explores the historical biogeography, current distribution patterns, population structure, and phenotypic differentiation of these montane taxa. Ecological niche models revealed that suitable habitat for M. coloratus and C. tacarcunae has contracted significantly since the Last Glacial Maximum and is projected to decline further under future climate scenarios, with potential refugia limited to high-elevation zones such as Cerro Tacarcuna and Cerro Chucantí. Morphometric analyses of M. coloratus populations indicated significant variation across isolated mountain ridges, suggesting restricted gene flow and local adaptation. Genomic analyses based on UCE-derived SNPs confirmed strong genetic structuring among populations, with the clearest differentiation between the eastern (Tacarcuna) and western (Chucantí) ranges. Phylogenetic and population structure analyses supported historical isolation and limited dispersal, consistent with long-term fragmentation across the montane landscape. Collectively, these findings highlight the combined effects of climate, geography, and evolutionary history in shaping the diversity and endemism of the Darién Highlands. The results underscore the urgency of protecting high-elevation habitats and maintaining connectivity among remnant populations to preserve evolutionary potential under ongoing environmental change.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

8-3-2025