Unveiling pattern of diversification of the birds in the Darien highlands region

Geographic isolation is a key driver of bird speciation, particularly in highland species, as barriers like mountain ranges restrict gene flow. Lowland areas often serve as inhospitable gaps that separate suitable habitats, influencing allopatric speciation. Additionally, environmental changes such as glacial-interglacial cycles and tectonic activity, including the uplift of the Panamanian Isthmus, have shaped genetic divergence by fragmenting and reconnecting montane forests. These cycles may have facilitated periods of isolation and secondary contact, impacted gene flow and promoting biodiversity in the Neotropics. Preliminary genetic studies on highland bird species in the Darien, such as Myadestes coloratus and Chlorospingus tacarcunae, suggest subtle divergence among isolated populations, but previous research was limited by small sample sizes and low-resolution molecular markers. Advances in genomic techniques, particularly Ultra-Conserved Elements (UCEs) and mitogenomic, provide powerful tools to examine historical factors influencing genetic divergence and speciation in montane birds. This study aims to investigate the phylogeographic patterns and genetic structure of M. coloratus and C. tacarcunae, using UCEs and mitochondrial markers. Given their limited dispersal and different forest strata occupancy, it is hypothesized that lowland barriers restrict gene flow, promoting genetic differentiation over time. Additionally, populations experiencing greater isolation are expected to exhibit higher levels of genetic divergence. Understanding these mechanisms will help clarify the role of the Darien highlands in avian diversification and endemism.