Degree
Doctor of Philosophy (PhD)
Department
Biological Sciences
Document Type
Dissertation
Abstract
The genus Centropogon subgenus Centropogon, offers an ideal system for studying macroevolutionary patterns due to its diverse floral morphologies and specialized pollinator interactions. This subgenus comprises 55 species, mostly found in mid-elevation Andean forests, where many species exhibit abruptly curved flowers, often associated with pollination by sicklebill hummingbirds. Using phylogenomic approaches, we conducted the first densely sampled analysis of this group, confirming the monophyly of two sections. Our study highlighted extensive gene tree discordance, likely driven by incomplete lineage sorting. Floral curvature and inflorescence structure evolved in a correlated fashion, leading to multiple independent losses of traits linked to sicklebill pollination providing evidence for a pollination syndrome.
Biogeographic and niche evolution analyses further enrich our understanding of this group. Ancestral range reconstruction points to the main clade having Central Andean origins, with multiple subsequent dispersals into Northen Andes and Central America. Centropogon cornutus stands out for its broad distribution across the Neotropics, ranging from lowlands in the Amazon Basin to the Andes. Additionally, using climatic variables, we identified shifts in niche evolution, especially related to temperature and precipitation, which influence key vegetative traits like leaf area. Leaf rea was found to decrease at in cooler, drier areas, while larger leaves were associated with species inhabiting wetter environments. Extrafloral nectaries (EFNs), which attract ants for herbivory defense, are more common at lower elevations where insect pressure is higher. However, this trait becomes less functional at higher elevations, reflecting a possible trade-off in resource investment.
Finally, we addressed Plant Awareness Disparity (PAD) through a course-based undergraduate research experience (CURE) focused on Centropogon cornutus. Students analyzed floral traits across populations, gaining skills in scientific research and communication. This hands-on experience not only increased student engagement with botany but also underscored the relevance of natural history collections for ecological and evolutionary studies. This research sheds light on the role of Neotropical landscapes, specifically the Andes mountain region, in shaping the evolutionary patterns of specialized traits.
Date
1-8-2025
Recommended Citation
Mansaray, Janet, "Using phylogenetics and floral evolution of sicklebill hummingbird-pollinated Centropogon subgenus Centropogon to support undergraduate research" (2025). LSU Doctoral Dissertations. 6654.
https://repository.lsu.edu/gradschool_dissertations/6654
Committee Chair
Laura Lagomarsino