Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : The roles of divergence and hybridization in shaping patterns of genetic and phenotypic variation across the evolutionary continuum in Juniperus and Piper

Auteur : Uckele, Kathryn Anne

Université de soutenance : University of Nevada Reno

Grade : Doctor of Philosophy (PhD) in Ecology, Evolution, and Conservation Biology 2022

Résumé
Genetic and phenotypic variation across populations, species, and radiations mediates the form and outcome of biotic and abiotic interactions and represents a major axis of biodiversity. Resolving patterns of variation across shallow and deep evolutionary divergences can provide key insights into the processes that generate and maintain this variation over micro- and macroevolutionary timescales. Additionally, variation in functional traits that interface with the biotic and abiotic environments plays an important role in adaptive evolution, and can shed light on the drivers of differentiation and diversification. Here, I analyzed genome-scale variation spanning individuals, populations, and species to 1) resolve complex diversification histories, 2) characterize landscape patterns of hybrid admixture and plant secondary chemistry, and 3) characterize macroevolutionary patterns of plant secondary chemistry. First, I reconstructed the evolutionary history of the serrate juniper clade of North America (Juniperus) as it diversified into arid habitats of the western United States and Mexico. Second, I examined how admixture across the species boundary influences patterns of genetic and phytochemical variation following secondary contact among three serrate juniper species. Finally, I resolve the timing and tempo of diversification in the Radula clade of Piper to understand how secondary chemistry evolves within a diverse tropical plant radiation. My work demonstrates the importance of evolutionary processes occurring along the evolutionary continuum for generating contemporary patterns of variation and diversity.

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