Date of Award

8-16-2024

Author's School

Graduate School of Arts and Sciences

Author's Department

Biology & Biomedical Sciences (Evolution, Ecology & Population Biology)

Degree Name

Doctor of Philosophy (PhD)

Degree Type

Dissertation

Abstract

Islands have played a crucial role in evolutionary biology, providing key insights for both Charles Darwin and Alfred Russel Wallace in formulating their theories of evolution. The development of Island Biogeography Theory and the General Dynamic Model of oceanic island biogeography have formed the theoretical foundation of island studies over the last sixty years, leading to substantial advancements in our understanding of biodiversity evolution. Despite their critical value for evolutionary theory, islands face unprecedented ecological collapse, with species on islands facing significantly higher extinction rates than on continents. The island extinction crisis highlights the need for integrating conservation perspectives into evolutionary research. This dissertation uses Hibiscus section Lilibiscus as a model group in which to examine three fundamental evolutionary processes — dispersal, speciation, and extinction — that have produced the incredible but vulnerable biodiversity exhibited by oceanic islands across the globe. Chapter 1 assesses ongoing conservation activities for the critically endangered Hibiscus liliiflorus in the Mascarene Islands, revealing a gap in the conservation of extant genetic diversity and making recommendations for improved conservation actions. Chapters 2 and 3 focus on speciation within the Mascarene Islands, resolving taxonomic confusion and producing a population-level genetic study that shows unique support for speciation predictions fundamental to the General Dynamic Model. Chapter 4 presents a global phylogeny of sect. Lilibiscus, revealing dispersal patterns that suggest islands may not be evolutionary dead ends, as is generally assumed, and may instead act as the launching point for the global diversification of the group. Together, these studies contribute to a deeper understanding of island biogeography while making a significant contribution to the conservation of sect. Lilibiscus. By linking evolutionary theory with practical conservation strategies, this dissertation underscores the importance of a holistic approach to studying and preserving island biodiversity.

Language

English (en)

Chair and Committee

Christine Edwards

Committee Members

Kenneth Olsen; David Queller; Michael Landis; Peter Wyse-Jackson

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