Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Plant Biology

First Advisor

David S. Barrington

Second Advisor

Catherine A. Paris


This dissertation is a study of the ecology of hybridization within the northeastern north American members of the Adiantum pedatum complex, a clade of maidenhair ferns. The primary focus is to characterize the ecological niche differences among two diploid progenitors (A. aleuticum and A. pedatum) and their allotetraploid derivative A. viridimontanum. In order to accomplish this task, untangling the drivers of geographic distribution within the clade has been of foundational importance, with special reference to 1) the unique aspects of fern life history, and 2) the importance of edaphic requirements across serpentine and rich-woods habitats. In Chapter 2, I report the results of a presence-only niche modeling approach developed to characterize the realized ecological niche of the sporophyte phase of the three members of the Adiantum pedatum complex across habitat and range scales. In Chapter 3, I detail the results of a reciprocal growth experiment in which I grew the three members of the Adiantum pedatum complex from spores across a range of soil types, in order to 1) assess the viability of allotetraploid gametophytes relative to those of the progenitor species across serpentine and rich woods soils, and 2) evaluate whether the ecological niche of the sporophyte and gametophyte phases are equivalent, or whether one is a subset of the other. In Chapter 4, I present a novel morphometric approach designed to model the leaf morphology of Adiantum sporophytes grown under a common light regime, in order to 1) validate the species identity of the plants emerging from my experimental work in Chapter 3, and 2) explore the effect of genotype and ontogeny on the phenotype of young Adiantum sporophytes.



Number of Pages

255 p.

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