Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Biology

First Advisor's Name

Kenneth J. Feeley

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Christopher Baraloto

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Maureen Donnelly

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Hong Liu

Fourth Advisor's Committee Title

Committee member

Fifth Advisor's Name

Jonathan B. Losos

Fifth Advisor's Committee Title

Committee member

Keywords

ecology, evolution, adaptive radiation, anolis, anole, adaptive radiation, community assembly, species coexistence, interspecific interactions, evolutionary ecology, invasive species, conservation biology

Date of Defense

3-2-2018

Abstract

Adaptive radiation – the proliferation of species from a single ancestor and diversification into many ecologically different forms – has long been heralded as an important process in the generation of phenotypic diversity. However, the early stages of adaptive radiation are notoriously elusive to observe and study. In this dissertation, I capitalize on communities of introduced non-native Anolis lizards as analogues of early stage adaptive radiations. In Chapter II, I begin by reviewing the concept of “ecological opportunity” – a classic hypothesis put forward as a potential key to understanding when and how adaptive radiation occurs. In Chapter III, I investigate the mechanisms which allow for coexistence and community assembly among ecologically-similar species. To do this I investigate range dynamics and assembly patterns of introduced anoles on the oceanic island of Bermuda. I discover that interspecific partitioning of the structural environment facilitates species coexistence, however the order of species assembly was an important predictor of final community composition. In Chapter IV, I then investigate how interspecific interactions between coexisting species may drive phenotypic divergence. This is the process of character displacement, which has been widely hypothesized to be an important mechanism driving phenotypic divergence in adaptive radiations. To do this I investigate sympatric and allopatric populations of introduced Cuban brown anoles (Anolis sagrei) and Puerto Rican crested anoles (A. cristatellus) in Miami FL, USA. I identify morphological shifts in sympatry, driven by divergence in habitat use and decreases in abundance. This study provides evidence of how selection on both ecologically and sexually-important traits can both drive phenotypic divergence during character displacement. Finally, in Chapter V, after taking advantage of non-native species as model eco-evolutionary systems in previous chapters, I investigate the potentially harmful effects that their presence may have on vulnerable native biodiversity. To do this I investigate the conservation risk posed by newly-discovered populations of A. sagrei on Bermuda to Critically Endangered endemic Bermuda skinks (Plestiodon longirostris). Through a detailed analysis of habitat use, diet, population size, and morphology of A. sagrei on Bermuda, we conclude it likely poses a high conservation threat to P. longirostris through interspecific competition.

Identifier

FIDC006576

ORCID

https://orcid.org/0000-0003-0734-6795

Available for download on Thursday, April 18, 2019

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