Date of Award

Fall 12-2018

Degree Type

Dissertation

Degree Name

Ph.D.

Degree Program

Integrative Biology

Department

Biological Sciences

Major Professor

Nicola Anthony

Second Advisor

Simon Lailvaux

Third Advisor

Joel Atallah

Fourth Advisor

Corinne Richards-Zawacki

Fifth Advisor

Eric Fokam

Abstract

Global climate change is projected to impact multiple levels of biodiversity by imposing strong selection pressures on existing populations, triggering shifts in species distributions, and reorganizing entire communities. The Lower Guineo-Congolian region in central Africa, a reservoir for amphibian diversity, is predicted to be severely affected by future climate change through rising temperatures and greater variability in rainfall. Geospatial modelling can be used to assess how environmental variation shapes patterns of biological variation – from the genomic to the community level – and use these associations to predict patterns of biological change across space and time. The overall goal of this dissertation is to examine potential impacts of climate change on amphibian diversity in central Africa. Geospatial modeling is used to: 1) map the distribution of the amphibian fungal pathogen, Batrachochytrium dendrobatidis (Bd) in a biodiversity hotspot in Cameroon under current and future climate; 2) assess phenotypic and adaptive genomic variation in a widespread frog species, Phrynobatrachus auritus, in order to predict areas where populations may best adapt under climate change; 3) determine how amphibian community composition may shift with climate change and which areas may experience greatest loss of functional groups. Findings show that most Bd samples belong to a globally hypervirulent lineage. However, areas of highest predicted environmental suitability for Bd are predicted to shrink under warming temperatures. Within P. auritus, most phenotypic and genomic turnover occurred across known ecological gradients and are heavily influenced by seasonal precipitation. Current amphibian beta diversity is greatest throughout the Cameroonian highlands and forest-savanna ecotones flanking the central Congolian lowland forests. Greatest shifts in community composition under climate change are predicted to occur in coastal Cameroon and its eastern border whereas the greatest predicted loss of functional richness was in central Gabon. Overall, this dissertation shows that areas of elevated environmentally-associated phenotypic, genomic, and community turnover are associated with key ecological gradients. Regions predicted to experience high genomic mismatch, large shifts in community composition, and high loss of functional richness resulting from climate change may warrant conservation attention.

Rights

The University of New Orleans and its agents retain the non-exclusive license to archive and make accessible this dissertation or thesis in whole or in part in all forms of media, now or hereafter known. The author retains all other ownership rights to the copyright of the thesis or dissertation.

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