Date of Award

Summer 8-2020

Degree Type


Degree Name


Degree Program

Integrative Biology


Biological Sciences

Major Professor

Nicola Mary Anthony

Second Advisor

T. Keith Philips

Third Advisor

Jerome J. Howard

Fourth Advisor

Charles D. Bell


The Guineo-Congolian (GC) region of West and Central Africa contains high levels of species richness (SR) and endemism. Within the GC region, the Cameroon Volcanic Line (CVL) is an important biodiversity hotspot in part due to montane habitats that constitute important ‘sky islands’ refugia during warm periods of the Pleistocene glacial cycles. However, little is known about the diversity of many taxa in the GC region, especially for insects. The main goals of this dissertation are to: 1) document dung beetle (Coleoptera: Scarabaeinae) species diversity across the GC region and assess the potential impacts of future climate change on species community composition, 2) examine the role that ‘sky islands’ may have played in driving the diversification of three common dung beetle species (Catharsius lycaon, Onthophagus fuscidorsis and Neosisyphus angulicollis) and 3) document dung beetle species diversity along an elevational gradient on Bioko, the largest oceanic island within the CVL. We used several non-parametric estimators and rarefaction to estimate SR at 23 sites across the GC region. We also adopted a Generalized Dissimilarity Matrix (GDM) modeling approach to predict patterns of beta diversity under present and future climate change. Additionally, we generated mitochondrial DNA sequence data from C. lycaon, O. fuscidorsis and N. angulicollis sampled across the CVL and surrounding lowlands to examine the role that ‘sky islands’ may have played in driving genetic differentiation. We recorded a total of 26,737 dung beetle specimens belonging to 188 species and 19 genera. The GDM results show that under current climate change, the wettest month and the driest quarter are the most important predictors of community composition and that under future climate change montane areas and forest-savanna transition zones across the GC region will experience the greatest shifts in species turnover. Evidence supports the ‘sky island’ hypothesis for all three focal species. Dung beetle SR decreased with increasing elevation on Bioko Island. Current dung beetle communities are likely greatly affected across the GC by defaunation and other anthropogenic activities. Future studies should examine the role of defaunation on dung beetle communities and the ecosystem services they provide.


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