Disputation: Dereje Tesfaye Delkaso

PhD candidate Dereje Tesfaye Delkaso at the Department of Biosciences will be defending the thesis "The Omo River guereza (Colobus guereza guereza) in habitats with varying  levels of fragmentation and disturbance in the southern Ethiopian Highlands:  behavioral ecology and phylogeny" for the degree of PhD.

Profile picture of Dereje Tesfaye Delkaso

Dereje Tesfaye Delkaso

The trial lecture is: "Conservation science and its links and impacts to international environmental policies, especially the Sustainable Development Goals and the UN Decade on Ecosystem Restoration".

Time and place: May.13, 2022 10:15 AM, Zoom and Nucleus, Bikuben, The Kristine Bonnevie building

The events will also be live streamed using Zoom. The host of the session will moderate the technicalities while the chair of the defence will moderate the events.

The events opens for participation just before they start, and closes for new participants approximately 15 minutes after it has begun.

Main research findings

The behavioral ecology of the Omo River guerezas (Colobus guereza guereza) in Ethiopia and the phylogeny of the subspecies of guereza across its ranges have not been studied well. We investigated the behavioral ecology and the diet of Omo River guerezas in three forest types with different level of fragmentation and disturbance histories. In our findings, guerezas exhibited flexible activity and ranging patterns, and diets that might help them adapt to fragmentation and disturbance in their habitats. Guerezas in the disturbed forests supplemented their diet by raiding cultivated crops from the nearby farms, consequently led to direct human-primate conflict in the areas.

Furthermore, the taxonomy of the subspecies of guereza was vague and inconclusive for decades. The two Ethiopian subspecies (C. g. guereza and C. g. gallarum) and their relative geographic ranges have also remained controversial and needed further investigation. Therefore, we carried out a mitochondrial phylogenetic analysis, using sequences obtained from GenBank and extracted from fecal samples, to investigate the taxonomy of the subspecies. Finally, we identified two major mitochondrial lineages in Ethiopia. C. g. gallarum proved to have a much smaller geographic range than previously believed, while C. g. guereza was more widely distributed than expected.

Adjudication committee

Professor Russel Hill, Durham University

Professor Nils Bunnefeld, University of Sterling

Professor emeritus Reidun Kavli Sirevåg

Chair of defence

Associate Professor Yngvild Vindenes


Professor Nils Christian Stenseth, University of Oslo

Professor Peter J. Fashing, California State University Fullerton

Professor Afework Bekele, Addis Ababa University

Published Apr. 29, 2022 10:17 AM - Last modified June 10, 2022 10:14 AM