ECR Feature: Gimo Mazembe Daniel on dung beetle diversification

Gimo is a recently appointed research scientist at the National Museum in Bloemfontein, South Africa. He is an entomologist with interests in understanding the systematics and biogeography of dung beetles and related scarab beetles. Gimo shares his recent work on the contributions of different environmental factors in shaping diversity in the dung beetle genus, Sisyphus.

Gimo at the Musem of Comparative Zoology, Harvard University, USA-2017, working on Sisyphini collection (credit to Philip).

Personal links. ResearchGate | Twitter

Institute. National Museum, Bloemfontein, South Africa

Academic life stage. I completed my PhD in Entomology 2019 from the University of Pretoria, South Africa and now hold a research appointment as Principal Museum Scientist at the National Museum, Bloemfontein, South Africa.

Major research themes. I am an entomologist with interests in the systematics and biogeography of dung beetles and related scarab beetles. I am cataloguing and describing the impressive biodiversity of Afrotropical dung beetles to address broader evolutionary questions, such as the role of geological uplift and climatic changes in the late Cenozoic in the diversification and possible extinction of scarab beetles in southern Africa.

Current study system. Dung beetles are a globally distributed insect taxon, but they exhibit their highest diversity in tropical forests and savannas. They feed on the microorganism rich liquid component of mammalian dung (and less commonly that of other vertebrates, as well as rotting fruit, fungi and carrion) and use more fibrous material to brood their larvae. They provide important ecosystem services, such as secondary seed dispersal, control of other insects or parasite suppression, dung and nutrient recycling in ecosystems and subsequent increasing of soil fertility.

Recent paper in JBI. Daniel, GM, Davis, ALV, Sole, CL, Scholtz, CH. Evolutionary history and eco‐climatic diversification in southern African dung beetle SisyphusJ Biogeogr. 2020; 47: 2698– 2713.

(left) Image of habitus of Sisyphus (Sisyphus) oralensis (credit to Christian). (right) Circelium bacchus on the elephant poo at the Addo Elephant National Park, Eastern Cape, South Africa.

Motivation behind this paper. During my PhD studies I was working on the systematics of the southern African dung beetle genus, Sisyphus, which led to a monographic revision of the genus and the first molecular phylogeny of sisyphines. Current biogeographical patterns of dung beetles in southern Africa are thought to have been driven by orogenic, climatic, edaphic and vegetation changes during the late Cenozoic. However, no study has explicitly tested hypotheses on the relative contributions of these factors. Therefore, we used the genus Sisyphus as a model to understand dung beetle evolution in southern Africa.

Key methodologies. A dated molecular phylogeny of southern African Sisyphus was compared with a factor analysis of species distribution data that statistically defined groups of species according to current climatic distribution. We used these climatic clusters to estimate ancestral ranges using BioGeoBEARS. We then used Bayesian diversification models (compound Poisson process on mass extinction times) to test whether late Cenozoic uplift and climatic changes affected speciation and extinction rates of Sisyphus species. Furthermore, we implemented ecological niche modelling in MaxEnt to predict the habitat suitability of species under present climatic conditions.

Major results. Four species groups of Sisyphines (that were defined from factor analysis of current climatic distribution data) were found to be primarily restricted to the moist summer rainfall region in the northeast. Phylogeographic analyses and ecological niche modelling revealed that southern African dung beetle Sisyphus species are not homogenously distributed with respect to geography and climate. The taxonomic and eco-climatic diversification of sisyphines is coincident with geological uplift and changes in climate in east-central southern Africa. Therefore, the combination of phylogenetic methods, climatic data, and ecological niche modelling allowed us to infer that dung beetle evolution in southern Africa is primarily driven by the combination of both orogenic events and climatic shifts in the late Cenozoic.

Unexpected challenges. Sometimes the challenges are not so much to do with the actual research, for instance, when I was writing this paper, I had a problem with my right shoulder, so it was difficult and took me a long time to type, especially coding in R the ecological niche modelling analysis. After several months of physiotherapy my shoulder healed and I was finally able to finish the manuscript.

(left) Gimo in a field work in uMkhuze Game Reserve, KwaZulu-Natal, South Africa-2016, collecting dung beetles (credit to Jorge). (right) Gimo in his lab at the National Museum, working on the revision of Odontoloma (credit to Precious).

Next steps for this research. I would like to carry on with more studies using different diversification methods and other genera of scarabs as study models to test evolutionary hypotheses for the southern African fauna against the current findings. For instance, two projects on Odontoloma and Epirinus are running in my lab, the latter one is currently under review. Furthermore, my collaborators and I are working on a scarab beetle discovery project, in which we are planning to collect in very remote and unsampled areas like those in the Eastern Cape region in South Africa and Mabu forest (Google forest) in northern Mozambique. The aim is to document dung beetle species new to science and provide local ecological data that can be placed in a regional biogeographical context for conservation planning.

If you could study any organism on Earth, what would it be? Dung beetles, of course. I am passionate about these insects because of their great diversity worldwide, and most importantly, they have vital ecosystems functions that provide important and/or economically beneficial ecological services to humans. For example: secondary seed dispersal, biological control of other insects, organic material recycling and consequently increasing of soil fertility.

Anything else to add? My childhood was characterised by interaction with nature, including insect collection, especially beetles while grazing cow and goats on the Save River, Machanga (my homeland), a rural area in Central Mozambique. Although I was always “fighting” with my mother because she believed that I could contract a disease when collecting insects; I never gave up on my passion. I continued collecting beetles but hiding them from my parents. Due to this love for insects, years later, I was enrolled in a BSc degree in Biology back home. Two years later after my BSc, I was awarded a scholarship to pursue an MSc degree in Entomology in Brazil, which was focused on my childhood favourite insects (dung beetles). Afterward, I completed my PhD also working on dung beetles. I am a passionate entomologist intent on spending a lifetime pursuing my interests and inspiring local and disadvantaged communities – where my fierce ambition about a career in insect systematics has originated.

Published by jbiogeography

Contributing to the growth and societal relevance of the discipline of biogeography through dissemination of biogeographical research.

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