Focus 1: How do plant traits influence the diets of large mammalian herbivores?

To answer this question, I have assembled detailed diet data using DNA metabarcoding and data on the traits of more than 200 locally collected diet plants. This novel pairing of data types enables testing new hypotheses such as the role of the leaf economic spectrum in herbivore niche partitioning. Surprisingly, we find that the LES is mostly an axis of inter-individual variation and not niche partitioning (Potter et al. 2022, J Ecology).

Our approach leverages DNA metabarcoding and is particularly powerful in quantifying animal nutrition. Together with colleagues, we’ve found that:

-Fear of predation has a nutritional cost in bushbuck (Atkins et al. 2019 Science)

-Crop raiding by elephants is driven by a demand for energy and not protein (Branco et al. 2019 J Animal Ecology)

-Restoration of wild herbivores controls a noxious but digestible weed Mimosa pigra (Guyton et al. 2020 Nature Eco Evo)

-A burgeoning waterbuck population forces certain age classes to eat tough and indigestible plants (Becker et al. 2021 Ecol. Monographs)

Focus 2: Body size and dietary quality

A large part of my PhD research is concerned with the Jarman-Bell principle. This idea concerns the classic negative relationship between dietary quality and herbivore body mass. The idea links animal physiology, behavior, metabolic scaling, and ecosystem functioning, and has important implications for climate change, paleoecology, biodiversity conservation, and the evolution of the microbiome.

I have tackled this topic with two projects: a book chapter (coauthored with Prof. Rob Pringle) and a mathematical model of herbivory.

Focus 3: Interactions between flooding and grazing

Some of the highest densities of large mammalian herbivores exist in floodplain grasslands. These grasslands are seasonally inundated and may be underwater for few months each year. I conduced a full factorial experiment to investigate the role of biomass removal and fertilization on vegetation dynamics.

So far, preliminary results suggest that the floodplain grasslands of Gorongosa NP, Mozambique are extensively utilized by herbivores during the dry season, but that this impact does not carry over from year to year. Flooding resets the system. The floodplain functions as a key bridging resource for herbivores during a period of forage scarcity.