How megaherbivores uniquely influence ecological communities
Terrestrial megaherbivores represent a diverse group of herbivorous mammals weighing over 1,000 kg. Unfortunately, less than 20% of megaherbivores from the Pleistocene Epoch remain today, and with their loss comes the loss of the crucial ecosystem services they provide. My PhD dissertation aims to illuminate the influence that the few remaining megaherbivores exhort on ecological communities.
Chapter 1 focuses on simulating the presence of megaherbivores (African bush elephants, black rhinoceros, and common hippopotamus) to identify what drives the ‘landscape of fear’ they create for smaller, mid-sized herbivores.
Chapter 2 investigates whether dominant megaherbivores drive spatiotemporal behavior of smaller, subordinate herbivores on the savanna. By identifying the mechanisms driving such interspecific fear responses, these two chapters will answer how megaherbivores shape the movements and behaviors of other large herbivores.
In Chapter 3, the focus shifts to examining diet partitioning among herbivores. Specifically, I will characterize how the diets of small mammals (<1kg) change when large herbivores are experimentally removed from the system, which will help pinpoint whether large herbivores exert top-down pressure on small mammals through direct food competition.
The final chapter will analyze how elephants housed in North American sanctuaries impact vegetation structure and primary productivity of local habitats. This investigation seeks to enhance our understanding of megaherbivore impacts in novel ecosystems, and identify if elephants, as ecological proxies of prehistoric megafauna, could improve primary productivity of North American ecosystems. This dissertation will fill gaps in our knowledge of the function megaherbivores have in ecological communities, which is key for maintaining dwindling megaherbivore populations and the ecosystem services they provide.