Changing herbivores and changing climate in the Great Plains: Effects on dung beetle communities and ecosystem services

Global change is altering interactions among species, with cascading effects on nutrient cycling and the physical environment. Dung beetles interact with plant and parasite populations, and play key roles in nutrient cycling, including carbon sequestration. We used data from dung beetle communities in the Great Plains to address the effects of two important global change drivers: land management and climate change. First, in the Great Plains, the mammalian community has been restructured due to European settlement and the extirpation of key native herbivores including bison. We ask how this shift and the arrival of non-native cattle has affected dung beetle communities. Across three sites, we found that dung beetle community composition differed in bison-grazed and cattle-grazed grasslands, suggesting a cascading effect on this key insect group. Second, as climate change alters the productivity and composition of Great Plains ecosystems, forage quality and parasites will reduce the carrying capacity of cattle. We ask how higher temperatures are impacting dung beetle species in grassland habitats. Further, to address both a different angle of our first question and our second question, we examined the interaction between dung quality and temperature in dung beetles reared on bison dung and cattle dung. We found that horn length and body size were similar between the dung treatments, but the underlying growth and developmental rates were higher in bison dung, especially at the highest temperatures. Overall, we show that dung beetle communities associated with native herbivores may increase ecosystem services and resiliency in the Great Plains.