Study led by UH Hilo alumna shows megaherbivores in danger of extinction

The findings of the study led by Trisha Atwood and published in Science Advances, challenge a two-decades-long perception that predators were the most likely group to fall victim to mass extinction.

Trisha Atwood
Trisha Atwood

A study led by a graduate of the marine science undergraduate program and the tropical conservation biology and environmental science graduate program at the University of Hawai‘i at Hilo shows modern-day megaherbivores (plant-eaters weighing more than 2,200 pounds) are at greater risk of extinction than other types of animals.

The consequences for Earth and all its inhabitants of losing animals such as elephants, hippopotamuses, and bison are unknown, according to the new study led by Utah State University Assistant Professor Trisha Atwood. Atwood received her doctor of philosophy in forest and conservation sciences from the University of British Columbia.

The study was co-authored by Elizabeth Madin, a researcher at the Hawaiʻi Institute of Marine Biology in the UH Mānoa School of Ocean and Earth Science and Technology.

The findings of the study, published in Science Advances, challenge a two-decades-long perception that meat-eating animals, or predators, were the most likely group to meet the ire of Earth’s sixth mass extinction.

One million years ago, the extinction of large-bodied herbivores (plant-eaters) changed the trajectory of life on Earth. Their disappearance reshaped plant life, altered fire regimes across Earth’s landscapes, and modified nutrient cycles in such a way that Earth’s climate became slightly colder.

Armed with a dataset of the diets of more than 24,500 mammals, birds and reptiles, a team of scientists set out to answer the question, “Are plant-eaters, meat-eaters, or animals who eat both plants and meat at the greatest risk of extinction?”

The study results indicate that with over a quarter of the world’s modern day herbivores threatened with extinction, plant-eaters have the highest representation of at-risk species in the present day. The study also highlights that this attack on herbivores is not a new phenomenon. Human activities have led to the disproportionate extinction of herbivores compared to predators since at least the late Pleistocene (11,000–50,000 years ago).

The results surprised the researchers. “We went into this project thinking that the data were likely to simply confirm our general perception that modern-day predators were most at risk of going extinct,” says Madin. “To me, this kind of thing is one of the most exciting parts of being a scientist.”

Full story at UH System News.