Herbivores, not predators, most at risk of extinction
Global study sheds new light on current species declines, past species extinctions, and disruptions to Earth's ecosystems

Date:
August 5, 2020
Source:
S.J. & Jessie E. Quinney College of Natural Resources, Utah State
University
Summary:
One million years ago, the extinction of large-bodied plant-eaters
changed the trajectory of life on Earth. The disappearance of
these large herbivores reshaped plant life, altered fire regimes
across Earth's landscapes, and modified biogeochemical cycling in
such a way that Earth's climate became slightly colder.



FULL STORY ==========================================================================
One million years ago, the extinction of large-bodied plant-eaters
changed the trajectory of life on Earth. The disappearance of these
large herbivores reshaped plant life, altered fire regimes across
Earth's landscapes, and modified biogeochemical cycling in such a way
that Earth's climate became slightly colder. A new study out today by
Utah State University Assistant Professor of Watershed Sciences, Trisha
Atwood, suggests that modern-day megaherbivores (plant-eaters weighing
more than 1000 kg) could soon suffer the same fate as their ancient
ancestors, with unknown consequences for Earth and all of its inhabitants.


========================================================================== Armed with a dataset of the diets of over 24,500 mammals, birds,
and reptiles, Atwood and her team 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?" Their findings, published in the
journal Science Advances, would challenge a two-decade-long perception
that meat-eating predators were the most likely group to meet the ire
of Earth's six mass extinction.

The 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 were somewhat shocking," said Atwood. "Our highly publicized
and fraught relationship with predatory animals such as lions and wolves
has led to the unfounded perception that we are losing predators more than
any other trophic group." Using evidence-based science to challenge misconceptions like the one Atwood's team uncovered is essential
for getting society on the right track towards addressing future
extinctions. Because a species' role in its ecosystem is intricately
linked to what it eats, understanding whether predators, herbivores,
or omnivores are at the highest risk of extinction helps scientists
and society understand what the potential consequences of losing those
species are.

Already the consequences of declines in modern herbivores from land-use
change and hunting have begun to echo those that occurred on Earth 1
million years ago; alterations to plant life, changes to fire regimes,
and disruptions to nutrient cycling. This study highlights that we
must redouble our efforts to strategically invest in conservation and management of herbivores to avoid future dramatic changes in the functions arising from animals at the base of global foodwebs.

Although the results of the study indicate that herbivores are the most
at-risk group, it is not clear sailing for predators. The study also
identified scavengers, which eat the remains of recently deceased animals (e.g., vultures) and animals that primarily eat fish, such as seabirds,
as having a heightened risk of extinction.

"Our results enable us to identify specialized diets within the
carnivores that are associated with higher extinction risk, and also
identify the habitats these species live in," says Edd Hammill an
Assistant Professor of Watershed Sciences at Utah State University and co-author of the study. "It would appear that seabirds across the globe
suffer disproportionately high levels of extinction" To better inform conservation actions, the researchers are now wrestling to understand
what it is about herbivores, scavengers, and piscivores (animals that
consume fish) that make them more susceptible to extinction compared to
other animals.

"Documenting a pattern in extinctions is only the first step towards
curbing the loss of species," says Atwood. "Our next step is to understand
the intricacies of why this pattern is occurring; only then will we
really have a chance at stopping these future extinctions."

========================================================================== Story Source: Materials provided by S.J._&_Jessie_E._Quinney_College_of_Natural_Resources,
Utah_State_University. Original written by Trisha Atwood. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Trisha B. Atwood, Shaley A. Valentine, Edd Hammill, Douglas
J. McCauley,
Elizabeth M. P. Madin, Karen H. Beard, William D. Pearse. Herbivores
at the highest risk of extinction among mammals, birds, and
reptiles.

Science Advances, 2020; 6 (32): eabb8458 DOI: 10.1126/sciadv.abb8458 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200805160949.htm

--- up 3 weeks, 1 hour, 55 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)