YSM Issue 95.1

Ecology / Environment FOCUS
THE META GUT
Conservational clues provided by hippo poop
As it turns out, hippo excrements contain multitudes. In fact, the organisms that live in
feces may be powerful enough to influence an entire ecosystem.
BY HANNAH SHI AND RISHA CHAKRABORTY
Conservation ecology is on
everyone’s mind today and with
good reason. With global warming
and imminent extinctions making daily
news, the preservation of ecological
biodiversity has never felt more urgent.
To this end, conservation ecologists have
made an effort to identify the key players
in the most ecologically diverse ecosystems
in the world, hoping to find clues about
the relationships between organisms
and nonliving factors that make such
ecosystems high-functioning.
Kenya’s Mara River Valley is a prime
example. The fish, birds, and hippos in the
Kenyan Masai Mara are interdependent
for survival, but recent evidence suggests
researchers have overlooked the key players:
microbiota. The ecological stability of the
Masai Mara is characterized by the relationship
between these two biotic spheres, described by
community coalescence
theory. The
basis of this relationship, as it turns out, can be
found in hippo poop.
The Meta-Gut
Thousands of hippos in Kenya’s Mara
River Valley excrete an estimated 9.3 tons
of feces each day. This waste contains gut
microbiomes with trillions of bacteria and
archaea, which may even function outside
the animal itself. Christopher Dutton
GRD ‘19, a postdoctoral associate in the
Department of Ecology and Evolutionary
biology at Yale, and collaborators such
as Amanda Subalusky GRD ‘16, who
is also a postdoctoral associate in the
same department, have found that the
microbiome of hippos may play an
unanticipated role in regulating biological
and chemical processes within their larger
ecosystem. “Is it possible
that these pools
could actually,
in a way, be functioning like an extension
of the hippo gut?” Dutton said. “It’s kind of
crazy to think that gut microbiota can be
driving what’s happening in this whole river.”
This continual exchange of organic matter
between hippos and their environment has
led to the proposition of a novel conceptual
framework known as the “meta-gut.”
Hippo Pools: What Makes Them Special?
All animals carry specialized
microorganisms in their digestive tract,
which help facilitate biologically essential
processes such as the metabolism of
carbohydrates and the synthesis of amino
acids, fatty acids, and vitamins. As hippos
wallow in the Mara River, they unload their
gut microbiota through the excretion of
waste, introducing
nutrients and microbes
into the river. The metagut
suggests that this
continual loading
of organic matter
results in an
environmental
patch within an
ecosystem that
shares similar
characteristics
to the gut
environment of
the host animal.
In other words, the
river ecosystem inherits
characteristics of the
hippo gut.
www.yalescientific.org
ART BY LUNA AGUILAR
March 2022 Yale Scientific Magazine 19