GATEKEEPERS
IN ARMS RACE
POST #23
An article by Donaldson et al (1) has broad implications for the concept
of co-evolutionary arms races between parasites and their hosts. It
reports that Bacteroides fragilis determines what other
bacteria can or cannot colonize a mammalian gut.
Having
one organism in a host act as a gatekeeper, determining what other
organisms can or cannot infect that host, means that the major
species interactions are not only between parasites and their hosts,
but are also between parasites and gatekeepers as well as between
gatekeepers and hosts.
The
substantial literature on parasite-host arms races now needs to be
reconsidered in terms of three species, not two.
Parasite
and host species not only have to interact with each other, they both
also have to interact with gatekeeper species. This makes the
gatekeeper species an integral, if not the main, participant in the
co-evolutionary arms race.
Not
all parasite-host interrelationships have gatekeepers, but the
presence of gatekeepers was probably not considered by authors of
arms race articles. From now on it should be.
Reference cited:
1.
G. P. Donaldson et al., Science 360, 795 (2018).
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