Symbiotic microbes can benefit their animal hosts by enhancing the diversity of communication signals available to them. ~ Kevin Theis
Microbes also facilitate their hosts’ communications. Many animals mark spots in their habitat to convey various messages: whether a claim of territoriality or notes to friends or potential partners.
Host-resident microbes, or their work products, are on the spot to convey the communiqué. Besides aforementioned hyenas, badgers and bats are known to employ microbial compatriots to yarn for them.
Mutualisms develop in an environment where cooperation is beneficial to both parties. If the environment changes, the costs and benefits of cooperating can change as well.
In one experiment, researchers studied a microbial cross-feeding mutualism, in which each yeast strain supplied an essential amino acid to its partner strain. Depending upon the amount of freely available amino acid in the environment, the yeast strains shifted between mutualism and competition.