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Systematics, Evolution, and Biodiversity

Section Symposium

Microbes Rulers of Us All: Microbial Interactions and Their Influence over Host Fitness

Digestive symbioses in Cephalotes turtle ants

Sunday, November 13, 2022

4:42 PM – 5:05 PM PT

Location: Vancouver Convention Centre, Meeting Room 109

Presenting Author(s)

Benoit Bechade

PhD Candidate
Drexel University
Philadelphia, Pennsylvania

Co-author(s)

YH

Yi Hu

Drexel University
Philadelphia, Pennsylvania
CC

Christian S. Cabuslay

Drexel University
Philadelphia, Pennsylvania

Co-Author(s)

DA

Dharman Anandarajan

Drexel University
Philadelphia, Pennsylvania

Co-author(s)

VF

Valerie J. Fiers

Drexel University
Philadelphia, Pennsylvania
RL

Richard Lu

Drexel University
Philadelphia, Pennsylvania

Co-Author(s)

BR

Benjamin E. Rubin

Post doctoral scholar
Princeton University
Princeton, New Jersey
Corrie S. Moreau

Professor/Curator
Cornell University
Ithaca, New York
JW

John T. Wertz

Calvin College
Grand Rapids, Michigan
JR

Jacob Russell

Drexel University
Philadelphia, Pennsylvania

Bacterial symbionts can support animal nutrition by facilitating digestion of recalcitrant dietary fibers. The symbiosis between turtle ants (genus Cephalotes) and their gut bacteria provides an intriguing model to study the nature and evolution of microbe-insect nutritional partnerships. Adult turtle ant workers harbor a diverse range of socially transmitted gut bacterial symbionts that are conserved across Cephalotes species, including several that recycle nitrogen. These ants feed substantially on pollen, but bacterial degradation of pollen-derived fibers has never been investigated in this system. Additionally, nothing is known about the roles of bacterial symbionts in larvae. To explore bacterial contributions toward Cephalotes host nutrition, we used shotgun metagenomics and metatranscriptomics on Cephalotes guts. Among larva-associated gut bacteria, environmentally acquired Enterobacteriales can catabolize abundant dietary fibers including cellulose, hemicelluloses and pectins (homogalacturonan, rhamnogalacturonan-I). At the adult stage, specialized gut symbionts encode conserved capacities to deconstruct a similar set of dietary fibers. This symbiotic digestive potential can be stimulated by a switch to pollen-rich diets in adult C. varians, with triggered expression of hemicellulose and rhamnogalacturonan-I degrading genes among symbionts from the Xanthomonadaceae. The diverse arsenal of symbiotic, fiber-degrading enzymes encoded by Cephalotes gut symbionts across life stages suggests symbiont-enhanced digestion of a fiber-rich diet. Such digestive functions have likely characterized >50 million years of Cephalotes evolution, shaping dietary exploitation and success of these diverse arboreal ants. This research project reveals how turtle ants, like other herbivorous social insects, have adopted symbiotic solutions to cope with limitations of plant-based diets.