High Symbiont Relatedness Stabilizes Mutualistic Cooperation in Fungus-Growing Termites

TY - JOUR

T1 - High Symbiont Relatedness Stabilizes Mutualistic Cooperation in Fungus-Growing Termites

AU - Aanen, Duur K

AU - de Fine Licht, Henrik H

AU - Debets, Alfons J M

AU - Kerstes, Niels A G

AU - Hoekstra, Rolf F

AU - Boomsma, Jacobus J

N1 - Keywords: Animals; Evolution; Genes, Fungal; Genetic Variation; Isoptera; Spores, Fungal; Symbiosis; Termitomyces

PY - 2009

Y1 - 2009

N2 - It is unclear how mutualistic relationships can be stable when partners disperse freely and have the possibility of forming associations with many alternative genotypes. Theory predicts that high symbiont relatedness should resolve this problem, but the mechanisms to enforce this have rarely been studied. We show that African fungus-growing termites propagate single variants of their Termitomyces symbiont, despite initiating cultures from genetically variable spores from the habitat. High inoculation density in the substrate followed by fusion among clonally related mycelia enhances the efficiency of spore production in proportion to strain frequency. This positive reinforcement results in an exclusive lifetime association of each host colony with a single fungal symbiont and hinders the evolution of cheating. Our findings explain why vertical symbiont transmission in fungus-growing termites is rare and evolutionarily derived.

AB - It is unclear how mutualistic relationships can be stable when partners disperse freely and have the possibility of forming associations with many alternative genotypes. Theory predicts that high symbiont relatedness should resolve this problem, but the mechanisms to enforce this have rarely been studied. We show that African fungus-growing termites propagate single variants of their Termitomyces symbiont, despite initiating cultures from genetically variable spores from the habitat. High inoculation density in the substrate followed by fusion among clonally related mycelia enhances the efficiency of spore production in proportion to strain frequency. This positive reinforcement results in an exclusive lifetime association of each host colony with a single fungal symbiont and hinders the evolution of cheating. Our findings explain why vertical symbiont transmission in fungus-growing termites is rare and evolutionarily derived.

U2 - 10.1126/science.1173462

DO - 10.1126/science.1173462

M3 - Journal article

C2 - 19965427

SN - 0036-8075

VL - 326

SP - 1103

EP - 1106

JO - Science

JF - Science

IS - 5956

ER -