TY - JOUR

T1 - Asexual and sexual reproduction are two separate developmental pathways in a Termitomyces species

AU - Vreeburg, Sabine M. E.

AU - de Ruijter, Norbert C. A.

AU - Zwaan, Bas J.

AU - da Costa, Rafael R.

AU - Poulsen, Michael

AU - Aanen, Duur K.

PY - 2020

Y1 - 2020

N2 - Although mutualistic symbioses per definition are beneficial for interacting species, conflict may arise if partners reproduce independently. We address how this reproductive conflict is regulated in the obligate mutualistic symbiosis between fungus-growing termites and Termitomyces fungi. Even though the termites and their fungal symbiont disperse independently to establish new colonies, dispersal is correlated in time. The fungal symbiont typically forms mushrooms a few weeks after the colony has produced dispersing alates. It is thought that this timing is due to a trade-off between alate and worker production; alate production reduces resources available for worker production. As workers consume the fungus, reduced numbers of workers will allow mushrooms to 'escape' from the host colony. Here, we test a specific version of this hypothesis: the typical asexual structures found in all species of Termitomyces-nodules-are immature stages of mushrooms that are normally harvested by the termites at a primordial stage. We refute this hypothesis by showing that nodules and mushroom primordia are macro- and microscopically different structures and by showing that in the absence of workers, primordia do, and nodules do not grow out into mushrooms. It remains to be tested whether termite control of primordia formation or of primordia outgrowth mitigates the reproductive conflict.

AB - Although mutualistic symbioses per definition are beneficial for interacting species, conflict may arise if partners reproduce independently. We address how this reproductive conflict is regulated in the obligate mutualistic symbiosis between fungus-growing termites and Termitomyces fungi. Even though the termites and their fungal symbiont disperse independently to establish new colonies, dispersal is correlated in time. The fungal symbiont typically forms mushrooms a few weeks after the colony has produced dispersing alates. It is thought that this timing is due to a trade-off between alate and worker production; alate production reduces resources available for worker production. As workers consume the fungus, reduced numbers of workers will allow mushrooms to 'escape' from the host colony. Here, we test a specific version of this hypothesis: the typical asexual structures found in all species of Termitomyces-nodules-are immature stages of mushrooms that are normally harvested by the termites at a primordial stage. We refute this hypothesis by showing that nodules and mushroom primordia are macro- and microscopically different structures and by showing that in the absence of workers, primordia do, and nodules do not grow out into mushrooms. It remains to be tested whether termite control of primordia formation or of primordia outgrowth mitigates the reproductive conflict.

KW - fungus-growing termites

KW - mushroom formation

KW - mutualism

KW - nodules

KW - symbiosis

KW - Termitomyces

U2 - 10.1098/rsbl.2020.0394

DO - 10.1098/rsbl.2020.0394

M3 - Journal article

C2 - 32781906

AN - SCOPUS:85089360118

VL - 16

JO - Biology Letters

JF - Biology Letters

SN - 1744-9561

IS - 8

M1 - 20200394

ER -