Low intraspecific genetic diversity indicates asexuality and vertical transmission in the fungal cultivars of ambrosia beetles
Peppel, L.J.J. van de; Aanen, D.K. ; Biedermann, P.H.W. - \ 2018
Fungal Ecology 32 (2018). - ISSN 1754-5048 - p. 57 - 64.
Ambrosia fungus - Ambrosiella - Anisandrus - Asexuality - Clonal fungiculture - Genetic diversity - Symbiosis - Vertical transmission - Xylosandrus
Ambrosia beetles farm ascomycetous fungi in tunnels within wood. These ambrosia fungi are regarded asexual, although population genetic proof is missing. Here we explored the intraspecific genetic diversity of Ambrosiella grosmanniae and Ambrosiella hartigii (Ascomycota: Microascales), the mutualists of the beetles Xylosandrus germanus and Anisandrus dispar. By sequencing five markers (ITS, LSU, TEF1α RPB2, β-tubulin) from several fungal strains, we show that X. germanus cultivates the same two clones of A. grosmanniae in the USA and in Europe, whereas A. dispar is associated with a single A. hartigii clone across Europe. This low genetic diversity is consistent with predominantly asexual vertical transmission of Ambrosiella cultivars between beetle generations. This clonal agriculture is a remarkable case of convergence with fungus-farming ants, given that both groups have a completely different ecology and evolutionary history.