Evolution of habitat preference and nutrition mode in a cosmopolitan fungal genus with evidence of interkingdom host jumps and major shifts in ecology.

Host jumps by microbial symbionts are often associated with bursts of species diversification driven by the exploitation of new adaptive zones. The objective of this study was to infer the evolution of habitat preference (decaying plants, soil, living fungi, and living plants), and nutrition mode (saprotrophy and mycoparasitism) in the fungal genus Trichoderma to elucidate possible interkingdom host jumps and shifts in ecology. Host and ecological role shifts were inferred by phylogenetic analyses and ancestral character reconstructions. The results support several interkingdom host jumps and also show that the preference for a particular habitat was gained or lost multiple times. Diversification analysis revealed that mycoparasitism is associated with accelerated speciation rates, which then suggests that this trait may be linked to the high number of species in Trichoderma. In this study it was also possible to infer the cryptic roles that endophytes or soil inhabitants play in their hosts by evaluating their closest relatives and determining their most recent ancestors. Findings from this study may have implications for understanding certain evolutionary processes such as species radiations in some hyperdiverse groups of fungi, and for more applied fields such as the discovery and development of novel biological control strategies.