Adaptive traits of bark and ambrosia beetle-associated fungi. Adaptive traits of bark and ambrosia beetle-associated fungi

A phenotype is the combined result of adaptive novelties and evolutionary constraints. We quantified the contributions of ecological and phylogenetic associations to phenotypic variation in Geosmithia fungi living in symbiosis with bark beetles. Geosmithia species are mostly generalists; nevertheless, others are long-term co-evolved specialists, obligatorily dependent ambrosia fungi or even a severe phytopathogen. We hypothesized that the Geosmithia species niche breadth is reflected in their enzymatic suites, and that the biochemical composition and antibiotic production of Geosmithia species are shaped by reciprocal co-evolution between fungi and their vectors to fulfil beetle needs. Our results confirmed our hypotheses. Long-term co-evolved specialists have reduced metabolic breadth in comparison to generalists. Phytopathogenic G. morbida produces enzyme suites with affinity to ligno-cellulose. Mycelia of ambrosia fungi contain large amount of oleic fatty acid with nutritive and possibly allelopathic function. Overall, our results indicate a high degree of evolutionary plasticity and adaptability of Geosmithia fungi.