Discordant phylogenies suggest repeated host shifts in the Fusarium-Euwallacea ambrosia beetle mutualism.

摘要: The mutualism between xyleborine beetles in the genus Euwallacea (Coleoptera: Curculionidae: Scolytinae) and members of Ambrosia Fusarium Clade (AFC) represents one 11 known evolutionary origins fungiculture by ambrosia beetles. Female transport fusarial symbionts paired mandibular mycangia from their natal gallery to woody hosts where they are cultivated galleries as a source food. Native Asia, several exotic species were introduced into United States Israel within past two decades now threaten urban landscapes, forests avocado production. To assess limits date diversification mutualists, we reconstructed histories key representatives clades using maximum parsimony likelihood methods. Twelve species-level lineages, termed AF 1-12, identified monophyletic AFC seven among Fusarium-farming Euwallacea. Bayesian diversification-time estimates placed origin Euwallacea-Fusarium near Oligocene-Miocene boundary ∼19-24 Mya. Most spp. appear be associated with Fusarium, but farmed closely related fusaria. sp. #2 Miami-Dade County, Florida AF-6 AF-8 on avocado, #4 ambrosium AF-1 AF-11 Chinese tea Sri Lanka. Cophylogenetic analyses indicated that phylogenies largely incongruent, apparently due switching (i.e., host shifts) at least five times during evolution this mutualism. Three cospeciation events detected, randomization tests failed reject null hypothesis putative parallel cladogenesis is stochastic pattern. Lastly, collections shared an identical cytochrome oxidase subunit 1 (CO1) allele validus, suggesting introgressive hybridization these and/or pseudogenous nature marker. Results present study highlight importance understanding potential for frequency host-switching AFC, shifts may bring together more aggressive virulent combinations invasive mutualists.