The phylogeography and microbial ecology of Australian ambrosia beetle taxa (Curculionidae: Platypodinae and Scolytinae)

Abstract

Little is known about the Australian ambrosia beetles beyond their initial taxonomic descriptions and revisions. Two species of Platypodinae, Austroplatypus incompertus and Platypus subgranosus, have been subject to detailed ecological studies due to their economic importance in forestry. Beyond this, the ecology of all other Australian ambrosia beetles, both Platypodinae and Scolytinae, remains mostly unknown. The aim of this thesis was to explore the effects of the biogeography on the Australian ambrosia beetle fauna and their microbial symbionts. This thesis consists of three data chapters detailing biogeographic impacts on three species of Platypodinae and two species of Scolytinae. Ambrosia beetle specimens were sampled along eastern Australia and characterised using Sanger and next generation sequencing techniques to conduct phylogenetic, population genetic and microbial ecology analyses of both ambrosia beetles and their microbial symbionts. The first research data chapter investigated the population genetic structure and phylogeography of the only eusocial beetle, Austroplatypus incompertus. The second research data chapter investigated the microbiome of specimens of two Australian-endemic platypodine ambrosia beetle species, Platypus omnivorus and Treptoplatypus crentatus, collected across a distance of over 2,200 km in eastern Australia. The third experimental data chapter explored the phylogeography of two endemic scolytine ambrosia beetle species, Cnestus solidus and Cnestus pseudsolidus, which are distributed in sympatry from Far North Queensland to Tasmania. This thesis has uncovered previously unknown diversity within Australian ambrosia beetle species. It also describes and details the ecology of several Australian ambrosia beetle taxa and their associated microbial symbionts, cryptic species, taxonomic resolutions, two new species of ambrosia fungi (Ambrosiella sp. 1 and Ambrosiella sp. 2), and a novel strain of Wolbachia. Furthermore, the presented research identified biogeographic processes which have extensively shaped the evolution and distribution of Australian ambrosia beetles. Interestingly, microbial symbiont communities remained stable throughout their host distribution. The presented research data will guide future research on ambrosia beetle diversity in Australia and elsewhere.

Date of Award	2021
Original language	English