Elizabeth H Neilson, Mette Clausen, Juliane FS Zibrandtsen, Sara Thodberg, Allison M Heskes, Birger Lindberg Møller
Eucalyptus leaves are not an average diet. Yet the koala is a specialist folivore, feeding exclusively on these poorly nutritious, highly fibrous and toxic leaves. The koala has to maintain a fine balance between the energy going in and the energy required to breakdown and detoxify the ingested leaves. Sleeping is the best way to conserve energy and the koala sleeps 18-20 h each day and does not move much staying within a small home range. Accordingly, it is posible to experimentally monitor and analyze the amount and types of eucalypt leaves ingested and to collect the resulting faecal pellets from individual koalas. Koalas are fussy feaders restricting their feeding to a low number of the ~700 different eucalypt species. The Eucalyptus genus dominate a wide range of environmental niches (alpine, temperate, semi-arid and arid zones) and the different species possess a wide array of different toxic specialized metabolites including mono- and sesqui terpenoids, phenolics, formylated phloroglucinol compounds (FPCs), calcium oxalate crystals, leaf waxes and cyanogenic glucosides. The synthesis of these metabolites is under environmental and ontogenetic control rendering the eucalypt genus an excellent system for investigating the effect of climate change on the diversity and regulation of plant specialized metabolite formation. In our study we want to link changes in metabolite content and composition to the feeding preferences and behavior of the koala. The metabolites present in the eucalypt and volatiles released are analyzed and pathways and genes involved in their formation are identified with special focus on terpenoids and cyanogenic glucosides, their spatial localization in different eucalypt tissues and cell types, and the ability of the koala and its different microbiomes (digestive tract, caecum, pouch and sternal gland) to handle the presence and detoxification of these toxins. Using the iconic koala in our studies, we aim to gain new basic knowledge on how climate changes may affect the wild life communities on our planet and to improve the awareness of the general public to such issues.


Talk at University of Queensland