Format: ORAL

Susan Rutherford1,2, Alison Paulo Bernardi2, Eva Montalban2, Justin SH Wan2,3, Maurizio Rossetto2

1 Department of Environmental Science, College of Science, Mathematics and Technology, Wenzhou-Kean University, Wenzhou, China 2 Research Centre for Ecosystem Resilience, Australian Institute of Botanic Science, Royal Botanic Garden Sydney, Mrs Macquaries Road, Sydney, New South Wales, Australia 3 School of Environment and Safety Engineering, Jiangsu University, China

Historical processes driving evolution have left a signature in genetic differentiation and gene flow across the landscape of present-day plant populations. Examining these patterns can enable us to better understand lineage divergence. Corymbia is a genus within the eucalypts comprising c. 100 species, most of which are endemic to Australia. Recent phylogenetic analyses suggest that Corymbia is paraphyletic (with another eucalypt genus Angophora nested within Corymbia). In the current study, we sampled leaf material from multiple populations of five co-occurring species from across the two paraphyletic clades of Corymbia for genome-wide sequencing. We found two species from one clade (C. maculata and a more restricted species, C. eximia) to be highly genetically differentiated compared to the other species. In contrast, there was evidence of high levels of introgression among two widespread and morphologically similar species from the other clade, C. gummifera and C. intermedia. To explore the impacts of climatic factors on species evolution, environmental niche models were generated using Maxent to determine the habitat suitability of each species under the Last Glacial Maximum. Overall, our findings offer unique insights into the processes underlying speciation and influencing species boundaries within complex lineages across diverse landscapes.