title: Climate, not Aboriginal landscape burning, controlled the historical demography and distribution of fire-sensitive conifer populations across Australia.
abstract: Climate and fire are the key environmental factors that shape the distribution and demography of plant populations in Australia. Because of limited palaeoecological records in this arid continent, however, it is unclear as to which factor impacted vegetation more strongly, and what were the roles of fire regime changes owing to human activity and megafaunal extinction (since ca 50 kya). To address these questions, we analysed historical genetic, demographic and distributional changes in a widespread conifer species complex that paradoxically grows in fire-prone regions, yet is very sensitive to fire. Genetic demographic analysis showed that the arid populations experienced strong bottlenecks, consistent with range contractions during the Last Glacial Maximum (ca 20 kya) predicted by species distribution models. In southern temperate regions, the population sizes were estimated to have been mostly stable, followed by some expansion coinciding with climate amelioration at the end of the last glacial period. By contrast, in the flammable tropical savannahs, where fire risk is the highest, demographic analysis failed to detect significant population bottlenecks. Collectively, these results suggest that the impact of climate change overwhelmed any modifications to fire regimes by Aboriginal landscape burning and megafaunal extinction, a finding that probably also applies to other fire-prone vegetation across Australia.
authors.affiliation: Graduate School of Arts and Sciences, The University of Tokyo, , Tokyo 153-8902, Japan, Japan Society for the Promotion of Science, , Kojimachi Business Center Building, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083, Japan, School of Plant Science, University of Tasmania, , Hobart, Tasmania 7001, Australia, Research School of Biology, The Australian National University, , Canberra, Australian Capital Territory 0200, Australia, Department of Forest Genetics, Forestry and Forest Products Research Institute, , 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan, Division of Forest and Biomaterials Science, Graduate School of Agriculture, Kyoto University, , Kyoto 6068502, Japan.
authors.forename: Shota
authors.initials: S
authors.lastname: Sakaguchi
authors.forename: David M J S
authors.initials: DM
authors.lastname: Bowman
authors.forename: Lynda D
authors.initials: LD
authors.lastname: Prior
authors.forename: Michael D
authors.initials: MD
authors.lastname: Crisp
authors.forename: Celeste C
authors.initials: CC
authors.lastname: Linde
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Tsumura
authors.forename: Yuji
authors.initials: Y
authors.lastname: Isagi
mesh_terms: D001315:Australia; D002980:Climate; D005390:Fires; D006801:Humans; D011156:Population Density; D011157:Population Dynamics; D064028:Tracheophyta / Q000502:physiology*
keywords: aboriginal fire management; climate change; conifer; fire; phylogeography; population demography