Conservation macrogenetics reveals the potential hidden consequences of the 2019-2020 Black Summer fires on Australian biodiversity

Jarrod Sopniewski , Rhiannon Schembri, Craig Moritz , Andrew M Baker, Stephane Batista, Stephen C. Donnellan, Mark D.B. Eldridge, Emma L Gray, Ian C Gynther, Greta J Frankham, Harry B Hines, Conrad Hoskin, Michael Mahony, Eugene D Mason, Jane Melville, Nicola J. Mitchell, Madeline Mutton, David Newell, Kate O'Hara, Paul M Oliver, Sally Potter, Jodi J. L. Rowley, Benjamin Scheele, Glenn M. Shea, Joanna Sumner, Renee A. Catullo

The use of genetic analyses has become ubiquitous in conservation planning and management.

Typically, such analyses are employed at the species-level, though as genetic data accrue, it is now

possible to consider the genetic composition of multiple species across landscapes. Such macrogenetic

perspectives can reveal the potential genetic ramifications of extreme disturbance events, such as the

catastrophic Australian ‘Black Summer’ wildfires of 2019–2020. This event severely impacted

forested habitats and fauna across much of eastern Australia – but whether there were differential

impacts upon genetically distinct populations, or a significant erosion of high diversity populations

across species, was not known. Here, we present a conservation macrogenetics framework to examine

the potential genetic impacts of this large-scale disturbance. Using hundreds of samples spanning

dozens of frog, mammal, and reptile species, we first demonstrate how reduced-representation

sequencing can be aggregated across species to describe the distribution of genetic diversity across a

landscape. We then show that, whilst variable across the study area, these unprecedented fires

generally burned areas where genetic diversity of sampled taxa was higher than for areas remaining

unburned. Additionally, areas with high concentrations of evolutionarily distinct and short-range

species were disproportionally represented in burned regions, and potential cross-taxonomic adverse

effects were greatest in Australia’s southeast and central eastern seaboard regions. More broadly, our

work demonstrates how the conservation genetics principles applied at a species level can be

expanded to landscapes, whilst accounting for the challenges that arise when aggregating across

taxonomic groups, thus improving our understanding of the overall impacts of large-scale disturbance

events upon genetic diversity.