Research
My research incorporates three major overlapping directions:
Helmeted Honeyeater photo by Peter Menkhorst
Incorporating evolutionary processes in species management
As a co-leader of Genetic Rescue project team, I am investigating how new genomic tools can assist us in better population management of threatened species. Our outreach article in Scientia outlines main concepts and showcases some examples of our current work on genetic management.
Our previous work on Birds in Fragmented Landscapes project yielded many useful conservation inferences and recommendations, summarized in Radford et al. 2021. We showed that habitat fragmentation can disrupt dispersal, gene flow, mate choice and communication even in relatively mobile common species, leading to genetic isolation of small fragmented populations, loss of genetic diversity and increased relatedness between individuals. In Amos et al. (2014) we showed that these effects can be hard to predict, because they can depend on sex- and species-specific dispersal abilities, extent of remnant habitat, and species biology.
Using examples, such as Macquarie perch (Pavlova et al 2017), helmeted honeyeater (Harrisson et al. 2016 and 2019) and Leadbeater's possum (Zilko et al. 2020) we showed that, left to their own devices, small and isolated populations of formerly widespread species will develop genetic health problems including loss of genetic diversity, inbreeding, inbreeding depression and loss of adaptive potential.
In our perspective (Harrisson et al. 2014) we make the case that maximizing genome-wide genetic diversity might be currently the most reliable way to improve populations’ ability to adapt to environmental change. Using empirical data we show that combining genetically compatible stocks is likely to benefit restoration of wildlife populations, even if one of the sources appears to be less fit (Lutz et al. 2021).
Thus, to reverse population declines and moderate the effects of climate change we need management solutions promoting gene flow. Assisted gene flow can be implemented in cases where natural gene flow is impossible.
Managers are taking our ideas on board:
· National Recovery Plan for the Macquarie Perch incorporates our recommendations (from Pavlova et al 2017)
· For Macquarie perch, cross-river pairs are used in the breeding program for stocking, fish are translocated from different rivers into the rehabilitated Ovens River (Lutz et al. 2021), and Cotter River population is supplemented by fish from Cataract Dam.
· Assisted gene flow from another subspecies is now endorsed by the Helmeted Honeyeater Recovery Team and now successfully implemented in captivity (Pavlova et al. 2023) and releases to the wild by Zoos Victoria and Department of Environment, Land, Water and Planning.
In collaboration with other researchers and wildlife managers we are producing high quality genomic resources to enable cutting-edge conservation genomics research. This include genome assemblies (Pavlova et al. 2021), including chromosomal-length ones accompanied by linkage map (Robledo-Ruiz et al. 2022) and tools for rapid processing of genomic data (Robledo-Ruiz 2023). These resources will be used to get the right balance between fixing the damage caused by inbreeding while retaining unique features of threatened populations under genetic rescue, as explained in this media release.
Understanding evolutionary history of biota to inform conservation efforts
Understanding the evolutionary drivers of spatial distribution of species and their lineages is essential for efficient conservation, and underlies our ability to predict future changes. Molecular tools can help us to uncover essential processes driving distribution of genetic diversity, including timing of population divergence, gene flow and selection.
Since my PhD on phylogeography of Holarctic and Eurasian birds with Prof Bob Zink, I have been using phylogeographic and population genetic tools to explore evolutionary history of birds, fish, mammals, invertebrates and plants.
For example, in Pavlova et al (2014) we asserted conservation merit of the helmeted honeyeater and recommended gene flow from a neighbouring subspecies to reverse decline in genetic diversity. In Lamb et al (2019) we explored the grey shrike thrush evolutionary history to show that new geographic barriers may drive divergence of the sedentary sex while the more dispersive sex continues to connect populations. In eastern yellow robin study Morales et al (2017) we demonstrate that environmental selection can also differently impact the sexes and, thus, the two genomes in animal cells. See Publications page for more examples.
Grey shrike-thrush photo by Chris Tzaros
Eastern yellow robin photo by Geoff Park
Understanding climatic adaption of wildlife
Together with many genes of nuclear genome, mitochondrial genome co-encodes and regulates protein machinery responsible for energy transformation and transduction in most eukaryotic cells. Thus, mito-nuclear genotypes could be a target for climate-driven selection.
In Lamb et al. (2018) we showed that mitochondrial lineages are associated with climate for half of the Australian songbirds studied. Molecular signatures of selection on mtDNA suggest that climate could be the major driver of mitochondrial evolution in some species.
In Pavlova et al. (2013), we discovered two divergent mitochondrial lineages in the eastern yellow robin that were associated with more arid inland vs more temperate coastal climates, despite generally north-south structure of the nuclear genome. This mito-nuclear discordance was likely driven by climate-linked female-limited natural selection. In a follow-up Morales et al (2018) study we discovered a diverged part of nuclear genome that co-evolved and co-introgressed with these mitochondrial lineages. In Gan et al. (2019) we show that chromosomal rearrangements involving sex chromosomes underlie sex-specific patterns of selection in robins and may facilitate climatic adaptation by linking nuclear genes with mitochondrial function to respective mitonuclear genome variants. See Eastern Yellow Robin project website for more information on current work, this link for some press coverage of mito-nuclear evolution and this link for the blog on discovery of neo-sex chromosomes in the eastern yellow robin.