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Temporal Changes in Tasmanian Devil Genetic Diversity at Sites With and Without Supplementation

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Type: Journal article

Reference: Schraven, A.L., McLennan, E.A., Farquharson, K.A., Lee, A.V., Belov, K., Fox, S., Grueber, C.E. and Hogg, C.J. (2025), Temporal Changes in Tasmanian Devil Genetic Diversity at Sites With and Without Supplementation. Mol Ecol e17671. https://doi.org/10.1111/mec.17671

Abstract

Management interventions for threatened species are well documented with genetic data now playing a pivotal role in informing their outcomes. However, in situ actions like supplementations (releasing individuals into an existing population) are often restricted to a singular site. Considerable research and management effort have been dedicated to conserving the Tasmanian devil (Sarcophilus harrisii), offering a unique opportunity to investigate the temporal genetic consequences of supplementation at multiple sites, in comparison to outcomes observed in the absence of management interventions. Using 1,778 genome-wide SNPs across 1,546 individuals, we compared four wild-supplemented sites to four monitoring-only sites (not supplemented; control sites) over 9 years (2014–2022). At the study completion, genetic differentiation among supplemented sites had significantly decreased compared to among not-supplemented sites. We found statistically significant variation in genetic change over time between sites using linear mixed-effects modelling with random slopes. Investigating this among-site variation showed that three of the supplemented sites conformed to predictions that supplementations would have a positive impact on the genetic diversity of devils at these sites. We predicted no change over time at our fourth site due to the observed relatively high gene flow, however, this site did not align with predictions, instead showing decreased genetic diversity and increased relatedness. Amongst not supplemented sites, there was no consistent pattern of temporal genetic change, suggesting devil sites across Tasmania are highly heterogeneous, likely reflecting variation in site connectivity and genetic drift. Our study demonstrates that long-term concurrent monitoring of multiple sites, including controls, is necessary to contextualise the influence of management interventions on natural species fluctuations.

Global meta-analysis shows action is needed to halt genetic diversity loss

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Type: Journal article

Reference: Shaw, R.E., Farquharson, K.A., Bruford, M.W. et al. Global meta-analysis shows action is needed to halt genetic diversity loss. Nature 638, 704–710 (2025). https://doi.org/10.1038/s41586-024-08458-x

Abstract

Mitigating loss of genetic diversity is a major global biodiversity challenge. To meet recent international commitments to maintain genetic diversity within species, we need to understand relationships between threats, conservation management and genetic diversity change. Here we conduct a global analysis of genetic diversity change via meta-analysis of all available temporal measures of genetic diversity from more than three decades of research. We show that within-population genetic diversity is being lost over timescales likely to have been impacted by human activities, and that some conservation actions may mitigate this loss. Our dataset includes 628 species (animals, plants, fungi and chromists) across all terrestrial and most marine realms on Earth. Threats impacted two-thirds of the populations that we analysed, and less than half of the populations analysed received conservation management. Genetic diversity loss occurs globally and is a realistic prediction for many species, especially birds and mammals, in the face of threats such as land use change, disease, abiotic natural phenomena and harvesting or harassment. Conservation strategies designed to improve environmental conditions, increase population growth rates and introduce new individuals (for example, restoring connectivity or performing translocations) may maintain or even increase genetic diversity. Our findings underscore the urgent need for active, genetically informed conservation interventions to halt genetic diversity loss.

AMPed Up Immunity: 418 Whole Genomes Reveal Intraspecific Diversity of Koala Antimicrobial Peptides

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Type: Journal article

Reference: Petrohilos C, Peel E, Silver LW, Belov K, Hogg CJ. AMPed up immunity: 418 whole genomes reveal intraspecific diversity of koala antimicrobial peptides. Immunogenetics. 2025 Jan 8;77(1):11. doi: 10.1007/s00251-024-01368-2.

Abstract

Characterising functional diversity is a vital element to understanding a species’ immune function, yet many immunogenetic studies in non-model organisms tend to focus on only one or two gene families such as the major histocompatibility complex (MHC) or toll-like receptors (TLR). Another interesting component of the eukaryotic innate immune system is the antimicrobial peptides (AMPs). The two major groups of mammalian AMPs are cathelicidins and defensins, with the former having undergone species-specific expansions in marsupials. Here, we utilised data from 418 koala whole genomes to undertake the first comprehensive analysis of AMP diversity across a mammalian wildlife species’ range. Overall, allelic diversity was lower than other immune gene families such as MHC, suggesting that AMPs are more conserved, although balancing selection was observed in PhciDEFB12. Some non-synonymous SNPs in the active peptide are predicted to change AMP function through stop gains, change in structure, and increase in peptide charge. Copy number variants (CNVs) were observed in two defensins and one cathelicidin. Interestingly, the most common CNV was the duplication of PhciCATH5, a cathelicidin with activity against chlamydia, which was more common in the southern part of the species range than the north. AMP copy number is correlated with expression levels, so we hypothesise that there is a selective pressure from chlamydia for duplications in PhciCATH5. Future studies should use phenotypic metadata to assess the functional impacts of this gene duplication.

A Genomic-Based Workflow for eDNA Assay Development for a Critically Endangered Turtle, Myuchelys georgesi

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Type: Journal article

Reference: Nelson, H.V., Georges, A., Farquharson, K.A., McLennan, E.A., DeGabriel, J.L., Belov, K. and Hogg, C.J. (2025), A Genomic-Based Workflow for eDNA Assay Development for a Critically Endangered Turtle, Myuchelys georgesi. Ecol Evol, 15: e70798. https://doi.org/10.1002/ece3.70798

Abstract

Environmental DNA (eDNA) analysis has become a popular conservation tool for detecting rare and elusive species. eDNA assays typically target mitochondrial DNA (mtDNA) due to its high copy number per cell and its ability to persist in the environment longer than nuclear DNA. Consequently, the development of eDNA assays has relied on mitochondrial reference sequences available in online databases, or in cases where such data are unavailable, de novo DNA extraction and sequencing of mtDNA. In this study, we designed eDNA primers for the critically endangered Bellinger River turtle (Myuchelys georgesi) using a bioinformatically assembled mitochondrial genome (mitogenome) derived from a reference genome. We confirmed the accuracy of this assembled mitogenome by comparing it to a Sanger-sequenced mitogenome of the same species, and no base pair mismatches were detected. Using the bioinformatically extracted mitogenome, we designed two 20 bp primers that target a 152-base-pair-long fragment of the cytochrome oxidase 1 (CO1) gene and a 186-base-pair-long fragment of the cytochrome B (CytB) gene. Both primers were successfully validated in silico, in vitro, and in situ.

Holly Nelson

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Bilby release

Holly Nelson (PhD Student) worked on how we can use genomics to revolutionise threatened species management. From genome assembly to downstream analyses using whole-genome data, Holly used her work to answer genetic questions on the Bellinger River Snapping Turtle, Koala, and other threatened species. Her work, in partnership with the NSW Governments Saving Our Species program, aimed to create more robust conservation strategies that can be developed and applied together with wildlife managers.

A reference genome for the eastern bettong ( Bettongia gaimardi)

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Type: Journal article

Reference: Silver, L. W., Edwards, R. J., Neaves, L., Manning, A. D., Hogg, C. J., & Banks, S. (2025). A reference genome for the eastern bettong ( Bettongia gaimardi). F1000Research, 13, 1544. https://doi.org/10.12688/f1000research.157851.1

Abstract

The eastern or Tasmanian bettong ( Bettongia gaimardi) is one of four extant bettong species and is listed as ‘Near Threatened’ by the IUCN. We sequenced short read data on the 10x system to generate a reference genome 3.46Gb in size and contig N50 of 87.36Kb and scaffold N50 of 2.93Mb. Additionally, we used GeMoMa to provide and accompanying annotation for the reference genome. The generation of a reference genome for the eastern bettong provides a vital resource for the conservation of the species.

Beyond nutrition: Exploring immune proteins, bioactive peptides, and allergens in cow and Arabian camel milk

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Type: Journal article

Reference: M.W. Jayamanna Mohottige, A. Juhász, M.G. Nye-Wood, K.A. Farquharson, U. Bose, M.L. Colgrave. 2024. Beyond nutrition: Exploring immune proteins, bioactive peptides, and allergens in cow and Arabian camel milk. Food Chemistry, 467. 142471, 10.1016/j.foodchem.2024.142471.

Abstract

Bovine milk has dominated the dairy segment, yet alternative milk sources are gaining attention due to perceived superior health benefits, with immune proteins and bioactive peptides (BPs) contributing to these benefits. Fractionation affects protein recovery and composition. Here, the cream fraction resulted in the highest yield of proteins, identifying 1143 camel and 851 cow proteins. The cream fraction contained a significantly higher concentration of immune system-related proteins. Straightforward filtration and protein precipitation methods achieved average BP detections of 170 and 177, compared to 31 by a solvent-solvent extraction method. Considering potentially allergenic proteins, 53 (camel) and 52 (cow) were identified. Of these, 62 % of the potential allergens in cow, had orthologous counterparts in camel milk. However, the major milk allergen β-lactoglobulin (β-Lg) was not detected in camel milk. Our results provide a comprehensive proteomic resource of camel and cow milk products, mapping potential allergens and BPs that affect health.

Spatial variation in toll-like receptor diversity in koala populations across their geographic distribution

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Type: Journal article

Reference: Cui J, Batley KC, Silver LW, McLennan EA, Hogg CJ, Belov K. Spatial variation in toll-like receptor diversity in koala populations across their geographic distribution. Immunogenetics. 2024 Nov 30;77(1):5. doi: 10.1007/s00251-024-01365-5

Abstract

The koala (Phascolarctos cinereus) is an iconic Australian species that is listed as endangered in the northern parts of its range due to loss of habitat, disease, and road deaths. Diseases contribute significantly to the decline of koala populations, primarily Chlamydia and koala retrovirus. The distribution of these diseases across the species’ range, however, is not even. Toll-like receptors (TLRs) play a crucial role in innate immunity by recognising and responding to various pathogens. Variations in TLR genes can influence an individual’s susceptibility or resistance to infectious diseases. The aim of this study was to identify koala TLR diversity across the east coast of Australia using 413 re-sequenced genomes at 30 × coverage. We identified 45 single-nucleotide polymorphisms (SNP) leading to 51 alleles within ten TLR genes. Our results show that the diversity of TLR genes in the koala forms four distinct genetic groups, which are consistent with the diversity of the koala major histocompatibility complex (MHC), another key immune gene family. The bioinformatics approach presented here has broad applicability to other threatened species with existing genomic resources.

Genomics identifies koala populations at risk across eastern Australia

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Type: Journal article

Reference: McLennan, Elspeth A., Toby G. L. Kovacs, Luke W. Silver, Zhiliang Chen, Frederick R. Jaya, Simon Y. W. Ho, Katherine Belov, and Carolyn J. Hogg. 2025. “ Genomics Identifies Koala Populations at Risk across Eastern Australia.” Ecological Applications 35(1): e3062. https://doi.org/10.1002/eap.3062

Abstract

Koalas are an iconic, endangered, Australian marsupial. Disease, habitat destruction, and catastrophic mega-fires have reduced koalas to remnant patches of their former range. With increased likelihood of extreme weather events and ongoing habitat clearing across Australia, koala populations are vulnerable to further declines and isolation. Small, isolated populations are considered at risk when there is increased inbreeding, erosion of genomic diversity, and loss of adaptive potential, all of which reduce their ability to respond to prevailing threats. Here, we characterized the current genomic landscape of koalas using data from The Koala Genome Survey, a joint initiative between the Australian Federal and New South Wales Governments that aimed to provide a future-proofed baseline genomic dataset across the koala’s range in eastern Australia. We identified several regions of the continent where koalas have low genomic diversity and high inbreeding, as measured by runs of homozygosity. These populations included coastal sites along southeast Queensland and northern and mid-coast New South Wales, as well as southern New South Wales and Victoria. Analysis of genomic vulnerability to future climates revealed that northern koala populations were more at risk due to the extreme expected changes in this region, but that the adaptation required was minimal compared with other species. Our genomic analyses indicate that continued development, particularly linear infrastructure along coastal sites, and resultant habitat destruction are causing isolation and subsequent genomic erosion across many koala populations. Habitat protection and the formation of corridors must be employed for all koala populations to maintain current levels of diversity. For highly isolated koala populations, active management may be the only way to improve genomic diversity in the short term. If koalas are to be conserved for future generations, reversing their genomic isolation must be a priority in conservation planning.

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Making it through the final stretch of a PhD in conservation genomics and bioinformatics

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by Holly Nelson (PhD Student)

Entering the final stage of a PhD is both a marathon and a sprint. After a quick 3-4 years of terminal windows, countless hours coding, latex gloves, tweaking plots to the perfect shade of maroon (#B03060), and obsessing over a turtle species that lives a world away, the world could be ending, and honestly, I wouldn’t even know.

One surprising obsession? Table spacing. Somehow, this has become the hill I’m willing to die on. Not to mention after three and a half years into postgrad education, I still don’t know whether it should be a comma or a semicolon. Who knew this was the pinnacle of academic thought? Shout-out to my colleagues who don’t blink when I send them scripts named things like “goNe_analysis__fix6_final_FINAL_v10.pbs” (you know who you are), and to my long-suffering supervisors who’ve received my manuscript drafts entitled “Manuscript_turtle_final_DEFSFinal4_v12.docx.” And Andrea—my fellow PhDer-in-crime who has joined me on the adventure. There’s something comforting in having a fellow office mate who reaches a delusion level just as unhinged as yours.

Honestly, perspective is nearly impossible when your days blur together into one big troubleshooting session, often caused by a stray space somewhere in a 94-line code. But at the end of the day the completion of a PhD is less about perfection or about how many pages are in pdf document you’ve spent years creating, and more about progress. My folders and directories may look like a chaotic labyrinth, but hey, they’re a testament to something resembling progress—90% of it’s stuff that would’ve looked like rocket science to me a couple of years ago. It’s about stepping back, handing in, disappearing, and leaving the pandora’s box of questions you opened during your thesis for the poor Honours student.

To anyone on the journey, hang in there. Or don’t, drop out and open a bakery if you feel like it. Either way, you’re not alone in those late-night bursts of productivity, never ending imposter syndrome, praying that the laptop you’ve run into the ground turns on every morning, or that compulsive need to move the plot legend just 0.5mm more to the left.

You’re the world expert in whatever obscure and niche little thing it is you do, even if no one, including you, fully understands it. Hold onto the fact that your work probably means something, and if it doesn’t, well, at least it’s given you something to do for the last few years.

As my daily reminder sticky-note says “it’s not that serious”.

Bilby release

Holly Nelson (PhD Student) is working on how we can use genomics to revolutionise threatened species management. From genome assembly to downstream analyses using whole-genome data, Holly is using her work to answer genetic questions on the Bellinger River Snapping Turtle, Koala, and other threatened species. Her work, in partnership with the NSW Governments Saving Our Species program, aims to create more robust conservation strategies that can be developed and applied together with wildlife managers.

@hollyvnelson