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Decoding the genetic landscape of subtropical Australian peatlands: Conservation genetics for short-range endemic invertebrates
Dissertation

Decoding the genetic landscape of subtropical Australian peatlands: Conservation genetics for short-range endemic invertebrates

Grace Smith
University of the Sunshine Coast, Queensland
Doctor of Philosophy, University of the Sunshine Coast, Queensland
2026
DOI:
https://doi.org/10.25907/01055
pdf
Thesis 3.15 MB
Thesis Embargoed Access, Embargo ends: 10-Dec-2026 CC BY-NC V4.0

Abstract

Freshwater ecology Invertebrate biology peat swamp K’gari invertebrates crayfish genetics barcoding DNA RNA fire biogeography
Understanding genetic and ecological relationships is a fundamental but often overlooked aspect of conservation biology. In the subtropical pyrophilic peatlands of eastern Australia, patterns of community, population and species diversity are poorly documented, limiting conservation information for threatened species, especially invertebrates. These ecosystems have been heavily cleared and degraded over recent decades as urban and agricultural development has expanded, much being lost before it was even properly documented. What remains is heavily threatened, and relatively little is understood about how these unique ecosystems function. Genetic approaches unlock a wealth of data that would otherwise be inaccessible, and we are increasingly seeing genetic data used to inform conservation decision making. This project used three biomolecular methods to describe the patterns of inter- and intra-species diversity of southeast Queensland's subtropical peatlands. At the community level, environmental DNA metabarcoding revealed an astonishing diversity of previously undocumented microfauna that appear to play vital roles in ecosystem functioning and trophic energy transfer. These included rotifers, gastrotrichs, and copepods functionally able to stabilise the ecosystem after disturbances such as fire with parthenogenic reproduction, rapid generation and desiccation-resistant dormancy. Looking across fragmented peatlands, population genetic analysis of the vulnerable endemic crayfish Cherax robustus showed that populations across disjunct sites have been isolated throughout the Holocene. This prolonged separation reinforces that each site harbours unique genetic diversity and should be managed as an independent sub-population. Comparative transcriptomics of key C. robustus tissues also reveals species-specific adaptions to the physiochemically harsh peat waters. Transcriptomic signatures showed adaptations to anoxia, ion dysregulation and toxicity, all critical requirements for survival in peat environments. We also identified metabolic pathways involved in digesting plant material and sulphur, helping to resolve the species diet and position within the food web. Together, these findings substantially improve our understanding of peatland functional ecology across scales of community composition, landscape evolution, and life history adaptation. These are key points of knowledge for ecosystems that remain severely understudied and lack baseline information. Like most ecosystems in southeast Queensland, these peatlands continue to face serious threats from encroaching urban development, ongoing degradation and altered fire regimes under a hotter and potentially drier future climate. Effective conservation requires understanding. In mapping the genetic landscape and uncovering undocumented diversity at both community and species levels, this project aims to support conservation efforts for these remarkable ecosystems. Based on the evidence provided, we recommend that any further clearing and drainage be prevented and all remaining habitat be protected against further degradation.

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