DNA barcoding to enhance conservation of Sunshine Coast heathlands

Hilary Pearl

doi:10.25907/00750

Habitat loss resulting from human modification of landscapes has accelerated over the last 50 years resulting in declining biodiversity, and quality of life for people. In one of the fastest growing regions of Australia, the Sunshine Coast, the pre-European mosaic of wetlands, heathlands, woodlands, and rainforest has been transformed into an urbanised landscape. This study developed out of concern for the continued losses, and fragmentation of heathlands in the region. The Sunshine Coast heathlands matter; they contain endemic and endangered species, areas of peat, and people have been deeply connected to them for millennia. To inform the conservation and management of Sunshine Coast heathlands, this study aimed to use new tools to assess their diversity and distinctiveness, determine factors which correlate with the variation in their diversity, and assess their conservation status, including their extent, fragmentation, and connectivity. Novel approaches including phylogenetic metrics were used to explore the diversity values of the heathlands. Eighty sites were sampled over the nine mapped heath Regional Ecosystems, to obtain species lists, structural, and abiotic data. Accepted plant barcode markers, rbcL, matK, and trnH-psbA, were extracted from 385 samples of DNA collected from the 366 heath flora species. After editing, quality control, alignment, and utilising any missing sequences from the public database GenBank, the markers were concatenated, and a Sunshine Coast heath phylogeny was constructed, producing a dated tree with calibrated molecular branch lengths. Using this, phylogenetic metrics for the whole community, for the nine Regional Ecosystems and for individual sites were produced. To investigate patterns and similarities among site communities, pairwise dissimilarity matrices were calculated based on vegetation composition, and phylogenetic distance, and visualised using non-metric multidimensional scaling. Diversity metrics for the 80 Sunshine Coast heathland sites over a variety of substrates, moisture levels, and topographic factors were compared using univariate and multivariate statistics. The global FungalRoot database was used to calculate proportions of mycorrhizal functional groups. Using the Queensland Regional Ecosystem data, the status of the heathlands across the Sunshine Coast was calculated using the estimated pre-European and current remnant (2019) extent of the nine heath Regional Ecosystems, along with their current protection status. Mapping tools were used to assess the extent of fragmentation and connectivity of remaining heath patches, compared to estimated pre-clearing patterns, and diversity metrics were tested for correlation with the extent of heath habitat, patch size, and number. This study found the phylogeny and the low phylogenetic diversity of the heathlands compared to the surrounding rainforest, is consistent with the theory that heath species evolved on the fringes of a wider Australian rainforest flora. The results highlighted distinctive heathland communities including those of the rocky volcanic substrates, and “phylogenetically clustered” heaths of the high dunes. The overlapping composition of heath on wetter and alluvial substrates confirms in this study, the tolerance of many heath species to a variety of substrates. The study found the existence of geographically scattered, but compositionally similar “phylogenetically even” sites, associated with ancient mounds and trenches, which points to a possible “refugial environment”, and indicator species were hypothesised for these areas. Moisture was found in this study to be associated with the higher phylogenetic dispersion of these moist and wet sites. Proportions of mycorrhizal functional groups in the Sunshine Coast heathlands align with those found in low fertility heathlands elsewhere and suggest these biotic interactions may be contributing to community assembly. Of the pre-clearing extent, 62% of Sunshine Coast heathlands remain, but protection levels of heath Regional Ecosystems vary widely. There has been habitat loss and reduced patch size, but connectivity in terms of distance between patches remains stable. This study found higher phylogenetic dispersion is correlated with the amount of habitat and with the number of patches. Conservation and management implications suggested by this study include the protection of distinctive communities, and of dynamic processes in wet and alluvial “refugial environments”, with the management of hydrological changes due to climate change and urban development. The thesis concludes that within the matrix of heathlands remaining on the Sunshine Coast, an opportunity exists using whole of landscape planning, to protect their overall diversity, distinctiveness, and connectivity, using the evolving Regional Ecosystem mapping as a framework, the targeting of specific locations, and with the engagement of the local community and Indigenous custodians.

DNA barcoding to enhance conservation of Sunshine Coast heathlands

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