Changes in soil microbial communities in post mine ecological restoration: Implications for monitoring using high throughput DNA sequencing.

The ecological restoration of ecosystem services and biodiversity is a key intervention used to reverse the impacts of anthropogenic activities such as mining. Assessment of the performance of restoration against completion criteria relies on biodiversity monitoring. However, monitoring usually overlooks soil microbial communities (SMC), despite increased awareness of their pivotal role in many ecological functions. Recent advances in cost, scalability and technology has led to DNA sequencing being considered as a cost-effective biological monitoring tool, particularly for otherwise difficult to survey groups such as microbes. However, such approaches for monitoring complex restoration sites such as post-mined landscapes have not yet been tested. Here we examine bacterial and fungal communities across chronosequences of mine site restoration at three locations in Western Australia to determine if there are consistent changes in SMC diversity, community composition and functional capacity. Although we detected directional changes in community composition indicative of microbial recovery, these were inconsistent between locations and microbial taxa (bacteria or fungi). Assessing functional diversity provided greater understanding of changes in site conditions and microbial recovery than could be determined through assessment of community composition alone. These results demonstrate that high-throughput amplicon sequencing of environmental DNA (eDNA) is an effective approach for monitoring the complex changes in SMC following restoration. Future monitoring of mine site restoration using eDNA should consider archiving samples to provide improved understanding of changes in communities over time. Expansion to include other biological groups (e.g. soil fauna) and substrates would also provide a more holistic understanding of biodiversity recovery.

Fine-scale species distribution modelling and genotyping by sequencing to examine hybridisation between two narrow endemic plant species.

Hybridization has an important and often positive role in plant evolution. However, it can also have negative consequences for species. Two closely related species of Ornduffia are endemic to the Porongurup Range in the South West Australian Global Biodiversity Hotspot. The rare Ornduffia calthifolia is found exclusively on the summits, while O. marchantii is more widely dispersed across a greater range of elevation and is not considered threatened. Hybridisation in suitable overlapping habitat has been suspected between them for decades. Here we combine genotyping by sequencing to verify hybridisation genetically, and fine scale (2 m resolution) species distribution modelling (SDM) to test if hybrids occur in suitable intersecting habitat. From a study area of c. 4700 ha, SDM identified c. 275 ha and c. 322 ha of suitable habitat for O. calthifolia and O. marchantii, respectively. We identified range overlap between species of c. 59 ha), which enveloped 32 individuals confirmed to be hybrids. While the hybrids were at the margin of suitable habitat for O. marchantii, their preference for elevated habitat was closer to the more narrowly distributed O. calthifolia. The combination of genetic data and fine scale spatial modelling approaches enabled a better understanding of hybridisation among taxa of conservation significance. However, the level to which hybrid proliferation and competition for habitat presents as a threat to O. calthifolia is currently unknown and requires priority in conservation management given the threats from global warming and disturbance by tourism.