Genetic data and climate niche suitability models highlight the vulnerability of a functionally important plant species from south‐eastern Australia

Abstract

Habitat fragmentation imperils the persistence of many functionally important species, with climate change a new threat to local persistence due to climate niche mismatching. Predicting the evolutionary trajectory of species essential to ecosystem function under future climates is challenging but necessary for prioritizing conservation investments. We use a combination of population genetics and niche suitability models to assess the trajectory of a functionally important, but highly fragmented, plant species from south‐eastern Australia (Banksia marginata, Proteaceae). We demonstrate significant genetic structuring among, and high level of relatedness within, fragmented remnant populations, highlighting imminent risks of inbreeding. Population simulations, controlling for effective population size (Ne), suggest that many remnant populations will suffer rapid declines in genetic diversity due to drift in the absence of intervention. Simulations were used to demonstrate how inbreeding and drift processes might be suppressed by assisted migration and population mixing approaches that enhance the size and connectivity of remnant populations. These analyses were complemented by niche suitability models that predicted substantial reductions of suitable habitat by 2080; ~30% of the current distribution of the species climate niche overlaps with the projected distribution of the species climate niche in the geographic region by the 2080s. Our study highlights the importance of conserving remnant populations and establishing new populations in areas likely to support B. marginata in the future, and adopting seed sourcing strategies that can help populations overcome the risks of inbreeding and maladaptation. We also argue that ecological replacement of B. marginata using climatically suited plant species might be needed in the future to maintain ecosystem processes where B. marginata cannot persist. We recommend the need for progressive revegetation policies and practices to prevent further deterioration of species such as B. marginata and the ecosystems they support.

Genomic, Habitat, and Leaf Shape Analyses Reveal a Possible Cryptic Species and Vulnerability to Climate Change in a Threatened Daisy

“…Notably, both Olearia (FR) collection localities have high genetic differentiation between them, low genetic diversity, and high historical inbreeding. These findings are consistent with results from other recent genomic studies of threatened and endangered species [67][68][69]. As far as we know, this is a new finding, signalling the need for taxonomic description of this newly discovered genetic group and a conservation management strategy to be developed to ensure its survival.…”

“…Therefore, the strong differentiation in isolated collection localities is unsurprising. Similar patterns have been found in other threatened species [67,68]. For example, genomic analysis of the endangered Australian daisy (Rutidosis leptorrhynchoides) found strong genetic differentiation between geographically isolated collection localities [69].…”

Managing Genetic Diversity and Representation in Banksia marginata (Proteaceae) Seed Production Areas Used for Conservation and Restoration

“…High relatedness based on SSRs was detected in more than half of the remnants as well as when trees were pooled as wild and SPA populations. This result has also been observed in other remnants of this species [72]. The kinship estimates using the SNP dataset provided a much more nuanced understanding of the relationships among our remnant and SPA trees with many trees determined to be more closely related than full-sibs as a result of selfing or mating between close relatives.…”

“…Similar levels of genetic diversity were observed among these B. marginata remnants irrespective of whether SSRs or SNPs were analyzed. Our SSR genetic diversity measures are lower than those found for this species by [72] but this is likely due to the different SSR marker panels used in the two studies and because our study populations were considerably smaller and likely to have lower genetic diversity.…”

Genomic Approaches for Conservation Management in Australia under Climate Change

“…Furthermore, less resilient species with specific habitat requirements are becoming increasingly vulnerable due to shifts in their climatic niche. For example, only 30% of the current distribution of Banksia marginata , a highly fragmented but ecologically significant plant species, overlaps with the projected distribution under climate change by 2080 [ 50 ].…”