Alexandra Campbell

Restoration is an emerging intervention to reverse the degradation and loss of marine forests and the ecosystem services they underpin. Genetic characteristics of restored populations have the potential to greatly influence both short and long-term success, however this is rarely empirically examined within restoration projects. We used genomics to design a restoration program for lost forests of Phyllospora comosa, a dominant macroalga that went locally extinct from reefs off Sydney, Australia. Population genetic diversity and structure of extant populations informed choice of donor sites. We tested whether donor provenance influenced adult transplant survival, condition and the genetic characteristics of recruits at restoration sites. Donor provenance influenced survival and condition of transplanted adults and recruitment levels varied significantly among restoration sites. Yet, recruitment was rapid and genetic diversity and structure of the F1 generation resembled extant populations, suggesting the ability to “design” populations. We then used seascape genomics to characterise gene-environmental associations along Phyllospora’s entire latitudinal (12o latitude), and thermal (~14oC) range to screen for potential thermally-adapted genotypes that may be used in future-proofing efforts. Despite low diversity, range-edge populations are likely to harbour beneficial adaptations to marginal conditions and the overall adaptability of this species may be compromised by their loss. As restoration and the need to ‘future‐proof’ marine ecosystems increase globally, it will be critical to understand and harness the role of donor provenance, genetic diversity and structure to optimise restoration success.