Assessing phylodiversity spatial patterns of Southern Ocean fauna for biodiversity conservation

CCAMLR has taken on an important role in the world oceans conservation planning and has agreed to develop a representative system of MPAs (RSMPA) based on the best available science in the Southern Ocean. The RSMPA aims to protect ecosystem processes and biodiversity, and to promote research. Here we explore phylodiversity measures at the Southern Ocean scale to include historical perspective in our future assessment of climate change impact on biodiversity. To map the cross-taxon phylogenetic diversity, we used species distribution data obtained from public occurrences databases GBIF and OBIS and phylogenetic trees of ray-finned fish, sea spiders and brittle stars. We calculated the phylogenetic diversity standardized by species richness and phylogenetic beta diversity to determine geographically cohesive phyloregions. We use rarefaction and extrapolation methods to reduce substantial differences in sampling effort across the Southern ocean areas and thus account for sampling bias. We identified individual hotspots and coldspots of phylogenetic diversity as well as complementary hotspots maximizing phylodiversity they represent and assessed the extent to with RSMPA of the Southern ocean cover these hotspots. We show that existing and proposed MPAs will protect a significant proportion of phylodiversity when implemented fully, but also that a significant proportion of phylodiversity would also fall outside RSMPA boundaries. Future efforts should focus on collecting, sequencing and databasing marine Antarctic fauna species to diminish sampling bias influencing conservation measures.