Mitochondrial haplotypes reveal low diversity and restricted connectivity in the critically endangered batoid population of a Marine Protected Area

Stability and long-term persistence of a species rely heavily on its genetic diversity, which is closely allied to their capacity for adaptation. In threatened species, population connectivity can play a major role in maintaining that diversity, and genetic assessments of their populations can be crucial for the design of effective spatial conservation management. Not only is it worth
evaluating the amount of diversity in a candidate population for protection, but the magnitude of outgoing gene flow can provide insight into their potential to replenish others via emigrants. While the critically endangered flapper skate Dipturus intermedius receives protection in the Loch Sunart to the Sound of Jura Marine Protected Area (MPA) in Scotland, there is insufficient knowledge of genetic diversity and connectivity across its range. Recent tagging studies in the MPA suggest the presence of animals with high levels of site fidelity and residency, as well as transient individuals, raising concerns of limited connectivity to populations beyond the MPA. A newly developed mitochondrial haplotype marker allowed use of DNA sourced from fin clips, mucus, and egg cases to investigate population structure and mitochondrial variability across several sites around the British Isles, including the MPA Unfortunately, this location was characterised by particularly low haplotype diversity and significant population differentiation from other sample sites. More than a quarter of its
individuals carry a haplotype rarely observed elsewhere, leaving outgoing gene flow questionable. The MPA appears unlikely to sustain the species´ existing mtDNA genetic diversity, or act as an effective source population