Data from: Depth specialization in mesophotic corals (Leptoseris spp.) and associated algal symbionts in Hawai‘i

Corals at the lower limits of mesophotic habitats are likely to have
unique photosynthetic adaptations that allow them to persist and dominate
in these extreme low light ecosystems. We examined the host–symbiont
relationships from the dominant coral genus Leptoseris in mesophotic
environments from Hawai'i collected by submersibles across a depth
gradient of 65–125 m. Coral and Symbiodinium genotypes were compared with
three distinct molecular markers including coral (COX1–1-rRNA intron) and
Symbiodinium (COI) mitochondrial markers and nuclear ITS2. The
phylogenetic reconstruction clearly resolved five Leptoseris species,
including one species (Leptoseris hawaiiensis) exclusively found in deeper
habitats (115–125 m). The Symbiodinium mitochondrial marker resolved three
unambiguous haplotypes in clade C, which were found at significantly
different frequencies between host species and depths, with one haplotype
exclusively found at the lower mesophotic extremes (95–125 m). These
patterns of host–symbiont depth specialization indicate that there are
limits to connectivity between upper and lower mesophotic zones,
suggesting that niche specialization plays a critical role in
host–symbiont evolution at mesophotic extremes.