Depth specialization in mesophotic corals ( Leptoseris spp.) and associated algal symbionts in Hawai'i

Abstract

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.

The New Systematics of Scleractinia: Integrating Molecular and Morphological Evidence

“…These include amplifications of the Pax-C intron (van Oppen et al 2001(van Oppen et al , 2004Márquez et al 2002;Richards et al 2008Richards et al , 2013, β-tubulin (Fukami et al 2004b;Stefani et al 2008a), ITS (Medina et al 1999;van Oppen et al 2000Diekmann et al 2001;Rodriguez-Lanetty and Hoegh-Guldberg 2002;Márquez et al 2003;Chen et al 2004;Vollmer and Palumbi 2004;Forsman et al 2005Forsman et al , 2006Forsman et al , 2009Forsman et al , 2010Forsman et al , 2015Wei et al 2006;Stefani et al 2011;Kitano et al 2013Kitano et al , 2014, and 28S rDNA Cuif et al 2003;Wolstenholme et al 2003). For regions that have not diverged considerably between paralogues, such as the ITS, mixed PCR products can be split into two dominant sequences based on phase reconstruction of forward and reverse chromatograms of distinct lengths (Flot and Tillier 2006;Flot et al 2006).…”

“…The noncoding intergenic region identified by Fukami et al (2004a), for instance, was too variable to be aligned across all of Merulinidae (Huang et al 2011) and is not orthologous with the intergenic region (or the putative control region) in Acropora (van Oppen et al 2001;Wolstenholme 2004;Richards et al 2008Richards et al , 2013, Montipora (van Oppen et al 2004;Forsman et al 2010), Porites (Forsman et al 2009) or Agariciidae (Luck et al 2013;Pochon et al 2015). These fast-evolving mitochondrial markers remain useful for phylogenetic studies among closely-related species.…”

Fluorescent proteins in dominant mesophotic reef-building corals

“…samples selected in this study were a subset of a more detailed host/symbiont genetic study (Pochon et al 2015). To address the high cryptic diversity in the genus Leptoseris (Luck et al 2013), we used the fast-evolving mitochondrial marker cox1-1-rRNA intron to assign host species following the protocol of Luck et al (2013).…”

Deep in shadows, deep in time: the oldest mesophotic coral ecosystems from the Devonian of the Holy Cross Mountains (Poland)

“…Photosymbiotic corals, however, occur much deeper than the 30 m broadly recognized as the lower depth limit of reefs (e.g., Fricke and Meischner 1985;Bridge et al 2011). Below 30 m, where light attenuation is stronger, zooxanthellate corals can still form reefs and many zooxanthellate species are known below the depth limit of 100 m (e.g., Dinesen 1980;Pochon et al 2015). The deepest zooxanthellates occur even below 150 m, as in the case of Leptoseris papyracea (e.g., Lesser et al 2009;Slattery et al 2011).…”