Abstract
In this study we compared genotypes of zoantharian host-associating algal symbionts among Palythoa species, which are among the dominant benthic reef organisms in the Ryukyu Archipelago, Japan, and evaluated Symbiodiniaceae diversities of closely related congeneric Palythoa species. We targeted a species complex of the zoantharian genus Palythoa (P. tuberculosa, P. sp. yoron, P. mutuki) living among different microhabitats in a narrow reef area of Tokunoshima Island. For phylogenetic analyses, we used two DNA marker regions; nuclear internal transcribed spacer (ITS) and plastid mini-circle non-coding region (psbAncr), both of which have previously been used to determine Symbiodiniaceae genotypes of zoantharian species. Our results showed that all Palythoa species hosted symbionts of the genus Cladocopium, with genotypic compositions of this genus showing some variations among the three different Palythoa species. Additionally, we found that the Cladocopium genotypic composition was statistically different among Palythoa species, and among P. tuberculosa specimens in different microhabitats. Our results suggest that ecological divergence among these three Palythoa species may be related to differing Symbiodiniaceae diversities that may in turn contribute to eco-physiological adaptation into different microhabitats on coral reefs.
Highlights
Zoantharians (Anthozoa: Zoantharia) belong to the phylum Cnidaria and can be dominant organisms in shallow coral reef areas (e.g., Burnett et al, 1994)
We recently reported on four putative Palythoa species (P. tuberculosa, P. sp. yoron, P. mutuki, and P. aff. mutuki) that form a species complex, and were observed to all occur within a narrow range of coral reefs in southern Japan (Mizuyama, Masucci & Reimer, 2018)
The total number of sequences of Symbiodiniaceae from specimens of the four Palythoa species obtained in this study was 98 sequences for the internal transcribed spacer (ITS)-rDNA region (513–773 bp), sequences for the psbAncr forward region (330–547 bp), and sequences for the psbAncr reverse region (352–494 bp)
Summary
Zoantharians (Anthozoa: Zoantharia) belong to the phylum Cnidaria and can be dominant organisms in shallow coral reef areas (e.g., Burnett et al, 1994). Molecular delineation of these Palythoa species groups was unsuccessful with molecular data, likely due to incomplete lineage sorting, they can be distinguished via morphological and reproductive data (Mizuyama, Masucci & Reimer, 2018). These Palythoa species display different microhabitat patterns within the coral reef, but it is still unclear how these species would have diversified under almost completely sympatric conditions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
