Evolution and biogeography of the Zanclea-Scleractinia symbiosis

Abstract
Abstract Scleractinian corals provide habitats for a broad variety of cryptofauna, which in turn may contribute to the overall functioning of coral symbiomes. Among these invertebrates, hydrozoans belonging to the genus Zanclea represent an increasingly known and ecologically important group of coral symbionts. In this study, we analysed 321 Zanclea colonies associated with 31 coral genera collected from 11 localities across the Indo-Pacific and Caribbean regions, and used a multi-disciplinary approach to shed light on the evolution and biogeography of the group. Overall, we found high genetic diversity of hydrozoans that spans nine clades corresponding to cryptic or pseudo-cryptic species. All but two clades are associated with one or two coral genera belonging to the Complex clade, whereas the remaining ones are generalists associated with both Complex and Robust corals. Despite the observed specificity patterns, no congruence between Zanclea and coral phylogenies was observed, suggesting a lack of coevolutionary events. Most Zanclea clades have a wide distribution across the Indo-Pacific, including a generalist group extending also into the Caribbean, while two host-specific clades are possibly found exclusively in the Red Sea, confirming the importance of this peripheral region as an endemicity hotspot. Ancestral state reconstruction suggests that the most recent common ancestor of all extant coral-associated Zanclea was a specialist species with a perisarc, occurring in what is now known as the Indo-Pacific. Ultimately, a mixture of geography- and host-related diversification processes is likely responsible for the observed enigmatic phylogenetic structure of coral-associated Zanclea.

Citation
Maggioni, D., Arrigoni, R., Seveso, D., Galli, P., Berumen, M. L., Denis, V., … Montano, S. (2020). Evolution and biogeography of the Zanclea-Scleractinia symbiosis. Coral Reefs. doi:10.1007/s00338-020-02010-9

Acknowledgements
The authors wish to thank all the people involved in collecting material or organising sampling campaigns: Tullia Isotta Terraneo (KAUST, Saudi Arabia), Malek Amr Gusti (KAUST, Saudi Arabia), Timothy Ravasi (OIST, Japan), the captain and crew of the MV Dream-Master (Saudi Arabia), the KAUST Coastal and Marine Resources Core Lab, Inga Dehnert (UNIMIB, Italy), Nicholas WL Yap (NUS, Singapore), Sudhanshi S Jain (NUS, Singapore), Stephen Keable (Australian Museum), Penny Berents (Australian Museum), Anne Hoggett (Australian Museum), Lyle Vail (Australian Museum), Masayuki Tamae (Marine Space, Japan), Hiroki Nakakouji (Marine Space, Japan), Yoshihiro Katsushima (Win Diving, Japan), Yuting V Lin (IONTU, Taiwan), Jian-Wen Chen (IONTU, Taiwan), and staff at the Green Island Marine Research Station (Taiwan) and Academia Sinica (Taiwan). Permissions relevant to undertake the research have been obtained from the applicable governmental agencies. The work was partially funded by PADI Foundation Grants #28634 and #14384 to DM and SM, and baseline research funds of PG and MLB. Samples from Eilat (Israel) were collected during the HyDRa Project funded by the EU FP7 Research Infrastructure Initiative ‘ASSEMBLE’ (Grant #227799) to DP. Samples from Ludao (Taiwan) were collected under the permit #1060174405 issued by Taitung County Government with the support of a grant from the Ministry of Science and Technology of Taiwan (#106-2611-M-002-008) to VD. Financial support to DP for collecting samples at Lizard Island (Australia) was provided by the 2018 John and Laurine Proud Fellowship and the Australian Museum’s Lizard Island Research Station. Fieldwork in Singapore was partially funded by the National Research Foundation, Prime Minister's Office, Singapore under its Marine Science R&D Programme (MSRDP-P03) to DH.

Publisher
Springer Nature

Journal
Coral Reefs

DOI
10.1007/s00338-020-02010-9

Additional Links
http://link.springer.com/10.1007/s00338-020-02010-9

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