Cryptic diversity within the harmful dinoflagellate Akashiwo sanguinea in coastal Chinese waters is related to differentiated ecological niches
|Author(s)||Luo Zhaohe1, Yang Weidong2, Leaw Chui Pin3, Pospelova Vera4, Bilien Gwenael5, Liow Guat Ru3, Lim Po Teen3, Gu Haifeng1|
|Affiliation(s)||1 : SOA, Inst Oceanog 3, Xiamen 361005, Peoples R China.
2 : Jinan Univ, Coll Life Sci & Technol, Guangzhou 510632, Guangdong, Peoples R China.
3 : Univ Malaya, Inst Ocean & Earth Sci, Bachok Marine Res Stn, Bachok 16310, Kelantan, Malaysia.
4 : Univ Victoria, Sch Earth & Ocean Sci, OEASB A405,POB 1700 16 STN CSC, Victoria, BC V8W 2Y2, Canada.
5 : IFREMER, LER BO, Stn Biol Marine, Pl Croix,BP40537, F-29185 Concarneau, France.
|Source||Harmful Algae (1568-9883) (Elsevier Science Bv), 2017-06 , Vol. 66 , P. 88-96|
|WOS© Times Cited||6|
|Keyword(s)||Biogeography, Cryptic species, Gymnodinium sanguineum, Seasonal occurrence, Speciation|
Blooms of the harmful dinoflagellate Akashiwo sanguinea are responsible for the mass mortality of fish and invertebrates in coastal waters. This cosmopolitan species includes several genetically differentiated clades. Four clonal cultures were established by isolating single cells from Xiamen Harbour (the East China Sea) for morphological and genetic analyses. The cultures displayed identical morphology but were genetically different, thus revealing presence of cryptic diversity in the study area. New details of the apical structure complex of Akashiwo sanguinea were also found. To investigate whether the observed cryptic diversity was related to environmental differentiation, 634 cells were obtained from seasonal water samples collected from 2008 to 2012. These cells were sequenced by single-cell PCR. For comparison with Chinese material, additional large subunit ribosomal DNA sequences were obtained for three established strains from Malaysian and French waters. To examine potential ecological differentiation of the distinct genotypes, growth responses of the studied strains were tested under laboratory conditions at temperatures of 12 °C to 33 °C. These experiments showed four distinct ribotypes of A. sanguinea globally, with the ribotypes A and B co-occuring in Xiamen Harbour. Ribotype A of A. sanguinea was present year-round in Xiamen Harbour, but it only bloomed in the winter and spring, thus corresponding to the winter type. In contrast, A. sanguinea ribotype B bloomed only in the summer, corresponding to the summer type. This differentiation supports the temperature optimum conditions that were established for these two ribotypes in the laboratory. Ribotype A grew better at lower temperatures compared to ribotype B which preferred higher temperatures. These findings support the idea that various ribotypes of A. sanguinea correspond to distinct ecotypes and allopatric speciation occurred in different climatic regions followed by dispersal.