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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03461

    Low internal transcribed spacer rDNA variation in New Zealand Bonamia ostreae: evidence for a recent arrival

    Henry S. Lane*, J. Brian Jones

    *Corresponding author:

    ABSTRACT: Bonamia ostreae is a haplosporidian parasite of oysters that was first reported in 2015 to occur in the Southern Hemisphere in the New Zealand flat oyster Ostrea chilensis. Until that report, B. ostreae had been restricted to populations of Ostrea edulis within the Northern Hemisphere. This large range extension raised questions regarding B. ostreae dispersal including whether B. ostreae is a recent introduction and from where it originated. The whole 18S rRNA gene of New Zealand B. ostreae revealed 99.9–100% sequence homology to other published B. ostreae 18S rDNA sequences. Internal transcribed spacer (ITS) rDNA sequences (n = 29) were generated from New Zealand B. ostreae and compared to published B. ostreae sequences from three Northern Hemisphere sites: California, USA (CA) (n = 18), Maine, USA (ME) (n = 7), and the Netherlands (NED) (n = 6) to investigate intraspecific variation. Low ITS rDNA variation was observed from New Zealand B. ostreae isolates and high levels of variation were observed from Northern Hemisphere B. ostreae sequences. It is hypothesised that the low ITS rDNA diversity found in New Zealand B. ostreae is the result of a founder effect resulting from a single introduction from a limited number of propagules. The high level of ITS rDNA variation from the Northern Hemisphere prevented inferences of dispersal origins. New Zealand B. ostreae were genetically differentiated from all sites and additional genetic data is required to better determine the origin of B. ostreae in New Zealand.