Comparative mitochondrial and chloroplast genomics of a genetically distinct form of <em>Sargassumem> contributing to recent “Golden Tides” in the Western Atlantic

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• 作者：Linda A. Amaral-Zettler ; Nicholas B. Dragone ; Jeffrey Schell ; Beth Slikas ; Leslie G. Murphy ; Clare E. Morrall and Erik R. Zettler
• 刊名：Ecology and Evolution
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：7
• 期：2
• 页码：516-525
• 全文大小：665K
• ISSN：2045-7758

文摘

Over the past 5 years, massive accumulations of holopelagic species of the brown macroalga <em>Sargassumem> in coastal areas of the Caribbean have created “golden tides” that threaten local biodiversity and trigger economic losses associated with beach deterioration and impact on fisheries and tourism. In 2015, the first report identifying the cause of these extreme events implicated a rare form of the holopelagic species <em>Sargassum natansem> (form <em>VIIIem>). However, since the first mention of <em>S. natans VIIIem> in the 1930s, based solely on morphological characters, no molecular data have confirmed this identification. We generated full-length mitogenomes and partial chloroplast genomes of all representative holopelagic <em>Sargassumem> species, <em>S. fluitans IIIem> and <em>S. natans Iem> alongside the putatively rare <em>S. natans VIIIem>, to demonstrate small but consistent differences between <em>S. natans Iem> and <em>VIIIem> (7 bp differences out of the 34,727). Our comparative analyses also revealed that both <em>S. natans Iem> and <em>S. natans VIIIem> share a very close phylogenetic relationship with <em>S. fluitans IIIem> (94- and 96-bp differences of 34,727). We designed novel primers that amplified regions of the <em>cox2em> and <em>cox3em> marker genes with consistent polymorphic sites that enabled differentiation between the two <em>S. natansem> forms (<em>Iem> and <em>VIIIem>) from each other and both from <em>S. fluitans IIIem> in over 150 <em>Sargassumem> samples including those from the 2014 golden tide event. Despite remarkable gene synteny and sequence conservation, the three <em>Sargassumem> forms differ in morphology, ecology, and distribution patterns, warranting more extensive interrogation of holopelagic <em>Sargassumem> genomes as a whole.