Genotyping an Emiliania huxleyi (prymnesiophyceae) bloom event in the North Sea reveals evidence of asexual reproduction
Genotyping an Emiliania huxleyi (prymnesiophyceae) bloom event in the North Sea reveals evidence of asexual reproduction
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DOI：
10.5194/bg-11-5215-2014
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发表时间：
2014-01-01
期刊：
影响因子：
4.9
通讯作者：
Schroeder, D. C.
中科院分区：
文献类型：
--
作者：
Krueger-Hadfield, S. A.;Balestreri, C.;Schroeder, D. C.
由于气候变化的速度前所未有，许多物种的最终后果可能是灭绝或迁移到其他栖息地。然而，某些物种的进化速度可能使它们能够适应快速变化的环境的影响。这种情况最有可能适用于种群规模大、世代时间短的物种，因此可以很容易地提供适应性进化所需的遗传变异。 Emiliania huxleyi (Lohm.) Hay and Mohler (Prymnesiophyceae) 很可能就是这样一个物种，因为它是我们海洋中现存最显着的钙质浮游植物物种，生长率为 1 天(-1)。在这里，我们报告了一组经过验证的微卫星，结合颗石藻形态基序遗传标记，对从世界各地收集的 93 个克隆分离株进行基因分型。其中，52 个来自于 2011 年 6 月至 7 月在 D366 英国海洋酸化巡航中收集的北海单一水华事件。有 26 个多位点基因型 (MLG) 在北海水华中只遇到过一次，8 个 MLG 遇到过两次或最多六次。这些重复的 MLG 中的每一个都表现出小于 0.05 的 P 性别值，表明每个重复的 MLG 都是无性繁殖的产物，而不是单独的减数分裂事件。此外，我们还发现两个最具多态性的微卫星位点 EHMS37 和 P01E05 正在报告无性繁殖期间可能经历快速遗传漂移的区域。尽管样本量很小，但与之前报道的其他水华形成浮游植物物种相比，重复基因型要多得多，包括之前基因分型的赫胥氏埃氏藻水华事件。这项研究挑战了目前有性繁殖在开花事件中占主导地位的假设。虽然赫胥黎现存种群的遗传多样性很高，但这种多样性的根本原因和这些种群的最终命运仍然需要进一步研究。尽管如此，我们发现某些 CMM 基因型随处可见，而其他基因型似乎存在区域偏差。
Due to the unprecedented rate at which our climate is changing, the ultimate consequence for many species is likely to be either extinction or migration to an alternate habitat. Certain species might, however, evolve at a rate that could make them resilient to the effects of a rapidly changing environment. This scenario is most likely to apply to species that have large population sizes and rapid generation times, such that the genetic variation required for adaptive evolution can be readily supplied. Emiliania huxleyi (Lohm.) Hay and Mohler (Prymnesiophyceae) is likely to be such a species, as it is the most conspicuous extant calcareous phytoplankton species in our oceans with growth rates of 1 day(-1). Here we report on a validated set of microsatellites, in conjunction with the coccolithophore morphology motif genetic marker, to genotype 93 clonal isolates collected from across the world. Of these, 52 came from a single bloom event in the North Sea collected on the D366 United Kingdom Ocean Acidification cruise in June-July 2011. There were 26 multilocus genotypes (MLGs) encountered only once in the North Sea bloom and 8 MLGs encountered twice or up to six times. Each of these repeated MLGs exhibited P-sex values of less than 0.05, indicating each repeated MLG was the product of asexual reproduction and not separate meiotic events. In addition, we show that the two most polymorphic microsatellite loci, EHMS37 and P01E05, are reporting on regions likely undergoing rapid genetic drift during asexual reproduction. Despite the small sample size, there were many more repeated genotypes than previously reported for other bloomforming phytoplankton species, including a previously genotyped E. huxleyi bloom event. This study challenges the current assumption that sexual reproduction predominates during bloom events. Whilst genetic diversity is high amongst extant populations of E. huxleyi, the root cause for this diversity and ultimate fate of these populations still requires further examination. Nonetheless, we show that certain CMM genotypes are found everywhere, while others appear to have a regional bias.