Onset of algal endosymbiont specificity varies among closely related species of Acropora corals during early ontogeny
Onset of algal endosymbiont specificity varies among closely related species of Acropora corals during early ontogeny
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DOI：
10.1111/j.1365-294x.2009.04276.x
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发表时间：
2009-08-01
影响因子：
4.9
通讯作者：
Willis, Bette L.
中科院分区：
文献类型：
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作者：
Abrego, David;Van Oppen, Madeleine J. H.;Willis, Bette L.
许多具有鞭毛内共生体水平传播的珊瑚幼体自然获得并维持与成年种群不同的共生类型。然而，这种早期共生体灵活性的持续时间和导致特征性成体（同源）类型优势的演替变化尚不清楚。为了记录共生菌类型在幼珊瑚体内的自然演替，我们对小Acropora tenuis和千孔Acropora幼珊瑚体内的共生菌群落进行了3.5年的监测。来自三个珊瑚礁种群之一的幼鱼，以不同的成年珊瑚共生关系为特征，在一个共同的环境中长大。在五分之四的案例中，幼体最初被非同源的成体类型所支配。与幼体相关的共生群落的变化导致在3.5岁左右形成成虫同源群落。这些变化与生殖成熟的开始无关，但可能与幼珊瑚垂直生长相关的微环境变化有关。我们假设，特异性机制的微调发生在棘猴个体发育过程中，最终导致了成虫同源关联的建立。然而，共生菌群落在3.5年的时间里没有显著变化，这可能反映了(i)缺乏特异性，（ii）特异性发生超过3.5年的延迟，或（iii）缺乏成虫共生菌类型的可用性。这项研究表明，幼珊瑚可以在非同源共生类型中存活很长一段时间，并且密切相关的Acropora物种在藻类共生体特异性开始的时间上有所不同。
Juveniles of a number of corals with horizontal transmission of dinoflagellate endosymbionts naturally acquire and maintain Symbiodinium types that differ from those found in adult populations. However, the duration of this early period of symbiont flexibility and successional changes leading to dominance by the characteristic adult (homologous) type are unknown. To document natural succession of Symbiodinium types within juvenile corals, we monitored Symbiodinium communities in juveniles of Acropora tenuis and Acropora millepora for 3.5 years. Juveniles originating from one of three reef populations, characterized by differing adult coral-Symbiodinium associations, were raised in a common environment. In four out of five cases, juveniles became dominated initially by a nonhomologous adult type. Changes in Symbiodinium communities associated with A. tenuis juveniles led to the establishment of the adult homologous association at similar to 3.5 years of age. These changes were not linked to the onset of reproductive maturity, but may be linked to micro-environmental changes associated with vertical growth of juvenile corals. We hypothesize that fine-tuning of specificity mechanisms takes place during ontogeny in A. tenuis, leading to the eventual establishment of the adult homologous association. However, Symbiodinium communities in A. millepora juveniles did not change significantly over the 3.5 years, potentially reflecting (i) lack of specificity, (ii) more than a 3.5-year delay in the onset of specificity, or (iii) lack of availability of the adult Symbiodinium type. This study demonstrates that juvenile corals may survive for extended periods of time with nonhomologous Symbiodinium types and that closely related species of Acropora differ in the timing of the onset of specificity for algal symbionts.