Cryptic diversity hides host and habitat specialization in a gorgonian-algal symbiosis
Cryptic diversity hides host and habitat specialization in a gorgonian-algal symbiosis
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DOI：
10.1111/mec.12808
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发表时间：
2014-07-01
影响因子：
4.9
通讯作者：
Coffroth, Mary Alice
中科院分区：
文献类型：
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作者：
Prada, Carlos;Mcilroy, Shelby E.;Coffroth, Mary Alice
浅水珊瑚虫是现代珊瑚礁的主要建造者，通过藻类共生体提高其代谢和钙化率。关于这些珊瑚虫-藻类组合是否在个体宿主的一生中具有灵活性，促进适应可塑性，或者是否密切相关，从而使宿主和共生体跨代共同进化，存在争议。考虑到藻类共生体的多样性和许多宿主物种的形态可塑性，任一伙伴内部的神秘变异可能会混淆对珊瑚虫-藻类关联的研究。在这里，我们使用核糖体、细胞器和核序列以及微卫星变异来研究常见的加勒比柳珊瑚及其藻类共生体的谱系之间的关系。柳珊瑚是一种广播产卵者，由两个最近分化的、遗传上不同的谱系组成，主要按深度分离。我们在加勒比海的三个地点跨越深度梯度对两个谱系的菌落进行了采样。我们发现每个宿主谱系都与独特的共生藻 B1/184 系统型相关。当宿主菌落相互移植时，宿主和共生体之间的这种关系得以维持，尽管也观察到了系统发育型内转换的情况。即使当两个伙伴的系统发育型都存在于中间深度时，宿主和共生体谱系之间的特异性仍然是绝对的。未被识别的神秘多样性可能掩盖宿主共生体的特异性，并改变互利关联中进化过程的推论。因此，共生特异性可能会导致两个伙伴的生态分歧，从而在珊瑚礁内产生物种多样性。
Shallow water anthozoans, the major builders of modern coral reefs, enhance their metabolic and calcification rates with algal symbionts. Controversy exists over whether these anthozoan-algae associations are flexible over the lifetimes of individual hosts, promoting acclimative plasticity, or are closely linked, such that hosts and symbionts co-evolve across generations. Given the diversity of algal symbionts and the morphological plasticity of many host species, cryptic variation within either partner could potentially confound studies of anthozoan-algal associations. Here, we used ribosomal, organelle and nuclear sequences, along with microsatellite variation, to study the relationship between lineages of a common Caribbean gorgonian and its algal symbionts. The gorgonian Eunicea flexuosa is a broadcast spawner, composed of two recently diverged, genetically distinct lineages largely segregated by depth. We sampled colonies of the two lineages across depth gradients at three Caribbean locations. We find that each host lineage is associated with a unique Symbiodinium B1/184 phylotype. This relationship between host and symbiont is maintained when host colonies are reciprocally transplanted, although cases of within phylotype switching were also observed. Even when the phylotypes of both partners are present at intermediate depths, the specificity between host and symbiont lineages remained absolute. Unrecognized cryptic diversity may mask host-symbiont specificity and change the inference of evolutionary processes in mutualistic associations. Symbiotic specificity thus likely contributes to the ecological divergence of the two partners, generating species diversity within coral reefs.