A tale of two chitons: is habitat specialisation linked to distinct associated bacterial communities?
A tale of two chitons: is habitat specialisation linked to distinct associated bacterial communities?
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DOI：
10.1111/1574-6941.12014
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发表时间：
2013-03-01
影响因子：
4.2
通讯作者：
Zbinden, Magali
中科院分区：
文献类型：
--
作者：
Duperron, Sebastien;Pottier, Marie-Anne;Zbinden, Magali
虽然大多数石鳖是浅水软体动物，但深海栖息地也有种类繁多的种类。我们调查了在西太平洋靠近瓦努阿图群岛的沉没木材上发现的两个物种--Leptochon Boucheti和Nierstraszella lineata的摄食策略。这两个物种与细菌伙伴表现出明显不同的联系。布氏细长壳虫在其肠道上皮的某些区域内藏有翻车鱼，其鳃上没有丰富的细菌。Nierstraszella lineata没有显示密集的肠道相关细菌，但其鳃上皮上附着着细菌丝，与食木的Pectinodonta sp的鳃中发现的三角洲蛋白细菌共生有关。稳定的碳和氮同位素特征以及没有纤维素分解活性证明了反对直接以木材为饲料的饮食；这两个物种都是木材食物网中的第二消费者。我们认为，与细菌伙伴的不同联系与这两个物种的生态位专门化有关。Nierstraszella lineata属于一个分类家族，仅限于沉没的木材，由于其与鳃相关的细菌，可能适应更多的缺氧条件。布氏细壳动物在系统发育上更接近于一种不是专门研究木材的祖先形式，本身可能更像是一种通才；这一观察结果与它与Mollicuts的联系是一致的，Mollicuts是一种细菌支系，由出现在几个后生动物门中的肠道相关细菌组成。
Although most chitons (Mollusca: Polyplacophora) are shallow-water molluscs, diverse species also occur in deep-sea habitats. We investigated the feeding strategies of two species, Leptochiton boucheti and Nierstraszella lineata, recovered on sunken wood sampled in the western Pacific, close to the Vanuatu Islands. The two species display distinctly different associations with bacterial partners. Leptochiton boucheti harbours Mollicutes in regions of its gut epithelium and has no abundant bacterium associated with its gill. Nierstraszella lineata displays no dense gut-associated bacteria, but harbours bacterial filaments attached to its gill epithelium, related to the Deltaproteobacteria symbionts found in gills of the wood-eating limpet Pectinodonta sp. Stable carbon and nitrogen isotope signatures and an absence of cellulolytic activity give evidence against a direct wood-feeding diet; both species are secondary consumers within the wood food web. We suggest that the distinct associations with bacterial partners are linked to niche specialisations of the two species. Nierstraszella lineata is in a taxonomic family restricted to sunken wood and is possibly adapted to more anoxic conditions thanks to its gill-associated bacteria. Leptochiton boucheti is phylogenetically more proximate to an ancestral form not specialised on wood and may itself be more of a generalist; this observation is congruent with its association with Mollicutes, a bacterial clade comprising gut-associated bacteria occurring in several metazoan phyla.