Phenotypic variation can lead to variation in the strength and outcome of species interactions. Variation in phenotypic traits can arise due to plastic responses to environmental stimuli, underlying genetic variation, or both, and may reflect differences in the focal organism or aspects of the extended phenotype (e.g., associated microbes). We used a reciprocal transplant experiment of Porites corals to evaluate the role of plasticity versus heritable diversity on phenotypic traits and performance of corals that varied in their prior exposure to vermetid gastropods, an organism known to reduce coral growth and survival. We measured a suite of phenotypic traits associated with coral performance, many of which showed a plastic response to vermetid exposure. Vermetids decreased calcification of corals, increased microbial diversity, and shifted microbial composition. Most traits also showed a signature of previous exposure environment that persisted even when exposure was reversed: i.e., under the same conditions, corals naïve to vermetids had slower calcification rates, thicker tissues, higher Symbiodiniaceae densities and different microbiomes than corals previously exposed to vermetids. We suggest the phenotypic differences are heritable, as reefs with and without vermetids were comprised of two different mitotypes, that revealed high, consistent genetic variation. Vermetids were only found on the fast-growing coral mitotype that was characterized by thin tissue, and that likely had a history of disturbance. As extended phenotypes can have community impacts, we suggest vermetid, in addition to microbes, are part of the extended community phenotype of these corals. Coral genotypes can establish different reef trajectories, with thin-tissue types more prone to disturbance and subsequent colonization by other species, like vermetids, which can further facilitate the degradation of coral reefs. The effects of the extended phenotype of species likely influence heterogeneity across landscapes as well as temporal differences in community composition.

中文翻译：

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珊瑚礁上的扩展表型：神秘的表型调节珊瑚-蚯蚓的相互作用

表型变异会导致物种相互作用的强度和结果发生变化。表型性状的变化可能是由于对环境刺激的可塑性反应、潜在的遗传变异或两者兼而有之，并且可能反映了焦点生物或扩展表型方面（例如相关微生物）的差异。我们使用了 Porites 珊瑚的相互移植实验来评估可塑性与可遗传多样性对珊瑚的表型特征和性能的作用，这些珊瑚在之前暴露于 vermetid 腹足动物（一种已知会减少珊瑚生长和存活的有机体）中有所不同。我们测量了一系列与珊瑚表现相关的表型特征，其中许多表现出对蚯蚓暴露的塑性反应。Vermetids 减少了珊瑚的钙化，增加了微生物的多样性，并改变了微生物组成。大多数特征还显示出先前暴露环境的特征，即使在逆转暴露时也会持续存在：即，在相同条件下，与之前暴露于蚯蚓的珊瑚相比，未接触过蚯蚓的珊瑚钙化速率较慢，组织较厚，共生科密度较高，微生物组不同。我们认为表型差异是可遗传的，因为有和没有蚯蚓的珊瑚礁由两种不同的有丝分裂型组成，显示出高度一致的遗传变异。Vermetids 仅在快速生长的珊瑚有丝分裂型上发现，其特征是组织薄，并且可能有干扰史。由于扩展表型会对群落产生影响，我们建议除微生物外，蚯蚓也是这些珊瑚扩展群落表型的一部分。珊瑚基因型可以建立不同的珊瑚礁轨迹，薄组织类型更容易受到其他物种（如蚯蚓）的干扰和随后的殖民，这可以进一步促进珊瑚礁的退化。物种扩展表型的影响可能会影响景观之间的异质性以及群落组成的时间差异。