Have we so far only seen the tip of the iceberg? Exploring species diversity and distribution of the giant amphipod Eurythenes
Have we so far only seen the tip of the iceberg? Exploring species diversity and distribution of the giant amphipod Eurythenes
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DOI：
10.1080/14888386.2016.1172257
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发表时间：
2016-01-01
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影响因子：
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通讯作者：
Havermans, Charlotte
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作者：
Havermans, Charlotte
对标志性的巨型片脚类动物欧律提尼的其他材料进行了研究。近年来，在形态学和遗传学的基础上，已将该物种分为12个不同的种级谱系，其中有几个已被描述为不同的物种。本研究从独特的采样地点发现了另外三个物种水平的谱系，表明在最小的采样努力下，Eurythenes内的物种多样性仍然可以增加。在印度洋发现了一个物种水平的谱系，在太平洋发现了另一个，后来被确定为瑟斯顿绦虫。除了已在南大洋发现的3种（E. maldoror， E. gryllus s.s和E. andhakarae）外，在威德尔海还发现了一种深海生物。经证实，E. gryllus属两栖物种，包括在Kerguelen群岛周围的新取样地点和在Svalbard群岛的额外样本。基于新的和早期的数据，本文介绍了迄今为止发现的不同物种的地理和水深分布，并评估了它们在这种食腐动物中引发过去物种形成事件的可能性的几个因素。讨论了地形和水文特征，但拒绝将其作为观测到的分布模式的充分原因。水深分离是根据已知的物种生态来解释的。先前报道的3000米左右的基因断裂在这个新的数据集中除了一个物种外，对所有物种都存在。这项研究强调需要处理所有取样的个体，因为发现两种或两种以上的同域物种的比例不同，而且随着取样强度和覆盖范围的增加，关于多样性和分布的结论可能会发生巨大变化。最后，我在这里提出，目前只发现了所有欧律提尼物种的一小部分，更全面地了解该物种的生态学对解释它们的进化至关重要。
Additional material of the iconic giant amphipod Eurythenes was investigated. Recently, the species E. gryllus has been separated into 12 distinct species-level lineages of which several have been described as distinct species, based on both morphology and genetics. This study revealed three additional species-level lineages from unique sampling localities, showing that with minimal sampling effort, species diversity within Eurythenes can still increase. One species-level lineage was found in the Indian Ocean and another one in the Pacific, which was subsequently identified as E. thurstoni. In addition to the three species already reported from the Southern Ocean (E. maldoror, E. gryllus s.s. and E. andhakarae), a supplementary bathyal species was found in the Weddell Sea. E. gryllus was confirmed to be amphitropical including newly sampled localities around the Kerguelen Islands and additional samples from the Svalbard Archipelago. Building on new and earlier data, geographic and bathymetric distributions of the different species that have been discovered so far are presented here and several factors are evaluated for their likelihood of having triggered past speciation events in this scavenger. Topographic and hydrographical features are discussed but rejected as sufficient reasons for the distributional patterns observed. Bathymetric segregation is interpreted with regard to what is known about the ecology of the species. The previously reported genetic break around 3000 m persists in this new data-set for all species but one. This study underlines the need of processing all individuals sampled, since two or more sympatric species are found in different proportions, and that conclusions regarding diversity and distribution may drastically change when increasing sampling intensity and coverage. Finally, I suggest here that only a mere fraction of all Eurythenes species has yet been discovered and that a more complete knowledge of the ecology of the species is of paramount importance for interpreting their evolution.