Phylogenomic analysis and morphological data suggest left-right swimming behavior evolved prior to the origin of the pelagic Phylliroidae (Gastropoda: Nudibranchia)
Phylogenomic analysis and morphological data suggest left-right swimming behavior evolved prior to the origin of the pelagic Phylliroidae (Gastropoda: Nudibranchia)
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DOI：
10.1007/s13127-020-00458-9
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发表时间：
2020-09-11
影响因子：
1.6
通讯作者：
Waegele, Heike
中科院分区：
文献类型：
--
作者：
Goodheart, Jessica A.;Waegele, Heike
从底栖生境向远洋生境的演变过渡是主要的适应性转变。对这种转变的调查对于理解将现有特征用于新功能与在过渡期间或过渡后产生的新特征之间的复杂相互作用至关重要。腹足类软体动物在底栖-中上层进化过渡方面特别令人感兴趣，因为从底栖生境向中上层生境转变的情况并不常见。Phylliroe是Phylliroidae中的一个中上层谱系，Phylliroidae是一个具有高度异常形态的全栖裸鳃类，似乎适应中上层生活。然而，这一神秘的远洋裸鳃类群体的系统发育位置从未被调查过。在这里，我们提出了一个新的基因组分析的地方Phylliroe在一组裸鳃类称为Dendronotida狭义。我们还讨论了一个子集的形态和行为特征thatPhylliroeshares与其他密切相关的谱系（Dendronotidae，特提斯，Scyllaeidae）和一些独特的Phylliroe。基于这些数据和文献综述，我们发现了一些独特的功能inPhylliroethat是适应远洋环境，如鱼一样的身体计划，高度减少的结缔组织和肌肉组织的背，和细长的鳃。然而，我们只能确定一个共同点Phylliroe及其密切相关的谱系，这是存在的左右游泳行为。我们进一步假设，在这个组的游泳行为可能代表了一个重要的特征，促进了从底栖到远洋环境的过渡，从而可能提供的证据表明，主要的远洋生活方式的转变可以依赖于行为exaptations。这些新的见解ofPhylliroenow的起源提供了一个系统发育框架，为测试适应必要的底栖-中上层过渡在这组。
Evolutionary transitions from benthic to pelagic habitats are major adaptive shifts. Investigations into such shifts are critical for understanding the complex interaction between co-opting existing traits for new functions and novel traits that originate during or post-transition. Gastropod mollusks are of particular interest in regard to benthic-pelagic evolutionary transitions, as shifts from benthic to pelagic habitats are uncommon.Phylliroeis one such pelagic lineage in Phylliroidae, a family of holoplanktonic nudibranchs with a highly aberrant morphology that appears to be adapted for life in the pelagic zone. However, the phylogenetic placement of this enigmatic group of pelagic nudibranchs has never been investigated. Here we present phylogenomic analyses which placePhylliroewithin a group of nudibranchs called Dendronotida sensu stricto. We also discuss a subset of the morphological and behavioral features thatPhylliroeshares with other closely related lineages (Dendronotidae, Tethyidae, and Scyllaeidae) and some that are unique toPhylliroe. Based on these data, and a literature review, we find a number of unique features found inPhylliroethat are adaptations to a pelagic environment, such as a fish-like body plan, highly reduced connective and muscular tissue in the notum, and elongated rhinophores. However, we were able to identify only a single commonality amongPhylliroeand its closely related lineages, which is the presence of left-right swimming behavior. We further hypothesize that swimming behavior in this group likely represents an important trait that facilitated the transition from benthic to pelagic environments, and thus may provide evidence that major pelagic lifestyle transitions can rely on behavioral exaptations. These new insights into the origins ofPhylliroenow provide a phylogenetic framework for testing for adaptations necessary for the benthic-pelagic transition in this group.