Ancestral morphology of Ecdysozoa constrained by an early Cambrian stem group ecdysozoan.
Ancestral morphology of Ecdysozoa constrained by an early Cambrian stem group ecdysozoan.
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DOI：
10.1186/s12862-020-01720-6
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发表时间：
2020-11-23
影响因子：
3.4
通讯作者：
Ma X
中科院分区：
文献类型：
--
作者：
Howard RJ;Edgecombe GD;Shi X;Hou X;Ma X
蜕皮动物是蜕皮的原口动物，包括节肢动物、缓步动物和线虫。分子和化石记录均表明，蜕皮动物是一个起源于元古代末期的古老类群，特殊的化石生物群在元古代初期就显示出其优势和多样性。然而，由于现存的蜕皮动物的极端形态多样性，以及在古生物化石中缺乏早期分歧的类群，因此很难确定蜕皮动物共同祖先的性质。本文重新描述了云南澄江生物群中的毛田无Cosmiamaotiania，并将其归属于茎组蜕皮动物门。嗅觉缺失的特征是身体由两部分组成，前部的长鼻有一个末端的嘴和肌肉发达的咽，后部的环状躯干有一个贯穿的肠道。形态系统发育分析的原口类使用简约，最大似然和贝叶斯推理，与编码通知发表的实验衰变研究，每个放置Acosmia作为姐妹分类群Cycloneuralia + Panarthropoda，即干组Ecdysozoa。祖先状态的概率计算的关键ecdysozoa节点，以测试字符推断化石是祖先的Ecdysozoa。结果支持冠组ecdysozoans的祖先共享一个环状的蠕虫状的身体与终端口像Acosmia，但也具有咽电枢和环口结构特征的寒武纪cycloneuralians和lobopodians。Acosmia是第一个分类群放置在蜕皮动物干组，并提供了一个约束，以测试假设的早期进化的蜕皮动物。我们的研究表明，收购的咽电枢，因此改变喂养策略（如捕食），可能具有特点的起源和辐射冠组蜕皮动物从无cosmia的祖先。
Ecdysozoa are the moulting protostomes, including arthropods, tardigrades, and nematodes. Both the molecular and fossil records indicate that Ecdysozoa is an ancient group originating in the terminal Proterozoic, and exceptional fossil biotas show their dominance and diversity at the beginning of the Phanerozoic. However, the nature of the ecdysozoan common ancestor has been difficult to ascertain due to the extreme morphological diversity of extant Ecdysozoa, and the lack of early diverging taxa in ancient fossil biotas. Here we re-describe Acosmia maotiania from the early Cambrian Chengjiang Biota of Yunnan Province, China and assign it to stem group Ecdysozoa. Acosmia features a two-part body, with an anterior proboscis bearing a terminal mouth and muscular pharynx, and a posterior annulated trunk with a through gut. Morphological phylogenetic analyses of the protostomes using parsimony, maximum likelihood and Bayesian inference, with coding informed by published experimental decay studies, each placed Acosmia as sister taxon to Cycloneuralia + Panarthropoda—i.e. stem group Ecdysozoa. Ancestral state probabilities were calculated for key ecdysozoan nodes, in order to test characters inferred from fossils to be ancestral for Ecdysozoa. Results support an ancestor of crown group ecdysozoans sharing an annulated vermiform body with a terminal mouth like Acosmia, but also possessing the pharyngeal armature and circumoral structures characteristic of Cambrian cycloneuralians and lobopodians. Acosmia is the first taxon placed in the ecdysozoan stem group and provides a constraint to test hypotheses on the early evolution of Ecdysozoa. Our study suggests acquisition of pharyngeal armature, and therefore a change in feeding strategy (e.g. predation), may have characterised the origin and radiation of crown group ecdysozoans from Acosmia-like ancestors.
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DOI：
10.1098/rstb.2015.0038
发表时间：
2015-12-19
期刊：
Philosophical transactions of the Royal Society of London. Series B, Biological sciences
影响因子：
--
作者：
Edgecombe GD;Ma X;Strausfeld NJ
通讯作者：
Strausfeld NJ
DOI：
10.1111/j.1096-0031.1996.tb00196.x
发表时间：
1994-09-01
期刊：
CLADISTICS-THE INTERNATIONAL JOURNAL OF THE WILLI HENNIG SOCIETY
影响因子：
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作者：
FARRIS, JS;KALLERSJO, M;BULT, C
通讯作者：
BULT, C
影响因子：
10.7
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Minh BQ;Nguyen MA;von Haeseler A
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13.6
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