Sexually dimorphic ornamentation in modern spinicaudatans and the taxonomic implications for fossil clam shrimps

IF 1.8 3区地球科学 Q2 PALEONTOLOGY

Acta Palaeontologica Polonica Pub Date : 2022-01-01 DOI:10.4202/app.00892.2021

Xiaoyan Sun, Jin-hui Cheng

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引用次数: 3

Abstract

The phylogenetic studies of clam shrimps (Branchiopoda, Crustacea) demonstrated that the significance of several morphological characters for classification of branchiopod shells should be critically re-evaluated. Such a venture is partic-ularly important for integrating the taxonomy of fossil and extant branchiopods. One of the shell characters widely used in the branchiopod classification is the carapace ornamentation pattern. This character might, however, be significantly influenced by intraspecific variability and in particular the sexual dimorphism. In this study we investigate the pattern of ornamentation in extant branchiopods—including differences resulting from sexual dimorphism—in order to assess its value for branchiopod taxonomy. We examined 184 individuals representing 10 living species belonging to 7 genera, 5 families, and 2 suborders from China, and compared with the results of previous studies. Although some differences in ornamentation were related to reproductive modes, the basic ornamentation patterns or combinations were stable within each extant species. We found out that some taxa indeed display sexually dimorphic ornamentations, but their basic ornamentation patterns or combinations are stable within each species so they do not significantly influence the taxonomic identification. Integration of data on fossil and extant taxa indicates that similar ornamentation patterns can be observed on familial level of fossil spinicaudatan branchiopods and indicates therefore that characteristic ornamentation patterns can help to identify these taxa in the fossil record. In light of the new molecular phylogeny, we re-evaluated the phylogenetic relationship between fossil and extant spinicaudatan taxa. The resulting tree suggests: (i) paraphyly of the traditional Eosestherioidea, (ii) an affinity between Ozestheria and Triglypta , and (iii) an affinity between Cyzicus and Diestheria or Aquilonoglypta .

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现代棘足动物的两性二形装饰及其蛤虾化石的分类学意义

对蛤蛄(鳃足纲，甲壳纲)的系统发育研究表明，一些形态学特征对鳃足纲贝壳分类的意义应重新进行批判性评价。这样的冒险对于整合化石和现存的枝足类动物的分类学尤其重要。甲壳纹饰图案是鳃足类动物分类中广泛使用的贝壳特征之一。然而，这一特性可能受到种内变异性，特别是两性二态性的显著影响。在本研究中，我们研究了现存的枝足动物的纹饰模式，包括两性二态性造成的差异，以评估其在枝足动物分类中的价值。本研究调查了中国2亚目5科7属10种184个个体，并与已有研究结果进行了比较。虽然纹饰的差异与繁殖方式有关，但基本的纹饰模式或组合在各现存种内是稳定的。结果表明，某些分类群确实表现出雌雄二型的纹饰，但其基本纹饰模式或组合在每个物种内都是稳定的，因此对分类鉴定没有显著影响。通过对化石和现存分类群的综合分析，发现棘足纲分支足类化石在科系水平上具有相似的纹饰特征，表明其纹饰特征有助于化石记录中这些分类群的识别。根据新的分子系统发育，我们重新评估了化石与现存棘足动物类群的系统发育关系。结果表明:(i)与传统的Eosestherioidea有亲缘关系，(ii) Ozestheria与Triglypta有亲缘关系，(iii) Cyzicus与Diestheria或Aquilonoglypta有亲缘关系。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Acta Palaeontologica Polonica 地学-古生物学

CiteScore

2.80

自引率

5.60%

发文量

审稿时长

12.5 months

期刊介绍： Acta Palaeontologica Polonica is an international quarterly journal publishing papers of general interest from all areas of paleontology. Since its founding by Roman Kozłowski in 1956, various currents of modern paleontology have been represented in the contents of the journal, especially those rooted in biologically oriented paleontology, an area he helped establish. In-depth studies of all kinds of fossils, of the mode of life of ancient organisms and structure of their skeletons are welcome, as those offering stratigraphically ordered evidence of evolution. Work on vertebrates and applications of fossil evidence to developmental studies, both ontogeny and astogeny of clonal organisms, have a long tradition in our journal. Evolution of the biosphere and its ecosystems, as inferred from geochemical evidence, has also been the focus of studies published in the journal.