Evidence map›Paper›PMID 41491790›Full record

ArticleBMC genomics2026

Decoding the first mitogenomes of Polycelis (Platyhelminthes, Tricladida, Planariidae): genomic architecture, evolutionary dynamics, and phylogenomic implication.

Ning Li, Yan-Kun Shen, De-Zeng Liu, Zi-Mei Dong, Guang-Wen Chen

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Article in BMC genomics, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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5 · Who and what money

Authors and funding

5 authors.

Ning Li *College of Life Science, Henan Normal University, Xinxiang, Henan, 453007, China.
Yan-Kun Shen *College of Life Science, Henan Normal University, Xinxiang, Henan, 453007, China.
De-Zeng LiuCollege of Life Science, Henan Normal University, Xinxiang, Henan, 453007, China.
Zi-Mei DongCollege of Life Science, Henan Normal University, Xinxiang, Henan, 453007, China. dzmhjx@163.com.
Guang-Wen ChenCollege of Life Science, Henan Normal University, Xinxiang, Henan, 453007, China. chengw0183@sina.com.

Funding

Henan Postdoctoral Science Foundation HN2024116Henan Youth Talent Support Program 2024HYTP004National Natural Science Foundation of China 32200376National Natural Science Foundation of China 32270501National Natural Science Foundation of China 32470463
6 · The paper itself

Abstract

backgroundThe genus Polycelis is characterized by the arrangement of multiple eye spots along the anterior dorsal margin of the head. These freshwater planarians are predominantly distributed in high-altitude ecosystems of temperate and subarctic zones across the Northern Hemisphere. Despite their significance as ecological bioindicators and models for regeneration, Polycelis remains controversial in taxonomy and phylogeny due to a critical lack of molecular data. Mitochondrial genomes (mitogenomes) have emerged as powerful tools for resolving deep phylogenetic relationships and species boundaries in morphologically conserved taxa. In this study, we present the first comparative mitogenomic analyses of four Polycelis species and phylogenetic reconstructions within Tricladida.

resultsThrough next-generation sequencing, we successfully assembled four complete mitogenomes of Polycelis species. Each circular mitogenome contains 12 protein-coding genes (PCGs), 22 tRNA genes (tRNAs), 2 rRNA genes (rRNAs), and a non-coding region. Comparative genomic analyses revealed conservation in both gene arrangement and nucleotide compositions across the four species. The tandem repeat sequences and stem-loop structures were identified in their non-coding regions. Evolutionary analyses integrating nucleotide diversity (Pi), genetic distance, and Ka/Ks ratios across 12 PCGs demonstrated significant evolutionary heterogeneity: cox1 showed relatively low evolutionary rate, while nad6 displayed the highest sequence variability. Phylogenomic reconstruction using Bayesian inference (BI) and maximum likelihood (ML) methods based on 30 triclad mitogenomes, consistently resolved Polycelis as a monophyletic clade within Planariidae. Four Polycelis species exhibited synapomorphic gene rearrangements.

conclusionsThis study firstly elucidates Polycelis mitogenome architecture, evolutionary dynamics, providing critical insights into the genomic basis of mitochondrial evolution, the utility of mitogenomic data for molecular taxonomy, and the phylogenetic position of Polycelis within Tricladida. Additionally, this research offers valuable references for conservation and utilization of Polycelis genetic resources.

Indexed as

Evolution, MolecularGenome, MitochondrialGenomicsPhylogenyPlatyhelminthsAnimalsHigh-Throughput Nucleotide SequencingRNA, TransferRNA, TransferComparative analysisMitogenomePhylogenyPolycelis

Identifiers

PMID41491790
PMCPMC12870015

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