Supporting data for "Telomere-to-telomere genome assembly of <i>Electrophorus electricus</i> provides insights into the evolution of electric eels"

Electric eels evolved remarkable electric organs that enable them to instantaneously discharge hundreds of volts for predation, defense, and communication. However, the absence of a high-quality reference genome has extremely constrained the studies of electric eels in various aspects. <br>Using high-depth, multi-platform sequencing data, we successfully assembled the first telomere-to-telomere high-quality reference genome of <i>Electrophorus electricus</i>, which has a genome size of 833.43 Mb and comprises 26 chromosomes. Multiple evaluations, including N50 statistics (30.38 Mb), BUSCO scores (97.30%), and mapping ratio of short-insert sequencing data (99.91%) demonstrate the high contiguity and completeness of the electric eel genome assembly we obtained. Genome annotation predicted 396.63 Mb repetitive sequences and 20,992 protein-coding genes. Furthermore, evolutionary analyses indicate that Gymnotiformes, which the electric eel belongs to, has a closer relationship with Characiformes than Siluriformes, and diverged from Characiformes at 95.00 million years ago. Pairwise sequentially Markovian coalescent analysis found a sharply decreased trend of the population size of E. electricus over the past few hundred thousand years. Furthermore, many regulatory factors related to neurotransmitters and classical signaling pathways during embryonic development were significantly expanded, potentially contributing to the generation of high-voltage electricity. <br>This study not only provided the first high-quality telomere-to-telomere reference genome of <i>E. electricus</i>, but also greatly enhanced our understanding of electric eels.

电鳗演化出了非凡的电器官，可瞬时释放数百伏特电压，用于捕食、防御及通讯交流。然而，缺乏高质量的参考基因组极大限制了电鳗在多个领域的研究。
本研究利用高深度多平台测序数据，成功组装出首个端粒到端粒（telomere-to-telomere）高质量参考基因组——美洲电鳗（*Electrophorus electricus*），其基因组大小为833.43 Mb，包含26条染色体。多项评估指标，包括N50统计值（30.38 Mb）、BUSCO评分（97.30%）以及短插入片段测序数据的比对率（99.91%），均证实本研究获得的电鳗基因组组装具有极高的连续性与完整性。基因组注释共预测出396.63 Mb的重复序列以及20992个蛋白质编码基因。此外，进化分析显示，电鳗所属的裸背电鳗目（Gymnotiformes）与脂鲤目（Characiformes）的亲缘关系较鲶形目（Siluriformes）更近，且二者于9500万年前发生分化。成对序列马尔可夫溯祖（Pairwise Sequentially Markovian Coalescent, PSMC）分析发现，美洲电鳗的种群规模在过去数十万年间呈现急剧下降的趋势。不仅如此，诸多与神经递质及胚胎发育经典信号通路相关的调控因子发生了显著扩张，这可能为高压放电能力的演化提供了分子基础。
本研究不仅获得了美洲电鳗（*E. electricus*）首个端粒到端粒的高质量参考基因组，也极大深化了我们对电鳗的认知与理解。