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• The small eye sizes of many mormyroids and gymnotiforms may be a direct result of their active electrosensory systems superseding the importance of vision.
• Gymnotiforms and mormyroids both possess high-frequency electroreceptors, which are derived from similar lateral line receptor precursors and underlie active electrolocation and electrocommunication.
• The authors refer to gymnotiforms and mormyroids as a textbook example of convergent evolution to highlight their independent origins from phylogenetically unrelated and phenotypically dissimilar teleost ancestors.
• The estimated time interval between the origins of teleost electroreception and the origins of electrogenesis is 22.7 million years for mormyroids and 25.6 million years for gymnotiforms under reconstruction #2.
• Gymnotiforms and mormyroids evolved novel myogenic electric organs (EOmyo) that are developmentally derived from skeletal muscle progenitor cells known as myoblasts.
• H.W. Lissmann proposed that the convergence upon an anguilliform body form with ribbon fin propulsion, seen in all gymnotiforms and some mormyroids, may have evolved to minimize body axis bending during active electrolocation.
• Similar patterns of amino acid substitution occurred in regions of the sodium channel α-subunit in both gymnotiforms and mormyroids, which are thought to contribute to electric signal variation.
• Gymnotiforms and mormyroids originated independently from non-electrogenic ancestors at approximately the same period in Earth's history.
• Zakon et al. and Arnegard et al. demonstrated that in both gymnotiforms and mormyroids, the same sodium channel α-subunit paralog (gene duplicate) was co-opted from skeletal muscle for exclusive expression in myogenic electric organs (EOmyo).
• Both mormyroids and gymnotiforms have diversified to a similar degree, with each group comprising approximately 200 named species.
• The estimated time interval between the origins of teleost electroreception and the origins of electrogenesis is 16.6 million years for mormyroids and 18.7 million years for gymnotiforms under reconstruction #1.
• Reduced mouth sizes and restricted gill openings in mormyroids and gymnotiforms likely evolved to reduce interfering electrical emissions from electrically active epithelial tissues.
• Mormyroids and gymnotiforms, with the exception of Electrophorus electricus, are classified as "weakly" electric fishes because the external potentials they produce are typically imperceptible to humans without amplification.
• Whole genome duplication (WGD) occurring just prior to the radiation of teleosts contributed to the origin of novel electrogenic systems in mormyroids and gymnotiforms.
• Myogenic electric organs in mormyroids and gymnotiforms are similar in many ways, but also exhibit significant differences between lineages and great diversity in structure and function among species.
• The elongate snouts or trunks of some mormyroids and gymnotiforms may have arisen secondarily as an adaptation to the specific types and habits of prey organisms found in the ecological niches exploited by active electrosensory predators.
• The two groups of weakly electric fishes, mormyroids and gymnotiforms, originated at nearly the same time in evolutionary history, with similar time intervals passing between the whole genome duplication (WGD) at the base of the teleost radiation and the origins of novel myogenic electric organs in each lineage.