02147nas a2200265 4500008004100000022001400041245013300055210006900188260001600257300001100273490000800284520132700292653002601619653002001645653002101665653000801686653001401694653001501708100001801723700002201741700002601763700002301789700002101812856004801833 2026 eng d a1055-790300aPhylogenetic reconstruction of African weakly electric fish (Campylomormyrus spp.) is suggestive of ancient introgression events0 aPhylogenetic reconstruction of African weakly electric fish Camp cJan-01-2026 a1084520 v2143 a

The African weakly electric fish genus Campylomormyrus belongs to the species-rich family Mormyridae and comprises 15 described species. Previous species trees that focus on the genus, have included at most ten species. The resulting phylogenies have been used to explain the evolution of the species-specific electrical organ discharge (EOD) and interpreted in the context of sympatric speciation caused by disruptive selection. However, available molecular phylogenies that are focused on the Campylomormyrus genus rely only on a limited number of genetic markers. Here, we used ddRAD sequencing to genotype 65 individuals from twelve Campylomormyrus species and Gnathonemus petersii at more than 8,000 SNPs. We reconstruct a robust species tree that is suggestive of ancient introgression events between different species, which might affect both genetic and trait variability in the genus. Different levels of genetic and EOD diversity in two significant Campylomormyrus clades reveals that i) certain species might be in early stages of their speciation process, ii) that hybridization/introgression occurs in mormyrids and iii) that EOD-related genes could be potential speciation genes. Our genomic approach demonstrates the significance of these findings in understanding the evolution of Campylomormyrus.

10aAncient introgression10aCampylomormyrus10addRAD sequencing10aEOD10aphylogeny10aspeciation1 aCanitz, Julia1 aKirschbaum, Frank1 aVendrami, David, L.J.1 aMamonekene, Victor1 aTiedemann, Ralph uhttps://doi.org/10.1016/j.ympev.2025.10845204135nas a2200193 4500008004100000022001400041245016700055210006900222260001600291490000700307520344900314100001603763700002203779700003003801700001803831700002203849700002103871856004903892 2023 eng d a1471-216400aA new genome assembly of an African weakly electric fish (Campylomormyrus compressirostris, Mormyridae) indicates rapid gene family evolution in Osteoglossomorpha0 anew genome assembly of an African weakly electric fish Campylomo cMar-20-20230 v243 a

Abstract Background Teleost fishes comprise more than half of the vertebrate species. Within teleosts, most phylogenies consider the split between Osteoglossomorpha and Euteleosteomorpha/Otomorpha as basal, preceded only by the derivation of the most primitive group of teleosts, the Elopomorpha. While Osteoglossomorpha are generally species poor, the taxon contains the African weakly electric fish (Mormyroidei), which have radiated into numerous species. Within the mormyrids, the genus Campylomormyrus is mostly endemic to the Congo Basin. Campylomormyrus serves as a model to understand mechanisms of adaptive radiation and ecological speciation, especially with regard to its highly diverse species-specific electric organ discharges (EOD). Currently, there are few well-annotated genomes available for electric fish in general and mormyrids in particular. Our study aims at producing a high-quality genome assembly and to use this to examine genome evolution in relation to other teleosts. This will facilitate further understanding of the evolution of the osteoglossomorpha fish in general and of electric fish in particular. Results A high-quality weakly electric fish (C. compressirostris) genome was produced from a single individual with a genome size of 862 Mb, consisting of 1,497 contigs with an N50 of 1,399 kb and a GC-content of 43.69%. Gene predictions identified 34,492 protein-coding genes, which is a higher number than in the two other available Osteoglossomorpha genomes of Paramormyrops kingsleyae and Scleropages formosus. A Computational Analysis of gene Family Evolution (CAFE5) comparing 33 teleost fish genomes suggests an overall faster gene family turnover rate in Osteoglossomorpha than in Otomorpha and Euteleosteomorpha. Moreover, the ratios of expanded/contracted gene family numbers in Osteoglossomorpha are significantly higher than in the other two taxa, except for species that had undergone an additional genome duplication (Cyprinus carpio and Oncorhynchus mykiss). As potassium channel proteins are hypothesized to play a key role in EOD diversity among species, we put a special focus on them, and manually curated 16 Kv1 genes. We identified a tandem duplication in the KCNA7a gene in the genome of C. compressirostris. Conclusions We present the fourth genome of an electric fish and the third well-annotated genome for Osteoglossomorpha, enabling us to compare gene family evolution among major teleost lineages. Osteoglossomorpha appear to exhibit rapid gene family evolution, with more gene family expansions than contractions. The curated Kv1 gene family showed seven gene clusters, which is more than in other analyzed fish genomes outside Osteoglossomorpha. The KCNA7a, encoding for a potassium channel central for EOD production and modulation, is tandemly duplicated which may related to the diverse EOD observed among Campylomormyrus species.

1 aCheng, Feng1 aDennis, Alice, B.1 aOsuoha, Josephine, Ijeoma1 aCanitz, Julia1 aKirschbaum, Frank1 aTiedemann, Ralph uhttp://dx.doi.org/10.1186/s12864-023-09196-603202nas a2200301 4500008004100000022001400041245015100055210006900206260000900275300001300284490000700297520224500304653001202549653001802561653001902579653001602598653002002614653003002634653003102664653001402695653003602709653002402745653001802769100001802787700002202805700002102827856005202848 2020 eng d a1932-620300aTranscriptome-wide single nucleotide polymorphisms related to electric organ discharge differentiation among African weakly electric fish species.0 aTranscriptomewide single nucleotide polymorphisms related to ele c2020 ae02408120 v153 a

African weakly electric fish of the mormyrid genus Campylomormyrus generate pulse-type electric organ discharges (EODs) for orientation and communication. Their pulse durations are species-specific and elongated EODs are a derived trait. So far, differential gene expression among tissue-specific transcriptomes across species with different pulses and point mutations in single ion channel genes indicate a relation of pulse duration and electrocyte geometry/excitability. However, a comprehensive assessment of expressed Single Nucleotide Polymorphisms (SNPs) throughout the entire transcriptome of African weakly electric fish, with the potential to identify further genes influencing EOD duration, is still lacking. This is of particular value, as discharge duration is likely based on multiple cellular mechanisms and various genes. Here we provide the first transcriptome-wide SNP analysis of African weakly electric fish species (genus Campylomormyrus) differing by EOD duration to identify candidate genes and cellular mechanisms potentially involved in the determination of an elongated discharge of C. tshokwe. Non-synonymous substitutions specific to C. tshokwe were found in 27 candidate genes with inferred positive selection among Campylomormyrus species. These candidate genes had mainly functions linked to transcriptional regulation, cell proliferation and cell differentiation. Further, by comparing gene annotations between C. compressirostris (ancestral short EOD) and C. tshokwe (derived elongated EOD), we identified 27 GO terms and 2 KEGG pathway categories for which C. tshokwe significantly more frequently exhibited a species-specific expressed substitution than C. compressirostris. The results indicate that transcriptional regulation as well cell proliferation and differentiation take part in the determination of elongated pulse durations in C. tshokwe. Those cellular processes are pivotal for tissue morphogenesis and might determine the shape of electric organs supporting the observed correlation between electrocyte geometry/tissue structure and discharge duration. The inferred expressed SNPs and their functional implications are a valuable resource for future investigations on EOD durations.

10aAnimals10aelectric fish10aelectric organ10aElectricity10aGene Expression10aGene Expression Profiling10aGene Expression Regulation10aPhenotype10aPolymorphism, Single Nucleotide10aSpecies Specificity10atranscriptome1 aCanitz, Julia1 aKirschbaum, Frank1 aTiedemann, Ralph uhttps://mormyrids.efishgenomics.com/en/node/62600584nas a2200121 4500008004100000245017900041210006900220260004800289300000800337490000800345100001800353856009100371 2019 eng d00aGenome and karyotype evolution underlying speciation and diversification of electric organ discharges in African weakly electric fish (Campylomormyrus, Mormyridae, Teleostei)0 aGenome and karyotype evolution underlying speciation and diversi aPotsdambUniversity of Potsdamc22 May 2019 a1120 vPhD1 aCanitz, Julia uhttps://publishup.uni-potsdam.de/opus4-ubp/frontdoor/index/index/year/2020/docId/44305