TY - JOUR A1 - Cheng, Feng A1 - Dennis, Alice B. A1 - Osuoha, Josephine Ijeoma A1 - Canitz, Julia A1 - Kirschbaum, Frank A1 - Tiedemann, Ralph T1 - A new genome assembly of an African weakly electric fish (Campylomormyrus compressirostris, Mormyridae) indicates rapid gene family evolution in Osteoglossomorpha JF - BMC genomics N2 - 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. KW - Campylomormyrus KW - Pacbio sequencing KW - Gene family KW - Osteoglossomorpha KW - Kv1 Y1 - 2023 U6 - https://doi.org/10.1186/s12864-023-09196-6 SN - 1471-2164 VL - 24 IS - 1 PB - BMC CY - London ER - TY - GEN A1 - Amen, Rahma A1 - Nagel, Rebecca A1 - Hedt, Maximilian A1 - Kirschbaum, Frank A1 - Tiedemann, Ralph T1 - Morphological differentiation in African weakly electric fish (genus Campylomormyrus) relates to substrate preferences T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Under an ecological speciation scenario, the radiation of African weakly electric fish (genus Campylomormyrus) is caused by an adaptation to different food sources, associated with diversification of the electric organ discharge (EOD). This study experimentally investigates a phenotype-environment correlation to further support this scenario. Our behavioural experiments showed that three sympatric Campylomormyrus species with significantly divergent snout morphology differentially react to variation in substrate structure. While the short snout species (C. tamandua) exhibits preference to sandy substrate, the long snout species (C. rhynchophorus) significantly prefers a stone substrate for feeding. A third species with intermediate snout size (C. compressirostris) does not exhibit any substrate preference. This preference is matched with the observation that long-snouted specimens probe deeper into the stone substrate, presumably enabling them to reach prey more distant to the substrate surface. These findings suggest that the diverse feeding apparatus in the genus Campylomormyrus may have evolved in adaptation to specific microhabitats, i.e., substrate structures where these fish forage. Whether the parallel divergence in EOD is functionally related to this adaptation or solely serves as a prezygotic isolation mechanism remains to be elucidated. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1416 KW - ecological speciation KW - feeding behaviour KW - electric fish KW - trophic apparatus KW - evolutionary ecology Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-518714 SN - 1866-8372 IS - 3 ER - TY - JOUR A1 - Amen, Rahma A1 - Nagel, Rebecca A1 - Hedt, Maximilian A1 - Kirschbaum, Frank A1 - Tiedemann, Ralph T1 - Morphological differentiation in African weakly electric fish (genus Campylomormyrus) relates to substrate preferences JF - Evolutionary Ecology N2 - Under an ecological speciation scenario, the radiation of African weakly electric fish (genus Campylomormyrus) is caused by an adaptation to different food sources, associated with diversification of the electric organ discharge (EOD). This study experimentally investigates a phenotype-environment correlation to further support this scenario. Our behavioural experiments showed that three sympatric Campylomormyrus species with significantly divergent snout morphology differentially react to variation in substrate structure. While the short snout species (C. tamandua) exhibits preference to sandy substrate, the long snout species (C. rhynchophorus) significantly prefers a stone substrate for feeding. A third species with intermediate snout size (C. compressirostris) does not exhibit any substrate preference. This preference is matched with the observation that long-snouted specimens probe deeper into the stone substrate, presumably enabling them to reach prey more distant to the substrate surface. These findings suggest that the diverse feeding apparatus in the genus Campylomormyrus may have evolved in adaptation to specific microhabitats, i.e., substrate structures where these fish forage. Whether the parallel divergence in EOD is functionally related to this adaptation or solely serves as a prezygotic isolation mechanism remains to be elucidated. KW - ecological speciation KW - feeding behaviour KW - electric fish KW - trophic apparatus KW - evolutionary ecology Y1 - 2020 U6 - https://doi.org/10.1007/s10682-020-10043-3 SN - 0269-7653 SN - 1573-8477 VL - 34 IS - 3 SP - 427 EP - 437 PB - Springer Science CY - Dordrecht ER - TY - JOUR A1 - Korniienko, Yevheniia A1 - Nguyen, Linh A1 - Baumgartner, Stephanie A1 - Vater, Marianne A1 - Tiedemann, Ralph A1 - Kirschbaum, Frank T1 - Correction to: Intragenus F1-hybrids of African weakly electric fish (Mormyridae: Campylomormyrus tamandua male x C. compressirostris female) are fertile (vol 206, pg 571, 2020) JF - Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology Y1 - 2021 U6 - https://doi.org/10.1007/s00359-021-01513-2 SN - 0340-7594 SN - 1432-1351 VL - 207 IS - 6 SP - 773 EP - 773 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Nguyen, Manh Duy Linh A1 - Mamonekene, Victor A1 - Vater, Marianne A1 - Bartsch, Peter A1 - Tiedemann, Ralph A1 - Kirschbaum, Frank T1 - Ontogeny of electric organ and electric organ discharge in Campylomormyrus rhynchophorus (Teleostei: Mormyridae) JF - Journal of comparative physiology; A, Neuroethology, sensory, neural, and behavioral physiology N2 - The aim of this study was a longitudinal description of the ontogeny of the adult electric organ of Campylomormyrus rhynchophorus which produces as adult an electric organ discharge of very long duration (ca. 25 ms). We could indeed show (for the first time in a mormyrid fish) that the electric organ discharge which is first produced early during ontogeny in 33-mm-long juveniles is much shorter in duration and has a different shape than the electric organ discharge in 15-cm-long adults. The change from this juvenile electric organ discharges into the adult electric organ discharge takes at least a year. The increase in electric organ discharge duration could be causally linked to the development of surface evaginations, papillae, at the rostral face of the electrocyte which are recognizable for the first time in 65-mm-long juveniles and are most prominent at the periphery of the electrocyte. KW - Weakly electric fish KW - Development KW - Electric organ discharge KW - Electric KW - organ KW - Electrocyte features Y1 - 2020 U6 - https://doi.org/10.1007/s00359-020-01411-z SN - 0340-7594 SN - 1432-1351 VL - 206 IS - 3 SP - 453 EP - 466 PB - Springer CY - Berlin ; Heidelberg ER - TY - JOUR A1 - Canitz, Julia A1 - Kirschbaum, Frank A1 - Tiedemann, Ralph T1 - Transcriptome-wide single nucleotide polymorphisms related to electric organ discharge differentiation among African weakly electric fish species JF - PLoS one N2 - 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. Y1 - 2020 U6 - https://doi.org/10.1371/journal.pone.0240812 SN - 1932-6203 VL - 15 IS - 10 PB - PLoS CY - San Francisco, California, US ER - TY - JOUR A1 - Korniienko, Yevheniia A1 - Nguyen, Linh A1 - Baumgartner, Stephanie A1 - Vater, Marianne A1 - Tiedemann, Ralph A1 - Kirschbaum, Frank T1 - Intragenus F1-hybrids of African weakly electric fish (Mormyridae: Campylomormyrus tamandua male x C. compressirostris female) are fertile JF - Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology N2 - Hybridization is widespread in fish and constitutes an important mechanism in fish speciation. There is, however, little knowledge about hybridization in mormyrids. F1-interspecies hybrids betweenCampylomormyrus tamandua male x C. compressirostris female were investigated concerning: (1) fertility; (2) survival of F2-fish and (3) new gene combinations in the F2-generation concerning the structure of the electric organ and features of the electric organ discharge. These F1-hybrids achieved sexual maturity at about 12-13.5 cm total length. A breeding group comprising six males and 13 females spawned 28 times naturally proving these F1-fish to be fertile. On average 228 eggs were spawned, the average fertilization rate was 47.8%. Eggs started to hatch 70-72 h after fertilization, average hatching rate was 95.6%. Average mortality rate during embryonic development amounted to 2.3%. Average malformation rate during the free embryonic stage was 27.7%. Exogenous feeding started on day 11. In total, we raised 353 normally developed larvae all of which died consecutively, the oldest specimen reaching an age of 5 months. During survival, the activities of the larval and adult electric organs were recorded and the structure of the adult electric organ was investigated histologically. KW - mormyridae KW - campylomormyrus KW - F1-hybrids KW - F2-hybrids KW - fertility Y1 - 2020 U6 - https://doi.org/10.1007/s00359-020-01425-7 SN - 0340-7594 SN - 1432-1351 VL - 206 IS - 4 SP - 571 EP - 585 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Korniienko, Yevheniia A1 - Tiedemann, Ralph A1 - Vater, Marianne A1 - Kirschbaum, Frank T1 - Ontogeny of the electric organ discharge and of the papillae of the electrocytes in the weakly electric fish Campylomormyrus rhynchophorus (Teleostei: Mormyridae) JF - The journal of comparative neurology N2 - The electric organ of the mormyrid weakly electric fish,Campylomormyrus rhynchophorus(Boulenger, 1898), undergoes changes in both the electric organ discharge (EOD) and the light and electron microscopic morphology as the fish mature from the juvenile to the adult form. Of particular interest was the appearance of papillae, surface specializations of the uninnervated anterior face of the electrocyte, which have been hypothesized to increase the duration of the EOD. In a 24.5 mm long juvenile the adult electric organ (EO) was not yet functional, and the electrocytes lacked papillae. A 40 mm long juvenile, which produced a short biphasic EOD of 1.3 ms duration, shows small papillae (average area 136 mu m(2)). In contrast, the EOD of a 79 mm long juvenile was triphasic. The large increase in duration of the EOD to 23.2 ms was accompanied by a small change in size of the papillae (average area 159 mu m(2)). Similarly, a 150 mm long adult produced a triphasic EOD of comparable duration to the younger stage (24.7 ms) but featured a prominent increase in size of the papillae (average area 402 mu m(2)). Thus, there was no linear correlation between EOD duration and papillary size. The most prominent ultrastructural change was at the level of the myofilaments, which regularly extended into the papillae, only in the oldest specimen-probably serving a supporting function. Physiological mechanisms, like gene expression levels, as demonstrated in someCampylomormyrusspecies, might be more important concerning the duration of the EOD. KW - Campylomormyrus KW - electric organ discharge KW - electrocyte ontogeny KW - electrocyte ultrastructure KW - papillae Y1 - 2020 U6 - https://doi.org/10.1002/cne.25003 SN - 0021-9967 SN - 1096-9861 VL - 529 IS - 5 SP - 1052 EP - 1065 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Nagel, Rebecca A1 - Kirschbaum, Frank A1 - Tiedemann, Ralph T1 - Electric organ discharge diversification in mormyrid weakly electric fish is associated with differential expression of voltage-gated ion channel genes JF - Journal of comparative physiology : A, Neuroethology, sensory, neural, and behavioral physiology N2 - In mormyrid weakly electric fish, the electric organ discharge (EOD) is used for species recognition, orientation and prey localization. Produced in the muscle-derived adult electric organ, the EOD exhibits a wide diversity across species in both waveform and duration. While certain defining EOD characteristics can be linked to anatomical features of the electric organ, many factors underlying EOD differentiation are yet unknown. Here, we report the differential expression of 13 Kv1 voltage-gated potassium channel genes, two inwardly rectifying potassium channel genes, two previously studied sodium channel genes and an ATPase pump in two sympatric species of the genus Campylomormyrus in both the adult electric organ and skeletal muscle. Campylomormyrus compressirostris displays a basal EOD, largely unchanged during development, while C. tshokwe has an elongated, putatively derived discharge. We report an upregulation in all Kv1 genes in the electric organ of Campylomormyrus tshokwe when compared to both skeletal muscle and C. compressirostris electric organ. This pattern of upregulation in a species with a derived EOD form suggests that voltage-gated potassium channels are potentially involved in the diversification of the EOD signal among mormyrid weakly electric fish. KW - Weakly electric fish KW - Ion channels KW - Electric organ KW - Gene expression KW - Campylomormyrus Y1 - 2017 U6 - https://doi.org/10.1007/s00359-017-1151-2 SN - 0340-7594 SN - 1432-1351 VL - 203 SP - 183 EP - 195 PB - Springer CY - New York ER - TY - JOUR A1 - Nagel, Rebecca A1 - Kirschbaum, Frank A1 - Engelmann, Jacob A1 - Hofmann, Volker A1 - Pawelzik, Felix A1 - Tiedemann, Ralph T1 - Male-mediated species recognition among African weakly electric fishes JF - Royal Society Open Science N2 - Effective communication among sympatric species is often instrumental for behavioural isolation, where the failure to successfully discriminate between potential mates could lead to less fit hybrid offspring. Discrimination between con- and heterospecifics tends to occur more often in the sex that invests more in offspring production, i.e. females, but males may also mediate reproductive isolation. In this study, we show that among two Campylomormyrus Africanweakly electric fish species, males preferentially associate with conspecific females during choice tests using live fish as stimuli, i.e. when all sensory modalities potentially used for communication were present. We then conducted playback experiments to determine whether the species-specific electric organ discharge (EOD) used for electrocommunication serves as the cue for this conspecific association preference. Interestingly, only C. compressirostris males associated significantly more with the conspecific EOD waveform when playback stimuli were provided, while no such association preference was observed in C. tamandua males. Given our results, the EOD appears to serve, in part, as a male-mediated pre-zygotic isolation mechanism among sympatric species. However, the failure of C. tamandua males to discriminate between con- and heterospecific playback discharges suggests that multiple modalities may be necessary for species recognition in some African weakly electric fish species. KW - Campylomormyrus KW - communication KW - electric fishes KW - pre-zygotic isolation KW - species recognition Y1 - 2018 U6 - https://doi.org/10.1098/rsos.170443 SN - 2054-5703 VL - 5 IS - 2 PB - Royal Society CY - London ER -