@article {634, title = {Diet in phenotypically divergent sympatric species of African weakly electric fish (genus: Campylomormyrus){\textemdash}A hybrid capture/HTS metabarcoding approach}, year = {2023}, month = {Dec-21-2023}, abstract = {

Ecological speciation within the mormyrid genus Campylomormyrus resulted in sympatric species exhibiting divergence in their feeding apparatus and electric organ discharge (EOD). This study documents the overall diet of the genus Campylomormyrus and examines the hypothesis that the Campylomormyrus radiation is caused by adaptation to different food sources. We performed diet assessment of five sympatric Campylomormyrus species (C. alces, C. compressirostris, C. curvirostris, C. tshokwe, C. numenius) and their sister taxon Gnathonemus petersii with markedly different snout morphologies and EODs using hybrid capture/HTS DNA metabarcoding of their stomach contents. Our approach allowed for high taxonomic resolution of prey items, including benthic invertebrates, allochthonous invertebrates and vegetation. Comparisons of the diet compositions using quantitative measures and diet overlap indices revealed that all species are able to exploit multiple food niches in their habitats, that is fauna at the bottom, the water surface and the water column. A major part of the diet is larvae of aquatic insects, such as dipterans, coleopterans and trichopterans, known to occur in holes and interstitial spaces of the substrate. The results indicate that different snout morphologies and the associated divergence in the EOD could translate into different prey spectra. This suggests that the diversification in EOD and/or morphology of the feeding apparatus could be under functional adaptation.

}, issn = {0962-1083, 1365-294X}, doi = {10.1111/mec.17248}, url = {http://dx.doi.org/10.1111/mec.17248}, author = {Amen, Rahma and Havenstein, Katja and Kirschbaum, Frank and Tiedemann, Ralph} } @article {630, title = {A new genome assembly of an African weakly electric fish (Campylomormyrus compressirostris, Mormyridae) indicates rapid gene family evolution in Osteoglossomorpha}, volume = {24}, year = {2023}, month = {Mar-20-2023}, abstract = {

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.

}, issn = {1471-2164}, doi = {10.1186/s12864-023-09196-6}, url = {http://dx.doi.org/10.1186/s12864-023-09196-6}, author = {Cheng, Feng and Dennis, Alice B. and Osuoha, Josephine Ijeoma and Canitz, Julia and Kirschbaum, Frank and Tiedemann, Ralph} } @article {608, title = {Intergenus F1-hybrids of African weakly electric fish (Mormyridae: Gnathonemus petersii ♂ {\texttimes} Campylomormyrus compressirostris ♀) are fertile.}, journal = {J Comp Physiol A Neuroethol Sens Neural Behav Physiol}, year = {2022}, month = {2022 Feb 04}, abstract = {

Hybridisation is an important element of adaptive radiation in fish but data are limited in weakly electric mormyrid fish in this respect. Recently, it has been shown that intragenus hybrids (Campylomormyrus) are fertile and are able to produce F2-fish. In this paper, we demonstrate that even intergenus hybrids (Gnathonemus petersii ♂ \× Campylomormyrus compressirostris ♀) are fertile. Three artificial reproduction (AR) trials, with an average fertilisation rate of ca. 23\%, yielded different numbers of survivals (maximally about 50\%) of the F1-hybrids. The complete ontogenetic development of these hybrids is described concerning their morphology and electric organ discharge (EOD). Two EOD types emerged at the juvenile stage, which did not change up to adulthood. Type I consisted of four phases and Type II was triphasic. The minimum body length at sexual maturity was between 10 and 11\ cm. Malformations, growth and mortality rates are also described.

}, issn = {1432-1351}, doi = {10.1007/s00359-022-01542-5}, author = {Korniienko, Yevheniia and Nzimora, Kingsley C and Vater, Marianne and Tiedemann, Ralph and Kirschbaum, Frank} } @article {602, title = {Intragenus F1-hybrids of African weakly electric fish (Mormyridae: Campylomormyrus tamandua ♂ {\texttimes} C. compressirostris ♀) are fertile}, journal = {Journal of Comparative Physiology A}, volume = {206}, year = {2020}, month = {Jan-07-2020}, pages = {571 - 585}, abstract = {

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 between Campylomormyrus tamandua ♂ \× C. compressirostris ♀ 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\%. Exog- enous 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.

}, issn = {0340-7594}, doi = {10.1007/s00359-020-01425-7}, url = {http://link.springer.com/10.1007/s00359-020-01425-7}, author = {Korniienko, Yevheniia and Nguyen, Linh and Baumgartner, Stephanie and Vater, Marianne and Tiedemann, Ralph and Kirschbaum, Frank} } @article {587, title = {Morphological differentiation in African weakly electric fish (genus Campylomormyrus) relates to substrate preferences}, journal = {Evolutionary Ecology}, year = {2020}, month = {Apr-04-2021}, abstract = {

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.

}, issn = {0269-7653}, doi = {10.1007/s10682-020-10043-3}, url = {http://link.springer.com/10.1007/s10682-020-10043-3}, author = {Amen, Rahma and Nagel, Rebecca and Hedt, Maximilian and Kirschbaum, Frank and Tiedemann, Ralph} } @article {559, title = {Electric pulse characteristics can enable species recognition in African weakly electric fish species}, journal = {Scientific Reports}, volume = {8}, year = {2018}, month = {Jan-12-2018}, abstract = {

Communication is key to a wide variety of animal behaviours and multiple modalities are often involved in this exchange of information from sender to receiver. The communication of African weakly electric fish, however, is thought to be predominantly unimodal and is mediated by their electric sense, in which species-specific electric organ discharges (EODs) are generated in a context-dependent and thus variable sequence of pulse intervals (SPI). While the primary function of the electric sense is considered to be electrolocation, both of its components likely carry information regarding identity of the sender. However, a clear understanding of their contribution to species recognition is incomplete. We therefore analysed these two electrocommunication components (EOD waveform and SPI statistics) in two sympatric mormyrid Campylomormyrus species. In a set of five playback conditions, we further investigated which components may drive interspecific recognition and discrimination. While we found that both electrocommunication components are species-specific, the cues necessary for species recognition differ between the two species studied. While the EOD waveform and SPI were both necessary and sufficient for species recognition in C. compressirostris males, C. tamandua males apparently utilize other, non-electric modalities. Mapped onto a recent phylogeny, our results suggest that discrimination by electric cues alone may be an apomorphic trait evolved during a recent radiation in this taxon.

}, doi = {10.1038/s41598-018-29132-z}, url = {http://www.nature.com/articles/s41598-018-29132-z}, author = {Nagel, Rebecca and Frank Kirschbaum and Hofmann, Volker and Engelmann, Jacob and Ralph Tiedemann} } @article {499, title = {Species delimitation and phylogenetic relationships in a genus of African weakly-electric fishes (Osteoglossiformes, Mormyridae, Campylomormyrus)}, journal = {Molecular Phylogenetics and Evolution}, year = {2016}, month = {Jan-04-2016}, abstract = {

African weakly-electric fishes (Mormyridae) are able to communicate through species-specific electric signals; this feature might have favoured the evolutionary radiation observed in this family (over 200 species) by acting as an effective pre-zygotic isolation mechanism. In the present study we used mitochondrial (cytb) and nuclear (rps7, scn4aa) markers in order to reconstruct a species-phylogeny and identify species boundaries for the genus Campylomormyrus, by applying inference methods based on the multispecies coalescent model. Additionally, we employed 16 microsatellite markers, landmark-based morphometric measurements, and electro-physiological analyses as independent lines of evidence to the results obtained from the sequence data. The results show that groups that are morphologically different are also significantly divergent at the genetic level, whereas morphologically similar groups, displaying dissimilar electric signals, do not show enough genetic diversity to be considered separate species. Furthermore, the data confirm the presence of a yet undescribed species within the genus Campylomormyrus.

}, keywords = {Campylomormyrus, Geometric morphometrics, Microsatellites, Mormyridae, Multispecies-coalescent, Species-delimitation}, issn = {10557903}, doi = {10.1016/j.ympev.2016.04.035}, url = {http://linkinghub.elsevier.com/retrieve/pii/S1055790316300781}, author = {Lamanna, Francesco and Frank Kirschbaum and Ernst, Anja R.R. and Philine G.D. Feulner and Victor Mamonekene and Paul, Christiane and Ralph Tiedemann} } @article {478, title = {Cross-tissue and cross-species analysis of gene expression in skeletal muscle and electric organ of African weakly-electric fish (Teleostei; Mormyridae)}, journal = {BMC Genomics}, volume = {16}, year = {2015}, month = {Jan-12-2015}, abstract = {

Background: African weakly-electric fishes of the family Mormyridae are able to produce and perceive weak electric signals (typically less than one volt in amplitude) owing to the presence of a specialized, muscle-derived electric organ (EO) in their tail region. Such electric signals, also known as Electric Organ Discharges (EODs), are used for objects/prey localization, for the identification of conspecifics, and in social and reproductive behaviour. This feature might have promoted the adaptive radiation of this family by acting as an effective pre-zygotic isolation mechanism. Despite the physiological and evolutionary importance of this trait, the investigation of the genetic basis of its function and modification has so far remained limited. In this study, we aim at: i) identifying constitutive differences in terms of gene expression between electric organ and skeletal muscle (SM) in two mormyrid species of the genus Campylomormyrus: C. compressirostris and C. tshokwe, and ii) exploring cross-specific patterns of gene expression within the two tissues among C. compressirostris, C. tshokwe, and the outgroup species Gnathonemus petersii.
Results: Twelve paired-end (100 bp) strand-specific RNA-seq Illumina libraries were sequenced, producing circa 330 M quality-filtered short read pairs. The obtained reads were assembled de novo into four reference transcriptomes. In silico cross-tissue DE-analysis allowed us to identify 271 shared differentially expressed genes between EO and SM in C. compressirostris and C.tshokwe. Many of these genes correspond to myogenic factors, ion channels and pumps, and genes involved in several metabolic pathways. Cross-species analysis has revealed that the electric organ transcriptome is more variable in terms of gene expression levels across species than the skeletal muscle transcriptome.
Conclusions: The data obtained indicate that: i) the loss of contractile activity and the decoupling of the excitation-contraction processes are reflected by the down-regulation of the corresponding genes in the electric organ\’s transcriptome; ii) the metabolic activity of the EO might be specialized towards the production and turn-over of membrane structures; iii) several ion channels are highly expressed in the EO in order to increase excitability; iv) several myogenic factors might be down-regulated by transcription repressors in the EO.

}, doi = {10.1186/s12864-015-1858-9}, url = {http://www.biomedcentral.com/1471-2164/16/668}, author = {Lamanna, Francesco and Frank Kirschbaum and Waurick, Isabelle and Dieterich, Christoph and Ralph Tiedemann} } @article {453, title = {De novo assembly and characterization of the skeletal muscle and electric organ transcriptomes of the African weakly electric fish Campylomormyrus compressirostris (Mormyridae, Teleostei)}, journal = {Molecular Ecology Resources}, volume = {14}, year = {2014}, month = {Jan-11-2014}, pages = {1222 - 1230}, abstract = {

African weakly electric fishes (Mormyridae) underwent an outstanding adaptive radiation (about 200 species), puta-tively owing to their ability to communicate through species-specific weak electric signals. The electric organdischarge (EOD) is produced by muscle-derived electrocytes organized in piles to form an electric organ. Despite theimportance of this trait as a prezygotic isolation mechanism, genomic resources remained limited. We present here afirst draft of the skeletal muscle and electric organ transcriptomes from the weakly electric fish species Camp-ylomormyrus compressirostris, obtained using the Illumina HiSeq2000 sequencing technology. Approximately 6.8Gbp of cDNA sequence data were produced from both tissues, resulting in 57 268 109 raw reads for the skeletal mus-cle and 46 934 923 for the electric organ, and assembled de novo into 46 143 and 89 270 contigs, respectively. About50\% of both transcriptomes were annotated after protein databases search. The two transcriptomes show similarprofiles in terms of Gene Ontology categories composition. We identified several candidate genes which are likely toplay a central role in the production and evolution of the electric signal. For most of these genes, and for many otherhousekeeping genes, we were able to obtain the complete or partial coding DNA sequences (CDS), which can beused for the development of primers to be utilized in qRT-PCR experiments. We present also the complete mitochon-drial genome and compare it to those available from other weakly electric fish species. Additionally, we located 1671SSR-containing regions with their flanking sites and designed the relative primers. This study establishes a first stepin the development of genomic tools aimed at understanding the role of electric communication during speciation

}, doi = {10.1111/men.2014.14.issue-610.1111/1755-0998.12260}, url = {http://doi.wiley.com/10.1111/men.2014.14.issue-6http://doi.wiley.com/10.1111/1755-0998.12260}, author = {Lamanna, Francesco and Frank Kirschbaum and Ralph Tiedemann} } @article {73, title = {Description de Mormyrid{\'e}s nouveaux. R{\'e}colt{\'e}s au Congo Belge par le Dr. Schouteden}, journal = {Revue Zoologique Africaine}, volume = {12}, number = {1}, year = {1924}, month = {03/1924}, pages = {1-8}, chapter = {1}, author = {Pellegrin, J.} } @article {267, title = {Le genre Campylomormyrus Bleeker, 1874, {\'e}tude systematique et description d{\textquoteright}une espece nouvelle (Pisces, Mormyridae)}, journal = {Bulletin de l{\textquoteright}Institut Royal des Sciences de Belgique Biologie}, volume = {54}, number = {5}, year = {1982}, month = {08/1982}, pages = {1{\textendash}34, Pls. 1{\textendash}13}, author = {Poll, M. and Gosse, J.-P. and Orts, S.} } @article {889, title = {Adaptive radiation in African weakly electric fish (Teleostei: Mormyridae: Campylomormyrus): a combined molecular and morphological approach}, journal = {Journal of Evolutionary Biology}, volume = {20}, year = {2007}, month = {01/2007}, pages = {403 - 414}, abstract = {

We combined multiple molecular markers and geometric morphometrics to revise the current taxonomy and to build a phylogenetic hypothesis for the African weakly electric fish genus Campylomormyrus. Genetic data (2039 bp DNA sequence of mitochondrial cytochrome b and nuclear S7 genes) on 106 specimens support the existence of at least six species occurring in sympatry. We were able to further confirm these species by microsatellite analysis at 16 unlinked nuclear loci and landmark-based morphometrics. We assigned them to nominal taxa by comparisons to type specimens of all Campylomormyrus species recognized so far. Additionally, we showed that the shape of the elongated trunk-like snout is the major source of morphological differentiation among them. This finding suggests that the radiation of this speciose genus might have been driven by adaptation to different food sources.

}, issn = {1420-9101}, doi = {10.1111/j.1420-9101.2006.01181.x}, author = {Philine G.D. Feulner and Frank Kirschbaum and Victor Mamonekene and Ketmaier, V. and Ralph Tiedemann} } @article {890, title = {Adaptive radiation in the Congo River: An ecological speciation scenario for African weakly electric fish (Teleostei; Mormyridae; Campylomormyrus)}, journal = {Journal of Physiology-Paris}, volume = {102}, year = {2008}, month = {7/2008}, pages = {340 - 346}, abstract = {

he ultimate aim of this study is to better understand the diversification of African weakly electric fish in the Congo River. Based on a robust phylogenetic hypothesis we examined the radiation within the mor- myrid genus Campylomormyrus. Morphological traits relevant for the divergence between the identified species were detected. Among them, the variation in the shape of the trunk-like elongated snout sug- gested the presence of different trophic specializations. Furthermore, the chosen model taxon, the genus Campylomormyrus, exhibits a wide diversity of electric organ discharge (EOD) waveforms. A comparison of EOD waveform types and phylogenetic relationships showed major differences in EOD between closely related species. This indicates that the EOD might function as a reproductive isolation mechanism. In con- clusion, we provide a plausible scenario of an adaptive radiation triggered by sexual selection and assor- tative mating based on EOD characteristics, but caused by a divergent selection on the feeding apparatus. These findings point towards an adaptive radiation of at least some Campylomormyrus species occurring in the Lower Congo River.

}, issn = {09284257}, doi = {10.1016/j.jphysparis.2008.10.002}, author = {Philine G.D. Feulner and Frank Kirschbaum and Ralph Tiedemann} } @article {891, title = {Electrifying love: electric fish use species-specific discharge for mate recognition}, journal = {Biology Letters}, volume = {520927419392041142915996351451455587020220191}, year = {2009}, month = {04/2009}, pages = {225 - 228}, abstract = {

A unique evolutionary specialization of African weakly electric fish (Mormyridae) is their ability to produce and perceive electric signals. Mormyrids use their electric organs discharge (EOD) for electrolocation and electrocommunication. Here we discuss the adaptive significance of the EOD in foraging (electric prey detec- tion) in light of recent results demonstrating that mormyrid fish mate assortatively according to EOD waveform characteristics (electric mate choice). Therefore the EOD as a single trait pleio- tropically combines natural divergent selection and reproductive isolation. Consequently we postulate the EOD as a \“magic trait\” promoting the diversification of African weakly electric fish.

}, issn = {0179-1613}, doi = {10.1098/rsbl.2008.0566}, author = {Philine G.D. Feulner and Plath, M. and Engelmann, J. and Frank Kirschbaum and Ralph Tiedemann} } @article {893, title = {De novo assembly and characterization of the skeletal muscle and electric organ transcriptomes of the African weakly-electric fish Campylomormyrus compressirostris (Mormyridae, Teleostei)}, journal = {Molecular Ecology Resources}, year = {2014}, month = {03/2014}, pages = {n/a - n/a}, keywords = {cSSR, electric fish, electric organ, skeletal muscle, transcriptome}, doi = {10.1111/1755-0998.12260}, author = {Lamanna, Francesco and Frank Kirschbaum and Ralph Tiedemann} }