@article {543, title = {Intragenus (Campylomormyrus) and intergenus hybrids in mormyrid fish: physiological and histological investigations of the electric organ ontogeny}, journal = {Journal of Physiology-Paris}, year = {2017}, month = {Jan-01-2017}, abstract = {

African weakly electric mormyrid fish show a high diversity of their electric organ discharge (EOD) both across and within genera. Thanks to a recently developed technique of artificial reproduction in mormyrid fish, we were able to perform hybridizations between different genera and within one genus (Campylomormyrus). The hybrids of intergenus hybridizations exhibited different degrees of reduced survival related to the phylogenetic distance of the parent species: hybrids of the crosses between C. rhynchophorus and its sister genus Gnathonemus survived and developed normally. Hybrids between C. rhynchophorus and a Mormyrus species (a more basal clade compared to Campylomormyrus s) survived up to 42 days and developed many malformations, e.g., at the level of the unpaired fins. Hybrids between C. numenius and Hippopotamyrus pictus (a derived clade, only distantly related to Campylomormyrus) only survived for two days during embryological development. Seven different hybrid combinations among five Campylomormyrus species (C. tamandua, C. compressirostris, C. tshokwe, C. rhynchophorus, C. numenius) were performed. The aim of the hybridizations was to combine species with (1) either caudal or rostral position of the main stalk innervating the electrocytes in the electric organ and (2) short, median or long duration of their EOD. The hybrids, though they are still juveniles, show very interesting features concerning electrocyte geometry as well as EOD form and duration: the caudal position of the stalk is prevailing over the rostral position, and the penetration of the stalk is dominant over the non-penetrating feature (in the Campylomormyrus hybrids); in the hybrid between C. rhynchophorus and Gnathonemus petersii it is the opposite. When crossing species with long and short EODs, it is always the long duration EOD that is expressed in the hybrids. The F1-Hybrids of the cross C. tamandua x C. compressirostris are fertile: viable F2-fish could be obtained with artificial reproduction

}, keywords = {Artificial reproduction, Campylomormyrus, Electric organ ontogeny, Hybrids, mormyrids}, issn = {09284257}, doi = {10.1016/j.jphysparis.2017.01.003}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0928425717300037}, author = {Frank Kirschbaum and Nguyen, Linh and Baumgartner, Stephanie and Chi, Linda and Wolfart, Rene and Elarbani, Khouloud and Eppenstein, Hari and Korniienko, Yevheniia and Guido-B{\"o}hm, Lilian and Victor Mamonekene and Vater, Marianne and Ralph Tiedemann} } @article {542, title = {Object discrimination through active electrolocation: Shape recognition and the influence of electrical noise}, journal = {Journal of Physiology-Paris}, year = {2016}, month = {Jan-12-2016}, abstract = {

The weakly electric fish Gnathonemus petersii can recognise objects using active electrolocation. Here, we tested two aspects of object recognition; first whether shape recognition might be influenced by movement of the fish, and second whether object discrimination is affected by the presence of electrical noise from conspecifics. (i) Unlike other object features, such as size or volume, no parameter within a single electrical image has been found that encodes object shape. We investigated whether shape recognition might be facilitated by movement-induced modulations (MIM) of the set of electrical images that are created as a fish swims past an object. Fish were trained to discriminate between pairs of objects that either created similar or dissimilar levels of MIM of the electrical images. As predicted, the fish were able to discriminate between objects up to a longer distance if there was a large difference in MIM between the objects than if there was a small difference. This supports an involvement of MIMs in shape recognition but the use of other cues cannot be excluded. (ii) Electrical noise might impair object recognition if the noise signals overlap with the EODs of an electrolocating fish. To avoid jamming, we predicted that fish might employ pulsing strategies to prevent overlaps. To investigate the influence of electrical noise on discrimination performance, two fish were tested either in the presence of a conspecific or of playback signals and the electric signals were recorded during the experiments. The fish were surprisingly immune to jamming by conspecifics: While the discrimination performance of one fish dropped to chance level when more than 22\% of its EODs overlapped with the noise signals, the performance of the other fish was not impaired even when all its EODs overlapped. Neither of the fish changed their pulsing behaviour, suggesting that they did not use any kind of jamming avoidance strategy.

}, issn = {09284257}, doi = {10.1016/j.jphysparis.2016.11.008}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0928425716300304}, author = {Schumacher, Sarah and Burt de Perera, Theresa and G. von der Emde} } @article {539, title = {Electric Fish Genomics: Progress, Prospects, and New Tools for Neuroethology}, journal = {Journal of Physiology-Paris}, year = {2016}, month = {Jan-10-2016}, abstract = {

Electric fish have served as a model system in biology since the 18th century, providing deep insight into the nature of bioelectrogenesis, the molecular structure of the synapse, and brain circuitry underlying complex behavior. Neuroethologists have collected extensive phenotypic data that span biological levels of analysis from molecules to ecosystems. This phenotypic data, together with genomic resources obtained over the past decades, have motivated new and exciting hypotheses that position the weakly electric fish model to address fundamental 21st century biological questions. This review article considers the molecular data collected for weakly electric fish over the past three decades, and the insights that data of this nature has motivated. For readers relatively new to molecular genetics techniques, we also provide a table of terminology aimed at clarifying the numerous acronyms and techniques that accompany this field. Next, we pose a research agenda for expanding genomic resources for electric fish research over the next 10 years. We conclude by considering some of the exciting research prospects for neuroethology that electric fish genomics may offer over the coming decades, if the electric fish community is successful in these endeavors.

}, keywords = {CRISPR, electric fish, genome editing, genomics, transcriptomics, transgenics}, issn = {09284257}, doi = {10.1016/j.jphysparis.2016.10.003}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0928425716300079}, author = {Pitchers, William R. and Constantinou, Savvas J. and Losilla, Mauricio and Jason R. Gallant} } @article {409, title = {Petrocephalus of Odzala offer insights into evolutionary patterns of signal diversification in the Mormyridae, a family of weakly electrogenic fishes from Africa}, journal = {Journal of Physiology-Paris}, volume = {102}, number = {4-6}, year = {2008}, note = {411CHTimes Cited:3Cited References Count:84}, month = {Jul-Nov}, pages = {322-339}, abstract = {

Electric signals of mormyrid fishes have recently been described from several regions of Africa. Members of the Mormyridae produce weak electric organ discharges (EODs) as part of a specialized electrosensory Communication and orientation system. Sympatric species often express distinctive EODs, which may contribute to species recognition during mate choice in some lineages. Striking examples of interspecific EOD variation within assemblages have been reported for two monophyletic radiations: the Paramormyrops of Gabon and the Campylomormyrus of Lower Congo. Here, we describe a speciose assemblage of Petrocephalus in the Lekoli River system of Odzala National Park, Republic of Congo. This widespread genus comprises the Subfamily (Petrocephalinae) that is the Sister group to all other mormyrids (Mormyrinae). Eleven Petrocephalus species were collected in Odzala, five of which are not described taxonomically. We quantify EOD variation within this assemblage and show that all eleven species produce EOD waveforms of brief duration (species means range from 144 to 663 mu s) compared to many other mormyrids. We also present reconstructed phylogenetic relationships among species based on cytochrome b sequences. Discovery of the Odzala assemblage greatly increases the number of Petrocephalus species for which EODs and DNA sequence data are available, permitting a first qualitative comparison between mormyrid Subfamilies of the divergence patterns that have been described within lineages. We find that the Petrocephalus assemblage in Odzala is not a monophyletic radiation. Genetic divergence among Petrocephalus species often appears higher than among Paramormyrops or Campylomormyrus species. In contrast, results of this study and others Suggest that Petrocephalus may generally exhibit less interspecific EOD divergence, as well as smaller sex differences in EOD waveforms, compared to Paramormyrops and Campylomormyrus. We discuss possible causes and consequences of EOD diversification patterns observed within mormyrid subfamilies as a framework for future comparative studies of signal evolution using this emerging model system. (c) 2008 Elsevier Ltd. All rights reserved.

}, keywords = {adaptive radiation, communication signals, electric organ anatomy, electric organ discharge, electrosensory modality, food-habits, gnathonemus-petersii mormyridae, molecular evolution, petrocephalus, pollimyrus-isidori, riverine species flock, sexual signal evolution, sexual-dimorphism, species marker, type npp electrocytes, wave-forms}, isbn = {0928-4257}, url = {://000263625100019}, author = {S{\'e}bastien Lavou{\'e} and Matthew E. Arnegard and John P. Sullivan and Carl D. Hopkins} } @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} }