title: Intragenus (Campylomormyrus) and intergenus hybrids in mormyrid fish: Physiological and histological investigations of the electric organ ontogeny.
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 42days 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. Eight 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×C. compressirostris are fertile: viable F2-fish could be obtained with artificial reproduction.
authors.affiliation: Humboldt University, Faculty of Life Sciences, Unit of Biology and Ecology of Fishes, Philippstr. 13, Haus 16, D-10115 Berlin, Germany. Electronic address: frank.kirschbaum@staff.hu-berlin.de.
authors.forename: Frank
authors.initials: F
authors.lastname: Kirschbaum
authors.affiliation: Humboldt University, Faculty of Life Sciences, Unit of Biology and Ecology of Fishes, Philippstr. 13, Haus 16, D-10115 Berlin, Germany; University of Potsdam, Institute of Biochemistry and Biology, Unit of Evolutionary Biology/Systematic Zoology, Karl-Liebknecht-Str. 24-25, Haus 26, D-14476 Potsdam-Golm, Germany.
authors.forename: Linh
authors.initials: L
authors.lastname: Nguyen
authors.affiliation: Humboldt University, Faculty of Life Sciences, Unit of Biology and Ecology of Fishes, Philippstr. 13, Haus 16, D-10115 Berlin, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Baumgartner
authors.affiliation: Humboldt University, Faculty of Life Sciences, Unit of Biology and Ecology of Fishes, Philippstr. 13, Haus 16, D-10115 Berlin, Germany.
authors.forename: Hiu Wan Linda
authors.initials: HWL
authors.lastname: Chi
authors.affiliation: Humboldt University, Faculty of Life Sciences, Unit of Biology and Ecology of Fishes, Philippstr. 13, Haus 16, D-10115 Berlin, Germany.
authors.forename: Rene
authors.initials: R
authors.lastname: Wolfart
authors.affiliation: Humboldt University, Faculty of Life Sciences, Unit of Biology and Ecology of Fishes, Philippstr. 13, Haus 16, D-10115 Berlin, Germany.
authors.forename: Khouloud
authors.initials: K
authors.lastname: Elarbani
authors.affiliation: Humboldt University, Faculty of Life Sciences, Unit of Biology and Ecology of Fishes, Philippstr. 13, Haus 16, D-10115 Berlin, Germany.
authors.forename: Hari
authors.initials: H
authors.lastname: Eppenstein
authors.affiliation: Humboldt University, Faculty of Life Sciences, Unit of Biology and Ecology of Fishes, Philippstr. 13, Haus 16, D-10115 Berlin, Germany.
authors.forename: Yevheniia
authors.initials: Y
authors.lastname: Korniienko
authors.affiliation: Humboldt University, Faculty of Life Sciences, Unit of Biology and Ecology of Fishes, Philippstr. 13, Haus 16, D-10115 Berlin, Germany.
authors.forename: Lilian
authors.initials: L
authors.lastname: Guido-Böhm
authors.affiliation: Ecole Nationale Supérieure d'Agronomie et de Foresterie, Université Marien Ngouabi, B.P. 69, Brazzaville, People's Republic of Congo.
authors.forename: Victor
authors.initials: V
authors.lastname: Mamonekene
authors.affiliation: University of Potsdam, Institute of Biochemistry and Biology, Unit of General Zoology, Karl-Liebknecht-Str. 24-25, Haus 26, D-14476 Potsdam-Golm, Germany.
authors.forename: Marianne
authors.initials: M
authors.lastname: Vater
authors.affiliation: University of Potsdam, Institute of Biochemistry and Biology, Unit of Evolutionary Biology/Systematic Zoology, Karl-Liebknecht-Str. 24-25, Haus 26, D-14476 Potsdam-Golm, Germany.
authors.forename: Ralph
authors.initials: R
authors.lastname: Tiedemann
mesh_terms: D000818:Animals; D004555:Electric Fish / Q000145:classification / Q000502:physiology*; D004557:Electric Organ / Q000166:cytology / Q000502:physiology*; D006824:Hybridization, Genetic; D010802:Phylogeny
keywords: Artificial reproduction; Campylomormyrus; Electric organ ontogeny; Hybrids; Mormyrids