02770nas a2200181 4500008004100000245017600041210006900217260002000286300001400306490000800320520210100328100002302429700002502452700002202477700002202499700002102521856004602542 2011 eng d00aSignal variation and its morphological correlates in Paramormyrops kingsleyae provide insight into the evolution of electrogenic signal diversity in mormyrid electric fish0 aSignal variation and its morphological correlates in Paramormyro bSpringer-Verlag a799–8170 v1973 a

We describe patterns of geographic variation in electric signal waveforms among populations of the mormyrid electric fish species Paramormyrops kingsleyae. This analysis includes study of electric organs and electric organ discharge (EOD) signals from 553 specimens collected from 12 localities in Gabon, West-Central Africa from 1998 to 2009. We measured time, slope, and voltage values from nine defined EOD “landmarks” and determined peak spectral frequencies from each waveform; these data were subjected to principal components analysis. The majority of variation in EODs is explained by two factors: the first related to EOD duration, the second related to the magnitude of the weak head-negative pre-potential, P0. Both factors varied clinally across Gabon. EODs are shorter in eastern Gabon and longer in western Gabon. Peak P0 is slightly larger in northern Gabon and smaller in southern Gabon. P0 in the EOD is due to the presence of penetrating-stalked (Pa) electrocytes in the electric organ while absence is due to the presence of non-penetrating stalked electrocytes (NPp). Across Gabon, the majority of P. kingsleyae populations surveyed have only individuals with P0-present EODs and Pa electrocytes. We discovered two geographically distinct populations, isolated from others by barriers to migration, where all individuals have P0-absent EODs with NPp electrocytes. At two sites along a boundary between P0-absent and P0-present populations, P0-absent and P0-present individuals were found in sympatry; specimens collected there had electric organs of intermediate morphology. This pattern of geographic variation in EODs is considered in the context of current phylogenetic work. Multiple independent paedomorphic losses of penetrating stalked electrocytes have occurred within five Paramormyrops species and seven genera of mormyrids. We suggest that this key anatomical feature in EOD signal evolution may be under a simple mechanism of genetic control, and may be easily influenced by selection or drift throughout the evolutionary history of mormyrids.

1 aGallant, Jason, R.1 aArnegard, Matthew, E1 aSullivan, John, P1 aCarlson, Bruce, A1 aHopkins, Carl, D uhttps://doi.org/10.1007/s00359-011-0643-801771nas a2200217 4500008004100000022001400041245006900055210006500124260001600189300001000205490000800215520117700223653001701400653001601417653000801433653001701441100001701458700001701475700002001492856004101512 1976 eng d a0302-982400aThe electric organ of a mormyrid as a current and voltage source0 aelectric organ of a mormyrid as a current and voltage source cJan-01-1976 a65-880 v1103 a

We have examined how the electric organ discharge (EOD) of a mormyrid (Gnathonemus petersii) is affected by changes in resistive load (Figs. 3, 4, 5). We have also shown how this load depends on resistivity and distance to non-conducting boundaries (Figs. 10, 11). When resistive load was varied, voltage and current were related in a linear, battery-like manner for the initial, head positive phase of the EOD (Figs. 4, 5). This linear relation made it possible to estimate first phase e.m.f, and source resistance. For the second, head negative phase, however, voltage rose to a peak and then fell as resistance increased. Furthermore, the waveform of the second but not the first phase was strongly affected by load changes. These second phase features were shown to reflect a dependence of second phase e.m.f, on first phase current. A linear and battery-like relation between second phase voltage and current was seen when first phase load was held constant while varying second phase load (Fig. 6). These results on the behavior of the whole electric organ can be understood in terms of the underlying properties of the cellular generators, the electrocytes

10aconductivity10aelectrocyte10aEOD10aeod waveform1 aBell, C., C.1 aBradbury, J.1 aRussell, C., J. uhttp://dx.doi.org/10.1007/bf0065678202043nas a2200205 4500008004100000022001400041245014400055210006900199260001600268300001400284490000800298520134200306100002601648700001701674700002701691700002001718700002101738700002201759856005601781 2020 eng d a0340-759400aIntragenus F1-hybrids of African weakly electric fish (Mormyridae: Campylomormyrus tamandua ♂ × C. compressirostris ♀) are fertile0 aIntragenus F1hybrids of African weakly electric fish Mormyridae  cJan-07-2020 a571 - 5850 v2063 a

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.

1 aKorniienko, Yevheniia1 aNguyen, Linh1 aBaumgartner, Stephanie1 aVater, Marianne1 aTiedemann, Ralph1 aKirschbaum, Frank uhttp://link.springer.com/10.1007/s00359-020-01425-702081nas a2200217 4500008004100000022001400041245012600055210006900181260001600250300001400266490000800280520136500288100002101653700002301674700002001697700002701717700002101744700002101765700002201786856005501808 2015 eng d a0340-759400aComparative histology of the adult electric organ among four species of the genus Campylomormyrus (Teleostei: Mormyridae)0 aComparative histology of the adult electric organ among four spe cJan-04-2015 a357 - 3740 v2013 a

The electric organ (EO) of weakly electric mormyrids consists of flat, disk-shaped electrocytes with distinct anterior and posterior faces. There are multiple species-characteristic patterns in the geometry of the electrocytes and their innervation. To further correlate electric organ discharge (EOD) with EO anatomy, we examined four species of the mormyrid genus Campylomormyrus possessing clearly distinct EODs. In C. compressirostris, C. numenius, and C. tshokwe, all of which display biphasic EODs, the posterior face of the electrocytes forms evaginations merging to a stalk system receiving the innervation. In C. tamandua that emits a triphasic EOD, the small stalks of the electrocyte penetrate the electrocyte anteriorly before merging on the anterior side to receive the innervation. Additional differences in electrocyte anatomy among the former three species with the same EO geometry could be associated with further characteristics of their EODs. Furthermore, in C. numenius, ontogenetic changes in EO anatomy correlate with profound changes in the EOD. In the juvenile the anterior face of the electrocyte is smooth, whereas in the adult it exhibits pronounced surface foldings. This anatomical difference, together with disparities in the degree of stalk furcation, probably contributes to the about 12 times longer EOD in the adult.

1 aPaul, Christiane1 aMamonekene, Victor1 aVater, Marianne1 aFeulner, Philine, G.D.1 aEngelmann, Jacob1 aTiedemann, Ralph1 aKirschbaum, Frank uhttp://link.springer.com/10.1007/s00359-015-0995-600512nas a2200133 4500008004100000022001400041245015200055210006900207260001200276300001400288490000800302100001700310856005100327 2008 eng d a1432-135100aEffect of conductivity changes on the stability of electric signal waveforms in dwarf stonebashers (Mormyridae; Pollimyrus castelnaui, P. marianne)0 aEffect of conductivity changes on the stability of electric sign c10/2008 a915 - 9190 v1941 aBaier, Bernd uhttps://mormyrids.efishgenomics.com/fr/node/33