02556nas a2200277 4500008004100000022002500041245011800066210006900184260001600253300001000269490000800279520169400287653002801981653001302009653002002022653002602042653002602068653001302094100001702107700002102124700002302145700001902168700002102187700002202208856004802230 2016 eng d a0378-1909, 1573-513300aReproduction and development in some species of the weakly electric genus Campylomormyrus (Mormyridae, Teleostei)0 aReproduction and development in some species of the weakly elect cDec-07-2016 a49-680 v1003 a

Reproduction in captivity of four species of the mormyrid genus Campylomormyrus was investigated. Cyclical reproduction was provoked by changing water conductivity (C) alone: decreasing C led to gonadal recrudescence, an increase induced gonad regression. Data on the reproduction and development of three species are presented. All three species are indeterminate fractional spawners. Spawning intervals ranged from 6 to 66 days in C. rhynchophorus, 10–75 days in C. tshokwe, and 18 days in C. compressirostris (calculated values). Fecundities (eggs per fractional spawning) ranged from 70 to 1570 eggs in C. rhynchophorus, 100–1192 in C. tshokwe, and 38–246 in C. compressirostris. Spawnings/ovipositions occurred during the second half of the night; no parental care was observed; no special spawning substrates were necessary. C. compressirostris successfully spawned in breeding groups, C. rhynchophorus as pair. Agonistic behavior in the C. tshokwe pair forced us to divide the breeding tank; therefore, only ovipositions occurred. However, injection of an artificial GnRH hormone allowed us to obtain ripe eggs and sperm and to perform successful artificial reproduction. All three species produce yolky, slightly sticky eggs. Egg diameter ranges from 2.3–3.0 mm. Hatching occurred on day 3, feeding started on day 11. Transition from larval to juvenile stage occurred at around 20 mm total length (TL). At this size C. rhynchophorus developed a higher body than the two other species and differences between the species in the melanin pigmentation of the unpaired fins occurred. Between 32 and 35 mm TL the upper and lower jaws started to elongate.

10aArtificial reproduction10aBehavior10aCampylomormyrus10aCyclical reproduction10aEnvironmental factors10aOntogeny1 aNguyen, Linh1 aPaul, Christiane1 aMamonekene, Victor1 aBartsch, Peter1 aTiedemann, Ralph1 aKirschbaum, Frank uhttp://dx.doi.org/10.1007/s10641-016-0554-102253nas a2200169 4500008004100000022001400041245012600055210006900181260001600250300001100266520166400277100002101941700002201962700002301984700002102007856005502028 2016 eng d a0022-284400aEvidence for Non-neutral Evolution in a Sodium Channel Gene in African Weakly Electric Fish (Campylomormyrus, Mormyridae)0 aEvidence for Nonneutral Evolution in a Sodium Channel Gene in Af cJan-08-2016 a1–173 a

Voltage-gated sodium channels, Nav1, play a crucial role in the generation and propagation of action potentials and substantially contribute to the shape of their rising phase. The electric organ discharge (EOD) of African weakly electric fish (Mormyroidea) is the sum of action potentials fired from all electrocytes of the electric organ at the same time and hence voltage-gated sodium channels are one factor—together with the electrocyte’s morphology and innervation pattern—that determines the properties of these EODs. Due to the fish-specific genome duplication, teleost fish possess eight copies of sodium channel genes (SCN), which encode for Nav1 channels. In mormyroids, SCN4aa is solely expressed in the electrocytes of the adult electric organ. In this study, we compared entire SCN4aa sequences of six species of the genus Campylomormyrus and identified nonsynonymous substitutions among them. SCN4aa in Campylomormyrus exhibits a much higher evolutionary rate compared to its paralog SCN4ab, whose expression is not restricted to the electric organ. We also found evidence for strong positive selection on the SCN4aa gene within Mormyridae and along the lineage ancestral to the Mormyridae. We have identified sites at which all nonelectric teleosts are monomorphic in their amino acid, but mormyrids have different amino acids. Our findings confirm the crucial role of SCN4aa in EOD evolution among mormyrid weakly electric fish. The inferred positive selection within Mormyridae makes this gene a prime candidate for further investigation of the divergent evolution of pulse-type EODs among closely related species.

1 aPaul, Christiane1 aKirschbaum, Frank1 aMamonekene, Victor1 aTiedemann, Ralph uhttp://link.springer.com/10.1007/s00239-016-9754-802056nas a2200265 4500008004100000022001300041245015000054210006900204260001600273520114000289653002001429653002801449653002001477653001501497653002801512653002501540100002301565700002201588700002201610700002701632700002301659700002101682700002101703856006601724 2016 eng d a1055790300aSpecies delimitation and phylogenetic relationships in a genus of African weakly-electric fishes (Osteoglossiformes, Mormyridae, Campylomormyrus)0 aSpecies delimitation and phylogenetic relationships in a genus o cJan-04-20163 a

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.

10aCampylomormyrus10aGeometric morphometrics10aMicrosatellites10aMormyridae10aMultispecies-coalescent10aSpecies-delimitation1 aLamanna, Francesco1 aKirschbaum, Frank1 aErnst, Anja, R.R.1 aFeulner, Philine, G.D.1 aMamonekene, Victor1 aPaul, Christiane1 aTiedemann, Ralph uhttp://linkinghub.elsevier.com/retrieve/pii/S105579031630078102081nas 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/s00359-015-0995-6