03199nas a2200301 4500008004100000022001400041245015100055210006900206260000900275300001300284490000700297520224500304653001202549653001802561653001902579653001602598653002002614653003002634653003102664653001402695653003602709653002402745653001802769100001802787700002202805700002102827856004902848 2020 eng d a1932-620300aTranscriptome-wide single nucleotide polymorphisms related to electric organ discharge differentiation among African weakly electric fish species.0 aTranscriptomewide single nucleotide polymorphisms related to ele c2020 ae02408120 v153 a

African weakly electric fish of the mormyrid genus Campylomormyrus generate pulse-type electric organ discharges (EODs) for orientation and communication. Their pulse durations are species-specific and elongated EODs are a derived trait. So far, differential gene expression among tissue-specific transcriptomes across species with different pulses and point mutations in single ion channel genes indicate a relation of pulse duration and electrocyte geometry/excitability. However, a comprehensive assessment of expressed Single Nucleotide Polymorphisms (SNPs) throughout the entire transcriptome of African weakly electric fish, with the potential to identify further genes influencing EOD duration, is still lacking. This is of particular value, as discharge duration is likely based on multiple cellular mechanisms and various genes. Here we provide the first transcriptome-wide SNP analysis of African weakly electric fish species (genus Campylomormyrus) differing by EOD duration to identify candidate genes and cellular mechanisms potentially involved in the determination of an elongated discharge of C. tshokwe. Non-synonymous substitutions specific to C. tshokwe were found in 27 candidate genes with inferred positive selection among Campylomormyrus species. These candidate genes had mainly functions linked to transcriptional regulation, cell proliferation and cell differentiation. Further, by comparing gene annotations between C. compressirostris (ancestral short EOD) and C. tshokwe (derived elongated EOD), we identified 27 GO terms and 2 KEGG pathway categories for which C. tshokwe significantly more frequently exhibited a species-specific expressed substitution than C. compressirostris. The results indicate that transcriptional regulation as well cell proliferation and differentiation take part in the determination of elongated pulse durations in C. tshokwe. Those cellular processes are pivotal for tissue morphogenesis and might determine the shape of electric organs supporting the observed correlation between electrocyte geometry/tissue structure and discharge duration. The inferred expressed SNPs and their functional implications are a valuable resource for future investigations on EOD durations.

10aAnimals10aelectric fish10aelectric organ10aElectricity10aGene Expression10aGene Expression Profiling10aGene Expression Regulation10aPhenotype10aPolymorphism, Single Nucleotide10aSpecies Specificity10atranscriptome1 aCanitz, Julia1 aKirschbaum, Frank1 aTiedemann, Ralph uhttps://mormyrids.myspecies.info/fr/node/62602227nas a2200181 4500008004100000022002500041245014800066210006900214260001600283300001200299490000700311520158600318100002301904700002101927700001901948700002501967856005301992 2020 eng d a1993-078X, 1993-077100aFirst cytogenetic information for five Nilotic elephantfishes and a problem of ancestral karyotype of the family Mormyridae (Osteoglossiformes)0 aFirst cytogenetic information for five Nilotic elephantfishes an cAug-19-2020 a387-3970 v143 a

The elephantfish family Mormyridae is the most diverse lineage of the primitive teleostean clade Osteoglossomorpha distributed in inland waters of all continents except Antarctica and Europe. The family Mormyridae is endemic to Africa and includes 22 genera and almost 230 species. The evolutionary radiation of mormyrids most probably should be attributed to their capability of both generating and receiving weak electric signals. Up-to-date cytogenetic studies have revealed substantial karyotype differentiation among the nine investigated elephantfish species and genera (a single species studied per each genus). In the present study, karyotypes of five species representing five mormyrid genera (four unexplored ones) collected from the White Nile system in southwestern Ethiopia are described for the first time. The results show substantial variety of the diploid chromosome and fundamental numbers: 2n = 48 and FN = 54 in Brevimyrus niger (Günther, 1866), 2n = 50 and FN = 72 in Cyphomyrus petherici (Boulenger, 1898), 2n = 50 and FN = 78 in Hippopotamyrus pictus (Marcusen, 1864), 2n = 50 and FN = 76 in Marcusenius cyprinoides (Linnaeus, 1758), 2n = 52 and FN = 52 in Mormyrops anguilloides (Linnaeus, 1758). Karyotype structure in the latter species seems to be close to the ancestral condition for the family. This hypothesis is discussed in the light of available data on karyotype diversity and phylogeny of mormyrids.

1 aSimanovsky, Sergey1 aMedvedev, Dmitry1 aTefera, Fekadu1 aGolubtsov, Alexander uhttp://dx.doi.org/10.3897/compcytogen.14i3.5272702538nas a2200145 4500008004100000020001800041245010100059210006900160250000800229260001300237300001200250520202300262100001802285856008902303 2020 eng d a978012805409300aCommunication and Waveform Analysis in Weakly Electric Fishes With Special Emphasis on Mormyrids0 aCommunication and Waveform Analysis in Weakly Electric Fishes Wi a2nd bElsevier a255-2803 a

The electric sense in fishes was discovered in the 1950s. African snoutfish (Mormyridae) and South American knifefishes (Gymnotiformes) generate electric fields for testing their environment by Active Electrolocation, and for communication. These fishes’ electric organ discharges (EODs) are species-specific (or –characteristic) pulses or continuous waves, and vary widely in waveform, duration (frequency) and strength. In mormyrids the sequence (or pattern) of pulse intervals carries motivational and species-specific information. In a natural hybrid species complex, choosy females of the parent species block a speciation reversal by their preference for conspecific EOD waveforms, and rejection of the hybrid form. Electrosensory discrimination thresholds appear adapted to the fine detail of the EOD pulse waveforms on a ms-scale, with spectral cues not required in Pollimyrus adspersus. In some mormyrid species, breeding males add a strong D.C. component to their EOD, which attracts females but also low-frequency sensitive catfish predators. In several species, specific EOD patterns, as well as loud vocalizing, accompany courtship and spawning. The larvaes’ early EODs of long pulse duration and initially low rate is replaced by an adult short EOD in young juveniles; parental care is present in Pollimyrus species. Three syntopic species gave examples of conflictual and cooperative electrocommunication in a semi-natural environment. Eigenmannia, a wave gymnotiform fish, is highly phase sensitive to stimuli of 0 Hz frequency difference, which evoke a Jamming Avoidance Response (which is a frequency shift away from the stimulus). The strength of the JAR depends on the phase difference stimulus to EOD. At a sufficient frequency difference, trained, food-rewarded Eigenmannia discriminate waveforms by a temporal mechanism that does not require spectral cues. Eigenmannia is incapable of discriminating stimuli that are phase-locked at maintained frequency identity.

1 aKramer, Bernd uhttps://epub.uni-regensburg.de/43937/1/Kramer%2C%20The%20Senses%202020_corrected.pdf02043nas 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/s00359-020-01425-702385nas a2200157 4500008004100000022001400041245011300055210006900168260001600237520163800253100002601891700002101917700002001938700002201958856024701980 2020 eng d a0021-996700aOntogeny of the electric organ discharge and of the papillae of the electrocytes in the weakly electric fish0 aOntogeny of the electric organ discharge and of the papillae of  cDec-08-20203 a

The electric organ of the mormyrid weakly electric fish, Campylomormyrus rhynchophorus (Boulenger, 1898), undergoes changes in both the electric organ discharge (EOD) and the light and electron microscopic morphology as the fish mature from the juvenile to the adult form. Of particular interest was the appearance of papillae, surface specializations of the uninnervated anterior face of the electrocyte, which have been hypothesized to increase the duration of the EOD. In a 24.5 mm long juvenile the adult electric organ (EO) was not yet functional, and the electrocytes lacked papillae. A 40 mm long juvenile, which produced a short biphasic EOD of 1.3 ms duration, shows small papillae (average area 136 μm2). In contrast, the EOD of a 79 mm long juvenile was triphasic. The large increase in duration of the EOD to 23.2 ms was accompanied by a small change in size of the papillae (average area 159 μm2). Similarly, a 150 mm long adult produced a triphasic EOD of comparable duration to the younger stage (24.7 ms) but featured a prominent increase in size of the papillae (average area 402 μm2). Thus, there was no linear correlation between EOD duration and papillary size. The most prominent ultrastructural change was at the level of the myofilaments, which regularly extended into the papillae, only in the oldest specimen – probably serving a supporting function. Physiological mechanisms, like gene expression levels, as demonstrated in some Campylomormyrus species, might be more important concerning the duration of the EOD.

1 aKorniienko, Yevheniia1 aTiedemann, Ralph1 aVater, Marianne1 aKirschbaum, Frank uhttps://onlinelibrary.wiley.com/doi/abs/10.1002/cne.25003https://onlinelibrary.wiley.com/doi/pdf/10.1002/cne.25003https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fcne.25003https://onlinelibrary.wiley.com/doi/pdf/10.1002/cne.2500302069nas a2200157 4500008004100000245015900041210006900200260001600269520141200285100001701697700002101714700002501735700002301760700002301783856010501806 2020 eng d00aGenetic drift does not sufficiently explain patterns of electric signal variation among populations of the mormyrid electric fish Paramormyrops kingsleyae0 aGenetic drift does not sufficiently explain patterns of electric cJan-04-20213 a

Communication signals serve crucial survival and reproductive functions. In Gabon, the widely distributed mormyrid fish Paramormyrops kingsleyae emits an electric organ discharge (EOD) signal with a dual role in communication and electrolocation that exhibits remarkable variation: populations of P. kingsleyae have either biphasic or triphasic EODs, a feature that characterizes interspecific signal diversity among the Paramormyrops genus. We quantified variation in EODs of 327 P. kingsleyae from nine populations and compared it to genetic variation estimated from microsatellite loci. We found no correlation between electric signal and genetic distances, suggesting that EOD divergence cannot be explained by drift alone. An alternative hypothesis is that EOD differences are used for mate discrimination, which would require P. kingsleyae be capable of differentiating between divergent EOD waveforms. Using a habituation-dishabituation assay, we found that P. kingsleyae can discriminate between biphasic and triphasic EOD types. Nonetheless, patterns of genetic and electric organ morphology divergence provide evidence for hybridization between these signal types. Although reproductive isolation with respect to signal type is incomplete, our results suggest that EOD variation in P. kingsleyae could be a cue for assortative mating.

1 aPicq, Sophie1 aSperling, Joshua1 aCheng, Catherine, J.1 aCarlson, Bruce, A.1 aGallant, Jason, R. uhttp://doi.wiley.com/10.1111/evo.13953https://onlinelibrary.wiley.com/doi/am-pdf/10.1111%2Fevo.1395301976nas a2200169 4500008004100000022001400041245012300055210006900178260001600247520138800263100001601651700001901667700002101686700002201707700002101729856005601750 2020 eng d a0269-765300aMorphological differentiation in African weakly electric fish (genus Campylomormyrus) relates to substrate preferences0 aMorphological differentiation in African weakly electric fish ge cApr-04-20213 a

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.

1 aAmen, Rahma1 aNagel, Rebecca1 aHedt, Maximilian1 aKirschbaum, Frank1 aTiedemann, Ralph uhttp://link.springer.com/10.1007/s10682-020-10043-302224nas a2200181 4500008004100000245016000041210006900201260001600270300001100286490000600297520155500303100002901858700002001887700001901907700002001926700001901946856007701965 2020 eng d00aAspects of life-history strategy of Marcusenius senegalensis (Pisces: Osteoglossiformes: Mormyridae; Steindachner, 1870) from Niger River in Northern Benin0 aAspects of lifehistory strategy of Marcusenius senegalensis Pisc cJan-01-2020 a1 - 130 v43 a

Marcusenius senegalensis (Steindachner, 1870) is the dominant mormyrid in Niger River in Northern-Benin where this fish species constitutes an important component of artisanal fisheries. The current study documented the reproductive biology of M. senegalensis in order to contribute to management and sustainable exploitation. Monthly samplings were conducted between February 2015 and July 2016 using gillnets, cast net, and seine. Males dominated the population with a sex ratio of 1:0.96 in favor of males. Sizes at first sexual maturity were 167.89 mm-TL for males and 163.81 mm-TL for females. Monthly gonadosomatic index (GSI) averaged 0.12 ± 0.09 for males and 1.32 ± 1.56 for female and peaks recorded indicated that spawning occured from June to September. Fecundity were moderate to low (844 – 12,643 eggs) and significantly (p < 0.05) increased with total length and body weight. Thespecies showed egg diameters varying between 0.21 and to 1.77 mm and ovaries comprised oocytes at all stages of maturation indicating that M. senegalensis displayed a multi-spawning behavior. Marcuseniussenegalensis exhibited a demographic strategy between r and K, yet more inclined towards K-selected strategy. In Niger River, reproduction grounds were being severely degraded affecting recruitment and stocks. The current findings are valuable data to design a species management scheme that should includes spawning ground protection, species conservation and valorization and fisheries/aquaculture development.

1 aAdjibade, Kayode, Nambil1 aAdite, Alphonse1 aArame, Hamidou1 aChikou, Antoine1 aAbou, Youssouf uhttps://www.doi.org/10.22161/ijfaf10.22161/ijfaf.4.110.22161/ijfaf.4.1.1