02056nas a2200241 4500008004100000022001400041245014300055210006900198260001600267300001100283520124300294653003801537653002201575653001801597653001801615653001501633653002801648100002401676700001801700700002301718700002401741856004901765 2024 eng d a0380-133000aBiogeographic barriers are differentially permeable based on traits: Movement of hypoxia tolerant mormyrid fish in the Lake Victoria basin0 aBiogeographic barriers are differentially permeable based on tra cNov-01-2024 a1024853 a

Lake Nabugabo is a small satellite lake separated from Lake Victoria by hypoxic swamps that impose a biogeographic barrier to fish assemblages. Some species occur exclusively in Nabugabo while others show high differentiation across this barrier, yet air-breathing fishes show nearly zero genetic differentiation between the two lakes. We hypothesize that hypoxia-tolerant fishes, unlike other non-air-breathing species, would have similarly low genetic differentiation across the barrier. We used pooled RAD-seq to examine the degree of genetic differentiation in two species of non-air-breathing but hypoxia-tolerant mormyrid fishes, Marcusenius victoriae and Petrocephalus degeni. Other non-air-breathing fishes have been shown to have FST values as low as 0.05 but mostly between 0.10 and 0.20; however, we discovered that the genetic differentiation in our focal species was very low, with FST values between 0.02 and 0.04, making them much more comparable to air-breathing fishes with FST values of near zero. We conclude that this and other analogous barriers should be understood as differentially permeable depending on the traits of the organisms crossing them, such as hypoxia tolerance in this case.

10aDifferentially permeable barriers10aHypoxia tolerance10aLake Nabugabo10aLake Victoria10aMormyridae10aPopulation connectivity1 aHunt, David, A.G.A.1 aThomas, Quinn1 aClarke, Shelby, B.1 aChapman, Lauren, J. uhttp://dx.doi.org/10.1016/j.jglr.2024.10248502522nas a2200289 4500008004100000022002500041245007300066210006900139260001600208490000700224520164700231653001401878653002001892653002001912653002101932653003201953100002401985700002502009700002202034700002902056700002402085700002002109700002302129700001802152700002102170856004102191 2024 eng d a2045-7758, 2045-775800aTrophic ecology of the African riverine elephant fishes (Mormyridae)0 aTrophic ecology of the African riverine elephant fishes Mormyrid cAug-01-20240 v143 a

Multiple species of the elephant fishes (Mormyridae) commonly coexist in sympatry in most African tropical rivers and lakes. In this study, we investigated the trophic ecology and potential trophic niche partitioning of eleven mormyrid fish species from the Sanaga River system in Cameroon using the stable isotope composition of carbon and nitrogen in the muscle samples. Albeit most mormyrids mainly feed on invertebrates, we found differences in isotope ratios, and we report signs of the trophic niche partitioning among species. We further found significant differences in isotopic signatures within the Mormyrus genus, suggesting ecological niche diversification among three closely related species. We have also evaluated differences in the isotopic signals between seasons in four species, which could be possibly caused by species migration and/or anthropogenic agricultural activities. To evaluate body shape, we applied geometric morphometric analyses, and we show that most of the species are clearly morphologically separated. We focused on the mormyrid ecomorphology to identify a possible interaction between shape and ecology, and we found a relationship between the δ13C (but not δ15N) isotopic signal and morphology, suggesting their interplay during mormyrid evolution. Overall, we present robust evidence of the trophic niche partitioning within the mormyrid species community, and we integrate trophic ecology with morphometrics, shedding light on the enigmatic evolutionary history of these fascinating African fishes.

10amormyrids10astable isotopes10atrophic ecology10atrophic position10atrophic resource portioning1 aSommer, Gina, Maria1 aNjom, Samuel, Didier1 aIndermaur, Adrian1 aNyom, Arnold, Roger Bitj1 aJandová, Kateřina1 aKukla, Jaroslav1 aPetrtýl, Miloslav1 aHorká, Petra1 aMusilova, Zuzana uhttp://dx.doi.org/10.1002/ece3.7017300461nas a2200109 4500008004100000245009000041210006900131260007900200490000700279100001300286856005200299 1976 eng d00aExploration du Parc National de l'Upemba Mission G.F. De Witte, Fascicule 73 Poissons0 aExploration du Parc National de lUpemba Mission GF De Witte Fasc aBrusselsbFondation Pour Favoriser Les Recherches Scientifiques en Afrique0 v731 aPoll, M. uhttps://mormyrids.efishgenomics.com/en/node/63300858nas a2200145 4500008004100000022001400041245009800055210006900153260001600222520037400238100001900612700002200631700001700653856004200670 2022 eng d a2687-794500aThe Complete Genome Sequences of 38 Species of Elephantfishes (Mormyridae, Osteoglossiformes)0 aComplete Genome Sequences of 38 Species of Elephantfishes Mormyr cNov-21-20223 a

We present the complete genome sequences of 38 species of elephantfishes from 20 genera. Illumina sequencing was performed on genetic material from single wild-caught individuals. The reads were assembled using a de novo method followed by a finishing step. The raw and assembled data is publicly available via Genbank.

1 aPeterson, Rose1 aSullivan, John, P1 aPirro, Stacy uhttp://dx.doi.org/10.56179/001c.5607701343nas a2200109 4500008004100000245015100041210006900192520086600261100001901127700001501146856007201161 2000 eng d00aA morphological description of the sagittal otoliths of two mormyrids, Marcusenius macrolepidotus and Petrocephalus catostoma (Family: Mormyridae)0 amorphological description of the sagittal otoliths of two mormyr3 a

The morphology of the sagittal otoliths of two South African mormyrid fish, Marcusenius macrolepidotus and Petrocephalus catostoma, were studied to determine possible morphological significance. The sagittae of M. macrolepidotus and P. catostoma are kidney-shaped and oblong, respectively. The ventral margin is slightly indented in the former and slightly flattened in the latter. The sulcus acusticus of both species is archaesulcoid but mesial in M. macrolepidotus and ostio-caudal in P. catostoma. The crista inferior in M. macrolepidotus is ridge-like and well defined posteriorly and anteriorly, whereas in P. catostoma it is clearly defined posteriorly and disappears anteriorly. The otoliths of both species do not have a rostrum, antirostrum or an excisura. The differences in sagittal morphology between the two mormyrid species are distinct.

1 aNicolaai, N.N.1 aJooste, A. uhttps://www.tandfonline.com/doi/full/10.1080/15627020.2000.1140719100486nas a2200109 4500008004100000245011200041210006900153260007500222300001100297100001600308856005200324 1967 eng d00aThe fishes and fisheries of the Ruaha River basin, Tanzania (systematics, ecology, zoogeography, fisheries)0 afishes and fisheries of the Ruaha River basin Tanzania systemati aJinja, UgandabEast African Freshwater Fisheries Research Organization a19 pp.1 aMatthes, H. uhttps://mormyrids.efishgenomics.com/en/node/59903260nas a2200157 4500008004100000022001400041245012600055210006900181260001600250300001100266520262900277100002202906700001902928700002202947856013302969 2019 eng d a0006-897700aSensory Specializations of Mormyrid Fish Are Associated with Species Differences in Electric Signal Localization Behavior0 aSensory Specializations of Mormyrid Fish Are Associated with Spe cJan-03-2019 a1 - 173 a

The ability to localize communication signals plays a fundamental role in social interactions. For signal localization to take place, the sensory system of the receiver must extract information about distance and direction to the sender from physical characteristics of the signal. In many sensory systems, information from multiple peripheral receptors must be integrated by central sensory pathways to determine the sender location. Here, we asked whether evolutionary divergence in the electrosensory and visual systems of mormyrid fish is associated with signal localization behavior. In mormyrids, differences in the distribution of electroreceptors on the surface of the skin are associated with differences in the midbrain exterolateral nucleus (EL). Species with electroreceptors clustered in three rosettes on both sides of the head have a small and undifferentiated EL. In contrast, EL is enlarged and subdivided into anterior (ELa) and posterior (ELp) regions in species that have electroreceptors broadly ­distributed throughout the body. Interestingly, species with EL and clustered electroreceptors also have larger visual systems and higher visual acuity than species with ELa/ELp and broadly distributed electroreceptors. Species with broadly distributed electroreceptors and ELa/ELp approached a simulated conspecific by following the curved electric field lines generated by the electrosensory stimulus. In contrast, a species with small EL and clustered electroreceptors, but an enlarged visual system, followed shorter and straighter paths to the stimulus source. In the central electrosensory system, evoked field potentials in response to stimuli delivered from the left versus the right differed more in EL than in ELa/ELp. Our results suggest that signal localization behavior is associated with differences in sensory specializations. We propose that the distribution of electroreceptors on the body affects the ability of individuals to align parallel to electric field lines and maintain such alignment while approaching the signal source. The spatial resolution of sensory information relayed from the periphery to the midbrain in species with clustered electroreceptors may allow for gross, but not fine, processing of sender location. Furthermore, visual information may play an important role in localizing signaling individuals in species with small EL and clustered electroreceptors. In line with previous studies, we suggest that the physiological and behavioral differences associated with signal localization reflect adaptations to different habitats and social environments.

1 aVélez, Alejandro1 aRyoo, Da, Yeon1 aCarlson, Bruce, A uhttps://www.karger.com/Article/FullText/496493https://www.karger.com/Article/Pdf/496493https://www.karger.com/Article/Pdf/49649300471nas a2200121 4500008004100000245010100041210006900142260001600211300001400227490000700241100002100248856008000269 1904 eng d00aOn the Cranial Osteology of the Fishes of the Families Mormyridae, Notopteridae and Hyodontidae.0 aCranial Osteology of the Fishes of the Families Mormyridae Notop cJan-11-1904 a188 - 2170 v291 aRidewood, W., G. uhttps://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1096-3642.1904.tb00435.x01591nas a2200133 4500008004100000245012000041210006900161260001600230490000600246520110100252100002201353700002201375856006001397 2016 eng d00aDetection of transient synchrony across oscillating receptors by the central electrosensory system of mormyrid fish0 aDetection of transient synchrony across oscillating receptors by cSep-06-20170 v53 a

Recently, we reported evidence for a novel mechanism of peripheral sensory coding based on oscillatory synchrony. Spontaneously oscillating electroreceptors in weakly electric fish (Mormyridae) respond to electrosensory stimuli with a phase reset that results in transient synchrony across the receptor population (Baker et al., 2015). Here, we asked whether the central electrosensory system actually detects the occurrence of synchronous oscillations among receptors. We found that electrosensory stimulation elicited evoked potentials in the midbrain exterolateral nucleus at a short latency following receptor synchronization. Frequency tuning in the midbrain resembled peripheral frequency tuning, which matches the intrinsic oscillation frequencies of the receptors. These frequencies are lower than those in individual conspecific signals, and instead match those found in collective signals produced by groups of conspecifics. Our results provide further support for a novel mechanism for sensory coding based on the detection of oscillatory synchrony among peripheral receptors.

1 aVélez, Alejandro1 aCarlson, Bruce, A uhttp://elifesciences.org/lookup/doi/10.7554/eLife.1685102363nas a2200145 4500008004100000022001400041245013300055210006900188260001600257300001200273490000800285520184500293100002202138856005702160 2016 eng d a0022-094900aDifferences in electrosensory anatomy and social behavior in an area of sympatry between two species of mormyrid electric fishes0 aDifferences in electrosensory anatomy and social behavior in an  cApr-11-2016 a31 - 430 v2193 a

Sensory systems play a key role in social behavior by mediating the detection and analysis of communication signals. In mormyrid fishes, electric signals are processed within a dedicated sensory pathway, providing a unique opportunity to relate sensory biology to social behavior. Evolutionary changes within this pathway led to new perceptual abilities that have been linked to increased rates of signal evolution and species diversification in a lineage called ‘clade A’. Previous field observations suggest that clade-A species tend to be solitary and territorial, whereas non-clade-A species tend to be clustered in high densities suggestive of schooling or shoaling. To explore behavioral differences between species in these lineages in greater detail, I studied population densities, social interactions, and electric signaling in two mormyrid species, Gnathonemus victoriae (clade A) and Petrocephalus degeni (non-clade A), from Lwamunda Swamp, Uganda. Petrocephalus degeni was found at higher population densities, but intraspecific diversity in electric signal waveform was greater in G. victoriae. In the laboratory, G. victoriae exhibited strong shelter-seeking behavior and competition for shelter, whereas P. degeni were more likely to abandon shelter in the presence of conspecifics as well as electric mimics of signaling conspecifics. In other words, P. degeni exhibited social affiliation whereas G. victoriae exhibited social competition. Further, P. degeni showed correlated electric signaling behavior whereas G. victoriae showed anti-correlated signaling behavior. These findings extend previous reports of social spacing, territoriality, and habitat preference among mormyrid species, suggesting that evolutionary divergence in electrosensory processing relates to differences in social behavior.

1 aCarlson, Bruce, A uhttp://jeb.biologists.org/cgi/doi/10.1242/jeb.12772000469nas a2200133 4500008004100000245010400041210007000145300001200215490000700227100001500234700001500249700002000264856005100284 1973 eng d00aContribution a l’étude de la faune ichthyologique du bassin du fleuve Sénégal. III. Mormyridae0 aContribution a l étude de la faune ichthyologique du bassin du f a665-7040 v351 aReizer, C.1 aMattei, X.1 aChevalier, J.L. uhttps://mormyrids.efishgenomics.com/en/node/98