02573nas a2200169 4500008004100000022001400041245012100055210006900176260001600245300001400261490000700275520199800282100002602280700002602306700002302332856004802355 2013 eng d a0006-897700aIndependent Evolution of Visual and Electrosensory Specializations in Different Lineages of Mormyrid Electric Fishes0 aIndependent Evolution of Visual and Electrosensory Specializatio cJan-01-2013 a185 - 1980 v823 a

African mormyrid fishes are by far the most diverse group of osteoglossomorph (bony tongue) fishes. Mormyrids communicate using pulses of electricity, and they process electric communication signals in the midbrain exterolateral nucleus (EL). In its ancestral form, the EL is relatively small and homogenous. In two different lineages, however, the EL expanded in size and increased in cytological complexity. This evolutionary change established the perceptual ability to distinguish variation in electric pulse waveform, which plays an important role in species recognition and mate choice. However, the sensory basis of social behavior in species with a small, homogenous EL remains unknown. Using published species descriptions, we found that species in one of these lineages have relatively large eyes. Using sectioned brains, we measured the volume of a major visual region, the optic tectum (OT), and found that this same lineage also has an enlarged OT. We also found that eye size and OT size are highly correlated across species. Phylogenetic analysis suggests that a reduced visual system evolved with the origins of an active electrosense, and that this one particular lineage secondarily evolved an enlarged visual system. Behavioral tests revealed that this enlargement of the visual system established increased visual acuity. Thus, our findings demonstrate that different lineages of mormyrids have evolved visual or electrosensory specializations, but that no lineages have specialized in both. This sensory divergence likely reflects fundamentally different ecologies and suggests that vision may play an especially important role in the social behavior of mormyrids that cannot detect variation in electric signal waveform. Our findings provide an example of evolutionary change in multiple sensory systems among closely related species that lays a foundation for relating ecological adaptation to evolutionary change in multisensory perception and social behavior.

1 aStevens, Jennifer, A.1 aSukhum, Kimberley, V.1 aCarlson, Bruce, A. uhttp://www.karger.com?doi=10.1159/00035536901772nas a2200145 4500008004100000022001400041245018700055210006900242260001200311300001200323490000700335520121500342100001801557856005101575 2013 eng d a1727-936400aMorphological and electrophysiological field observations on electric freshwater fish of the genus Mormyrops Müller 1843 (Teleostei: Mormyridae) from West and southern Africa0 aMorphological and electrophysiological field observations on ele c11/2013 a31 - 410 v383 a

Different specimens of Mormyrops anguilloides (Linnaeus 1758) were reported to display electric organ discharge (EOD) pulses of either initially head-positive or initially negative polarity, a hypothetical sex difference that has not been substantiated to date. The morphology and EODs of M. anguilloides of both sexes and a sexually mature size from the Comoé and Bandama rivers, Côte d’Ivoire, and the Lower and Middle Zambezi, Mozambique, displayed initially positive EODs. The morphologically similar M. breviceps Steindachner 1895 of both sexes and a sexually mature size from the Bandama River displayed initially head-negative EODs of biphasic waveform and long duration (0.93–1.15 ms) in the very-low-frequency spectral range. Mormyrops anguilloides from the Comoé and Bandama rivers were differentiated in caudal peduncle depth and in EOD waveform, pulse duration and spectral energy content. The former samples displayed a biphasic, lower-frequency EOD pulse of up to 0.42 ms duration, the latter a tetraphasic, high-frequency EOD of up to 0.33 ms. It is suggested that reports of EODs of both polarities in M. anguilloides indicate the presence of an unrecognised species.

1 aKramer, Bernd uhttp://dx.doi.org/10.2989/16085914.2013.79124402317nas a2200157 4500008004100000022001400041245010500055210006900160260001200229300001400241490000700255520178100262100002302043700002302066856007002089 2013 eng d a1563-526000aFrom Sequence to Spike to Spark: Evo-devo-neuroethology of Electric Communication in Mormyrid Fishes0 aFrom Sequence to Spike to Spark Evodevoneuroethology of Electric c09/2013 a106 - 1290 v273 a

Mormyrid fishes communicate using pulses of electricity, conveying information about their identity, behavioral state, and location. They have long been used as neuroethological model systems because they are uniquely suited to identifying cellular mechanisms for behavior. They are also remarkably diverse, and they have recently emerged as a model system for studying how communication systems may influence the process of speciation. These two lines of inquiry have now converged, generating insights into the neural basis of evolutionary change in behavior, as well as the influence of sensory and motor systems on behavioral diversification and speciation. Here, we review the mechanisms of electric signal generation, reception, and analysis and relate these to our current understanding of the evolution and development of electromotor and electrosensory systems. We highlight the enormous potential of mormyrids for studying evolutionary developmental mechanisms of behavioral diversification, and make the case for developing genomic and transcriptomic resources. A complete mormyrid genome sequence would enable studies that extend our understanding of mormyrid behavior to the molecular level by linking morphological and physiological mechanisms to their genetic basis. Applied in a comparative framework, genomic resources would facilitate analysis of evolutionary processes underlying mormyrid diversification, reveal the genetic basis of species differences in behavior, and illuminate the origins of a novel vertebrate sensory and motor system. Genomic approaches to studying the evo-devo-neuroethology of mormyrid communication represent a deeply integrative approach to understanding the evolution, function, development, and mechanisms of behavior.

1 aCarlson, Bruce, A.1 aGallant, Jason, R. uhttp://informahealthcare.com/doi/abs/10.3109/01677063.2013.79967001603nas a2200145 4500008004100000022001400041245017700055210006900232260001200301300001400313490000700327520105700334100001801391856004801409 2013 eng d a1029-036200aDifferentiation in morphology and electrical signalling in four species of para- and sympatric Marcusenius (Teleostei: Mormyridae) from Côte d’Ivoire, West Africa0 aDifferentiation in morphology and electrical signalling in four  c03/2013 a105 - 1330 v463 a

Marcusenius Gill, 1862 species were sampled from the Bandama River and the Comoé River in Côte d’Ivoire, West Africa. Marcusenius gracilis sp. nov. was differentiated from M. senegalensis (Steindachner, 1870), Marcusenius ussheri (Günther, 1867) and M. furcidens (Pellegrin, 1920) in electric organ discharges (EOD), and morphologically from all other West African congeners. Principal component analysis showed significant morphological differentiation among the four Ivorian species. Principal component 1 was loaded most strongly by characters affecting swimming power and manoeuvrability. The morphologically most similar pair, M. furcidens and M. gracilis sp. nov., are distinguished by their EOD waveforms and a sexual dimorphism in the anal fin base in the latter not present in the former. M. ussheri is distinguished by a sexual dimorphism in its EOD waveform not observed in the other three species. This system is an opportunity to study how far the fine-tuning of char- acter displacement among syntopic species can go.

1 aKramer, Bernd uhttps://mormyrids.myspecies.info/en/node/1301677nas a2200157 4500008004100000022001400041245020200055210007100257260001200328300001600340490000700356520107200363100001801435700001801453856004801471 2013 eng d a1464-526200aEast–west differentiation in the Marcusenius macrolepidotus species complex in Southern Africa: the description of a new species for the lower Cunene River, Namibia (Teleostei: Mormyridae)0 aEast–west differentiation in the iMarcusenius macrolepidotusi sp c09/2013 a2327 - 23620 v473 a

This paper critically compares the Southern African bulldog fish species Marcusenius macrolepidotus (Peters, 1852), inhabiting the eastern Lower Zambezi River, and Marcusenius altisambesi Kramer et al., 2007, inhabiting the central Upper Zambezi River, with bulldog fish samples from the western lower Cunene River, a 2600-km range from the Indian Ocean to the Atlantic. The three species or forms are well differentiated in morphology and molecular genetics, and dif- ferentiation is also present in electric organ discharges. Marcusenius altisambesi and the Cunene sample, which we recognize as Marcusenius multisquamatus sp. nov., are closely related and form a sister taxon to M. macrolepidotus. This result is based on the analysis of mitochondrial cytochrome b sequences and genomic Inter-simple-sequence-repeat fingerprinting. Morphological adaptations to life in a torrential escarpment river seem to be present in M. multisquamatus sp. nov. when compared with M. altisambesi, which lives in a reservoir river that periodi- cally floods the savannah.

1 aKramer, Bernd1 aWink, Michael uhttps://mormyrids.myspecies.info/en/node/11