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/s00359-011-0643-800459nas a2200121 4500008004100000245011900041210006900160260001200229300001200241490000900253100002400262856005100286 2011 eng d00aA new species of Petrocephalus Marcusen 1854 (Osteoglossomorpha: Mormyridae) from the Sanaga River basin, Cameroon0 anew species of Petrocephalus Marcusen 1854 Osteoglossomorpha Mor c06/2011 a20–280 v29341 aLavoué, Sébastien uhttps://mormyrids.efishgenomics.com/fr/node/1901506nas a2200133 4500008004100000245008200041210006900123300001400192490000600206520105200212100002201264700002501286856006101311 2011 eng d00aNeural innovations and the diversification of African weakly electric fishes.0 aNeural innovations and the diversification of African weakly ele a720–7250 v43 a

In African mormyrid fishes, evolutionary change in a sensory region of the brain established an ability to detect subtle variation in electric communication signals. In one lineage, this newfound perceptual ability triggered a dramatic increase in the rates of signal evolution and species diversification. This particular neural innovation is just one in a series of nested evolutionary novelties that characterize the sensory and motor systems of mormyrids, the most speciose group of extant osteoglossomorph fishes. Here we discuss the behavioral significance of these neural innovations, relate them to differences in extant species diversity, and outline possible scenarios by which some of these traits may have fueled diversification. We propose that sensory and motor capabilities limit the extent to which signals evolve and, by extension, the role of communication behavior in the process of speciation. By expanding these capabilities, neural innovations increase the potential for signal evolution and species diversification.

1 aCarlson, Bruce, A1 aArnegard, Matthew, E uhttp://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?01512nas a2200121 4500008004100000245020200041210006900243490000700312520097300319100001801292700002901310856005101339 2011 eng d00aThe Victoria Falls, a species boundary for the Zambezi Parrotfish, Cyphomyrus discorhynchus (Peters, 1852), and the resurrection of Cyphomyrus cubangoensis (Pellegrin, 1936) (Mormyridae: Teleostei)0 aVictoria Falls a species boundary for the Zambezi Parrotfish Cyp0 v453 a

Cyphomyrus discorhynchus occurs in the Zambezi River and in the linked systems of the Kwando and the Okavango. We collected specimens from both above and below the Victoria Falls and recorded Electric Organ Discharges. We found a marked degree of anatomical differentiation among the specimens from the Zambezi delta to the Victoria Falls that represents a subspecific, geographical cline, reflecting the great length (1400 km) and high ecological diversity of that river section (Lower and Middle Zambezi). We confirm that the populations above the Falls (i.e. Upper Zambezi, Kwando and Okavango) are differentiated from those below, possessing fewer dorsal fin rays (a median of 30-31 rather than 33-34). The waveforms of the electric organ discharge pulses have four phases and show geographic variation but were briefer for specimens from below the Falls. We resurrect Cyphomyrus cubangoensis (Pellegrin, 1936) for the Upper Zambezi/Kwando/Okavango system

1 aKramer, Bernd1 avan der Bank, F., Herman uhttps://mormyrids.efishgenomics.com/fr/node/2201297nas a2200181 4500008004100000245007400041210006900115300001400184490000800198520073000206100002200936700001600958700001600974700001700990700002101007700002501028856006201053 2011 eng d00aBrain Evolution Triggers Increased Diversification of Electric Fishes0 aBrain Evolution Triggers Increased Diversification of Electric F a583–5860 v3323 a

Communication can contribute to the evolution of biodiversity by promoting speciation and reinforcing reproductive isolation between existing species. The evolution of species-specific signals depends on the ability of individuals to detect signal variation, which in turn relies on the capability of the brain to process signal information. Here, we show that evolutionary change in a region of the brain devoted to the analysis of communication signals in mormyrid electric fishes improved detection of subtle signal variation and resulted in enhanced rates of signal evolution and species diversification. These results show that neural innovations can drive the diversification of signals and promote speciation.

1 aCarlson, Bruce, A1 aHasan, S, M1 aHollmann, M1 aMiller, D, B1 aHarmon, Luke, J.1 aArnegard, Matthew, E uhttp://www.sciencemag.org/cgi/doi/10.1126/science.1201524