@article {350, title = {Allopatric differentiation in the acoustic communication of a weakly electric fish from southern Africa, Marcusenius macrolepidotus (Mormyridae, Teleostei)}, journal = {Behavioral Ecology and Sociobiology}, volume = {61}, year = {2006}, month = {12/2006}, pages = {385 - 399}, abstract = {

A few species of the weakly electric snoutfish, the African freshwater family Mormyridae, have been reported to vocalise. However, allopatric populations of a single species were never compared. Members of three allopatric Marcusenius macrolepidotus populations, originating from the Upper Zambezi River in Namibia, the Buzi River (Mozambique), and the Incomati River system in South Africa, vocalised with pulsatile growl- and tonal hoot sounds in dyadic confrontation experiments. A high rate of growling accompanied territorial and agonistic interactions and also non-threatening interactions between males and females, which in one pair appeared to be courtship. Growl sound characteristics of M. macrolepidotus from the Incomati system differed from those of the Upper Zambezi in a significantly higher frequency of the first harmonic (mean, 355 Hz vs 266 Hz). The two vocalising males from the Buzi River generated growls about twice as long as the other fish. Furthermore, the growl pulse period was about 4 ms in M. macrolepidotus from the Upper Zambezi River and from the Incomati system, but 6 ms in M. macro- lepidotus from the Buzi River. Hoots were only observed in agonistic encounters. Hoot oscillograms showed a sinusoi- dal waveform, and the mean duration of this sound was similar in Incomati system fish (mean, 161 ms), Upper Zambezi fish (172 ms) and Buzi fish (103 and 145 ms for\ the two vocalising individuals). The mean frequency of the first hoot harmonic was higher in Incomati system fish (326 Hz) than in Upper Zambezi fish (245 Hz). Both growl and hoot occurred only in the presence of conspecifics, probably signalling the presence and condition of an opponent, territory owner or potential mate. This is the first evidence for (1) sound production and acoustical commu- nication in another species and genus, M. macrolepidotus, from southern Africa to be (2) geographically differentiated.

}, issn = {1432-0762}, doi = {10.1007/s00265-006-0267-0}, author = {Lamml, Michael and Bernd Kramer} } @article {821, title = {A portable bio-amplifier for electric fish research: design and construction}, journal = {Neotropical Ichthyology}, volume = {4}, number = {2}, year = {2006}, pages = {295-299}, type = {Scientific note}, chapter = {295}, abstract = {

The weak electric organ discharges (EODs) of gymnotiform knife fishes can be readily amplified with a wideband amplifier connected to submerged electrodes. The output from such an amplifier can then be monitored with audio speakers or digitized for subsequent analysis. Commercially available devices are expensive and usually require mains electrical power. Here we provide design notes and instructions for the construction and calibration of a cheap, portable, battery-powered, AC-coupled wideband bio-amplifier. This device was designed to allow electric fishes to be located in the field, and also to permit the relatively noise-free acquisition of EOD waveforms from specimens held in temporary captivity. This contribution is intended to encourage students of neotropical ichthyology to explore electric signaling in gymnotiform fishes.

}, doi = {10.1590/S1679-62252006000200018 }, url = {http://www.scielo.br/scielo.php?script=sci_arttext\&pid=S1679-62252006000200018}, author = {Wells, J.K. and William G.R. Crampton} } @article {137, title = {Time-domain signal divergence and discrimination without receptor modification in sympatric morphs of electric fishes}, journal = {Journal of Experimental Biology}, volume = {208}, year = {2006}, pages = {2182-2198}, author = {Matthew E Arnegard and Jackson, B. S. and Carl D Hopkins} } @article {167, title = {Electrophysiological and molecular genetic evidence for sympatrically occuring cryptic species in African weakly electric fishes (Teleostei: Mormyridae: Campylomormyrus)}, journal = {Biology Letters Evolutionary Biology}, volume = {39}, year = {2006}, pages = {198-208}, abstract = {

For two sympatric species of African weakly electric Wsh, Campylomormyrus tamandua and Campylomormyrus numenius, we moni- tored ontogenetic diVerentiation in electric organ discharge (EOD) and established a molecular phylogeny, based on 2222 bp from cyto- chrome b, the S7 ribosomal protein gene, and four Xanking regions of unlinked microsatellite loci. In C. tamandua, there is one common EOD type, regardless of age and sex, whereas in C. numenius we were able to identify three diVerent male adult EOD waveform types, which emerged from a single common EOD observed in juveniles. Two of these EOD types formed well supported clades in our phyloge- netic analysis. In an independent line of evidence, we were able to aYrm the classiWcation into three groups by microsatellite data. The correct assignment and the high pairwise FST values support our hypothesis that these groups are reproductively isolated. We propose that in C. numenius there are cryptic species, hidden behind similar and, at least as juveniles, identical morphs.

}, doi = {10.1016/j.ympev.2005.09.008}, author = {Philine G.D. Feulner and Frank Kirschbaum and Victor Mamonekene and Ketmaier, V. and Ralph Tiedemann} }