@article {626,
	title = {Transcriptome-wide single nucleotide polymorphisms related to electric organ discharge differentiation among African weakly electric fish species.},
	journal = {PLoS One},
	volume = {15},
	year = {2020},
	month = {2020},
	pages = {e0240812},
	abstract = {<p>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.</p>
},
	keywords = {Animals, electric fish, electric organ, Electricity, Gene Expression, Gene Expression Profiling, Gene Expression Regulation, Phenotype, Polymorphism, Single Nucleotide, Species Specificity, transcriptome},
	issn = {1932-6203},
	doi = {10.1371/journal.pone.0240812},
	author = {Canitz, Julia and Kirschbaum, Frank and Ralph Tiedemann}
}
@article {10.1371/journal.pone.0036287,
	title = {Comparable Ages for the Independent Origins of Electrogenesis in African and South American Weakly Electric Fishes},
	journal = {PLoS ONE},
	volume = {7},
	number = {5},
	year = {2012},
	month = {05/2012},
	pages = {e36287},
	abstract = {<p>One of the most remarkable examples of convergent evolution among vertebrates is illustrated by the independent origins of an active electric sense in South American and African weakly electric fishes, the Gymnotiformes and Mormyroidea, respectively. These groups independently evolved similar complex systems for object localization and communication via the generation and reception of weak electric fields. While good estimates of divergence times are critical to understanding the temporal context for the evolution and diversification of these two groups, their respective ages have been difficult to estimate due to the absence of an informative fossil record, use of strict molecular clock models in previous studies, and/or incomplete taxonomic sampling. Here, we examine the timing of the origins of the Gymnotiformes and the Mormyroidea using complete mitogenome sequences and a parametric Bayesian method for divergence time reconstruction. Under two different fossil-based calibration methods, we estimated similar ages for the independent origins of the Mormyroidea and Gymnotiformes. Our absolute estimates for the origins of these groups either slightly postdate, or just predate, the final separation of Africa and South America by continental drift. The most recent common ancestor of the Mormyroidea and Gymnotiformes was found to be a non-electrogenic basal teleost living more than 85 millions years earlier. For both electric fish lineages, we also estimated similar intervals (16\&ndash;19 or 22\&ndash;26 million years, depending on calibration method) between the appearance of electroreception and the origin of myogenic electric organs, providing rough upper estimates for the time periods during which these complex electric organs evolved <italic>de novo</italic> from skeletal muscle precursors. The fact that the Gymnotiformes and Mormyroidea are of similar age enhances the comparative value of the weakly electric fish system for investigating pathways to evolutionary novelty, as well as the influences of key innovations in communication on the process of species radiation.</p>
},
	doi = {10.1371/journal.pone.0036287},
	url = {http://dx.doi.org/10.1371/journal.pone.0036287},
	author = {S{\'e}bastien Lavou{\'e} and Miya, Masaki and Matthew E Arnegard and John P Sullivan and Carl D Hopkins and Nishida, Mutsumi}
}
