Genes linked to species diversity in a sexually dimorphic communication signal in electric fish

• Published in: Journal of Comparative Physiology Vol. 204; no. 1; pp. 93 - 112
• Main Authors: Smith, G. Troy, Proffitt, Melissa R., Smith, Adam R., Rusch, Douglas B.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.01.2018; Springer Nature B.V
• Subjects: Androgen receptors; Androgens; Animal Physiology; Aromatase; Biodiversity; Biomedical and Life Sciences; Courtship; Electric communication; Estrogen receptors; Estrogens; Gender aspects; Gender differences; Gene expression; Genes; Ion channels; Life Sciences; Metabolism; Neuromodulation; Neurosciences; Neurotransmitter receptors; Original Paper; Potassium; Potassium channels; Potassium channels (inwardly-rectifying); Receptors; Sex; Sex differences; Sex hormones; Sexual behavior; Sexual dimorphism; Sodium; Species diversity; Steroid 5α-reductase; Steroid hormone receptors; Steroids; Zoology; Gonadal steroid hormone; Ion channels; Gene expression; Sex difference; Electric fish
• ISSN: 0340-7594; 1432-1351
• DOI: 10.1007/s00359-017-1223-3

Sexually dimorphic behaviors are often regulated by androgens and estrogens. Steroid receptors and metabolism are control points for evolutionary changes in sexual dimorphism. Electric communication signals of South American knifefishes are a model for understanding the evolution and physiology of sexually dimorphic behavior. These signals are regulated by gonadal steroids and controlled by a simple neural circuit. Sexual dimorphism of the signals varies across species. We used transcriptomics to examine mechanisms for sex differences in electric organ discharges (EODs) of two closely related species, Apteronotus leptorhynchus and Apteronotus albifrons , with reversed sexual dimorphism in their EODs. The pacemaker nucleus (Pn), which controls EOD frequency (EODf), expressed transcripts for steroid receptors and metabolizing enzymes, including androgen receptors, estrogen receptors, aromatase, and 5α-reductase. The Pn expressed mRNA for ion channels likely to regulate the high-frequency activity of Pn neurons and for neuromodulator and neurotransmitter receptors that may regulate EOD modulations used in aggression and courtship. Expression of several ion channel genes, including those for Kir3.1 inward-rectifying potassium channels and sodium channel β1 subunits, was sex-biased or correlated with EODf in ways consistent with EODf sex differences. Our findings provide a basis for future studies to characterize neurogenomic mechanisms by which sex differences evolve.