| hormonal and behavioral correlates of morphological variation in an amazonian electric fish (sternarchogiton nattereri: apteronotidae). | the weakly electric fish from the main channel of the amazon river, sternarchogiton nattereri, offers a striking case of morphological variation. females and most males are toothless, or present only few minute teeth on the mandible, whereas some males exhibit exaggerated, spike-like teeth that project externally from the snout and chin. androgens are known to influence the expression of sexually dimorphic traits, and might be involved in tooth emergence. in this study we assess the relationship ... | 2010 | 20561524 |