P1.95 Wednesday, Jan. 4 Morphological correlates of vocal traits in a clade of Neotropical catfishes (Siluriformes: Doradidae and Auchenipteridae): an adaptive radiation driven by vocal traits? KAATZ, I.M.*; STEWART, D.J.; SUNY-ESF Syracuse NY email@example.com
Signal divergence can drive speciation events. We found phylogenetic shifts in disturbance sound and vocal morphology traits at the genus level among doradoids, a catfish superfamily (Doradidae and Auchenipteridae; 20 genera, 25 species, 1-15 individual/species). The basal condition, represented by the Aspredinidae, is low dominant frequency and absence of accessory vocal mechanism structures. Doradoid derived vocal morphology includes an ESA (elastic spring apparatus) with vocal muscles that arise on the posterior cranium attaching to the anterior face of the ESA that inserts into the swimbladder. Diverticula, outpocketings of the swimbladder wall, are also derived. Vocal morphotypes and signal traits were compared between outgroups and doradoid families using t-tests, ANOVA and ANCOVA. In the family Doradidae sounds with lower dominant frequency are present in genera with larger (>1cm long) diverticula, although genera with different types of diverticula or their absence have similar sounds. Doradids producing the highest dominant frequency sounds have reduced (conical and plug-shaped) ESA processes while genera that produce lower dominant frequency sounds have discoid ESA processes. Auchenipterids varied in dominant frequency but lacked diverticula and had discoid ESA processes. Recurring transitions in sound frequency among doradoids suggests that these traits may correlate with an evolutionary driver that could be either: 1) incidental change along an ecomorphological gradient effecting changes in body form; or 2) changes in vocal morphology directly selected to serve sound communication functions in different behavioral contexts or under different environmental constraints.