Meeting Abstract

76.1  Sunday, Jan. 6  Can exaptation facilitate terrestrial invasion? Oral kinematics of climbing and feeding in a waterfall-climbing gobiid fish CULLEN, J.A.**; MAIE, T.; SCHOENFUSS, H.L.; BLOB, R.W.; Clemson Univ.; Clemson Univ.; St. Cloud State Univ.; Clemson Univ. jcullen@clemson.edu

Species of the gobiid fish genus Sicyopterus use a novel inching behavior to climb waterfalls, in which an oral sucker is cyclically protracted and attached to the climbing surface. This genus also has a distinctive feeding behavior in which the premaxilla is cyclically protracted to scrape diatoms from the substrate. With such generally similar motions, it is possible that one of these distinctive patterns was coopted from the other, representing an example of evolutionary exaptation. To evaluate this possibility, we used high-speed video to film climbing and feeding in S. stimpsoni from Hawai’i, and measured oral kinematics for two comparisons: (1) Feeding kinematics of S. stimpsoni vs two suction feeding gobies (Awaous guamensis and Lentipes concolor), to assess what novel jaw movements are required for algal grazing; (2) Oral kinematics in feeding vs climbing for S. stimpsoni, to quantify their similarity and evaluate the potential for either to represent an exaptation from the other. Premaxillary movements were most different between scraping and suction feeding taxa. Between climbing and feeding, S. stimpsoni showed significant differences in the maximum values of several kinematic variables, but overall profiles of motion through the cycle matched very closely for most variables, even with differences in maximum values. Current data cannot resolve whether oral kinematics for climbing was coopted from feeding, or feeding kinematics coopted from climbing, but similarities between feeding and climbing in S. stimpsoni are consistent with evidence of exaptation, with modifications, between these behaviors. NSF-IOS 0817911, 0817794.