Meeting Abstract
The branchiostegal apparatus forms the ventro-lateral wall of the gill chamber of ray-finned fishes and consists of a membrane supported by many long bony rays that articulate with ventral elements of the hyoid arch. Its role in ventilation is to expand and compress the gill chamber, working in parallel with the operculum. Across ray-finned fishes, there is great diversity in skeletal and soft tissue components of the branchiostegal apparatus. Here, we focus on Cottoidei (sculpins and relatives), a group of mostly benthic fishes that exhibits a high amount of variation in branchiostegal morphology. We collected functional (pressure recordings in the oral and gill chamber) and anatomical measurements for four cottoid species representing three recently redefined families. Pressure recordings show that Leptocottus armatus (Cottidae) has a powerful oral pump, Hemilepidotus hemilepidotus (Agonidae) and Dasycottus setiger (Psychrolutidae) have powerful gill-chamber pumps, and Myoxocephalus polyacanthocephalus (Psychrolutidae) has an intermediate condition. Using recently published sequence data, we performed phylogenetically independent contrasts for each functional and anatomical variable and regressed contrasts of anatomical measurements against those of functional variables. We found that the relative size of the branchiostegal apparatus predicts the relative contributions of the oral and gill-chamber pumps to driving ventilatory currents. We use our findings to discuss the functional implications of branchiostegal morphology across Cottoidei. NSF DEB-1310812 (WEB and SCF) and Stephen and Ruth Wainwright Fellowship.
