Meeting Abstract

32.5  Thursday, Jan. 5  Does feeding mode constrain diversification of the skull in elopomorph fishes? COLLAR, David*; MEHTA, Rita; REVELL, Liam; ALFARO, Michael; WAINWRIGHT, Peter; Univ. California, Santa Cruz; Univ. California, Santa Cruz; Univ. Massachusetts, Boston; Univ. California, Los Angeles; Univ. California, Davis

Behavioral innovations dramatically alter the way morphological traits interact with the environment and may cause shifts in the selective regime those traits experience. An intriguing model for examining the effects of behavioral innovation is the origin of biting as a mode of prey capture in anguilliform fishes (i.e., true eels). Whereas most teleost fishes expand the oral cavity to generate a suction-induced water flow that draws prey into the mouth, many anguilliform species apprehend prey by making contact with the oral jaws, a feeding mode that imposes very different functional demands on aquatic predators compared to suction feeding. In this study we assess whether biting behavior has led to a change in the pattern of diversification of three skull modules--the oral jaws, hyoid, and opercular series. We infer phylogenetic relationships among 60 elopomorph fishes (anguilliform eels plus the tarpons, bonefishes and ladyfishes), reconstruct the history of biting and suction feeding in this clade, and fit evolutionary models that allow rates and covariances of trait change to vary in suction feeding and biting lineages. Although feeding mode does not alter the rate of evolution of skull modules, biting is associated with substantially weaker correlations between evolutionary changes in the oral jaws and opercular series and between the hyoid and opercular series. We suggest that biters have experienced relaxation of the suction-imposed demand for highly coordinated movements between cranial modules, resulting in greater independence among cranial modules and ultimately evolution of a wider array of skull forms.