Meeting Abstract

36.4  Jan. 5  Discordance between mechanical and morphological diversity in the suction feeding mechanism of centrarchid fishes COLLAR, DAVID C; University of California, Davis dccollar@ucdavis.edu

Morphological diversity is widely used to infer ecological variation among species because differences in form underlie variation in functional performance of ecological tasks. However, complexity in the relationship between form and function can weaken associations between these levels of variation. I investigate the link between morphological and functional diversification in a mechanically explicit model of fish suction feeding performance, where the map of head morphology to feeding mechanics is many-to-one: multiple, alternative forms can produce the same mechanical property. In the freshwater fish radiation, the Centrarchidae, many-to-one mapping leads to discordance between variation in a suction index, which is proportional to the buccal pressure drop a fish is capable of producing, and variation in the underlying morphology. The major centrarchid clades exhibit an order of magnitude range of diversity in suction mechanics despite similar levels of diversity in the morphological variables. This cryptic pattern of mechanical diversity suggests an evolutionary history for suction performance that is unlike the one inferred from comparisons of morphology. Inasmuch as many-to-one mapping is common in functional systems, this property of design may lead to widespread discordance between functional and morphological variation.