Meeting Abstract
It has been appreciated for some time that the oral and pharyngeal jaws of fishes decouple prey capture and processing functions and their physical independence may permit considerable evolutionary independence and promote trophic diversity. However, the degree of evolutionary independence of these jaw systems is rarely estimated and continues to be poorly known. We tested the independence of oral and pharyngeal jaw diversification rates in New World cichlids. We measured functional morphological traits of the oral and pharyngeal jaws of 218 individuals representing 84 species. We assessed multivariate branch-specific rates of evolution using Bayesian inference in RevBayes. Overall, oral and pharyngeal jaw diversification rates were only weakly correlated. We found that only a few traits (15%) were more correlated between the jaw systems than expected based on Brownian motion. These tended to be negative correlations between traits associated with the biting strength of the pharyngeal jaws and the magnitude of oral jaw protrusion. This pattern may be due to a functional trade-off between suction feeding on evasive prey (e.g., fish) and sessile prey that requires intensive processing by the pharyngeal jaws (e.g., molluscs, algae). We found several instances of conflicting evolutionary patterns between the two jaw systems. Some piscivores exhibit dramatic diversification of oral jaw traits (i.e., Petenia), whereas others exhibit dramatic diversification of pharyngeal jaw traits (i.e., Cichla). Substrate sifting lineages consistently exhibited low diversification rates of both oral and pharyngeal jaws. Diversification of oral and pharyngeal jaws has largely been independent during the Neotropical cichlid adaptive radiation.
