Meeting Abstract
Mosaic evolution refers to the pattern whereby different organismal traits exhibit differential rates of evolution; typically, due to reduced levels of trait covariation through deep time (i.e. modularity). These differences in rates can be attributed to variation in responses to selective pressures between individual traits. These differential responses to selective pressures can also facilitate functional specialization allowing certain traits to track environmental stimuli more closely than others. The teleost skull is an excellent system for which to study mosaic evolution as it is comprised of a complex network of bones; each of which may be experiencing different selective pressures and constraints. Here we use three-dimensional geometric morphometrics to investigate patterns of mosaic evolution in the skull and jaws in a clade of Neotropical electric fishes (Apteronotidae: Gymnotiformes). We find strong support for a three-module hypothesis that consists of the face, braincase, and mandible and we find that the mandible has evolved four times faster than its neighboring modules. We hypothesize that the functional specialization of the mandible in this group of fishes has allowed it to outpace the face and braincase and modularize over time. We also hypothesize that this pattern of mosaicism may be widespread across other clades of teleost fishes.
