Meeting Abstract
The cranial asymmetry of flatfishes (Pleuronectiformes: Teleostei) is perhaps, one of the most striking morphological features found anywhere in the animal kingdom. Their unifying and unique characteristic is the migration of one of their eyes to the opposite side of their head during both development and during their evolutionary history. This results in both eyes residing on one side of their body, while fish rests on the opposite side. This orbital migration has been described at the developmental level across several species, and was found to recapitulate the evolutionary transition towards asymmetry in the fossil record. However, the evolutionary tempo and mode of this orbital migration has not yet been examined in a rigorous quantitative and phylogenetic comparative framework. Here we use three-dimensional geometric morphometrics and a phylogenetic comparative toolkit to examine evolutionary patterns of shape variation in these fishes and compare rates of shape evolution between different regions of the skull. We find distinct patterns of variation across the skull with the facial region exhibiting more variation than the braincase region. We hypothesize that the orbital migration (localized to the facial region) experienced by all of these species, is driving the elevated levels of variation in the faces of these fishes.
