Meeting Abstract
Minnows (Family Cyprinidae) are a trophically diverse clade, with species that specialize on myriad prey: shearing plants, crushing snails, chewing insects or sifting detritus. These diverse prey types make minnows a phenomenal model system for studying the interplay between diet and evolutionary history in shaping anatomy. However, the anatomy of this family has only been marginally investigated in published literature (only 3% of species have been imaged); even this sample size has shown that trophic anatomy of the pharyngeal jaws is strongly correlated to their diet specialization. Here, we used micro-computed tomographic imaging of 315 species of North American minnows (over 98% of species diversity) to evaluate how anatomical specialization, evolutionary history, and dietary ecology have shaped trophic diversity in this clade. Preliminary results show high rates of trophic convergence among genera (i.e. many overlapping trophic guilds), and we observed immense variation in morphology of several aspects: 1) muscle attachment area (a proxy for muscle force); 2) relative size of the ligament spanning left and right hemi-mandibles (a proxy for range of motion and skeletal flexibility); and 3) tooth robustness (a proxy for biting force application). For example, herbivorous and durophagous species show large muscle attachment areas and robust ligaments in contrast to lean, thin-ligamented jaws seen in insectivores. Interestingly, this variation is less prominent within closely-related species, suggesting that phylogenetic history is important. These trends show that convergence is widespread among minnow dietary guilds, and relatively small changes in skeletal anatomy between congeners accompany large shifts in diet.
