Meeting Abstract
Understanding how organisms adapt to novel ecological niches is an outstanding question in evolutionary biology. Adaptation often includes shifts in foraging preferences, kinematics, and trophic morphology. Here we investigated behavioral, kinematic, and morphological adaptations to the novel ecological niches of of scale- and snail-eating in a recent radiation of Cyprinodon pupfishes endemic to San Salvador Island, Bahamas. Scale-eating and snail-eating pupfish both arose from an algae eating ancestor 10 kya, but display unique adaptations which allow them to occupy novel niches. First, we compared the feeding kinematics across pupfish species and their F1 hybrids during scale-biting and suction-feeding in the lab. We found that scale-eaters had peak gapes that were twice as large as other groups, but simultaneously had gape angles that were 32% smaller—which appears to be behaviorally mediated. We also found that the scale-eater’s unique kinematic profile resides on a performance peak. Second, we investigated whether the novel nasal protrusion of the snail-eating pupfish is adapted for the novel behavior of ‘shelling’ (i.e. removing snails from their shells). We measured snail-shelling preferences across pupfish species and F1 and F2 hybrids using behavioral assays and their nasal protrusion distance. We found that snail-eaters and snail-eating hybrids consumed more snails than other groups, but that nasal protrusion distance did not affect an individual’s ability to consume more or larger snails in the F2 hybrids. Similar to scale-eating, this suggests that a shift in feeding behavior, such as foraging preference, is driving the evolution of the snail-eating specialist. Ultimately, we found evidence for the importance of behaviorally-mediated traits during adaptation to novel trophic niches.
