RT Journal Article
SR Electronic
T1 Scale-eating specialists evolved adaptive feeding kinematics within a microendemic radiation of San Salvador Island pupfishes
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 648451
DO 10.1101/648451
A1 Michelle E. St. John
A1 Christopher H. Martin
YR 2019
UL http://biorxiv.org/content/early/2019/05/24/648451.abstract
AB Adaptation to novel ecological niches often includes shifts in behaviors, such as new foraging preferences or changes in kinematics. Investigating prey capture kinematics is an excellent way to understand behavioral mechanisms underlying the origins of novel trophic specialization, in which organisms begin to exploit novel resources. We investigated the contribution of kinematics to the origins of a novel ecological niche for scale-eating within a microendemic adaptive radiation of pupfishes on San Salvador Island, Bahamas. We compared the feeding kinematics of scale-eating, generalist, snail-eating, and F1 hybrid pupfishes while they consumed scales and shrimp in the lab and compared them to scale-eating kinematics observed in situ in the wild. We then connected variation in feeding kinematics to scale-biting performance by measuring the area removed per strike from standardized gelatin cubes. We found that scale-eating pupfish exhibited divergent feeding kinematics compared to all other groups and that these differences were consistent across food items. The peak gapes of scale-eaters were twice as large as all other groups, but their gape angles were simultaneously 32% smaller, in both laboratory and in situ wild observations. We also show that this kinematic combination of large peak gape and small gape angle resides on a performance optimum for scale-biting. Finally, F1 hybrid kinematics and performance were not additive, and were instead closer to the generalist pupfish. This suggests that impaired hybrid performance in the scale-eating niche may contribute to extrinsic postzygotic reproductive isolation between species. Ultimately, our results suggest that shifts in kinematics (i.e. peak gape and gape angle) are an adaptation to the novel niche of scale-eating and contribute to reproductive isolation between species.