fish motion

Collaborators: Matthew G. McGee; Samuel R. Borstein; Peter C. Wainwright

A major axis of feeding diversity in ray-finned fishes concerns a trade-off between force application and the speed at which the jaw can open and expand. Furthermore, a complex feeding apparatus, consisting of numerous mobile components, has allowed fishes to occupy a variety of trophic niches in aquatic systems. This research seeks to understand the evolution of feeding motions in a diverse assemblage of African cichlids from lakes Malawi and Tanganyika, where species vary in feeding apparatus morphologies and diets. We used geometric morphometrics to compare cranial/jaw shapes with patterns of kinesis produced during suction feeding strikes.

 

sample trajectory
Figure 1. Principle components 1 and 2 for a single motion trajectory (solid blue line) in Lamprologus lemairii. A linear baseline between start and end shapes is also plotted (blue dotted line). Selected video frames are shown with landmarks (light blue dots) and sliding semilandmarks (yellow dots).

   

 

motion PC
Figure 2. Principle components 1 and 2 for motion shapes from 326 suction feeding strikes in 56 species of African rift lake cichlid. PC 1 captures a common axis of kinesis, where PC 2 represents interspecific variation of cranial shape. Note that trajectory lengths increase as PC 2 values decrease.

 

Fig 2
Figure 3. Maximum likelihood (ML) phylogeny of African rift lake cichlids compared in this study, with the most heavily sampled tribes labeled, “A” Haplochromini and “B” Lamprologini. The magnitude of kinesis is mapped onto branches, based on ML ancestral reconstruction and assigned feeding categories are shown as colored dots. Video frames from the start and end of strikes are shown for selected species to represent cranial morphologies associated with kinematic diversity.

Funding Sources:

UC Davis Chancellor’s Postdoctoral Fellowship (UCD)

Relevant Publications:

Martinez CM, McGee MD, Borstein SR, Wainwright PC. In Press. Feeding ecology underlies the evolution of cichlid jaw mobility. Evolution.