I’m happy to announce a paper I collaborated on investigating how feeding modes effect jaw kinesis in cichlids was recently published in Proceedings of the Royal Society B: Biological Sciences.
In this paper we used a combination of ultra-conserved element sequencing (UCE) and high-speed video to investigate if the mode at which fish procure their food effects the evolution of jaw protrusion in Lake Malawi and Tanganyikan fishes. A distinctive feature of ray-finned fishes (which include cichlids) is that many of them are able to protrude the upper jaw when feeding. This jaw protrusion is especially useful when feeding on evasive prey items as it enhances the suction force and aides in sucking the prey into the mouth. For the most part, fish feed by two methods. Suction feeding, where prey is obtained by the method described above or biting, where prey is forcefully removed/captured by the jaws themselves (e.x. fish feeding of algae/sponged off rocks, scale eaters, mollusk shellers).
Our results showed that species that obtain prey via biting have much less jaw protrusion and overall movement of the cranial bones during a feeding event relative to suction feeders. This is not necessarily surprising as biting fish face certain functional demands on the jaws, like stress placed by forcible contact to extract prey, where additional jaw protrusion would be ineffective. Our results highlight the contrasting functional demands and trade-offs both modes of feeding have and how these demands have shaped the evolution of head morphology and feeding ecology in the Malawi and Tanganyikan cichlid radiations.
Paper Citation & Link : McGee MD, Faircloth BC, Borstein SR, Zheng J, Hulsey CD, Wainwright PC, and Alfaro ME. 2016. Replicated divergence in cichlid radiations mirrors a major vertebrate innovation. Proceedings of the Royal Society B: Biological Sciences 283. http://dx.doi.org/10.1098/rspb.2015.1413