Meeting Abstract
Among fishes, feeding mode is often considered the major axis of divergence and has been shown to produce extraordinarily rapid adaptive radiations. This behavioral evolution is often accompanied by a morphological shift in the craniofacial skeleton. One example of this can be found in the divergence between ecologically dissimilar species of cichlids from Lake Malawi, where the phenotypic novelty in the derived craniofacial morphology can be attributed in part to increased endogenous Wnt/β-catenin signaling. This developmental shift appears to be highly conserved as a similar morphological changes have been shown in zebrafish by increasing Wnt signaling. However, we have little idea how the resultant morphological shift is associated with functional variation. Here we experimentally manipulate Wnt expression in larval and juvenile zebrafish, then directly measure the resulting functional effects on suction feeding ability. We first use lithium chloride (LiCl) treatments to temporarily upregulate Wnt signaling at either three or fifteen days post-fertilization. We then raise these zebrafish to thirty days, the end of their larval period, and test their feeding performance using high-speed video to measure jaw kinematics and the flow velocity field. Finally, we compare morphological and kinematic variation between treated and control individuals. We find that zebrafish treated with LiCl can have improved feeding performance compared to the control fish. However, this effect depends on the age at which they received LiCl. Furthermore, there are differences in the craniofacial morphology and feeding strike kinematics in treated fish, suggesting that Wnt mediated morphological shifts can alter post-development feeding performance. This result gives us insight into the functional effects of rapid morphological shifts and therefore into the evolution of ecological novelty in fishes.
