Development and Evolution of an Adaptive Phenotype in the Mechanosensory Lateral Line System of Cichlid Fishes

The mechanosensory lateral line system is a structurally diverse sensory system present in all fishes. It is responsible for detection of unidirectional and oscillatory water flow and is of critical importance in a variety of behavioral contexts. It is composed of sensory organs (neuromasts) located on the skin as well as in bony lateral line canals, which are contained in a subset of bones in the skull and in the scales on the trunk. Of the four cranial lateral line canal morphologies, widened canals are more sensitive to hydrodynamic stimuli and are considered to be an adaptation for the non-visual detection of prey. However, species that have widened canals and that are suitable for laboratory studies are rare. We are using two genera of Lake Malawi (Africa) cichlid fishes (Aulonocara [widened canals], and Tramitichromis [narrow canals]) for a study that uses comparative anatomical, developmental and behavioral approaches to address the adaptive signifiance of widened canals in prey detection.

This project is funded by National Science Foundation grant IOS-0843307.

This project is investigating:

1. The convergent evolution of widened canals among cichlids and among fishes more generally to more precisely define common features of its anatomy.

2. The pattern and timing of development of widened and narrow canals and the sensory organs contained within them to determine the developmental basis for evolutionary change in the lateral line canal system.

3. The role of widened canals in the detection of sand-dwelling prey using a behavioral assay and video analysis.

This work will have important implications for our understanding of the evolution of feeding habits of cichlids in the African Rift Lakes, and of marine and freshwater fishes that feed on benthic prey, especially those in disturbed habitats in which non-visual predators may have an ecological advantage. Collaborations with Drs. Karen Carleton and Tom Kocher at U. Maryland (cichlid genetics), Dr. Matt McHenry at UC Irvine (biomechanical modeling of neuromasts), and Dr. Jim Miller at URI Ocean Engineering (design of stimulus delivery apparatus), will provide new interdisciplinary training opportunities for students. This funding will enhance research infrastructure in Rhode Island, an EPSCoR state with a research focus in marine life sciences.