The role of lateral line diversification in adaptive radiation of fishes - NERC GW4+ DTP

Fishes have remarkable abilities to sense movement, and they use information gained for important tasks such as finding food, avoiding predators, avoiding obstacles, and gauging water flow. One system used is the "lateral line", comprised of clusters of jelly-covered “neuromasts” that bend with water movement, that are either in fluid-filled canals or on the surface of the fish. The lateral line is believed to be particularly important to fish that operate in dark or turbid places where visual information is absent, such as caves, deep water, or sediment-rich habitats. We have recently conducted the first comprehensive survey of craniofacial lateral line canals across the Lake Malawi cichlid species "radiation" and revealed an unexpected diversity in lateral line morphology that associates strongly with diet. This project aims to further explore the role of lateral line diversification in cichlid fish speciation and adaptive radiation, using microCT scanning, fluorescence microscopy and comparative genomics.

The project will aim to:
1) Use microCT images to compare the lateral line diversity of the Victoria, Tanganyika and Malawi cichlid radiations, using museum collections, and test for associations with environmental preferences.
2) Quantify the surface (superficial) neuromast diversity of Lake Malawi NERC GW4+ DTP Projects 2018-19 cichlids. We will use fluorescence microscopy to image superficial neuromasts on the head, body and fins of species.
3) Uncover the genetic basis of craniofacial lateral line diversity, and associated behaviour. We will use new and existing lateral line morphology and behavioural data from a segregating F2 cross of two Lake Malawi cichlid species that have diverged in lateral line structure (Otopharynx lithobates and Aulonocara stuartgranti). We will then use a genotype-by-sequencing approach to identify genetic variants that associate with phenotypic variation in the F2 cross.
4) Test for a role of lateral line diversification in cichlid speciation. We will use microCT scans to compare craniofacial lateral line structures of the recently (<50,000 years) diverged benthic and littoral ecomorphs of Astatotilapia calliptera in Lake Massoko, Tanzania – part of the Lake Malawi radiation. We will focus the work on 196 individuals with full genomes already sequenced, and test for associations between genetic variants and lateral line morphology.