Genetic basis of bilateral asymmetry in a scale-eating fish
Xiaomeng Tian – Hector Fellow Axel Meyer
Most animals exhibit bilateral symmetry, but asymmetric traits have repeatedly evolved in different taxonomic groups. However, the genetic mechanisms responsible for asymmetric trait variation remain unclear. We will use the scale-eating fish, Perissodus microlepis, to dissect the genetic basis of its remarkable morphological and behavioural asymmetry. This study will yield important insights into the mechanistic underpinnings of asymmetric development and the origin of evolutionary novelty.
While most vertebrates exhibit a bilaterally symmetric body plan, cases of asymmetric traits have been well documented across the animal kingdom, the most famous example being behavioural laterality, “handedness,” of humans. However, the origin and maintenance of such asymmetric variation remain an unresolved question in evolutionary biology.
The scale-eating cichlid fish, Perissodus microlepis, from Lake Tanganyika is a remarkable example of morphological and behaviour asymmetry. Like human handedness, this species is characterized by lateralized foraging behaviours, with some individuals preferentially feeding on scales from the right side of prey, and others from the left. This behavioural laterality is coupled with asymmetric head morphology that facilitates feeding on scales from the preferred side. The abundance of individuals with left or right laterality has been shown to fluctuate around 50% over long time periods, making this species a textbook example for the maintenance of variation in nature. However, the molecular mechanisms underlying this morphological and behavioural asymmetry remain elusive.
This project will investigate the genetic basis of head asymmetry and lateral foraging behaviour in this system. By combining high resolution phenotyping methods (micro-CT analyses) with forward genetic approaches and experimental manipulation, we will reveal the genetic and environmental mechanisms controlling this textbook example for a stable polymorphism of asymmetry.
The scale-eating cichlid fish Perissodus microlepis
Xiaomeng TianUniversity of Konstanz
Hector Fellow since 2011