Behavioral evolution drives hindbrain diversification among Lake Malawi cichlid fish

BioRxiv : the Preprint Server for Biology
Ryan YorkR D Fernald

Abstract

The evolutionary diversification of animal behavior is often associated with changes in the structure and function of nervous systems. Such evolutionary changes arise either through alterations of individual neural components (mosaically) or through scaling of the whole brain (concertedly). Here we show that the evolution of a specific courtship behavior in Malawi cichlid fish, the construction of mating nests known as bowers, is associated with rapid, extensive, and specific diversification of orosensory, gustatory centers in the hindbrain. We find that hindbrain volume varies significantly between species that build pit (depression) compared to castle (mound) type bowers and that hindbrain features evolve rapidly and independently of phylogeny among castle-building species. Using immediate early gene expression, we confirmed a functional role for hindbrain structures during bower building. Comparisons of bower building species in neighboring Lake Tanganyika show patterns of neural diversification parallel to those in Lake Malawi. Our results suggest that mosaic brain evolution via alterations to individual brain structures is more extensive and predictable than previously appreciated.

Related Concepts

Brain
Cichlids
Mental Depression
Biological Evolution
Gene Expression
Hindbrain
Health Center
Neuron Component
Structure
Neural Stem Cells

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