Molecular Evolution of Dim-light Visual Pigments in Neotropical Geophagine Cichlids

• Main Author: Refvik, Shannon
• Other Authors: Lopez-Fernandez, Hernan
• Language: en_ca
• Published: 2012
• Subjects: Cichlid; Rhodopsin; Vision; dN/dS; Neotropical; 0329
• Online Access: http://hdl.handle.net/1807/42407

Neotropical cichlid fishes are highly diverse and occupy diverse environments. Visual pigment evolution has been important in the diversification of African rift lake cichlids, but little is known of Neotropical cichlid visual systems. This thesis addresses the molecular evolution of rhodopsin in the Geophagini tribe of Neotropical cichlids. We use likelihood-based codon models of molecular evolution and newly isolated sequences for Neotropical cichlid rhodopsin to compare patterns of selective constraint among Neotropical, African rift lake, and African riverine cichlid rhodopsin. We provide evidence for differences in selective constraint among clades, with positive selection occurring in the Neotropical and African rift lake clades. Further, we find variation in selective constraint within geophagine cichlids. Our results suggest that Clade model C may be more appropriate than branch-site models for investigating variation in selective constraint among clades. Neotropical cichlids are emerging as an excellent system for investigating molecular evolution in visual pigments.