Long-wavelength sensitive opsin (LWS) gene variability in Neotropical cichlids (Teleostei: Cichlidae).

Thomaz M.C Fabrin,Alberto José Prioli,Sonia Maria A.P Prioli

doi:10.1590/0001-3765201720150692

Thomaz M.C Fabrin, Alberto José Prioli + Show 1 more

Open Access

https://doi.org/10.1590/0001-3765201720150692

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Abstract

Cichlid fishes are an important group in evolutionary biology due to their fast speciation. This group depends widely of vision for feeding and reproduction. During the evolutionary process it plays a significant role in interspecific and intraspecific recognition and in its ecology. The molecular basis of vision is formed by the interaction of the protein opsin and retinal chromophore. Long-wavelength sensitive opsin (LWS) gene is the most variable among the opsin genes and it has an ecological significance. Current assay identifies interspecific variation of Neotropical cichlids that would modify the spectral properties of the LWS opsin protein and codons selected. Neotropical species present more variable sites for LWS gene than those of the African lakes species. The LWS opsin gene in Crenicichla britskii has a higher amino acid similarity when compared to that in the African species, but the variable regions do not overlap. Neotropical cichlids accumulate larger amounts of variable sites for LWS opsin gene, probably because they are spread over a wider area and submitted to a wider range of selective pressures by inhabiting mainly lotic environments. Furthermore, the codons under selection are different when compared to those of the African cichlids.

Highlights

The Cichlid family is an important freshwater group of fish that presents a varied color pattern and widely uses the visual system (Nelson 2006)
The amino acid and nucleotide genetic distances were calculated according to the JonesTaylor-Thornton (Jones et al 1992) and Kimura2-parameters (Kimura 1980) models, respectively, among the Neotropical and African cichlids (Table SI - Supplementary Material)
Two species of the genus Crenicichla, C. britskii and C. frenata, evidenced evolutionary convergence in one amino acidic site, and they rated a smaller genetic distance when compared to some African species rather than to species of the genus Cichla, which is a basal group for Neotropical cichlids (López-Fernández et al 2010) (Table SII)

Summary

Introduction

The Cichlid family is an important freshwater group of fish that presents a varied color pattern and widely uses the visual system (Nelson 2006). They are considered a model in evolutionary studies due to their fast radiation and speciation in several African lakes (Seehausen et al 1999, Smith et al 2011). The genus Cichla has been used for phylogenetic and population structure studies (Oliveira et al 2006, Willis et al 2007, 2012) since it is one of the most basal (Poletto and Ferreira 2010) which forms a monophyletic group when compared to other Neotropical cichlids (López-Fernández et al 2010). There is no evidence of natural hybrids between the two species in the Tocantins-Araguaia basin where the two species coexist (Willis et al 2007, 2012)

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