Widespread nocturnality of living birds stemming from their common ancestor

Yonghua Wu

doi:10.1186/s12862-019-1508-y

Abstract

BackgroundMany living birds exhibit some nocturnal activity, but the genetic basis and evolutionary origins of their nocturnality remain unknown.ResultsHere, we used a molecular phyloecological approach to analyze the adaptive evolution of 33 phototransduction genes in diverse bird lineages. Our results suggest that functional enhancement of two night-vision genes, namely, GRK1 and SLC24A1, underlies the nocturnal adaption of living birds. Further analyses showed that the diel activity patterns of birds have remained relatively unchanged since their common ancestor, suggesting that the widespread nocturnal activity of many living birds may largely stem from their common ancestor rather than independent evolution. Despite this evolutionary conservation of diel activity patterns in birds, photoresponse recovery genes were found to be frequently subjected to positive selection in diverse bird lineages, suggesting that birds generally have evolved an increased capacity for motion detection. Moreover, we detected positive selection on both dim-light vision genes and bright-light vision genes in the class Aves, suggesting divergent evolution of the vision of birds from that of reptiles and that different bird lineages have evolved certain visual adaptions to their specific light conditions.ConclusionsThis study suggests that the widespread nocturnality of extant birds has a deep evolutionary origin tracing back to their common ancestor.

Highlights

Many living birds exhibit some nocturnal activity, but the genetic basis and evolutionary origins of their nocturnality remain unknown
Using the molecular phyloecological (MPE) approach to infer the ancestral states of diel activity patterns [8,9,10,11], we analyzed the adaptive evolution of 33 phototransduction genes (Additional file 1) among diverse lineages of birds in the sauropsid phylogeny (Fig. 1) using the branch model, the branch-site model and clade model C implemented in PAML software [26]
Both genes are involved in photoresponse recovery, and evidence of positive selection on these genes, which was supported by a branch-site unrestricted statistical test for episodic diversification (BUSTED), which provides a gene-wide robust test for evidence of selection (Additional file 2), suggests that ancestral Carinatae may have evolved a enhanced capacity for motion detection in at least dim-light conditions

Summary

Introduction

Many living birds exhibit some nocturnal activity, but the genetic basis and evolutionary origins of their nocturnality remain unknown. While recent studies show that nocturnal taxa frequently exhibit functional enhancement of dim-light vision genes involved in. It remains unknown whether the widespread nocturnality of living birds has been retained from their common ancestors or evolved independently in diverse bird lineages. Widespread nocturnality may have evolved independently in diverse bird lineages To distinguish between these two possibilities, it is necessary to reconstruct the evolutionary history of the diel activity patterns within the class Aves

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Results

Conclusion