The Diel Activity Patterns Of Ancestral Birds

Extant birds are mainly diurnal,but the diel activity pattern of the common ancestors of living birds remains unknown.In this study,we used a molecular phyloecological approach to reconstruct the diel activity pattern of our focal taxa,and we found dim-light vision gene and one bright-light vision gene to be under positive selection along the ancestral bird branch,suggesting the common ancestors of living birds may have been active in both daytime and nighttime.We also reconstruct the diel activity pattern of ancestral archosaur,and our result detected four dim-light vision gene to be under positive selection,suggesting their predominate nocturnality.The finding of the nocturnality of the common ancestors of living birds shed light on the evolution of many bird-specific characteristics,for instance endothermy and feather.