• Rui Borges
  • Warren E. Johnson
  • Stephen J. O'Brien
  • Cidalia Gomes
  • Christopher P. Heesy
  • Agostinho Antunes

Background: Based on evolutionary patterns of the vertebrate eye, Walls (1942) hypothesized that early placental mammals evolved primarily in nocturnal habitats. However, not only Eutheria, but all mammals show photic characteristics (i.e. dichromatic vision, rod-dominated retina) suggestive of a scotopic eye design.

Results: Here, we used integrative comparative genomic and phylogenetic methodologies employing the photoreceptive opsin gene family in 154 mammals to test the likelihood of a nocturnal period in the emergence of all mammals. We showed that mammals possess genomic patterns concordant with a nocturnal ancestry. The loss of the RH2, VA, PARA, PARIE and OPN4x opsins in all mammals led us to advance a probable and most-parsimonious hypothesis of a global nocturnal bottleneck that explains the loss of these genes in the emerging lineage (> > 215.5 million years ago). In addition, ancestral character reconstruction analyses provided strong evidence that ancestral mammals possessed a nocturnal lifestyle, ultra-violet-sensitive vision, low visual acuity and low orbit convergence (i.e. panoramic vision).

Conclusions: Overall, this study provides insight into the evolutionary history of the mammalian eye while discussing important ecological aspects of the photic paleo-environments ancestral mammals have occupied.

Original languageEnglish
Article number121
Number of pages12
JournalBMC Genomics
Volume19
Issue number1
DOIs
StatePublished - 5 Feb 2018

    Scopus subject areas

  • Genetics
  • Biotechnology

    Research areas

  • Nocturnal bottleneck, Mammals, Opsins, Nocturnal lifestyle, Ultra, violet sensitive vision, Panoramic vision, Visual acuity, VERTEBRATE VISUAL PIGMENTS, DIM-LIGHT-VISION, MOLECULAR EVOLUTION, ULTRAVIOLET VISION, ORBIT ORIENTATION, PRIMATES, PHOTORECEPTORS, ADAPTATION, LIKELIHOOD, ACCURACY, Ultra-violet sensitive vision, Opsins/chemistry, Synteny, Adaptation, Biological, Selection, Genetic, Mammals/genetics, Biological Evolution, Animals, Environment, Genome, Evolution, Molecular

ID: 36790169