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Evolutionary analysis of vision genes identifies potential drivers of visual differences between giraffe and okapi
Edson Ishengoma1, Morris Agaba2, Douglas R Cavener3
1The School of Life Sciences and Bio-Engineering, Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania; Mkwawa University of College of Education, University of Dar-es-Salaam, Iringa, Tanzania.
Peerj
|April 12, 2017
Summary
Giraffe vision genes show adaptive evolution, particularly in genes affecting eye optics and light signaling. These genetic changes may reflect adaptations to their specific habitats and long-distance visual needs.
Area of Science:
- Genomics
- Evolutionary Biology
- Ophthalmology
Background:
- Visual capacity is crucial for species' survival and evolution.
- Giraffes possess higher visual acuity than other artiodactyls, despite ecological similarities with okapi.
- Genetic basis for giraffe and okapi visual differences remains unclear.
Purpose of the Study:
- To identify vision genes in giraffes and okapi.
- To investigate genetic adaptations in vision between giraffes and okapi.
- To understand the molecular underpinnings of visual differences.
Main Methods:
- Comparative genomics of giraffe and okapi genomes.
- Identification of 36 candidate mammalian vision genes.
- Analysis of selection pressure using branch-site tests and clade models.
Main Results:
- Signatures of selection identified in genes related to optical transparency and light signaling.
- Significant selection divergence in CRYAA and OPN1LW between giraffes and ruminants.
- Adaptive evolution detected in SAG and LUM genes when comparing okapi with other mammals.
Conclusions:
- Provides first molecular insights into giraffe and okapi vision adaptations.
- Selected genes may reflect adaptation to distinct habitats.
- Long-distance vision for predation and communication likely drove adaptive pressures on giraffe vision genes.