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H2020Individual fellowship2016–2019

Evol-Eyes · Elaboration and degeneration of complex traits: The visual systems of lizards and snakes

Horizon 2020 — Marie Skłodowska-Curie Actions

Duration
2016-10-01 → 2019-09-30
EU contribution
€258,107
Participants
2
Scheme
MSCA-IF-GF

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Results in brief

Elaboration and degeneration of complex traits: The visual systems of lizards and snakes

How are complex traits lost during evolution, and once lost how can they be regained? Our project addresses these fundamental questions using the exceptionally diverse visual systems of squamate reptiles (snakes and lizards). Specialist nocturnal and burrowing lineages have evolved many times in squamates, offering multiple in- dependent comparisons of taxa that have lost genes in functionally redundant visual pathways. Two groups, snakes and geckos, lost several key visual genes during such ‘sensory bottlenecks’, but both show remarkable re-innovation of eye anatomy and physiology: diurnal snakes inherited incomplete cone (bright-light) photoreceptor and transduction pathways from their nocturnal/burrowing ancestors but have highly sensitive colour vision; geckos are descended from diurnal lizards and lack major components of the rod (low-light) pathway, but secondarily nocturnal species have superb night vision. We will use this powerful comparative framework to 1) thoroughly reconstruct patterns of reduction and loss of visual gene function in squamates that have entered low light environments, and 2) discover the molecular mechanisms that have compensated for ancestral gene losses in exemplar snake and gecko taxa with secondarily evolved visual capabilities. This will yield significant new knowledge of the fundamental processes of gene loss in evolution and provide a paradigmatic case of evolutionary re-innovation following degeneration in complex traits.

Data: CORDIS, © European Union

Project objective

In “On the origin of species” Charles Darwin used the human eye as an example of a complex character the evolution of which would have been hard to explain. Since then the vertebrate eye and the origin of vision more broadly held a central role in evolutionary biology. Recent advances in genomics, developmental biology and physiology, have allowed some advancement in our understanding of the origin of animal vision that however, is still patchy at best. Surprisingly, modern integrative studies have largely overlooked the visual systems of the Squamata (i.e. the lizards and snakes), a group comprising ~25% of terrestrial vertebrates, displaying exceptional diversity, and with greater variation in eye morphology and retinal photoreceptors than all other vertebrates combined. I propose to use the powerful but overlooked squamate system to answer major questions in visual science. I will integrate genomic, physiological and anatomical data to understand the genomic underpinning of phenotypic variation in the vertebrate visual system the relative roles of adaptation and constraints in the origin of novel visual phenotypes, and to understand whether complex visual systems can be re-elaborated following evolutionary degeneration. This is a blue skies project however, studying the evolution of the exceptionally plastic squamate visual system, will generate information that can be applied to other animals, and perhaps most importantly, used to increase our understanding of the human visual genetic disorders under the newly emerging Phylomedicine paradigm.

Original text from CORDIS.

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Data: CORDIS, © European Union