title: Sensory evolution in blind cavefish is driven by early embryonic events during gastrulation and neurulation.
abstract: Natural variations in sensory systems constitute adaptive responses to the environment. Here, we compared sensory placode development in the blind cave-adapted morph and the eyed river-dwelling morph of Astyanax mexicanus Focusing on the lens and olfactory placodes, we found a trade-off between these two sensory components in the two morphs: from neural plate stage onwards, cavefish have larger olfactory placodes and smaller lens placodes. In a search for developmental mechanisms underlying cavefish sensory evolution, we analyzed the roles of Shh, Fgf8 and Bmp4 signaling, which are known to be fundamental in patterning the vertebrate head and are subtly modulated in space and time during cavefish embryogenesis. Modulating these signaling systems at the end of gastrulation shifted the balance toward a larger olfactory derivative. Olfactory tests to assess potential behavioral outcomes of such developmental evolution revealed that Astyanax cavefish are able to respond to a 105-fold lower concentration of amino acids than their surface-dwelling counterparts. We suggest that similar evolutionary developmental mechanisms may be used throughout vertebrates to drive adaptive sensory specializations according to lifestyle and habitat.
authors.affiliation: DECA group, Paris-Saclay Institute of Neuroscience, CNRS, Université Paris Sud, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette 91198, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Hinaux
authors.affiliation: DECA group, Paris-Saclay Institute of Neuroscience, CNRS, Université Paris Sud, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette 91198, France.
authors.forename: Lucie
authors.initials: L
authors.lastname: Devos
authors.affiliation: DECA group, Paris-Saclay Institute of Neuroscience, CNRS, Université Paris Sud, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette 91198, France.
authors.forename: Maryline
authors.initials: M
authors.lastname: Blin
authors.affiliation: DECA group, Paris-Saclay Institute of Neuroscience, CNRS, Université Paris Sud, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette 91198, France.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Elipot
authors.affiliation: DECA group, Paris-Saclay Institute of Neuroscience, CNRS, Université Paris Sud, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette 91198, France.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Bibliowicz
authors.affiliation: DECA group, Paris-Saclay Institute of Neuroscience, CNRS, Université Paris Sud, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette 91198, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Alié
authors.affiliation: DECA group, Paris-Saclay Institute of Neuroscience, CNRS, Université Paris Sud, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette 91198, France retaux@inaf.cnrs-gif.fr.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Rétaux
mesh_terms: D000818:Animals; D001766:Blindness / Q000196:embryology*; D019521:Body Patterning / Q000502:physiology*; D055415:Bone Morphogenetic Protein 4 / Q000378:metabolism; D060126:Characidae / Q000196:embryology*; D051524:Fibroblast Growth Factor 8 / Q000378:metabolism; D054262:Gastrulation / Q000502:physiology*; D006257:Head / Q000196:embryology; D053823:Hedgehog Proteins / Q000378:metabolism; D007908:Lens, Crystalline / Q000196:embryology*; D054258:Neural Plate / Q000196:embryology; D054261:Neurulation / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D055415:Bone Morphogenetic Protein 4; D053823:Hedgehog Proteins; D051524:Fibroblast Growth Factor 8
keywords: Complex trait; Lens placode; Olfactory placode; Olfactory skills; Signaling; Trade-off