title: Eye development in the four-eyed fishAnableps anableps: cranial and retinal adaptations to simultaneous aerial and aquatic vision.
abstract: The unique eyes of the four-eyed fishAnableps anablepshave long intrigued biologists. Key features associated with the bulging eye ofAnablepsinclude the expanded frontal bone and the duplicated pupils and cornea. Furthermore, theAnablepsretina expresses different photoreceptor genes in dorsal and ventral regions, potentially associated with distinct aerial and aquatic stimuli. To gain insight into the developmental basis of theAnablepsunique eye, we examined neurocranium and eye ontogeny, as well as photoreceptor gene expression during larval stages. First, we described six larval stages during which duplication of eye structures occurs. Our osteological analysis of neurocranium ontogeny revealed another distinctive Anablepid feature: an ossified interorbital septum partially separating the orbital cavities. Furthermore, we identified the onset of differences in cell proliferation and cell layer density between dorsal and ventral regions of the retina. Finally, we show that differential photoreceptor gene expression in the retina initiates during development, suggesting that it is inherited and not environmentally determined. In sum, our results shed light on the ontogenetic steps leading to the highly derivedAnablepseye.
authors.affiliation: Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: Louise N
authors.initials: LN
authors.lastname: Perez
authors.affiliation: Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: Jamily
authors.initials: J
authors.lastname: Lorena
authors.affiliation: Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: Carinne M
authors.initials: CM
authors.lastname: Costa
authors.affiliation: Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: Maysa S
authors.initials: MS
authors.lastname: Araujo
authors.affiliation: Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: Gabriela N
authors.initials: GN
authors.lastname: Frota-Lima
authors.affiliation: Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Gabriel E
authors.initials: GE
authors.lastname: Matos-Rodrigues
authors.affiliation: Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Rodrigo A P
authors.initials: RA
authors.lastname: Martins
authors.affiliation: Departamento de Biologia, Universidade Federal de São Carlos, Campus Sorocaba, São Paulo, Brazil.
authors.forename: George M T
authors.initials: GM
authors.lastname: Mattox
authors.affiliation: Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil schneider@ufpa.br.
authors.forename: Patricia N
authors.identifier: http://orcid.org/0000-0002-9745-0694
authors.initials: PN
authors.lastname: Schneider
mesh_terms: D000818:Animals; D003532:Cyprinodontiformes / Q000196:embryology*; D005123:Eye / Q000196:embryology*; D012160:Retina / Q000502:physiology*; D012886:Skull; D014785:Vision, Ocular
keywords: Anableps; eye duplication; four-eyed fish; novelty; opsin