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Molecular Evidence for Convergence and Parallelism in Evolution of Complex Brains of Cephalopod Molluscs: Insights from Visual Systems
- Source :
- Integrative and Comparative Biology. 55:1070-1083
- Publication Year :
- 2015
- Publisher :
- Oxford University Press (OUP), 2015.
-
Abstract
- Coleoid cephalopods show remarkable evolutionary convergence with vertebrates in their neural organization, including (1) eyes and visual system with optic lobes, (2) specialized parts of the brain controlling learning and memory, such as vertical lobes, and (3) unique vasculature supporting such complexity of the central nervous system. We performed deep sequencing of eye transcriptomes of pygmy squids (Idiosepius paradoxus) and chambered nautiluses (Nautilus pompilius) to decipher the molecular basis of convergent evolution in cephalopods. RNA-seq was complemented by in situ hybridization to localize the expression of selected genes. We found three types of genomic innovations in the evolution of complex brains: (1) recruitment of novel genes into morphogenetic pathways, (2) recombination of various coding and regulatory regions of different genes, often called "evolutionary tinkering" or "co-option", and (3) duplication and divergence of genes. Massive recruitment of novel genes occurred in the evolution of the "camera" eye from nautilus' "pinhole" eye. We also showed that the type-2 co-option of transcription factors played important roles in the evolution of the lens and visual neurons. In summary, the cephalopod convergent morphological evolution of the camera eyes was driven by a mosaic of all types of gene recruitments. In addition, our analysis revealed unexpected variations of squids' opsins, retinochromes, and arrestins, providing more detailed information, valuable for further research on intra-ocular and extra-ocular photoreception of the cephalopods.
- Subjects :
- Opsin
genetic structures
Plant Science
Biology
Deep sequencing
Evolution, Molecular
Phylogenetics
Convergent evolution
Lens, Crystalline
Gene duplication
Animals
Protein Isoforms
Photoreceptor Cells
Amino Acid Sequence
Nautilus
Ocular Physiological Phenomena
Gene
Phylogeny
Arrestin
Brain
Gene Expression Regulation, Developmental
Anatomy
biology.organism_classification
eye diseases
Cephalopod
Cephalopoda
Evolutionary biology
Animal Science and Zoology
sense organs
Origins of Neurons and Parallel Evolution of Nervous Systems: The Dawn of Neuronal Organization
Subjects
Details
- ISSN :
- 15577023 and 15407063
- Volume :
- 55
- Database :
- OpenAIRE
- Journal :
- Integrative and Comparative Biology
- Accession number :
- edsair.doi.dedup.....22d644d3aeefd5492f0d71955bdc6987