Origin and evolution of animal eyes and light-guided behaviours
Nencki Open Lab Academy of Neuroscience – Faculty of Physics of the University of Warsaw
July 12, 2024
Gáspár Jékely
Centre for Organismal Studies, Heidelberg University
Charles Darwin set us a problem…
… and gave us the solution
Gradual evolution by natural selection
Variation
Inheritance
Differential survival
Darwin’s ‘proto-eye’
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“We can commence a series with an optic nerve merely coated with pigment”
Charles Darwin
Natural selection for a gradual increase in resolution
A pessimistic estimate of the time required for an eye to evolve
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Proto-eyes still exist in marine plankton
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Platynereis dumerilii
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- breeding culture
- microinjection, transgenesis
- neuron-specific promoters and antibodies
- knock-out lines
- neuronal connectome
- neuronal activity imaging 😎
Platynereis dumerilii
Spawning
movie by Albrecht Fischer
Synchronously developing larvae
Proto-eyes still exist in marine plankton
trochophora larva
Direct sensory-motor coupling of eyes to cilia
pigment cup of eye
photoreceptor cell
Helical swimming, sensing and turning are tightly linked
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Visual phototaxis with 2-pixel eyes
Whole-body volume EM of an entire Platynereis larva
The nervous system of the larva
~2,000 neurons
Synaptic connectome
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Neural circuit of the visual eyes
Diversity of larval eyes
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In quest of the origin of eyes
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Ciliated zooplankton larvae
Coral larvae
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In collaboration with Kirsty Wan (LSI Exeter) and Jamie Craggs (Horniman Museum)
Coral larvae
Emelie Brodrick
Rebecca Poon & Kirsty Wan
Coral larvae react to light
Light-off induces contraction and ciliary arrest
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A coral larval nerve net - simplest nervous system?
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Hydrozoan larval phototaxis
Jeff Goddard, iNaturalist
GJ & Jürgen Berger
Field trips to explore marine plankton
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Ischia, Sorgeto, 2024
Field trips lead to unexpected discoveries
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with Alexandra Kerbl, Ischia May 31, 2024
What is this??
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with Alexandra Kerbl, Ischia May 31, 2024
Egg plates and Müller’s larvae of polyclad flatworms
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-> brought them back to Heidelberg
Planocera ceratommata
But are we sure…?
Müller’s larvae are phototactic and have three eyespots
Rhabdomeric and ciliary photoreceptors
Platynereis
Müller’s larva
Natural selection for a gradual increase in resolution
coral larvae, helical phototaxis
2-pixel eyes
Lamprey
Human
Eagle
Acknowledgements
- Emelie Brodrick
- Cyrielle Kaltenrieder
- Réza Shahidi
- Milena Marinkovic
- Daniel Thiel
- Sanja Jasek
- Cameron Hird
- Rebecca Turner
- Luis A. Bezares-Calderón
- Kei Jokura
- Luis Yanez Guerra
- Alexandra Kerbl
Former lab members
- Albina Asadulina
- James Beard
- Markus Conzelmann
- Nadine Randel
- Philipp Bauknecht
- Martin Gühmann
- Cristina Pineiro-Lopez
- Nobuo Ueda
- Aurora Panzera
- Csaba Verasztó
- Elizabeth Williams