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
Centre for Organismal Studies, Heidelberg University
Charles Darwin set us a problem…
“To suppose that the eye, with all its inimitable contrivances […] could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree.”
“Yet reason tells me …”
… and gave us the solution
Gradual evolution by natural selection
Variation
Inheritance
Differential survival
Darwin’s ‘proto-eye’
“We can commence a series with an optic nerve merely coated with pigment”
Charles Darwin
Natural selection for a gradual increase in resolution
?
?
Lamprey
Human
Eagle
A pessimistic estimate of the time required for an eye to evolve
Proto-eyes still exist in marine plankton
Platynereis dumerilii
- 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
The eyespots mediate phototaxis
Helical swimming, sensing and turning are tightly linked
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
Neural circuit of the visual eyes
Diversity of larval eyes
In quest of the origin of eyes
Ciliated zooplankton larvae
Coral larvae
In collaboration with Kirsty Wan (LSI Exeter) and Jamie Craggs (Horniman Museum)
Coral larvae
Emelie Brodrick
Hannah Laeverenz
Rebecca Poon & Kirsty Wan
Coral larvae react to light
Light-off induces contraction and ciliary arrest
A coral larval nerve net - simplest nervous system?
Hydrozoan larval phototaxis
Jeff Goddard, iNaturalist
GJ & Jürgen Berger
Clava multicornis
Field trips to explore marine plankton
Ischia, Sorgeto, 2024
Field trips lead to unexpected discoveries
with Alexandra Kerbl, Ischia May 31, 2024
What is this??
with Alexandra Kerbl, Ischia May 31, 2024
OMG
Egg plates and Müller’s larvae of polyclad flatworms
-> 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
