Collective and Individual Problem-Solving in Insects · 2020-03-04 · Correct choices (%) sugar...
Transcript of Collective and Individual Problem-Solving in Insects · 2020-03-04 · Correct choices (%) sugar...
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Collective and Individual Problem-Solving in
Insects
Anna DornhausEcol & Evol Bio, University of Arizona (Tucson)
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Insects solving problems?
Individual insects
• Are insects really suitable as model systems for research on complex behavior?
• Don’t they have fixed, instinctual, repeatable, machine-like behaviors?
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Individual insects
“Delayed matching-
to-sample tests”:
Learning the
concepts ‘same’ and
‘different’Giurfa (2003)
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Learning from each other & teaching
Worden & Papaj (2005)
Leadbeater & Chittka
(2005)
Möglich et al. (1974)
Individual insects
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Tool use in ants
Sand pellets as
sponges
Stones as
ammunition
Morrill (1972)
Grasso et al. (2004)
Individual insects
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Target selection by individual bees
colony
?
Bees are trained to target color and rewarded there
Individual insects
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Accurate decisions come at a cost
Nature 424: 388
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Decision time (sec)
Co
rre
ct
ch
oic
es (
%)
Each dot is one individual bee
Bees are trained to target
color; targets and distractors
only slightly different
Individual insects
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45
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Decision time (sec)
Co
rre
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oic
es (
%)
sugar vs. water
sugar vs. quinine: making errors more costly
Individual insects
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Nature 424: 388
Individuality & flexibility
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Decision time (sec)
Co
rre
ct
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oic
es (
%)
sugar vs. watersugar vs. quinine
… more time for better decisions.
Individual insects
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Social insects• Social: colony sizes
of 1 - 10 million
• Cooperative: most
individuals are non-
reproducing workers
– ‘superorganisms’
• ‘Complex systems’ –
patterns created by
interaction, without
central control
Collective behavior
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Complex systems: common problems & solutions?
information flow
task allocation
minimization of delays
Collective behavior
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©A
lex W
ild
Temnothorax ants
Collective behavior
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©A
lex W
ild
©T
uan C
ao
Temnothorax ants
Collective behavior
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Colony emigrations
Collective decisions
If the nest is destroyed, a new one has to be found
� comparison
� consensus decision
� transport
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Colony emigrations
Collective decisions
1. Search2. Recruitment3. Quorum attained:
decision4. Transport
Nigel Franks,
Stephen Pratt
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( )
Why wait for a quorum?
Delay before
start of carrying a disadvantage?
Tandem
runs are
slow!
Collective decisions
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Individual scouts make their own decisions if in a hurry
Individual decisions: scouts start carrying even though they have not encountered ANY other ant in the new nest (quorum threshold of 1). (Fisher’s Exact Test, n=16)
individualcollective
p<0.01
benign harsh
Collective decisions
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… which is fast but faulty
0
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p<0.05
Median, quartiles, range of 16 colonies; each tested once in each condition; Wilcoxon Tests.Proc. R. Soc. Lond. B 270: 2457-2463
Collective decisions
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Even more ants involved if speed not important
Anim Behav 67: 959-963
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destroyednest
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harshconditions
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rward
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destroyednest
intact nest(mediorce)
destroyed
nest, harsh
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p<0.05 p<0.01
Collective decisions
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Two strategies
I’ll do it myself!
Call a meeting!
Collective decisions
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Two strategies
• Low quorum threshold (sometimes =1: individualistic decision-making)
• Quick decision
• Error prone
• High quorum theshold: collective decision-making
• Takes time
• Accurate decisions
• Favored in benign conditions
Proc. R. Soc. Lond. B 270: 2457-2463
Collective decisions
Anim Behav 67: 959-963
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Collective decision
Collective decisions
1. Search2. Recruitment3. Quorum attained:
decision4. Transport
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Collective decision
Collective decisions
1. Information collection
2. Recruitment3. Activation
threshold:
decision
Alternative 1 Alternative 2
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Decision-making in the brain
Collective decisions
1. Information collection
2. Recruitment3. Activation
threshold: decision
Alternative 1 Alternative 2
sensory information
inhibition
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Decision-making in the brain
Collective decisions
1. Information collection
2. Recruitment3. Activation
threshold
Alternative 1 Alternative 2
sensory information
inhibition
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Collective decisionsAnt colonies
• populations of ants committed to each site
Brain
• populations of neurons committed to each alternative
• as information is collected, active population
committed to ‘correct’ alternative increases
• decision is made when active population exceeds
a threshold
• threshold � speed & accuracy of decision
Collective behavior
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1. Individual & collective decision-making
– flexible choice of speed over accuracy when necessary
2. Communication: push or pull
3. Division of labor
4. Spatial sorting
5. Optimal search
6. Colony size
Research areas
http://eebweb.arizona.edu/Faculty/Dornhaus/
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Communication systems in social insects
• usefulness of information depends on
environment
• collective behavior can often be optimized and sophisticated without
coordination
Group-level information flow
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Collective strategies
• May be surprisingly intricate
• May be surprisingly non-intuitive
� to understand their evolution, careful, quantitative measurement of costs and benefits under different conditions necessary
Conclusion
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My lab group: Jenny Jandt, Tuan Cao, Nhi Duong, Maggie Couvillon, AmelieSchmolke, and the undergraduate students
Lars Chittka
Nigel Franks
Axel Brockmann
Franziska Klügl
Acknowledgements
DFG
EEB Department U of A
http://eebweb.arizona.edu/Faculty/Dornhaus/