Photos by Joan unless
otherwise specifiedStrassmann/ Queller lab group
The importance of property and privatization in social evolution
Joan E. Strassmann & David C. [email protected]
Read my blog on how to become a professor!http://sociobiology.wordpress.com
John Templeton Foundation
What unites us?
What unites us?Insects: social wasps, social bees, ants, & termites
What unites us?Insects: social wasps, social bees, ants, & termites
Topic: altruism, sociality, and their evolutionary, behavioral, physiological, and ecological consequences
Why is what we do so important?
Theories derived from studies of social insect altruism and its consequences are powerful for understanding life.
Privatization and property
Privatization is a neglected topic in biology
Strassmann and Queller, Animal Behaviour, 2014
Private property includes all resources kept from others, excluding one’s own
body, or those of one’s progeny.
What is privatizing behavior?• Actions that restrict a resource from others,
taking it for oneself.
Territoriality is perhaps the best known kind of privatization
Sometimes defense covers a single resource
Broad-tailed hummingbird defends feeder
An individual may attempt to privatize a group of mates
Female elk and young
Another way to privatize a resource is to hide it
Pygmy nuthatch collects and caches seeds
You can defend a resource by internalizing itGiant clams contain algae
Tridacna giant clam from Komodo National Park, Nick Hobgood, Wikimedia Commons CC 3.0
Giant clam Tridacna gigas, alga Symbiodinium croadriaticum, from Douglas
A fortress may privatize a resource, making it easier to defend
How to privatize resources:
Great egret nests at High Island, Texas
• Territoriality• Defense• Concealment• Fortress• Internalization
What are the benefits of privatizing?
• Restricted access to resources
• Increases future resource predictability
• Resource enhancement benefits self, or family
What are the costs to
privatizing?
• Privatizing takes energy
• Might involve conflict
• Takes away from other activities
Special relationship of
privatization with sociality
• Benefits can go to relatives
– Includes next generations, so enhancement can pay off even when slow
Special relationship of
privatization with sociality
• Easier to privatize with division of labor
– Even a group of just two can have a forager and a guard
– Larger groups can have specialists of many kinds
Special relationship of
privatization with sociality
• Resource can be used prudently
– Can save some of the resource for time of scarcity
– Avoid tragedy of the commons
– Allow living resource to grow
Special relationship of privatization with sociality
• Allows longer term relationships and resource enhancement
• Can lead to spectacular structures http://upload.wikimedia.org/wikipedia/common
s/4/42/Cathedral_Termite_Mound_-_brewbooks.jpg
Special relationship of privatization with
sociality
• Benefits can go to relatives
• Easier to privatize with division of labor
• Resource can be used prudently
• Allows longer term relationships and resource enhancement
How might social insect studies benefit from attention to privatization?
Perhaps most interesting are those cases where privatization is lost.
Scott Bauer, http://www.ars.usda.gov/is/graphics/photos/
The combination of
privatization and sociality is very important
in microbesCDC Public Domain
Staphylococcus aureus on catheter
Bacteriocins are produced by bacteria that die to help relatives
Dying bacteriocin producing bacteria are black.Their zone of bacteriocin influence is red.
Bacteriocins do not kill bacteria of their own type
Close relatives immune to bacteriocin are open black shapes, indicating they are alive
Bacteriocins do kill less related bacteria
Non-relative bacteria are green, die (solid shape) when hit by bacteriocin, live (empty green) when away from bacteriocin
Dictyostelium discoideum, a social amoeba
Social cycle develops under starvation when some cells die to become stalk
Kessin 2000
Some clones carry bacteria through the social stage
Micrographs of sorus contents
Spores
Spores
Bacteria 5µm
12 genetically-distinct clones collected from a small transect in Va.Experienced same environment; access to same potential food
Study population:
Non-farmer
Farmer
0
10
20
30
40
Soil 1 Soil 2
Fold
incr
eas
e
in s
po
res
Farmer
Farmer clones have their own lunch kit when the spores hatch in a new place.
1.3-2.2 x 108
CFU’s/gm soil
0.6-0.64 x 108
CFU’s/gm soil
What keeps farmers from losing their carried bacteria to non-farmer clones?
Besides the food bacteria, the farmers also carry bacteria they use as weapons
D.discoideum farmer clones
Location collected Closest relative in GenBank % Identity
5 clones Mt. Lake, VA Burkholderia xenovorans LB400 98
2 clones Mt. Lake, VA Stenotrophomonas maltophilia K279a 98
2 clones Mt. Lake, VA Enterobacter sakazakii ATCC BAA-894 98
3 clones Mt. Lake, VA Pseudomonas fluorescens Pf-5 98
2 clones Mt. Lake, VA Burkholderia phytofirmans psJN 97
4 clones Lake Itaska, MN Flavobacterium johnsoniae UW101 93
Supernatants from B. xenovorans cultures harm non-farmers and benefit host farmers
36
% c
han
ge in
sp
ore
pro
du
ctio
n
FarmerNon-farmer
We have identified the small molecules responsible for privatizing in another weapon, Pseudomonas fluorescens
We have identified the small molecules responsible for this effect in another weapon, Pseudomonas fluorescens
Chromene diminishes non-farmer growth, augments farmer growth
Stallforth et al. PNAS 2013
Pyrrolnitrin diminishes non-farmer growth, augments farmer growth
Privatizing is probably the commonest and most effective solution to the
tragedy of the commons
Isn’t it ironic that selfish gene, sociobiology turned first to cooperative
solutions to social problems?
© 2005 Tree of Life Web Project
A little taxonomic adventurousness is fun!
John Templeton Foundation