Alleles held at equilibrium by balancing selection

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2 Alleles held at equilibrium by balancing selection

3 Alleles held at equilibrium by balancing selection Neutral mutation

4 Alleles held at equilibrium by balancing selection Lost by drift Neutral mutation

5 Alleles held at equilibrium by balancing selection Lost by drift Neutral mutation Increased by drift

6 Alleles held at equilibrium by balancing selection

7 Alleles held at equilibrium by balancing selection

8 Alleles held at equilibrium by balancing selection

9 Alleles held at equilibrium by balancing selection

10 Alleles held at equilibrium by balancing selection

11 Alleles held at equilibrium by balancing selection

12 Minority neutral variants Favorable mutation

13 selection Minority neutral variants Favorable mutation

14 TgrB polymorphic positions (n=30) N sig seq Ig-1 Ig-2 Ig-3 TM C TgrC polymorphic positions (n=29) N sig seq Ig-1 Ig-2 Ig-3 Ig-4 Ig-5 Ig-6 TM C Benabentos et al., 2009 Current Biol. 19(7): Immunoglobulin-like domain

15 TgrD polymorphic positions out of 15 wild strains TgrE polymorphic positions out of 6 wild strains Benabentos et al., 2009 Current Biol. 19(7):

16 r = P < tgrb1 and tgrc1 are nearly identical to AX4 Genetic distance from AX4 Microsatellite-based Ostrowski et al. PLoS Biology 2008

17 12h 17h tgrc1 - tgrb1 - Ax4 qrt-pcr profile in Ax4 0.5mm

20 Kin recognition suggests that cheating was important Prediction: If ability to cheat is a part of evolved fitness, then that ability should decline when selection is removed and drift increased.

21 Sara Fox

22 MA

23 Control lines do compete evenly against ancestor control line Ancestor-gfp Percent change of evolved lines compared to ancestor

24 Mutation accumulation lines highly variable; tend to lose against ancestor MA line Ancestor-gfp Percent change of evolved lines compared to ancestor

27 Sequence another species for comparison Schaap et al Science

28 Xiangjun Tian

30 Kuzdzal-Fick, Fox, Strassmann & Queller, Science 334:1548

31 Select for success of new natural cheater mutants under low relatedness Kuzdzal-Fick

38 Cooperation is often treated as a topic apart, but it is basic to the evolution of life

39 In the major transitions in evolution, conflict must be resolved for formerly independent units to become selected together John Maynard Smith, Eörs Sathmáry Chromosome Prokaryote Cell Eukaryote Cell Multicellular Organism Colonial Superorganism

42 High cooperation among parts, Low actual conflict among parts Consolidation of adaptations making the organism a unit of near unanimous design Queller & Strassmann Phil. Trans. R. Soc.,Strassmann & Queller Evolution

43 1. What are the possible fitness benefits to grouping?

44 1. What are the possible fitness benefits to grouping?

45 1 a. Rise above the hazards of the soil, dispersal is facilitated

46 1b. Larger groups move farther Distance travelled (cm) Slug size (total volume of spores producted mm 3 ) Spearman rank correlation, p<0.001 Foster et al. Proc Royal Soc. B, 2002

47 Dicty slugs Bacteria slurry

48 1d. Exploit other cells to make better spores

49 2a. Exploitation by some clones avoiding the sterile, altruist role of stalk For 12 mixtures, we genotyped the head and tail of 7 individual slugs from each plate (Strassmann et al. Nature, 2000)

50 Within 2-clone chimeras, in 6/12 mixes one contributes more to spore than to stalk clone 1 clone 2 NC60.1 NC105.1 NC28.1 NC63.2 NC98.1 NC101.1 NC94.2 NC85.1 NC75.2 NC4 NC34.1 NC85.2 T T The image The image cannot be displayed. Your computer The image cannot be T Proportion of clone 1 NC60.2 NC34.1 NC28.2 NC69.1 NC70.1 NC99.1 NC94.1 NC85.2 NC28.1 NC47.2 NC34.2 NC39.1 % clone 1 % clone 2 Spores : top bar Stalk : bottom bar Neutral Prediction: Strassmann, Zhu, and Queller, Nature, 2000

51 Within 2-clone chimeras, in 6/12 mixes one contributes more to spore than to stalk clone 1 clone 2 NC60.1 NC105.1 NC28.1 NC63.2 NC98.1 NC101.1 NC94.2 NC85.1 NC75.2 NC4 NC34.1 NC85.2 T T The image The image cannot be displayed. Your computer The image cannot be T Proportion of clone 1 NC60.2 NC34.1 NC28.2 NC69.1 NC70.1 NC99.1 NC94.1 NC85.2 NC28.1 NC47.2 NC34.2 NC39.1 % clone 1 % clone 2 Spores : top bar Stalk : bottom bar Neutral Prediction: Strassmann, Zhu, and Queller, Nature, 2000

53 2b. Cells that have starved 4 hours are more likely to become spores Random Stalk * Spores Kudzdal-Fick et al. Biology Letters 2010 *Fisher s PLSD p<0.05

54 Huang et al. 1997

55 2c. Do chimeras move as far as pure clones?

56 5 Chimaeric slugs move less far Mean distance migrated (cm) different single clones 10 different clone pairs 1 mix of five clones (5 reps) 1 mix of ten clones (5 reps) N=30, ANOVA, p< Number of clones in slug Foster et al., 2002

57 2c. Chimeras move less far than pure clones, for a given number of cells Kevin Foster Angelo Fortunato Foster et al., Royal Society Proceedings B, 2002

58 There are benefits and costs to grouping, making this an excellent system for studying sociality

61 Transect location Number isolates clones

63 r = P < Genetic distance from AX4 Microsatellite-based Ostrowski et al. PLoS Biology 2008

66 5. How common are genes involved in cheating?

67 Great molecular biology collaborators Adam Kuspa Gadi Shaulsky

68 Do a selection on a pool of insertion mutants.

69 Does the interaction affect life history traits? Non-farmer Farmer Fb s: Fb s: Bacteria 3 mm 5 days of development Farmer clones enter the social stage before all food is exhausted

70 Dicty gene DpnII BamHI linearize plasmid and insert into random spot in Dicty Blasticidin Bs R pbsr Kb REMI knockouts Amp R Ampicillin

71 Selection to find cheater mutations 10,000 REMI generated mutants 1 round SM plate SM plate

72 Select for cheaters that get into spores instead of stalk Generation 1 Generation 20

73 Test for cheating mix 1:1 with wildtype AX4, labeled with green flourescent protein Selected population AX4 GFP

74 Santorelli et al. Nature, 2008

76 Dictyostelium discoideum as a social organism 1. Benefits to grouping 2. Costs to grouping 3. Relatedness and kin discrimination 4. Experimental evolution: Impact of low relatedness 5. Genes involved in cheating are common and show rapid evolution.

77 In the lab, on agar and on soil, clones mix readily.

78 1) Is the farming trait stable? Bacteria Dictyostelium discoideum

79 Farmers regain their association with bacteria after curing with antibiotics; non-farmers do not acquire an association 100 % Reassociation Farmers Non-farmers 10 random sori; 4 farmers and 4 non-farmers; F 1,6 =48.864, p<0.001

80 2a) What proportion of clones are farmers? 100 % occurrence /14 3/9 1/3 4/9 Non-farmer Farmer Average proportion of farmers 35.5% 0 Virginia Minnesota Farmers and partners isolated from 4 independent collections of soil samples

81 QS8 QS21 QS14 QS11 QS18 QS22 QS15 QS9 QS23 disc NW QS4 QS1 QS12 QS6 QS17 citr DQ340385

Sociobiology Goes Micro

Sociobiology Goes Micro Long used for studying development, Dictyostelium now also provides a model for analyzing social interactions Joan E. Strassmann and David C. Queller Joan Strassmann and David Queller