Origin of sociality 2, 3, 9

Question 1

how is competition resolved?

Answer 1

conflict or cooperation, resulting in division of labour, leading to sociality.

Question 2

what 4 principles must be considered to understand behaviour?

Answer 2

Adaptation/function
Experience/development
Evolution
Causation

Question 3

why is cooperation a challenge to evolutionary theory?

Answer 3

selfish individuals should be expected to gain benefits of cooperative acts of others whilst not cooperating themselves.

Question 4

example of cooperation in Pied babblers

Answer 4

Sentinel behaviour

• one individual acts as a look out for the group, gives a watchmans song.
• benefits foragers in increased food intake if the sentinel is indicated by acoustic signals, spread out more in open patches and reduce vigilance.
• foragers use variations in watchman’s song as indication of current risk. call rate increases in danger
• can calculate the height of the sentinel, if higher, more view so more accurate and reliable, so spread out and forage more.
• foragers and sentinels negotiate as to which individual will take a turn next.

Question 5

how do dwarf mongooses use sentinel behaviour?

Answer 5

adjust vigilance based on dominance status of individual on sentinel duty

Question 6

how has conflict lead to niche partitioning in Green Woodhoopoes?

Answer 6

conflict over food resources driver of sexual dimorphism in beak length which minimises conflict whilst foraging together. this is the biggest difference in bill length known in birds.

Question 7

effect of conflict in cichlids on within group behaviour.

Answer 7

group members show more affiliation to one another in aftermath of conflict with out group rivals.

Question 8

what is sociality, is all sociality the same?

Answer 8

group of organisms co-existing. interactions lead to conflict, cooperation and coercion.
sociality is on a spectrum:
simple - ccoperation and division of labour, butterflies, grasshoppers…
mid - mogooses, mammals, some birds, humans
complex - conflict, coercion, slime moulds, hymenoptera, snapping shrimp, mole rats.

Question 9

what are problems wit the idea of sociality?

example

Answer 9

co-operation / altruism:
Social behaviours that are costly and
reduce the actor’s fitness but increase the fitness of others.
this is an evolutionary puzzle, how can a beh evolve which reduces the actors fitness?

eg honey bee worker’s suicidal sting. forfeits reproduction, only the queen lays eggs, defending the colony causes them to die.
Darwin - sterile ants may be a flaw to NS.

Question 10

how did sociality evolve then? 3 basic steps.

Answer 10

• Non-social ancestor -> social
• Shift in how information is
  stored and transmitted to the
  next generation
• Shared across levels of
  biological organisation.

Question 11

Major transitions in evolution, with 1 origin

Answer 11

1. Replicating molecules -> Populations of molecules in compartments
2. Independent replicators -> Chromosomes
3. RNA -> DNA (as genes); proteins (as enzymes)
4. Prokaryotes -> Eukaryotes
5. Asexual clones -> Sexual populations
6. Primate societies -> Human societies

Question 12

Major transitions in the origin of sociality with many origins.

Answer 12

1. Protists -> multicellular organisms (>25 origins)
2. solitary individuals -> colonies (<24 origins)
3. Separate species -> Interspecific mutualisms.

Question 13

3 levels of sociality across biological organisation

Answer 13

• Social genome: bases to codons, genes to chromosomes, chromosomes to cells.
• social cells: single cells to multicellular org, cells divide and cooperate in a fertilised egg, slime moulds aggregate.
• animal societies

Question 14

Is there a unified theory of
evolution that can explain the repeated evolution of
sociality in nature?

Answer 14

debateable

Question 15

3 different theories regarding social evolution

Answer 15

inclusive fitness theory
Group selection/Multilevel selection
Price equation

Question 16

what equation underlies inclusive fitness theory?

Answer 16

hamilton’s rule
this is currently the best way of describing the role of relaedness.
IF = Direct fitness (offspring) + indirect fitness (relatives fitness)

rb>c
r- relatedness of actor to other individuals involved compared to average population relatedness.
b- extra offspring of beneficiary conferred by altruism
c - offspring of actor lost due to altruism.

Question 17

how does haldane’s lake describe IF?

Answer 17

You think about your own fitness frst before jumping in a lake to save someone

Question 18

what effect does IF have on NS?

Answer 18

massively shapes NS

beh affects success of actors relatives and own.

Question 19

what was E.O Wilson’s view of IF?

Answer 19

1975 - Inclusive fitness theory is the answer to everything!
2000s - wrote a paper on how relatedness is not enough to cause sociality - ‘Eusociality:origin and consequences’ Said kinship is a consequence rather than a cause of eusociality.Instead suggested group selection was key to origin of eusociality.
many scientists published a response paper arguing against this.

Question 20

what was Richard Dawkin’s view ofsociality?

Answer 20

Altruism at an organismal level evolves due to selfishness at a genetic level.

Question 21

define relatedness

Answer 21

Probability of sharing genes that are identical by descent, relative to population average.

Question 22

easy way to visualise Alan Grafen’s geometric view of relatedness

Answer 22

continuum of gene freq
0———————————-1
P R A
If recipient is closer to the altruist than population agerage is, the altruism will be beneficial.

Question 23

what is the ancestral state for evolution of sociality in which groups?

Answer 23

high relatedness is the ancestral state.

in: Social insects, birds, Mammals, multicellularity.

Question 24

examples of costs to the actor

Answer 24

Cliff Swallows - increased transmission of parasitesas colony size increases. Brown and Bomberger 1986.

Pinyon Jay - Comp for resources increased when in social group. Anderson and Wicklund 1978

Question 25

examples of benefits to the actor

Answer 25

Aggregation of wood pigeons deters attack by Goshawks.

Individual vigilance in Harbour seals decreases with increasing group size

Question 26

what are 3 common fallacies about IF and the realities behind them?

Answer 26

1. Kin selection suggests relatedness is the DOMINANT force in the evolution of social actions.
   reality: costs and benefits can be dominant forces
2. kin selection predicts conflicts so therefore cannot favour altruism.
   reality: kin selection predicts both conflicts and cooperation.
3. kin selection assumes there are no colony level effects.
   reality: kinselection models do include colony level effects.

Question 27

who came up with the idea of group selection?

Answer 27

Wynne-Edwards
‘Natural selection favours traits because
they benefit the whole group, rather than individuals”

Question 28

what are two distinct forms of group selection?

Answer 28

MLS2/Naive/Old group selection - ‘Natural selection favours traits because they benefit the whole group, rather than individuals’

MLS/MLS1 - changed meaning of ‘group selection’, adapted ‘old’ GS.

Question 29

what are fundementals and problems of ‘old’ group selection?

Answer 29

Fundamentals of GS:
•Interactions between groups are all that matter
•Fitness attributed to the group only
•Basic rules of NS apply only to the group –>
change in frequency of groups, not individuals or genes

Problem

• only hold in VERY limited conditions
• vulnerable to within group defection

Question 30

define and what are fundementals of Multi level selection?

Answer 30

Natural selection operates on more that one biological level

fundementals;

• interactions within levels affects fitness between levels
• basic rules of NS and fitness atributed to all levels
• Generally accepted as correct

Question 31

recap definitions
IF
GS
MLS

Answer 31

IF - NS shapes individual behaviour according to the effects the beh has on the rep success of the actors relatives as well as their own.

GS - NS favours traits because they benefit the group as a whole rather than individuals. this is a legitimate evo force but it is weak.

MLS - NS operates on more than one level

Question 32

what does the Price equation do?

Answer 32

Describes how the average value of a trait changes in a population
from one generation to the next.
Takes into account many variables
Concludes that IF and MLS and mathematically equivalent.

Question 33

what are 3 stages in becoming Eusocial?

Answer 33

1. overlap of generations
2. cooperative brood care
3. Diversion of reproductive labour

Question 34

What occurs in the first stage of becoming eusocial and how?

Answer 34

1. over lap of generations:
   adult young emerge and stay at home with their mother. Mother stays to guard/provision young.
   how: monogamous breeding system, Extended parental care.

Question 35

What occurs in the second stage of becoming eusocial and how?

Answer 35

2.Cooperative brood care:
Adult young stay in the nest to help mother to rear siblings
How: Mis-directed parental care

Question 36

What occurs in the third stage of becoming eusocial and how?

Answer 36

3. Division of reproductive labour
   A rep caste and a non rep caste forms
   How? Conflict over reproduction

Question 37

what is the monogamy window?

Answer 37

When rb>c
Ancestral to eusociality
monogamy retains high relatedness btw offspring, maximises R, which gives massive benefits to staying in the group.

Question 38

how can we determine the mating system?

Answer 38

High through put genotyping.

• cost effective, rapid, uses tiny amounts of DNA.
• take wasp leg tissue, extract DNA. locus specific PCR at a mendelian marker eg microsatellite.Genotype at multiple loci, and find the number of repeats sharing allelic variants (indicates relatedness)

Method 2: Quantify mating system. takes longer. Pedigree assignment.?????

Question 39

show how monogamy maximises R

Answer 39

50% chance of inheriting the same allele as each parent at point X in the genome.
so 0.5 r to each parent.
0.5 to siblings.

Question 40

what is relatedness between relatives in monogamous haplodiploid systems?

Answer 40

SONS: haploid. only inherit 50% of mothers genes.
DAUGHTERS: diploid. r to mother = 0.5, r to father = 1.

sperm don’t undergo meiosis, so all identical. therefore, r to father = 1.

Sisters r = 0.75
(0.5 x 0.5 = 0.25 - maternal relatedness)
(both get half of their genes from dad so this half must be identical, so + 0.5)

brother to sister, r = 0.25
(maternal relatedness - 0.5 x 0.5 = 0.25, no genes from dad in a son).

Question 41

why does it make sense for workers in monogamous haplodiploid systems to raise sisters who will be queen rather than to have own offspring?

Answer 41

worker will be related to own offspring by 50%

worker related to sister by 75%

Question 42

is it better for a worker to raise brother than to have own offspring, in monogamous haplodiploid systems?

Answer 42

no
r to brother = 0.25
r to offspring = 0.5
however, often policing mechanisms are in place to stop this.

Question 43

when genotyping to find monogamous haplodiploid relatedness,
how would you work out which the father is

Answer 43

father: only one locus
sisters will share a maternal locus
there will be one paternal and 2 maternal loci,
see diagram

Question 44

how would you use microsatellite genotyping data to work out which the maternal and paternal genes are?

Individual    L1  L2       L3
1     101/103  254/296  89/92
2    101/103  254/296  92/98
3    103/105  222/296  89/92
4    103/105  254/296  92/98
5    101/103  254/296  92/98
6    103/105  222/296  89/92I

Answer 44

L1 - maternal: 101/105
paternal: 103

L2 - maternal: 222/254
paternal: 296

L3 - maternal: 89/98
paternal: 92

Question 45

what is a quick way to tell from r(offspring) if a system is monogamous in diploids and haploids?

Answer 45

Diploids: Monogamous if r(offspring) not different from 0.5
Haplodiploids: Monogamous if r(offspring) not different from 0.75 (female)

Question 46

how does haploidiploidy promote overlap of generations?

Answer 46

females are more related to sisters than to own offspring, so likely to stay in colony to raise sisters offspring. only occurs on monogamous mating systems.

Question 47

why is monogamy important in eusocial insects?

Answer 47

Choosing who to nest with has high impacts on your life time fitness (indirect fitness). high r is imp.

Question 48

describe some empirical evidence that monogamy is at the origin of social systems, in hymenoptera

Answer 48

hughes et al, 2008
used 267 sp of eusocial bees, wasps and ants, within which there has been 8 independent origins of sociality. constructed phylogenetic tree, shows that single mating is ancestral to all 8 origins.

Question 49

describe some empirical evidence that monogamy is at the origin of social systems, in coop breeding birds.

Answer 49

there are multiple transitions to cooperative breeding in birds
coop beh favoured by low promiscuity, giving high relatedness.
However, many birds are promiscuous and coop breeders, and many vertebrates are coop and low R.
phylogenetic analysis of 267 bird species showed coop ancestors give rise to all types of offspring: coop, non coop and both.

Question 50

describe some empirical evidence that high relatedness is at the origin of social systems in multicellularity

Answer 50

Why should single cells become mutually
dependent on other cells?
perhaps for reduced conflict or alignment of interests.
to see if high relatedness was important in transition to multicellularity, compared clonal vs non clonal multicellularity across species.
found Clonal groups more likely to undergo transition to obligate multicellularity.

Question 51

what is another step requires for overlap of generations, alongside monogamy?

Answer 51

Extended parental care.

Question 52

what was a possible mechanism for the evolution of extended parental care, and why may this have evolved?

Answer 52

mass provisioning evolved to progressive provisioning.
eg mass provisioner - Ammophila sabulosa, gives all food to young quickly, on average will leave more independent offspring.
progressive pro - Ammophila pubescens. provisions young over an extended period. average, leaves fewer independent offspring and mother more likely to die before provisioning is complete.
Why?
- young are vulnerable to parasitism and may be wasted investment if parasitised in mass provisioning. in progressive, can terminate investment is parasitised.

Question 53

what benefits are from progressive provisioning?

Answer 53

Progressive provisioned brood are better protected 
from parasitism
seen in no. larvae killed in:
Ammophilia sabulosa - 11/36 killed.
Ammophilia pubescens - 3/22 killed.

Question 54

What must occur in mis-directed parental care?

Answer 54

Uncoupling of solitary traits
seen in solitary ancestors,go through periods of rep and then provisioning.
eg in social cells, helping beh = stalk, fuiting body = rep beh.

social animals - provisioning = helping behaviour.
rep beh = egg laying. often have to gain dominance before getting to rep stage.