Eusociality Flashcards Preview

Genes and Genomes II > Eusociality > Flashcards

Flashcards in Eusociality Deck (36)
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1
Q

what does eusociality mean?

A

‘truly’ social

2
Q

what four characteristics does a eusocial animal show?

A
  1. communal living
  2. cooperative care for the young
  3. overlap of generations
  4. reproductive division of labour
3
Q

what is meant by reproductive division of labor?

A

cannot pass on their genes

4
Q

what is relatedness?

A
  • probability that two individuals share an allele due to recent common ancestry
  • represented as the coefficient of relatedness
5
Q

what are solitary animals?

A

show none of the 4 charactersitics

6
Q

what is pre - sociality?

A

some of the 4 characterics

7
Q

what is sub social?

A

parents and offspring cooperate

8
Q

what is parasocial?

A

individuals of the same generation live in a single dwelling and interact

9
Q

why is eusociality important?

A

it is one of the 9 major transitions in evolution (solitary individuals to colonies)

10
Q

what are some examples of eusocial animals?

A

bees, wasps, ants, termites, shrimp, mole rats

11
Q

how many times has eusociality occurred?

A

there are around 20 independent origins

12
Q

what does eusociality challenge?

A

natural selection

13
Q

how did eusociality evolve?

A
  1. the parasocial route

2. the subsocial route

14
Q

outline the steps of the parasocial route.

A
  • reproductives build nests close together
  • cooperate in nest construction and defence but all reproduce
  • one female dominates reproduction, others hope to inherit the nest later on
  • overlap of generations, young females become workers
15
Q

why share a nest?

A
  • ecological constraints

- protestion and nest

16
Q

what are the genetic benefits of the parasocial route?

A

individuals found in the nest are related

17
Q

use wasps as an example of the parasocial route

A

2 sisters - one dominates reproduction
joint nesters more likely to be succesful - alpha females benefit
beta females do no worse than solitary nesters
- if alpha dies the beta could inherit the nest

18
Q

what does the parasocial route lead to?

A

lead to helping behavior but not to irreversible sterility (not a major transition)

19
Q

outline the steps of the subsocial route.

A
  • solitary wasp, safe site to rear young
  • female guards nest
  • young help defend the nest
  • young permanently at home and never breed
20
Q

why will ecological constraints lead to the subsocial route?

A
  • nests are vulnerbale to predators and parasties
  • nest building is time consuming and costly
  • saves a ;pt of time and effort
21
Q

why will genetic gains and losses lead to the subsocial route?

A

mothers gain from having helpers - get offspring

helpers are on average related to siblins and offspring by 0.5 so they don’t lose

22
Q

how does haplodiploidy affect eusociality?

A

can be conflicts due to genetic systems as there is asymmetric sibling relatedness

23
Q

outline the problems of haplodiploidy

A
  • works normally females
  • have half the mother genome
  • sex is determined by whether the egg is ferilised
  • unfertilised = male
  • fertilised = female
  • unequal relatedness
24
Q

how do different sexes occur in an insect colony?

A
  • queen has a sperm storage organ and decides whether to let the sperm fertilise the egg
  • males can’t have sons
25
Q

in haplodiploidy how related are sisters to sisters?

A

0.75

26
Q

in haplodiploidy how related are sisters to brothers?

A
  1. 25

- there is no male genetics

27
Q

describe the queen/worker conflict over sex ratio

A
  • Queen daughter and queen son relatedness is 0.5
  • Worker sibling relatedness is 0.75 and 0.25
  • 3x as related to females
  • Females are 3x as valuable  passing on her genes
28
Q

what sex ratio does the queen favour?

A

1:1

29
Q

what sex ratio do the workers favour?

A

3:1

30
Q

how is the sex ratio determined?

A
  • workers can decide who gets fed
  • queen decides the primary sex ratio
  • if workers have no control over the sex ratio then the benefits of helping are reduced
31
Q

what happens if the sex ratio deviates from 1:1?

A
  • one sex becomes more common

- find it harder to mate and the other sex will do better

32
Q

how is genetic value calculated?

A

relatedness x frequency x relative mating success

33
Q

what happens when the sex ratio is 3:1 in haplodiploidy?

A

helping is not advantageous

34
Q

describe halicitine mining bees as an example

A
  1. Mated females overwinter
  2. Females produce an early brood
  3. These mate and produce later summer brood
  4. The later mated females overwinter
35
Q

when is C low?

A

when ecological conditions mea the chances of being successful alone are low

36
Q

when is B high?

A

when ecological conditions mean that having a helper brings significant benefit