12: eusociality

Question 1

what are the 3 main orders with eusocial systems ?

Answer 1

hymenoptera
isoptera
homoptera

Question 2

within hymenoptera how many species are eusocial? (3)

Answer 2

bees: 1,000
wasps: 800
ant: 9,500/all

Question 3

in isoptera how many species are eusocial?

Answer 3

termites: 2,000

Question 4

in homoptera what species is eusocial?

Answer 4

aphids

Question 5

what are the 3 main features of eusocial species?

Answer 5

• cooperative brood care (non parents help raise brood)
• sterile castes
• overlapping generations (workers raise subsequent broods)

Question 6

how many total species of social insects? - how many birds and mammals?

Answer 6

14,000

birds: 10,000
mammals: 4,000

Question 7

how many ants in the driver ant colony?

Answer 7

22 million

Question 8

in the brazilian rainforest what % of insect and animal biomass is eusociall?

Answer 8

insect: 70-80%
animal: 33%

Question 9

what is an example of sophisticated communication in eusocial species?

Answer 9

waggle dance

Question 10

what is the ant myrmica rubra life cycle? (6)

Answer 10

1. queen founds nest
2. sterile workers produced
3. 9 years for colony to be large enough
4. after 9 years winged females and males produced
5. nuptial flight and mating
6. males die and females find a nest

Question 11

list the 2 hypotheses for why eusociality evolved

Answer 11

• staying at home/subsocial

- sharing a nest/ parasocial

Question 12

what is the ecology for how eusociality evolved by the staying at home hypothesis? (4)

Answer 12

• ancestors are solitary parasitoids
• advantage to nest guarding by females against parasites
• if enough predation pressure young stay and help mother defend and build nest
• will stay at home and never breed

Question 13

what is the genetic predisposition for how eusociality evolved by the staying at home hypothesis? (3)

Answer 13

• for daughters at home raising full siblings (r=0.5) is the same as raising offspring (r= 0.5)
• for queen producing offspring (0.5) is better that grand offspring (0.25)
• queen should prefer daughters to stay as workers

Question 14

what is the ecology for how eusociality evolved by the sharing a nest hypothesis? (4)

Answer 14

• cooperating sisters build nests close together
• cooperative defence but separate reproduction
• one female dominates reproduction
• young females become workers

Question 15

what is the genetic predisposition for how eusociality evolved by the staying at home hypothesis? (3)

Answer 15

• for cooperative sisters there is benefit to raising dominants offspring
• this may outweigh benefit of breeding alone if it is risky
• relatedness ensures non reproductive female benefits from queens reproduction

Question 16

what is an example of a species that fits with the stay at home hypothesis?

Answer 16

subsocial halictine bees

Question 17

what is an example of 2 species that fit with the sharing a nest hypothesis?

Answer 17

polistes

stenogastrine waps

Question 18

what did W.D Hamilton say about haplodiploidy?

Answer 18

it predisposes hymenoptera to evolve sterile castes

Question 19

what are features of M and F in haplodiploidy?

Answer 19

M: from unfertilised eggs, haploid and form gametes without meiosis so all sperm identical
F: from fertilised eggs, diploid and form gametes with meiosis

Question 20

where do sons and daughters receive their genes in terms of mother and father?

Answer 20

• sons: only from mother

- daughters: identical genes from father and other half from diploid mother

Question 21

in the sister-sister pedigree what is the relatedness

a) via mother
b) via father
c) total

Answer 21

a) 0.5 X 0.5 =0.25
b) 0.5 X 1 = 0.5
c) 0.25 + 0.5= 0.75

Question 22

in the sister-brother pedigree what is the relatedness

a) via mother
b) via father
c) total

Answer 22

a) 0.5 X 0.5 =0.25
b) 0.5 X 0 = 0
c) 0.25

Question 23

in the brother-sister pedigree what is the relatedness

a) via mother
b) via father
c) total

Answer 23

a) 1 X 0.5 =0.5
b) 0.5 X 0 = 0
c) 0.5

Question 24

what is the genetic relatedness between female and

a) mother
b) father
c) sister
d) brother
e) son
f) daughter

Answer 24

a) 0.5
b) 0.5
c) 0.75
d) 0.25
e) 0.5
f) 0.5

Question 25

what is the genetic relatedness between male and

a) mother
b) father
c) sister
d) brother
e) son
f) daughter

Answer 25

a) 1
b) 0
c) 0.5
d) 0.5
e) 0
f) 1

Question 26

what is it better the female worker produces and what does it explain?

Answer 26

sisters rather than daughters

- explains why females rear sisters

Question 27

in hymenoptera what are workers always?

Answer 27

female

Question 28

what are diploid termites like?

Answer 28

M and F equally related to siblings and both sexes become sterile workers

Question 29

what are clonal aphids like?

Answer 29

• all are genetically identical r=1

- sterility is not an evolutionary puzzle as is no conflict over reproduction

Question 30

what is the preferred sex ratio for the queen and why?

Answer 30

son r=0.5
daughter r=0.5
1F:1M

Question 31

what is the preferred sex ratio for the worker and why?

Answer 31

brother r=0.25
sister r=0.75
3F:1M

Question 32

what did Trivers and Hare 1976 study and find? (3)

Answer 32

• sex ratio in 21 ant species
• suggested workers win
• but the preferred ratio is influence by local mate competition and queen mating frequency affecting relatedness

Question 33

what is local mate competition? (2)

Answer 33

• if sons/brothers compete to mate such as in fig waps then it should pay to produce fewer of them
• benefit to female biased sex ratio

Question 34

what is queen mating frequency affecting relatedness? (3)

Answer 34

• if females mate with multiple males then workers are less closely related
• if 2 possible fathers: r= 1 X 0.5 X 0.5 = 0.25 (+ 0.25 from mother = 0.5 relatedness)
• if infinite males then r= 0

Question 35

what are ecological constraints important in?

Answer 35

evolutionary origins

Question 36

what can eusocial species also be characterised by?

Answer 36

conflict within and between castes