Lecture 13: Eusociality

Question 1

what is eusociality?

Answer 1

it describes social systems where there is cooperative brood care, generational overlap, and, critically, sterile castes

Question 2

diversity of eusocial systems = how has it evolved?

Answer 2

involved independently in hymemoptera (bees, wasps ants), isoptera, homoptera

Question 3

three features of a eusocial system:

Answer 3

• cooperative brood care
• sterile castes
• overlapping generations

Question 4

why are eusocial systems ecologically important?

Answer 4

spread across world in many systems, evolved remarkable specialisation to suit social way of life

Question 5

how man species of insect show eusocial systems?

Answer 5

14,000 (10,000 birds, 4000 mammals)

Question 6

eusociality driver ant colony: how many ants

Answer 6

22 million ants

Question 7

brazillian rainforest % of insects

Answer 7

70-80%, 33% animal biomass

Question 8

example of sophisticated communication

Answer 8

waggle dance

Question 9

Myrmica rub life cycle

Answer 9

• nuptial flight and they mate just ONCE
• queen then founds nest
• production of sterile female workers
• around 9 years later
• produce winged females and males

Question 10

how many hypothesis’ to suggest how eusociality evolved from solitary ancestral forms?

Answer 10

2

1. staying at home
2. sharing a nest

Question 11

hypothesis of eusociality evolution: Staying at home

Answer 11

• solitary parasitoid
• nest guarding by female
• young then stay & help defend/build (help outweighs benefits of them having own young)
• young permanently at home and never breed
• –Relativeness makes it worthwhile; daughters raising full siblings = as good as raising offspring
• queen should prefer daughters to stay as workers

Question 12

hypothesis of eusociality; sharing a nest

Answer 12

• sisters build nest close together
• cooperative defence, separate reproduction
• one female dominates reproduction
• young females become workers
• helping sisters may outweigh the benefits of breeding alone as may be high risk activity

Question 13

who proposed haplodiploid & what is it

Answer 13

W.D Hamilton

• M from unfertilised eggs = haploid
• F from fertilised eggs = diploid

-males form gametes without meiosis (all gametes identical)
F form gametes with meiosis

Question 14

haploiddipoidy: daughter and sons genetic make up

Answer 14

• daighters receive identical genes from father & the other half from diploid mother
• sons receive genes only from mother

Question 15

haplodiploid = in eusocial insects sisters are related by

Answer 15

0. 75

0. 25 from mother and 0.5 from dad

Question 16

haplodiploid = in eusocial insects sis to bro

Answer 16

0.25

Question 17

haplodiploid = in eusocial mother to son and daughter

Answer 17

0.5

Question 18

so female worker point of view better to produce daughter / sisters?

Answer 18

DAUGHTERs as = 0.75 relatedness

-explains why females (not males) rear sisters

Question 19

compare haplodiploid to diploid termites

Answer 19

m & f equally reloads to siblings ad both sexes become sterile workers

Question 20

consequences with haplodiploid who studied this

Answer 20

-Trivers & Hare 1976 sex ratio in 21 ant spp,
generates conflict between queen and daughters
- queen want to produce 1 daughter for every son
-but worker would favour daughters (0.75 relatedness) (3:1 f:m)
-WORKERS WIN

Question 21

criticism of consequences with haplodiploid who studied this studies Trivers & Hare 1976

Answer 21

• local mate competition -> queen may want females too

- queen mating frequency affects relatedness

Question 22

Local mate competition: Fig wasps

Answer 22

• fig wasps lay eggs into figs through outer surface, larvae develop in fig and eventually emerge
• male have large penis’ allowing them to mate with females before they’ve emerged
• female putting eggs in figs, would make sense for them to bias females

Question 23

Queen mating frequency affects relatedness

Answer 23

reduction in relatedness the more males she mates with

Question 24

eusociality has evolved …

Answer 24

multiple times in various taxa

Question 25

ecological constraint likely tone important in ____

Answer 25

Evolutionary origins

Question 26

incentive of genetic predisposition to help, especially in

Answer 26

haplodiploid Hymenoptera

Question 27

Eusocial species are also characterised by conflict within and between ___

Answer 27

castes