Lecture 14- The evolution of eusociality

Question 1

wilson definition of eusociality

Answer 1

cooperative care of young
reproductive division of labour
overlap in generations

Question 2

why is the wilson definition generally not useful

Answer 2

doesnt actually describe the evolutionary process that led to eusociality developing, and is generally based on a single species

Question 3

alternative eusociality definition

Answer 3

presence of distinct ‘castes’, which are irreversibly behaviourally distinct before maturity
helping behaviour in the non-reproductive caste
loss of ability to behave differently when a caste is assigned, or no ability to do this at all

Question 4

example of extreme morphology due to these caste roles

Answer 4

turtle ants with flat plates on the head so individuals can act as ‘doors’
honeypot ants- individuals existing as food stores, huge abdomens filled with sugar

Question 5

how many times is it estimated that obligate eusociality has evolved

Answer 5

4

Question 6

important precursor to eusociality

Answer 6

strict lifetime monogamy- keeps relatedness high enough, hamilton’s rule turns into b>c

Question 7

evidence that the idea of correlation between cooperation and monogamy

Answer 7

less promiscuity in bird groups with more cooperation

Question 8

why may benefits of a eusocial system exceed costs

Answer 8

life insurance
fortress defence
ecological benefit

Question 9

idea of ‘life insurance’

Answer 9

helpers can help maintain offspring if the ancestral group had extended parental care and a high chance of mortality- splitting care provided benefits to offspring survival

Question 10

idea of ‘fortress defense’

Answer 10

useful if living within a food source to have individuals defend it better than they would if reproducing, e.g. having soldiers