Cooperative Breeding

Question 1

What is altruism?

Answer 1

An extreme form of co-operation, involving unselfish behaviour performed for the benefit of others.

Question 2

What 3 hypotheses explain the evolution of altruism?

Answer 2

1. Kin selection - altruism is favoured when recipient shares same genes as donor.
2. Reciprocal altruism - donor performs altruistic act in expectation that ‘favour’ will be returned one day.
3. By-product mutualism - donor & recipient gain survival benefit from co-operative act (e.g. alloparenting).

Question 3

What is solitary, colonial and communal breeding?

Answer 3

• Solitary = no co-operation or in monogamy, co-operation between parents.
• Colonial = several (or many) breeding pairs share breeding site but there’s no active co-operation.
• Communal = group members co-operate for reproduction & participate in co-operation.

Question 4

What is eusociality?

Answer 4

• Specialisation between reproductive individuals & several sterile castes.
• E.g. some castes are responsible for foraging & defence (bees, wasps & some termites).

Question 5

What is co-operative breeding?

Answer 5

A system in which tasks associated with breeding & rearing young are shared between individuals & helpers.

Question 6

What are the 2 components of inclusive fitness?

Answer 6

1. Direct fitness - personal reproductive success (i.e. offspring).
2. Indirect fitness - through reproductive success of relatives.

Question 7

What are the 2 main types of co-operative breeding?

Answer 7

• Helpers at nest/den - a breeding pair with helpers.
• Plural breeders - more than 1 breeding pairs, extended family groups, overlapping generations.

Question 8

Give an example of helpers.

Answer 8

• Florida scrub jay.
• Groups consist of a monogamous pair & 1-6 helpers.

Question 9

What do the helpers do?

Answer 9

• Defend natal territory.
• Help feed young.
• Defend nest when adults are away.
• Protect fledglings.
• Act as sentinels.
• Usually leave pair after a couple of years.

Question 10

Give an example of plural breeders.

Answer 10

• Mexican jay.
• Lives in extended family groups
• Several breeding pairs in each group.
• Helpers assist in feeding young & nest defence.
• When fledged, young are fed by all group members.

Question 11

Give an example of an obligate co-operative breeder.

Answer 11

Ground hornbills.

Question 12

What are the benefits of helpers?

Answer 12

• Increased success of breeding attempts.
• Increased frequency of breeding.
• May grow faster.
• Fed more.
• Enhanced breeder survival.
• Increased fecundity in helpers.
• Increased production of non-descendent kin for helpers.

Question 13

What is the habitat saturation hypothesis?

Answer 13

• Lack of vacant territories.
• Some species need a territory to breed & available habitat or territories may be limiting.