Lecture 4: parental care and mating systems

Question 1

reproductive potential of males and females

Answer 1

• males have higher reproductive potential than females
• due to isogamy
• M limited by access females
• F limited by resources

Question 2

F dispersion dependent on

Answer 2

resource dispersion (food, shelter etc) but when males care then females should also be interested in dispersion of males

Question 3

M dispersion dependent on

Answer 3

F location

Question 4

when Male parental care oversees that of females what happens to reproductive potential

Answer 4

females may be higher than males

Question 5

sex role depends on _____, which in turn depends on relative provision of parental care

Answer 5

potential reproductive rate

-Clutton-Brock & Vincent 1991

Question 6

__% of bird species have biparental care

Answer 6

81% (Cockburn 2006)

Question 7

obligate monogamy =

Answer 7

both parents essential for successful reproduction

Question 8

conditions for obligate monogamy

Answer 8

• parents must forage a long way from nest (i.e seabirds (puffin))
• parents have specialised caring roles (i.e amazon parrots)

Question 9

hornbills & monogamy

Answer 9

females seals herself into nest

• complete moult of flight feathers
• female and chick depend on male for all food for up to 137 days
• BUT if male doesn’t return F will eat chick

Question 10

extra pair paternity is low / high in obligate monogamy

Answer 10

LOW

Question 11

obligate monogamy: interests of parents are alinged, so in general, conflict between parents is

Answer 11

REDUCED

Question 12

2 types of monogamy

Answer 12

obligate & facultative

Question 13

facultative monogamy =

Answer 13

male care is not essential, although it usually increases productivity, so monogamy is facultative

Question 14

experiment to see effect of facultative monogamy

Answer 14

removal experiments

Question 15

if male desertion reduces reproductive success to 1/x when is it still worthwhile for hi to desert

Answer 15

when he can get > x partners

Question 16

males prefer polyandry / polygyny?

Answer 16

polygyny

lions, gorillas, red deer etc

Question 17

why do females agree to polygyny>

Answer 17

• no cost to females
• –> no male care & females settle in relation to resources & other females
• costly BUT have no choice
• benefits outweight the costs (polygyny threshold model)

Question 18

polygyny: when females have no choice WHEN

Answer 18

–when female biased population e.g. marsh wren 1M : 1.5F

– or when deceived by males e.g. pied flycatcher M once F lays eggs leaves to find new F then abandons her and goes back to primary F

Question 19

polygyny threshold model

Answer 19

benefits to f in polygyyny outweigh the costs

• quality of male or territory
• F choose polygyny if difference in quality exceeds polygyny threshold (diff between Monogamy & polygyny)

Question 20

is there any evidence for polygyny threshold model?

Answer 20

good genes? little evidence
better resources? some evidence e.g. Great Reed Warbler F visit 3-11 paired / un-paired males, sometimes chosed paired
–NS diff between Monog, primary and secondary reproductive success of females

Question 21

why do males agree to polyandry?cooperative polyandry

Answer 21

• cooperative polyandry -> when M coop in raising brood
• –> increased productivity from more paternal care outweighs costs of shared paternity
• e.g. Galapagos Hawk
• • 1F : 1-8M

Question 22

2 forms of polyandry

Answer 22

cooperative polyandry

sequential polyandry

Question 23

sequential polyandry

Answer 23

males have little choice
=females lays series of clutches for multiple males,; males provide care
WHY? male biased sex ratio
-abundant good & precocious chicks allows uniparental care
-MALES this time are stuck in ‘Cruel bind’

Question 24

what determines intensity of conflict in mating systems

Answer 24

• life history constraints: how much care is needed?
• ecological differences: distribution & abundance of resources?
• social conflicts: individuals try to maximise RS at partners expense

Question 25

in facultative, polygyny & polyandry there is likely to be __

Answer 25

conflict over the preferred mating system