Lecture 10a - conflict within families Flashcards
what is intersexual conflict?
The reproductive interests of males and females often differ - this conflict is a fundamental component of sexual selection
describe intersexual conflict in langurs
Matrilineal societies with single reproductive male. In one troop, four males ‘ruled’ over 5 years… - 83% of infants died - if you’re a male taking over a group your opportunity to reproduce might be very small before your ousted by another male - so they can’t wait for the females to be fertile again after they have let the infants grow up
describe intersexual conflict in wattled jacanas
Polyandrous female has 2+ males- Female removal expts: new female kills original broods and starts afresh with the original males - the males would try to defend the nest but because the female is bigger they were always successful
when does infanticide usually occur?
when the window of reproduction is short
why does conflict among co-breeding members of cooperative groups occur?
Competition to maximise reproduction often results in conflict among co-breeding members of cooperative groups, despite that fact that group members are close relatives
describe conflict over reproduction in acorn woodpeckers
acorn woodpeckers Females are joint-nesters
usually close related but nevertheless 38% of eggs laid in joint nests are destroyed by other females of the same group
- Each female in a co- nest wants to maximise their own reproduction - females were destroying the eggs of other females before they start incubating
- They couldn’t recognise eggs but they just got rid of any that appeared in the nest before they started laying their own clutch
- As laying period progresses it becomes more likely that they are both laying so they can no longer be confident that the eggs they get rid of are the other females
- 10% of eggs laid by joint-nesting females are runt eggs that are laid early when the risk of egg destruction is high
- Acorn woodpeckers lay a high proportion of runt eggs - too small to survive
Helpers may also seek reproductive opportunities within cooperative groups resulting in conflict with breeders, give an example of this
Subordinate reproduction by meerkats - Similarly, the negative effect of subordinate reproduction on the fitness of dominants’ pups results in reproductive suppression by dominants of subordinate reproduction- Pregnant dominants evict subordinates especially if less related
what is haplodiploidy?
In some social insects, workers retain functional ovaries and can produce sons (i.e. from unfertilized eggs)
Haplodiploid sex determination results in unusual patterns of relatedness within colonies of Hymenoptera
what is worker policing?
when workers should prevent other workers reproducing
if the queen mates several times because the workers are more related to their brothers (0.25) than nephews (0.125)
if the queen mates only once why would workers want to lay eggs to produce sons?
because workers will be more related to their sons(0.5) than their brothers (0.25)
what does worker reproduction depend on?
mating frequency (r)- When relatedness is high you get a lot of worker reproduction - opposite when relatedness is low -Workers always try to reproduce but it depends on relatedness for how much other workers will police it
what does policing serve to enforce?
altruism
describe worker policing in honey bees?
workers eat introduced eggs from other workers more than they eat introduced eggs from queens, so they can discriminate between eggs laid by workers and those laid by queens
describe queen killing in Dolichovespula wasps
When colony switches from producing workers to producing sexuals (inc. males), workers should kill queen in monogamous colonies
what is harassment in white-fronted bee-eaters?
Breeders harass close kin to induce breeding failure and hence to recruit helpers. Breeders gain more inclusive fitness if their kin help rather than breeding independently. For the recruited helpers, the pay-offs are similar if breeders are closely related to them
