Lecture 10: manipulation & spite

Question 1

manipulation and parasites

Answer 1

parasites manipulate their hosts to be altruistic

Question 2

two examples of intraspecific brood parasitism

Answer 2

• European starling

- Burying beetle

Question 3

example of intraspecific brood parasitism Masked Weaver

Answer 3

Jackson 1993

• breed in large colonies
• around a 1/3 eggs layed in a colony are parasitic
• egg divergence & recognition

Question 4

example of intraspecific brood parasitism American coot

Answer 4

Lyon 2003
41% of pairs are parasitised
43% of hosts reject at least one parasitic egg
-background colour varies so can identify and reject

Question 5

Interspecific brood parasitism: Tawny-flanked prinia and cuckoo finch

Answer 5

• Spottiswoode & Stevens (2012)
• Prinia has extreme egg polymorphism
• cuckoo finches vary, try to match hosts
• clutches egg collected from 1970’s confirmed an evolutionary arms race between the 2 spp.
• parasites have tracked host eggs

Question 6

how do cuckoos persuade host parents to care for young?

Answer 6

Kilner et al 1999

• host = reed warbler
• hunger signalled by calls & gape
• parents respond to bigger signal
• host feeds 1 cuckoo at similar rate to 4 reed warbler chicks
• cuckoo vs RW gapes = smaller than 4 RW
• but beg at higher rate than 4 RW chicks
• cuckoos don’t mimic RW hosts, they exploit hosts provisioning rules
• nests over water so nest safe

Question 7

Hors fields hawk-cuckoo

Answer 7

• nest on ground
• single cuckoo chick evict hosts chicks
• evolved yellow patch under wing which they display to parent (false gape)

Question 8

mutualisms are ___

Answer 8

unstable

Question 9

interspecific brood parasitism –> mutualism example: great spotted cuckoo vs carrion crow

Answer 9

• ## cuckoos benefit the host by emitting foul-smelling section that repels predators

Question 10

mutualism –> interspecific brood parasitism example: ants and lycaenid butterfly larvae

Answer 10

• hojo et al 2015
• ants that feed on the nectary organ are more likely to attend the larva
• larva enlists a ‘standing guard’ of aggressive ants to defend them, using a manipulative drugs that decreases dopamine in and brains

Question 11

spiteful =

Answer 11

act is costly to actor and to recipient

Question 12

rule used for spiteful

Answer 12

hamilton rule
rB>C
B is negative, C is positive so relatedness must be negative!
– not related

Question 13

how can R be negative

Answer 13

relatedness is measure relative to population

• 50% of individuals share alleles
• if an individual shares less than 50% of relatedness, then its negative

Question 14

how does a spiteful gene spread though population

Answer 14

a spiteful gene may spread through population if it harms individuals not carrying that gene, thereby benefitting other carriers of the spiteful gene

Question 15

spite example: Polyembryonic parasitoid wasp

Answer 15

• male & female egg laid into moth larva
• each egg divides asexually = 1000’s of larva
• some F eggs develop as sterile soldiers that attack other larvae
• soldier relatedness: F = 1, M = 0.25
• – is spite as behaviour is costly, attack unrelated individuals (i.e. males), close kin benefit harmful behaviour (i.e. females)