Lecture 3: Stable biparental care

Question 1

biparental distribution among taxa

Answer 1

unevenly

• birds common, rare in mammals
• some beetles & fish

Question 2

parental care is __

e.g. matrophagy

Answer 2

costly

matrophagy spider where young eats mothers

Question 3

why is parental care costly and what could it then lead to

Answer 3

costs are borne individually and the benefits of biparental care are shared —> may lead to “tragedy of the commons” (Hardin 1968)

Question 4

study biparental care using

Answer 4

game theory

Question 5

Houston & Davies 1985

Answer 5

‘sealed bid’ model –> parents efforts evolves through time
(effort can only change through generations)

• each parent has an optimal response to partners effort
• -> more parent 1 invests, less parent 2 must
• > until ESS is reached (evolutionarily stable strategy)

Question 6

sealed bid model:

outcome when females best response if always greater than the male

Answer 6

= pure female only care

Question 7

sealed bid model:

outcome when males best response if always greater than the females

Answer 7

= pure male only care

Question 8

sealed bid model:

male line is steeper than the females

Answer 8

either male only care or female only care as optimum is unstable e.g. penduline tit

Question 9

sealed bid model: female line is steeper than the males

Answer 9

over evolutionary time come to optimum responses in care

Question 10

penduline tit: sexual conflict over care

Answer 10

• males build a nest and advertise it to female
• near clutch completion 1/both parents desert nest
• • 50-70% female only care
• • 5-20% male only care
• • 30-40% both parents desert

Question 11

house sparrows and fixed effort

Answer 11

males parental effort is repeatable within and between years
hard working m always hard working, low working m always low
-females moderately repeatable

Question 12

long tailed tits and individuals parental effort

Answer 12

parental effort is heritable, so to some extent is genetically determined

Question 13

commonly is parental effort fixed?

Answer 13

no, varies due to number of factors

• -nestling age
• brood size
• food supply
• numbers of carers

Question 14

McNamara et al (1999, 2003)

Answer 14

‘negotiation’ model – parents to respond to each other in real time

Question 15

which model (negotiation or sealed bid) is more likely

Answer 15

negotiation

Question 16

both the sealed bid and negotiation models predict:

Answer 16

Stable biparental care evolves only when one parent compensates INCOMPLETELY for reduced effort by partner

Question 17

types of experiments to test for biparental care compensation

Answer 17

• removal experiments (remove one parent, does other compensate incompletely)
• handicapping experiments (reduce effort of one parent)

Question 18

e.g. of removal experiment

Markman et al 1996

Answer 18

orange-tufted sunbirds

• • ‘widowed’ female increases effort
• compensation incomplete so supports negotiation model
• ->chicks when M removed = less body mass

Question 19

meta-analysis from removal experiments Harrison et al 2009

Answer 19

• left F/M increased effort

- total effort falls below so incomplete total effort

Question 20

issues with removal experiments

Answer 20

• no negotiation can be made if M/F is removed

Question 21

handicapping experiments methods

Answer 21

• add fishing weights to tail of birds

- tie some feathers together restricting of efficiency of flying

Question 22

meta-analysis of 54 handicapping experiments

Answer 22

Harrison et al 2009
- handicapped reduce their effort, partners increase their efforts but again incompletely but results of experiments are extremely variable

Question 23

handicapping experiment, variable results Starling

Answer 23

Wright & Cuthill 1990

• partner of handicapped bird increases effort BUT compensate complete

Question 24

handicapping experiment, variable results Blue tit

Answer 24

Slagsvold & Lifjeld 1990

• partner of handicapped bird did not increase effort
  NO compensation

Question 25

handicapping experiment, variable results Dark-eyed junco

Answer 25

• Ketterson et al 1992
• testosterone experiments (increase T Males just sing)
• females compensate completely for reduced male effort

Question 26

cause of inconsistent responses when looking at reproductive effort from mates

Answer 26

• METHODOLOGY
• -removal -> no negotiation
• -handicap -> partner perceived as poor quality
• -testosterone -> partner perceived as high quality
• INFORMATION
• -models assume parents have knowledge of partner effort and offspring need

Question 27

information model (johnstone & Hinde 2006)

Answer 27

a parent may use partners effort as a cue to the needs of a brood, or may integrate information from partner & brood –> variable response to manipulation

Question 28

experiment looking at information model

Answer 28

nestling playback experiments

• increase one partners effort, what does partner do
  e. g. great tits (hide 2006)
• parent MATCHES increased effort of partner

Question 29

negotiation via conditional cooperation

Answer 29

Johnstone et al 2014 
-negotiation via 'tit-for-tat' 
-great tits & long-tailed tits 
-parents should alternate their visits to the nest more than expected by chance 
-F then M etc 
==there form of negotiation

Question 30

stable biparental care evolves via a process of ____ in ___ & __ time

Answer 30

negotiation

in evolutionary and behavioural times

Question 31

models predcit __ compensation for changes in partner effort

Answer 31

incomplete