ZOO 4070 Lecture Notes - Lecture 7: Kentish Plover, Kin Recognition, Parental Investment
2 May 2018
School
Department
Course
Professor
*mix of cooperation and conflict
Maternal vs parental care
•
Parent vs offspring
•
Kin discrimination
•
Topics:
Establishing and maintaining nests or territories
•
Production and provisioning of gametes
•
Care of fertilized eggs
•
Provisioning after hatching or birth
•
Care after nutritional independence
•
Types of Parental Care:
When two parents can raise more offspring than
one, selection should favour bi-parental care
•
Ignores the role of initial investment
•
Females initial investment commits her to
additional investment
•
Increases linearly in males
!
Increases to 1 in females, and then
changes insignificantly
!
Bateman gradient: number of offspring
produced vs. number of mates
○
Selection should act against male investment
because males can increase reproductive success
by mating with additional females
•
*see slide
○
Female has higher investment from
copulation/egg-laying all the way to
feeding young
○
Male investment slowly increases
throughout breeding stage
○
Individuals with lower parental
investment lose less if no offspring are
raised
○
Parental investment over a single season
•
Maternal and Paternal Care:
Survival rates: biparental >
male > female (M and F sim)
□
More frequent feeding
trips
!
Better defence against
predators
!
Hypotheses:
□
Habitat A:
!
Survival rates: male >
female > biparental (all sim)
□
Habitat B:
!
B had faster chick growth
rates = higher food
availability
□
Differences between habitat A & B:
!
B had higher quality parents
!
Tested value of parent care by removing
each parent (biparental vs. male only vs.
female only)
○
Males require larger time to find
new mates (compared to females)
!
Females would travel larger
distances to find a new mate
!
Females are more likely to
desert their brood (can find
new mate easily)
□
Difference in desertion between
sexes is a consequence of biased
operational sex ratio
!
Tested benefits of deserting in each sex
○
Ex. In the Kentish plover
•
Value of Parental Care:
Desert vs. Care
•
More parents = higher survival of young
(not sex specific)
○
Male can re-mate with another female if
he deserts
○
Female can lay more eggs with same male
if she deserts
○
Assume:
•
Probability of offspring surviving from
parental care: P0 < P1 <P2
○
Male deserts: p=probability of male
mating again
○
Male with new female: both provide
parental care (P2)
○
W > w
!
Female deserts: lays W total eggs; female
stays: lays w total eggs
○
Factors:
•
Game Theory Model for Desertion:
Female
Cares Deserts
Cares wP2, wP2 WP1, WP1
Deserts wP1 +
wP2p, wP1
WP0 +
wP2p, WP0
*if the female cares, then wP1 +
wP2p > wP2 for male to desert
Conditions: P2 must only be
slightly higher than P1, p should be
high
*if male cares, then WP1>wP2 for
female to desert
Conditions: P2 should only be
slightly larger than P1 and W
should be high
Female
!
Cares Deserts
Cares 6, 64, 4
Deserts 3.6, 2.4 1.2, 0
Using real numbers (see slide)
○
Large clutch sizes (up to 13 eggs)
○
Both sexes incubate
○
Eggs need to be constantly incubated
○
Desertion by handicapped sex was
uncommon (12%)
!
In cases of desertion, non-
handicapped sex also abandoned
!
Females were more likely to desert
their mate than males
!
Study examined the parental care of one
parental when the other parent was
handicapped (randomly attached a small
lead weight to the tail feather)
○
After treatment, non-handicapped
males still spent more time
incubating than non-handicapped
females --> compensation
!
Males spend more time incubating eggs
than females (before treatment)
○
Ex. Northern flicker
•
If handicapped sex deserted, the other did
as well because one sex could not reach
the threshold along
○
Desertion is related to body condition
○
If handicapped sex did not desert, then the
other sex compensated to maintain level
of parental care above the threshold
○
Evidence for a threshold:
•
Parental Effort and Offspring Success:
Offspring typical thought of as 'passive'
actors in this 'parental optimization model'
○
Parental investment: anything done by the
parent to increase the chances of an offspring
surviving while decreasing the parents ability to
invest in other offspring
•
Parents are related to their offspring the
same
○
Offspring are less related to siblings than
themselves
○
Should offspring have a different view of how
parental care should be allocated?
•
Benefit of providing care by parent
decreases with time (high parental
care would mess with future
potential reproduction)
!
Benefit/cost ratio decreases over time
○
Cost = parental investment
○
Optimal time to give up parental care: b=c
(when benefit/cost=1)
○
Conflict over continued investment:
•
Adjust amount of care over time
○
If younger groups were placed in the nest
(foster chicks) parents would have a
longer care period (vs. older group)
○
Ex. Zebra Finches
•
Mother: equally related to current
and future offspring
!
Offspring: more related to itself
than to siblings
!
There is a different cost of parental
investment from the offspring's
perspective
○
Parents: B/C = 1/1 = 1
□
*longer time than
optimal time for parents
!
Offspring: B/(C/r) = 1/(1/0.5)
= 0.5
□
Optimal time to cease receiving
care is b/(c/r)
!
Time between optimal times = time
when conflict should occur
!
PI cost from offspring's perspective is
discounted (devalued) by relatedness
○
Psychological manipulation
complete with current offspring
siblicide
!
Reading: "avian siblicide"
!
Offspring:
○
Be able to recognize "cheater"
offspring
!
Ignore signals from older offspring
!
Adjust amount and duration of care
!
Manipulate brood size
!
Infanticide
!
Parent:
○
Is there an optimal time for offspring to cease
receiving parental care?
•
Give birth to 1 pup at a time
○
Some females give birth again
before first pup is weaned (mostly
half sibs)
!
Wean at 1-3 years; begin foraging at sea
before they are weaned
○
Mother is ~75% aggressive towards
yearlings
!
Mother is ~10% aggressive towards
newborn
!
--> preference for newborn
!
After giving birth to another pup,
○
The growth rate of newborns is higher
without an older sibling (with higher
survival)
○
Ex. Galapagos Fur Seal
•
Tested whether mothers provide less
resources than what the piglets actually
want
○
Nursing per day decreased as the age of
piglets increased when the sow was not
confined (vs. confined)
○
The weight of the piglets (on day 28 and
49) was significantly larger when the sow
was confined
○
Ex. Domesticated Pigs
•
Parent-Offspring Relationships
Reptiles: egg production is 20% of annual
energy budget
○
Birds: laying 29-35% BMR, 230% daily
protein
○
Can be substantial
•
Brooding individuals (males) can use a
large amount of mass (55.6%) while
callings only lose 9.5%
○
Think of the deserting game theory
!
Males mate year round --> trade off
between parental care and mating
○
Costs of parental care in common coqui:
•
*see slide
○
Costs of parental care in bass:
•
Selection should favour parents to
discriminate between their own offspring
and others because of the high energetic
cost of parental care (kin discrimination)
○
Hypothesis:
•
Examined hypothesis that males have the
ability to provide parental care according
to the evolutionary value of young
○
Sneaker males try to fertilize eggs as
well --> kin discrimination is needed
○
Put a bunch of sneaker males in a
glass compartment near the parental
male (make him feel uncertain)
!
Control --> no sneaker males
!
Females laid eggs and males
defended eggs
!
Treatment --> less
parental care during
egg stage
!
Amount of parental care by
male differed between egg
stage but not fry stage
□
*may be able to discriminate
offspring in fry stage
□
Outcome:
!
Experiment 1:
○
Treatment: eggs of sneaker males
too
!
Amount of parental care differed
!
Experiment 2:
○
Ex. Bluegill
•
Costs of Parental Care:
Conflict between sexes and between parent-
offspring over the amount of parental care
•
How game theory can be used to predict the
evolutionary outcomes of parental decisions
•
Adaptations to avoid costs of parental care
Parental Care:
Male
Male
*this is not a prisoner's
dilemma, it is more beneficial
for both parents to provide
parental care
Parental Care
Monday,*October*23,*2017
11:34*AM
*mix of cooperation and conflict
Maternal vs parental care
•
Parent vs offspring
•
Kin discrimination
•
Topics:
Establishing and maintaining nests or territories
•
Production and provisioning of gametes
•
Care of fertilized eggs
•
Provisioning after hatching or birth
•
Care after nutritional independence
•
Types of Parental Care:
When two parents can raise more offspring than
one, selection should favour bi-parental care
•
Ignores the role of initial investment
•
Females initial investment commits her to
additional investment
•
Increases linearly in males
!
Increases to 1 in females, and then
changes insignificantly
!
Bateman gradient: number of offspring
produced vs. number of mates
○
Selection should act against male investment
because males can increase reproductive success
by mating with additional females
•
*see slide
○
Female has higher investment from
copulation/egg-laying all the way to
feeding young
○
Male investment slowly increases
throughout breeding stage
○
Individuals with lower parental
investment lose less if no offspring are
raised
○
Parental investment over a single season
•
Maternal and Paternal Care:
Survival rates: biparental >
male > female (M and F sim)
□
More frequent feeding
trips
!
Better defence against
predators
!
Hypotheses:
□
Habitat A:
!
Survival rates: male >
female > biparental (all sim)
□
Habitat B:
!
B had faster chick growth
rates = higher food
availability
□
Differences between habitat A & B:
!
B had higher quality parents
!
Tested value of parent care by removing
each parent (biparental vs. male only vs.
female only)
○
Males require larger time to find
new mates (compared to females)
!
Females would travel larger
distances to find a new mate
!
Females are more likely to
desert their brood (can find
new mate easily)
□
Difference in desertion between
sexes is a consequence of biased
operational sex ratio
!
Tested benefits of deserting in each sex
○
Ex. In the Kentish plover
•
Value of Parental Care:
Desert vs. Care
•
More parents = higher survival of young
(not sex specific)
○
Male can re-mate with another female if
he deserts
○
Female can lay more eggs with same male
if she deserts
○
Assume:
•
Probability of offspring surviving from
parental care: P0 < P1 <P2
○
Male deserts: p=probability of male
mating again
○
Male with new female: both provide
parental care (P2)
○
W > w
!
Female deserts: lays W total eggs; female
stays: lays w total eggs
○
Factors:
•
Game Theory Model for Desertion:
Female
Cares Deserts
Cares wP2, wP2 WP1, WP1
Deserts wP1 +
wP2p, wP1
WP0 +
wP2p, WP0
*if the female cares, then wP1 +
wP2p > wP2 for male to desert
Conditions: P2 must only be
slightly higher than P1, p should be
high
*if male cares, then WP1>wP2 for
female to desert
Conditions: P2 should only be
slightly larger than P1 and W
should be high
Female
!
Cares Deserts
Cares 6, 64, 4
Deserts 3.6, 2.4 1.2, 0
Using real numbers (see slide)
○
Large clutch sizes (up to 13 eggs)
○
Both sexes incubate
○
Eggs need to be constantly incubated
○
Desertion by handicapped sex was
uncommon (12%)
!
In cases of desertion, non-
handicapped sex also abandoned
!
Females were more likely to desert
their mate than males
!
Study examined the parental care of one
parental when the other parent was
handicapped (randomly attached a small
lead weight to the tail feather)
○
After treatment, non-handicapped
males still spent more time
incubating than non-handicapped
females --> compensation
!
Males spend more time incubating eggs
than females (before treatment)
○
Ex. Northern flicker
•
If handicapped sex deserted, the other did
as well because one sex could not reach
the threshold along
○
Desertion is related to body condition
○
If handicapped sex did not desert, then the
other sex compensated to maintain level
of parental care above the threshold
○
Evidence for a threshold:
•
Parental Effort and Offspring Success:
Offspring typical thought of as 'passive'
actors in this 'parental optimization model'
○
Parental investment: anything done by the
parent to increase the chances of an offspring
surviving while decreasing the parents ability to
invest in other offspring
•
Parents are related to their offspring the
same
○
Offspring are less related to siblings than
themselves
○
Should offspring have a different view of how
parental care should be allocated?
•
Benefit of providing care by parent
decreases with time (high parental
care would mess with future
potential reproduction)
!
Benefit/cost ratio decreases over time
○
Cost = parental investment
○
Optimal time to give up parental care: b=c
(when benefit/cost=1)
○
Conflict over continued investment:
•
Adjust amount of care over time
○
If younger groups were placed in the nest
(foster chicks) parents would have a
longer care period (vs. older group)
○
Ex. Zebra Finches
•
Mother: equally related to current
and future offspring
!
Offspring: more related to itself
than to siblings
!
There is a different cost of parental
investment from the offspring's
perspective
○
Parents: B/C = 1/1 = 1
□
*longer time than
optimal time for parents
!
Offspring: B/(C/r) = 1/(1/0.5)
= 0.5
□
Optimal time to cease receiving
care is b/(c/r)
!
Time between optimal times = time
when conflict should occur
!
PI cost from offspring's perspective is
discounted (devalued) by relatedness
○
Psychological manipulation
complete with current offspring
siblicide
!
Reading: "avian siblicide"
!
Offspring:
○
Be able to recognize "cheater"
offspring
!
Ignore signals from older offspring
!
Adjust amount and duration of care
!
Manipulate brood size
!
Infanticide
!
Parent:
○
Is there an optimal time for offspring to cease
receiving parental care?
•
Give birth to 1 pup at a time
○
Some females give birth again
before first pup is weaned (mostly
half sibs)
!
Wean at 1-3 years; begin foraging at sea
before they are weaned
○
Mother is ~75% aggressive towards
yearlings
!
Mother is ~10% aggressive towards
newborn
!
--> preference for newborn
!
After giving birth to another pup,
○
The growth rate of newborns is higher
without an older sibling (with higher
survival)
○
Ex. Galapagos Fur Seal
•
Tested whether mothers provide less
resources than what the piglets actually
want
○
Nursing per day decreased as the age of
piglets increased when the sow was not
confined (vs. confined)
○
The weight of the piglets (on day 28 and
49) was significantly larger when the sow
was confined
○
Ex. Domesticated Pigs
•
Parent-Offspring Relationships
Reptiles: egg production is 20% of annual
energy budget
○
Birds: laying 29-35% BMR, 230% daily
protein
○
Can be substantial
•
Brooding individuals (males) can use a
large amount of mass (55.6%) while
callings only lose 9.5%
○
Think of the deserting game theory
!
Males mate year round --> trade off
between parental care and mating
○
Costs of parental care in common coqui:
•
*see slide
○
Costs of parental care in bass:
•
Selection should favour parents to
discriminate between their own offspring
and others because of the high energetic
cost of parental care (kin discrimination)
○
Hypothesis:
•
Examined hypothesis that males have the
ability to provide parental care according
to the evolutionary value of young
○
Sneaker males try to fertilize eggs as
well --> kin discrimination is needed
○
Put a bunch of sneaker males in a
glass compartment near the parental
male (make him feel uncertain)
!
Control --> no sneaker males
!
Females laid eggs and males
defended eggs
!
Treatment --> less
parental care during
egg stage
!
Amount of parental care by
male differed between egg
stage but not fry stage
□
*may be able to discriminate
offspring in fry stage
□
Outcome:
!
Experiment 1:
○
Treatment: eggs of sneaker males
too
!
Amount of parental care differed
!
Experiment 2:
○
Ex. Bluegill
•
Costs of Parental Care:
Conflict between sexes and between parent-
offspring over the amount of parental care
•
How game theory can be used to predict the
evolutionary outcomes of parental decisions
•
Adaptations to avoid costs of parental care
Parental Care:
Male
Male
*this is not a prisoner's
dilemma, it is more beneficial
for both parents to provide
parental care
Parental Care
Monday,*October*23,*2017 11:34*AM
*mix of cooperation and conflict
Maternal vs parental care
•
Parent vs offspring
•
Kin discrimination
•
Topics:
Establishing and maintaining nests or territories
•
Production and provisioning of gametes
•
Care of fertilized eggs
•
Provisioning after hatching or birth
•
Care after nutritional independence
•
Types of Parental Care:
When two parents can raise more offspring than
one, selection should favour bi-parental care
•
Ignores the role of initial investment
•
Females initial investment commits her to
additional investment
•
Increases linearly in males
!
Increases to 1 in females, and then
changes insignificantly
!
Bateman gradient: number of offspring
produced vs. number of mates
○
Selection should act against male investment
because males can increase reproductive success
by mating with additional females
•
*see slide
○
Female has higher investment from
copulation/egg-laying all the way to
feeding young
○
Male investment slowly increases
throughout breeding stage
○
Individuals with lower parental
investment lose less if no offspring are
raised
○
Parental investment over a single season
•
Maternal and Paternal Care:
Survival rates: biparental >
male > female (M and F sim)
□
More frequent feeding
trips
!
Better defence against
predators
!
Hypotheses:
□
Habitat A:
!
Survival rates: male >
female > biparental (all sim)
□
Habitat B:
!
B had faster chick growth
rates = higher food
availability
□
Differences between habitat A & B:
!
B had higher quality parents
!
Tested value of parent care by removing
each parent (biparental vs. male only vs.
female only)
○
Males require larger time to find
new mates (compared to females)
!
Females would travel larger
distances to find a new mate
!
Females are more likely to
desert their brood (can find
new mate easily)
□
Difference in desertion between
sexes is a consequence of biased
operational sex ratio
!
Tested benefits of deserting in each sex
○
Ex. In the Kentish plover
•
Value of Parental Care:
Desert vs. Care
•
More parents = higher survival of young
(not sex specific)
○
Male can re-mate with another female if
he deserts
○
Female can lay more eggs with same male
if she deserts
○
Assume:
•
Probability of offspring surviving from
parental care: P0 < P1 <P2
○
Male deserts: p=probability of male
mating again
○
Male with new female: both provide
parental care (P2)
○
W > w
!
Female deserts: lays W total eggs; female
stays: lays w total eggs
○
Factors:
•
Game Theory Model for Desertion:
Female
Cares
Deserts
Cares
wP2, wP2
WP1, WP1
Deserts
wP1 +
wP2p, wP1
WP0 +
wP2p, WP0
*if the female cares, then wP1 +
wP2p > wP2 for male to desert
Conditions: P2 must only be
slightly higher than P1, p should be
high
*if male cares, then WP1>wP2 for
female to desert
Conditions: P2 should only be
slightly larger than P1 and W
should be high
Female
!
Cares
Deserts
Cares 6, 64, 4
Deserts 3.6, 2.4 1.2, 0
Using real numbers (see slide)
○
Large clutch sizes (up to 13 eggs)
○
Both sexes incubate
○
Eggs need to be constantly incubated
○
Desertion by handicapped sex was
uncommon (12%)
!
In cases of desertion, non-
handicapped sex also abandoned
!
Females were more likely to desert
their mate than males
!
Study examined the parental care of one
parental when the other parent was
handicapped (randomly attached a small
lead weight to the tail feather)
○
After treatment, non-handicapped
males still spent more time
incubating than non-handicapped
females --> compensation
!
Males spend more time incubating eggs
than females (before treatment)
○
Ex. Northern flicker
•
If handicapped sex deserted, the other did
as well because one sex could not reach
the threshold along
○
Desertion is related to body condition
○
If handicapped sex did not desert, then the
other sex compensated to maintain level
of parental care above the threshold
○
Evidence for a threshold:
•
Parental Effort and Offspring Success:
Offspring typical thought of as 'passive'
actors in this 'parental optimization model'
○
Parental investment: anything done by the
parent to increase the chances of an offspring
surviving while decreasing the parents ability to
invest in other offspring
•
Parents are related to their offspring the
same
○
Offspring are less related to siblings than
themselves
○
Should offspring have a different view of how
parental care should be allocated?
•
Benefit of providing care by parent
decreases with time (high parental
care would mess with future
potential reproduction)
!
Benefit/cost ratio decreases over time
○
Cost = parental investment
○
Optimal time to give up parental care: b=c
(when benefit/cost=1)
○
Conflict over continued investment:
•
Adjust amount of care over time
○
If younger groups were placed in the nest
(foster chicks) parents would have a
longer care period (vs. older group)
○
Ex. Zebra Finches
•
Mother: equally related to current
and future offspring
!
Offspring: more related to itself
than to siblings
!
There is a different cost of parental
investment from the offspring's
perspective
○
Parents: B/C = 1/1 = 1
□
*longer time than
optimal time for parents
!
Offspring: B/(C/r) = 1/(1/0.5)
= 0.5
□
Optimal time to cease receiving
care is b/(c/r)
!
Time between optimal times = time
when conflict should occur
!
PI cost from offspring's perspective is
discounted (devalued) by relatedness
○
Psychological manipulation
complete with current offspring
siblicide
!
Reading: "avian siblicide"
!
Offspring:
○
Be able to recognize "cheater"
offspring
!
Ignore signals from older offspring
!
Adjust amount and duration of care
!
Manipulate brood size
!
Infanticide
!
Parent:
○
Is there an optimal time for offspring to cease
receiving parental care?
•
Give birth to 1 pup at a time
○
Some females give birth again
before first pup is weaned (mostly
half sibs)
!
Wean at 1-3 years; begin foraging at sea
before they are weaned
○
Mother is ~75% aggressive towards
yearlings
!
Mother is ~10% aggressive towards
newborn
!
--> preference for newborn
!
After giving birth to another pup,
○
The growth rate of newborns is higher
without an older sibling (with higher
survival)
○
Ex. Galapagos Fur Seal
•
Tested whether mothers provide less
resources than what the piglets actually
want
○
Nursing per day decreased as the age of
piglets increased when the sow was not
confined (vs. confined)
○
The weight of the piglets (on day 28 and
49) was significantly larger when the sow
was confined
○
Ex. Domesticated Pigs
•
Parent-Offspring Relationships
Reptiles: egg production is 20% of annual
energy budget
○
Birds: laying 29-35% BMR, 230% daily
protein
○
Can be substantial
•
Brooding individuals (males) can use a
large amount of mass (55.6%) while
callings only lose 9.5%
○
Think of the deserting game theory
!
Males mate year round --> trade off
between parental care and mating
○
Costs of parental care in common coqui:
•
*see slide
○
Costs of parental care in bass:
•
Selection should favour parents to
discriminate between their own offspring
and others because of the high energetic
cost of parental care (kin discrimination)
○
Hypothesis:
•
Examined hypothesis that males have the
ability to provide parental care according
to the evolutionary value of young
○
Sneaker males try to fertilize eggs as
well --> kin discrimination is needed
○
Put a bunch of sneaker males in a
glass compartment near the parental
male (make him feel uncertain)
!
Control --> no sneaker males
!
Females laid eggs and males
defended eggs
!
Treatment --> less
parental care during
egg stage
!
Amount of parental care by
male differed between egg
stage but not fry stage
□
*may be able to discriminate
offspring in fry stage
□
Outcome:
!
Experiment 1:
○
Treatment: eggs of sneaker males
too
!
Amount of parental care differed
!
Experiment 2:
○
Ex. Bluegill
•
Costs of Parental Care:
Conflict between sexes and between parent-
offspring over the amount of parental care
•
How game theory can be used to predict the
evolutionary outcomes of parental decisions
•
Adaptations to avoid costs of parental care
Parental Care:
Male
Male
*this is not a prisoner's
dilemma, it is more beneficial
for both parents to provide
parental care
Parental Care
Monday,*October*23,*2017 11:34*AM
Document Summary
When two parents can raise more offspring than one, selection should favour bi-parental care. Females initial investment commits her to additional investment. Selection should act against male investment because males can increase reproductive success by mating with additional females. Bateman gradient: number of offspring produced vs. number of mates. Increases to 1 in females, and then changes insignificantly. Female has higher investment from copulation/egg-laying all the way to feeding young. Individuals with lower parental investment lose less if no offspring are raised. Tested value of parent care by removing each parent (biparental vs. male only vs. female only) Survival rates: biparental > male > female (m and f sim) Survival rates: male > female > biparental (all sim) B had faster chick growth rates = higher food availability. Males require larger time to find new mates (compared to females) Females would travel larger distances to find a new mate.
