BIO220H1 Lecture 5: Lec.5

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23 Jan 2019
School
Department
Course
Professor
Conflict
Parent‐offspring (PO) conflict
Parent‐parent (PP) conflict
Theory (pretty straightforward)
Data (less straightforward)
An example: parent‐offspring conflict over money $$
You want to take more than they want to give
BENEFITS of you having more:
You are richer
COSTS of youhaving more:
Your sibs are poorer
If you and your parents weigh these costs and benefits differently, then there will be a
CONFLICT
(How related is one parent to one of the offspring?)
Parent‐Offspring Conflict
Offspring begs for food
Parent provides the food
QUESTION 1:
How much should OFFSPRING try to acquire?
QUESTION 2:
How much should the PARENT provide?
The Trade-off
+
Current offspring fitness
B(p) = fitness of current offspring
(Can’t be used for future offspring)
-
Number of future offspring
C(p) = # of future offspring “given up”
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Provisioning, p
Natural selection maximize benefit-Cost
Offspring (benefits costs)
Benefits
B(p) = fitness of self
Costs
C(p) = # of future siblings “given up”
(likely related to the current offspring)
Siblings are genetically related (R=½)
A gene that causes an offspring to take more resources now will reduce its own
replication through future siblings
Offspring should maximize B(p) ½ C(p)
Parent (benefits costs)
All offspring are genetically related
to the parent by R=½
Parents should maximize ½ B(p) – ½ C(p)
(50% receiving the gene)
Optimal provisioning rate is in CONFLICT
(between parents and offspring)
In general, we expect an evolutionary conflict between parents and offspring over the
level of care
This conflict can be resolved in many ways
Parent wins
Offspring wins
A compromise
Optimal provisioning in stitchbirds
Stitchbird parents have to pay some attention to the begging
of their offspring, but balance this with the potential for future reproduction
(cost of making future offspring)
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