6 - Parental care Flashcards
What are three main components for parental investment?
- Parent investment (which sex cares for offspring)
- Sexual conflict
- Parent-offspring conflict
What are 5 parts of parental care?
- Build nest/burrow
- Produce large, yolked egg
- Care of eggs inside or outside parent
- Feed/defend young
- Care after independence
What is the trade-off in parental care for offspring?
Trade-off between caring for self versus offspring
Increasing parental care associated with reduced future fitness
What two factors determine (most strongly) which sex cares for offspring?
- Internal fertilization (female care)
- External fertilization (No parent care > male care > female care)
Describe how the mean number of offspring changes for males and females depending on male/female help. What is this an example of?
Females
- No male help (2.95)
- With male help (3.53)
Males
- 1 female (helping female) 3.53
- 2 females (no help) 7.88
- 3 females (no help) 12.80
Females do better with male help, but males do better with multiple females and helping none of them.
Example of sexual conflict where the best ESS strategy may differ for males and females.
Describe parent-offspring conflict in pigs and how the success of either side can be a good ESS
If offspring piglets do better:
- Nurse more
- Heavier
- Grow fatter
If mother does better:
- Nurses less frequently
- Interval to oestrus shorter
- Lower weight loss
What is argument for parents putting more care into young? What dictates when they should stop?
The more care you put in, the better their survival, increasing your own fitness. Eventually they get independent and bigger, and the costs increase.
- Losing energy over long reproductive cycle damages parents
- Trade off on future fitness (cost curve is only meaningful in terms of fitness, if there is no fitness cost later, there is no curve)
- Benefits decrease over time and costs rise over time (parent-offspring conflict)
What is sexual conflict?
Sexual conflict or sexual antagonism occurs when the two sexes have conflicting optimal fitness strategies concerning reproduction, particularly over the mode and frequency of mating, potentially leading to an evolutionary arms race between males and females
- Also concerning whether males/females help raise offspring
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When resources are scarce, do parents invest more or less into their offspring?
Parents hold back more on offspring investment in order to care for themselves
What do the two curves on the polygyny threshold model represent?
Where is the polygyny threshold on the model?
Top curve: monogamous
Bottom curve: bigamous
The horizontal difference between two vertical intersection points is the PT. It is the gain of environmental quality for the female when she chooses the bigynous relationship, and thus the minimum environmental quality difference necessary to make polygyny beneficial for the female
Define the following:
- Kin selection
- Interchange
- Coercion
- Direct benefits
- Indirect benefits
- Kin selection (natural selection in favor of behavior by individuals that may decrease their chance of survival but increases that of their kin (who share a proportion of their genes)
- Interchange (I’ll scratch your back, then you scratch mine)
- Coercion (forcing altruism by manipulation - eg. induced abortion)
- Direct benefits (non-genetic)
- Indirect benefits (genetic)
Why is external fertilization associated with more male parental care and no parental care?
- Not too costly for males for males to sometimes leave
- Some males can sit at past eggs, and new females will come to him
How does the benefit curve for offspring compare to the benefit curve for parents?
Benefit curve for offspring is twice as big as parents (parents only give half their genes to offspring).
Parent-offspring conflict
Period where there’s selective conflict between parent/offspring. Period where it benefits offspring, but costs more to parent than it benefits (weening period).
How does parent-offspring conflict relate to extrapair young?
Loudness of begging increases with lower relatedness among the brood
