Lectures 10-18 Flashcards
What did Herbert Spencer believe about evolution?
Rival to Darwin
Organism changes as it interacts with its environment but once the organism reaches an equilibrium, change is no longer necessary
What did Herbert Spencer believe about mother nature?
the act of reproduction limited the development of the female sex
Is it true that females are static?
No, females are active participants and undergo evolutionary changes as do men
What are the findings of the fruit fly experiment?
Females evolve and make choices and have strategies on reproduction and nurturing offspring
What is the female Heron, gulls, eagles strategy?
Lay 2 eggs days apart and commence incubation immediately after first egg is laid
The first chick is older than the second and the parents are able to care for both chicks since they have different ages
What is a then cause of the birds hatching their eggs days apart?
One chick may attack the other and no parent will intervene. Food aggression is the issue
Is there a benefit for mother birds laying their eggs days apart?
Found that mothers with chicks of identical age were twice as likely to lose all their chicks compared to controlled chicks
What species eats their young?
Female wolf spiders, mice
Why will females eat or abandon their young?
- Stress
- Babies aren’t healthy
- Mother is mutant: can’t smell their offspring
What is it called when mothers eat their babies?
Filial Cannibalism
Why is filial cannibalism a viable strategy?
Can coexist with parenting and can help select appropriate parenting behavior that provides the most fitness units
How does female coercion work in bees?
The queen gives off a chemical pheromone to all the female workers
What is the Bruce effect?
When females terminate their young or pregnancy when a new male takes over
What happened when a virgin female rat was injected blood from a mother rat?
When the female was presented with young pups (unrelated) she started to care for them
What do women produce during pregnancy?
Prolactin (increases 40-50%)
How do men testosterone react to women’s pregnancy?
Men have been reported to have lower testosterone (reduced aggression towards baby, more bonding)
How long is the window of infertility?
~14 months so woman can care for baby
What is parent-offspring conflict?
Natural selection favors the selfish offspring, always demanding a little more than the female wants to give
the selfish offspring will have more resources, better health
mother wants to move onto next offspring, offspring does not want her to move on and continues to be nurtured
What are the advantages and costs of parent-offspring conflict
pros:
- fetus gains from mom’s immune system
- mother gains from fetal immune cells
cons:
- some fetuses are aborted, after mom gains her immune boost (choose selfish)
-some mothers can suffer from autoimmune diseases
What is the Maternal Effect?
Mom is giving information to offspring, and this information is not orchestrated from offspring genes
- Maternal effect is not maternal inheritance
- effect can have pros and cons
What is the maternal effect in Fish?
More nutrients in eggs when food is scarce so offspring are fatter
How does the maternal effect work in canaries?
Mothers pass down testosterone in the eggs which causes variation in the group
How does mom’s rank impact female effect?
low ranking baboon mothers were less likely to survive due to harassment than sons (sons will leave)
How is the maternal effect seen in humans?
If a woman is pregnant with limited food during early part of pregnancy, the infant may be born at a (relatively) normal birth weight