Day 19 October 31st Chapter 9

8/3/2019 Day 19 October 31st Chapter 9

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Day 19 October 31st

Chapter 9

Happy Halloween!!!


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Darwin

Natural selection generally works toproduce selfish behavior.

Altruistic-appearing behavior is common.

Fatal to his theory?


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Apparent Acts of Altruism

Kindness toward close relatives: kinselection increased fitness of yourrelatives

Kindness toward unrelated individuals:reciprocal altruismhelp me, and Ill helpyou back


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Hamiltons Rule

Altruistic-appearing behavior will occurwhen the benefits to close relatives aregreater than the cost to the individual

performing the behavior.

They are really acting in their owngenes best interests.


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According to Hamiltons rule, if an

individual could only help oneperson, who would they prefer tohelp?

1. Son with a flat tire

2. Aunt with a flat tire

3. Cousin with a flat tire4. Stranger with a flat tire


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According to Hamiltons rule, if an

individual could only help oneperson, who would they prefer tohelp?

1. Son with a flat tire

2. Aunt with a flat tire

3. Cousin with a flat tire4. Stranger with a flat tire


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Who are people most likelyto bequeath money to upontheir death?


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Redefining an Individuals Fitness

Direct fitness

An individuals total reproductive output

Indirect fitness The reproductive output brought about byaltruistic behaviors toward close kin

Inclusive fitness

The sum of an individuals indirect and directfitness


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Conflicts

Because different individuals do not shareall of the same alleles, we should alwaysexpect some conflict.

Example: gestational diabetes mother isproducing a THOUSAND times the normalamount of insulin


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9.7 Apparent altruism towardunrelated individuals can evolvethrough reciprocal altruism.


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Vampire Bats

In many cases, individuals give blood tounrelated individuals.

How might this behavior have arisen?

First, -recognize more than a hundred distinctindividuals. Second, -receive blood donations

from non-relatives reciprocate significantly morethan average. And third, -not familiar with eachother (and do not have a history of helping eachother) generally do not regurgitate for each other.


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Are they repaid the favor?

Reciprocal Altruism

Storing goodwill

Im doing this for you so thatyou will do it for me in the

future


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Were all born with a spare kidney,yet virtually no one donates theirs

to non-relatives in need.

Why?


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Certain Conditions Must Be Met

1) Repeated interactions among individuals

2) The benefits to the recipient must besignificantly greater than the costs to thedonor.

3) The ability to recognize and punishcheaters


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Why are humans amongthe only species to havefriendships?


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Why is it easier toremember gossip than

physics equations?- it helps us survive if we

recognize cheaters


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9.8 In an alien environment,behaviors produced by naturalselection may no longer beadaptive.


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Behaviors favored by natural selectionover evolutionary time can causeindividuals to behave in a way thatreduces their fitness.

Beldings ground squirrels

Craving high-fat foods

Donations to refugees


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Feels good to help


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9.9 Selfish genes win outover group selection.

Does evolution ever lead to behaviors thatare for the good of the species or population,

while being detrimental to the individual?


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If we donate money to save thechildren or another international

charity, is this a purely altruisticbehavior?

1. Strongly agree2. Agree

3. Neutral

4. Disagree

5. Strongly disagree


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9.10 There are big differences

in how much males andfemales invest in reproduction.


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Russian woman

had 69 children (in

27 pregnancies).

888 offspringproduced by a

male (the Emperor

of Morocco from

1672 to 1727)


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Definition of Male and FemaleAfemale produces the larger gamete.

Amale produces the smaller gamete.

The mothers material contribution to theoffspring exceeds the fathers.


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Evolution of Differences inMale/Female Behaviors

1) Extent of energetic differences in thereproductive investment.


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Why do malesusually competefor females ratherthan the opposite?


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About how much greateris the male reproductive

output with three mateswhen compared to thefemale?

1. 2 times greater2. 4 times greater

3. 6 times greater

4. 8 times greater

5. 10 times greater


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About how much greateris the male reproductive

output with three mateswhen compared to thefemale?

1. 2 times greater2. 4 times greater

3. 6 times greater

4. 8 times greater

5. 10 times greater


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Differences in ReproductiveInvestments

Fertilization within the female

Lactation in female mammals


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Offsets and Reversalsin Reproductive Investment

Examples:

Birds

Gestation external No lactation


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Examples:

Fish and amphibians

External fertilization

Offsets and Reversalsin Reproductive Investment


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Evolution of Differences inMale/Female Behaviors

1) Extent of energetic differences in thereproductive investment

2) Paternity uncertainty also has profound influence on reproductive behavior

Day 19 October 31st Chapter 9

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