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Homework 2 due today Bonus 1 due W 2/28
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Evolution: A species’ genetic component changes as the individuals reproduce. These changes are based on how the DNA changes and who reproduces.
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How does monogamy work? from “The Myth of Monogamy” by Barash and Lipton
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Mating pairs share genetic information and possibly help in child-rearing
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10-40% of offspring in a socially monogamous bird species are fathered by an extra-pair male
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Social Monogamy = pair lives/works together, but not “faithful”
Sexual Monogamy = pair raise young and only copulate with each other
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Do males and females have different attitudes towards reproduction
Do males and females have different attitudes towards reproduction? (results from class survey)
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Would you have dinner with a boy/girl you met today. Male “yes” 76%
Would you have dinner with a boy/girl you met today? Male “yes” 76% Female “yes” 57%
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Would you have dinner with a boy/girl you met today. Male “yes” 76%
Would you have dinner with a boy/girl you met today? Male “yes” 76% Female “yes” 57% 2. Would you go to a boy’s/girl’s house who you met today? Male “yes” 76% Female “yes” 15%
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Would you have dinner with a boy/girl you met today. Male “yes” 76%
Would you have dinner with a boy/girl you met today? Male “yes” 76% Female “yes” 57% Would you go to a boy’s/girl’s house who you met today? Male “yes” 76% Female “yes” 15% Would you sleep with a boy/girl who you met today? Male “yes” 28% Female “yes” 0%
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Eggs require large resource input.
A clutch of bird eggs can be ~20% of bird’s weight. Sperm are cheap.
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Human Females: ~1 egg/month Human Males: 250,000,000 sperm/ ejaculation
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What are the consequences of the different male and female attitudes toward sex and relationships?
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The female reproductive system
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Sperm competition: = sperm competition.
Sperm can survive for several days in a woman’s reproductive tract. In Great Britain in a survey of 4,000 women… 0.5% had sex with 2 different men within 30 minutes… 30% within 24 hours = sperm competition.
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The female reproductive system
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Zebra Finch
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Zebra finch pairs were allowed to mate ~9 times
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Then a new male was brought in and allowed to mate with the female once.
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Last male advantage Original male (mated 9 times) fathered 46% of offspring The last male that only mated once fathered 54% of offspring
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Last male advantage To ensure fatherhood males mate guard and produce copious quantities of sperm
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After successfully mating, male purple martins call and attract younger males
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The older males then cuckold the younger male’s females
Younger males with nests near older males only father 29% of eggs in their nests.
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Older males produce 4. 1 offspring with their mate and 3
Older males produce 4.1 offspring with their mate and 3.6 by younger neighbor’s mate. Younger males with nests near older males only father 29% of eggs in their nests.
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What advantage is their for females to accept or solicit EPCs?
Older males produce 4.1 offspring with their mate and 3.6 by younger neighbor’s mate. What advantage is their for females to accept or solicit EPCs?
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Gunnison’s Prairie Dogs
Sexually monogamous female squirrels have a 92% chance of successfully giving birth.
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Gunnison’s Prairie Dogs
Sexually monogamous female squirrels have a 92% chance of successfully giving birth. Non-monogamous females have a 100% chance of giving birth
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Mating pairs may be genetically incompatible
Cystic Fibrosis: F= normal, f= cystic fibrosis Mom=Ff F f F FF Ff Versus Dad=Ff Mom=Ff f Ff ff F f F FF Ff Dad=FF F FF Ff
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How can a female know which male has successful genes?
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Females may choose traits, like large displays, that are disadvantageous for male survival.
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How can females determine “good” males?
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Color: Bright coloring can be correlated with health…
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But a male with a mate is judged as being high quality even if he is less colorful
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better off helping with these kids or should I mate with someone else?
Am I the only one? Am I better off helping with these kids or should I mate with someone else? Is this the best I can do? Maybe I can find someone with better genes or more genetic diversity.
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