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Exams back W 2/18 Bonuses. Do Males and Females have different attitudes toward sex and relationships?

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Presentation on theme: "Exams back W 2/18 Bonuses. Do Males and Females have different attitudes toward sex and relationships?"— Presentation transcript:

1 Exams back W 2/18 Bonuses

2 Do Males and Females have different attitudes toward sex and relationships?

3 Screw worm flies

4 Sterile male screw worm flies led to decreased populations because of screw worm monogamy. FM sterile

5 Sterile male screw worm flies led to decreased populations because of screw worm monogamy. In most other species, because females mate with multiple males, introduction of sterile males has little effect. F F M sterile M

6 In most other species, because females mate with multiple males, introduction of sterile males has little effect. FM sterilefertile F M Hi, want to study biology together?

7 These birds are nesting together, they must be an “item”

8 10-40% of offspring in “monogamous” bird species are fathered by an extra-pair male

9 Social Monogamy = pair lives/works together, but not “faithful” Sexual Monogamy = pair raise young and only copulate with each other

10 Mating pairs share genetic information and possibly help in child-rearing

11 In mammals, child-rearing is most commonly done by the female. She provides milk.

12 Less than 0.01% of mammals are monogamous

13 Do Males and Females have different attitudes toward sex and relationships?

14 On a college campus an attractive male or female asked the opposite sex: “I have been noticing you around campus. I find you very attractive…” Male answers: …Would you go out with me tonight? = 50% yes Female answers: …Would you go out with me tonight? = 50% yes

15 On a college campus an attractive male or female asked the opposite sex: “I have been noticing you around campus. I find you very attractive…” Male answers: …Would you go out with me tonight? = 50% yes …Would you come to my apartment tonight? = 69% yes Female answers: …Would you go out with me tonight? = 50% yes …Would you come to my apartment tonight? = 6% yes

16 On a college campus an attractive male or female asked the opposite sex: “I have been noticing you around campus. I find you very attractive…” Male answers: …Would you go out with me tonight? = 50% yes …Would you come to my apartment tonight? = 69% yes …Would you go to bed with me tonight? = 75% yes Female answers: …Would you go out with me tonight? = 50% yes …Would you come to my apartment tonight? = 6% yes …Would you go to bed with me tonight? = 0% yes

17 Why do Males and Females have different attitudes toward sex and relationships?

18 The male perspective on monogamy

19 Eggs require large resource input. A clutch of bird eggs can be ~20% of bird’s weight. Sperm are cheap.

20 The female reproductive system

21 Sperm can survive for several days in a woman’s reproductive tract.

22 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.

23 The female reproductive system

24 Female mammals provide additional resources in form of milk.

25 What are the consequences of the different male and female attitudes toward sex and relationships?

26 Zebra Finch

27 Zebra finch pairs were allowed to mate ~9 times

28 Then a new male was brought in and allowed to mate with the female once.

29 Original male (mated 9 times) fathered 46% of offspring The last male that only mated once fathered 54% of offspring Last male advantage

30 To ensure fatherhood males mate guard and produce copious quantities of sperm Last male advantage

31 Fig 48.4 Why does the 2 nd male have an advantage?

32 Fig 48.4 Why does the 2 nd male have an advantage?

33 Why might females choose to mate with multiple males?

34 Gunnison’s Prairie Dogs Sexually monogamous female squirrels have a 92% chance of successfully giving birth.

35 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

36 Mating pairs may be genetically incompatible Cystic Fibrosis: F= normal, f= cystic fibrosis Mom=Ff Dad=Ff fF F f FFFf ffFf Mom=Ff Dad=FF fF F F FFFf FF Versus

37 Can females detect compatible genes?

38 How can a female know which male has successful genes?

39 Females may choose traits, like large displays, that are disadvantageous for male survival.

40 How can females determine “good” males?

41 Color: Bright coloring can be correlated with health…

42 But a male with a mate is judged as being high quality even if he is less colorful

43 Purple Martins After successfully mating, male purple martins call and attract younger males

44 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.

45 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.

46 Females use several factors to select a mate.

47 Reproductive success = Evolutionary success

48

49 Choosing a mate and reproductive strategies are based on methods to succesfully pass on genes

50 Exams back W 2/18 Bonuses


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