ANIMAL REPRODUCTION. Possibilities: Asexual or Sexual. Fact: Most animals reproduce sexually. BUT a strange way to propagate!!!

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2 ANIMAL REPRODUCTION Possibilities: Asexual or Sexual Fact: Most animals reproduce sexually. BUT a strange way to propagate!!!

3 Necessities for Sexual Reproduction: * 2 versions of individual male version & female version * Each version must produce a gamete egg or sperm cell *The male version gives his gamete to the female version * The female version grows a new individual * Female version releases a tiny version of a new individual

4 ZYGOTE = 1 cell

5 Sexual Reproduction involves THE ACT

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9 Galapagos Tortoises

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17 External Fertilization

18 SPAWNING Clam Fish Sponge

19 Besides being a strange way to propagate, there are Costs of Sexual Reproduction i) Much reproductive anatomy has to be produced and maintained. EXAMPLES: uterus, vagina, epididymis, prostate, ovaries, testis, oviduct, vas deferens etc.

20 Cricket Reproductive Anatomy

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22 Primate Penises (more than just urine ejectors)

23 More Costs. ii) sexual behavior burns time & energy. iii) sexual behavior (colors) often conspicuous (predators) iv) pregnant females more vulnerable. v) sexually transmitted diseases. For all this negativity there must be advantages

24 EXAMPLE: Female deep sea fish!!!! Male attachment point

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26 What is the overwhelming advantage of sexual reproduction?? a mechanism to produce. new genetic combinations ***sperm s paternal genes join egg s maternal genes*** New gene combinations -- useful in changing environments.

27 Evolution by Natural Selection Know This!! New genetic combinations are created via sexual reproduction!!

28 Darwin s natural selection shapes animal evolution by eliminating poorly adapted individuals. But Darwin noted some male traits that seemed to be non-adaptive. Some males - are brightly colored (many birds) - have excessive ornamentation (peacock, dung beetles) - develop huge weapons (horns & antlers) - fight ferociously among themselves

29 And this leads me to say a few words on what I call Sexual Selection. This depends, not on a struggle for existence, but on a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor, but few or no offspring. Charles Darwin (1859) On the Origin of Species, Chp 4, p. 88

30 This makes sense only in terms of Sexual Selection

31 WHY?? Long-tailed widow bird. MALE!!

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33 Also sexual selection results in sexual DIMORPHISM --- i.e., differences in size, appearance, & behavior female and male elephant seals

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35 SEXUAL SELECTION 2 types: 1) Intersexual Selection - males advertise their worthiness in the presence of potential mates. Many female animals choose their reproductive partners. Males with particular appearances or courtship behaviors gain advantage over other males.

36 Borrowing language from Economics Males market themselves physically or behaviorally Female are the consumers must be sold on the product Free-market system best product gets consumed Do females consciously evalute & decide?? All that matters is that she consents to the displayer

37 10-05 Vogelkop Bowerbird A rranges Bower.mpg BOWER Adornments

38 10-01 Bowerbird Building.mpg

39 Some males do very well others don t McMansion Bowers?? Trailer Park Bowers?? 30 Males were observed for mate attractiveness Total Losers

40 Male Hangingflies offer NUPTIAL GIFTS to mating partners

41 GIFT SIZE Generous males copulate longer transfer more sperm Fee-based Sex?

42 The Ultimate Nuptial Gift male Copulation The Somersault Sexual Suicide in the Redback Spider Being Consumed COST-BENEFIT?

43 Cost Benefit for the male redback spider Cost: His life (big loss) Benefit: 1) he got to mate 2) he supplied a good meal to the mother of his many offspring

44 Masai father will receive cattle from groom s family before marriage takes place Father Daughter

45 2) Intrasexual Selection (= male rivalry ) involves direct competition to gain control over females. EXAMPLES: kangaroos, bighorn sheep, elephant seals

46 Elephant seals large males do better

47 2 BIG behavioral questions: Why do males do what they do?? (display, fight, get big & dangerous, driven to copulate ) Why do females do what they do?? (be conservative, be choosy) (take 2 minutes to write an answer) A simple explanation: ANISOGAMY (gametes of unequal size)

48 ANISOGAMY EGG SPERM

49 Anisogamy Tiny Sperm Massive Egg accounts for Gamete asymmetry Behavioral asymmetry

50 DNA with a tail D N A

51 Female strategy: invest in small numbers of huge energy-rich eggs. Male strategy: vast numbers of sperm cells that contain only DNA. Human males produce 1500 new sperm per heartbeat!!

52 Women At birth: 200,000 2,000,000 oogonia & primary oocytes per ovary At puberty: 40,000 Only 400 will mature & ovulate during a reproductive lifetime Men 50,000, ,000,000 sperm per ml of semen ml semen per ejaculation 125,000, ,000,000 sperm per ejaculation Every Day!!

53 Supply and Demand Reasoning?? Females eggs are the prize commodity no need to compete for males. Males compete for access to the limited number of available eggs.

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55 6 satellite males hoping to copulate following 1 dominant male and the female he controls

56 10-12 Mate Guarding by Bighorn Ram 2.mpg Access directly from disc

57 M Male s Brain is Sucked out F Male s Genitalia breaks off Male Wins? Male Nightmare? Mating Flies

58 Males knock themselves out to copulate Male-male competition may continue after copulation This competition may occur in the female s vagina, uterus, or oviducts

59 SPERM COMPETITION Can t occur in monogamous species Can occur if a female mates with several males First male may fertilize or Secondary males may fertilize Some females store sperm before using How is it stored? How is it retrieved for use?

60 Q: Which male does the fertilizing?

61 Mammals: After mating, a COPULATORY PLUG may form Plug vulva

62 Plug: Bricks and Mortar Construction Bricks Abnormal Sperm + Trapped Normal Sperm Mortar Prostate Gland Coagulinogen COPULATORY PLUG

63 Why so many abnormal sperm in semen?? - Maybe lousy & inefficient developmental pathway - Or abnormal sperm actually have a critical function Abnormal Normal

64 Sperm may be polymorphic and adapted to various roles blockers getters

65 A male black-winged damselfly removes another male s sperm before depositing his own. M F

66 SPERM COMPETITION Black-winged damselfly Sperm-removal Spines on Penis

67 Cloaca-pecking in the European dunnock

68 COURTSHIP Member of 1 sex will often display behaviors to entice the other sex to engage in reproductive behaviors.

69 What does courtship actually do? 1) Most basic: ID of proper species & sex 2) Synchronization of motivation to reproduce. 3) Overcoming of aggression -- males are often aggressive during breeding season. 4) Mating orientation - promoting the correct anatomical alignment.

70 5) Allows the female to "look the male over" & determine the "worth" of this potential mate.

71 MATING SYSTEMS the way in which male & female sexual behaviors interact Named according to the number of bonds formed. mono = one poly = many gyn = female and = male

72 MONOGAMY prolonged association of 1 male & 1 female POLYGYNY - 1 male & more than 1 female POLYANDRY 1 female & more than 1 male POLYGYNANDRY (= PROMISCUITY) Which are common which are rare??

73 MONOGAMY Relatively rare in the Animal Kingdom Church leaders & politicians cannot look to the nonhuman world for support for human monogamy

74 Birds: Strong candidates for monogamy? WHY??

75 Reason 1: Father can do everything for the young that mother can do. Everyone benefits when the male helps with food gathering, nest defense, etc.

76 If male starlings help incubate eggs temperature is better controlled

77 In extreme circumstances, male has to be helpful. Otherwise, his offspring perish.

78 Reason 2: Long-term monogamy eliminates the need to acquire a new mate each breeding season (e.g., bald eagle) 12 study of kittiwake gulls Females who retained their mate from the previous year. * bred earlier * laid more eggs

79 Bird Monogamy is now being questioned DNA fingerprinting is revealing much EPC Extra-Pair Copulation

80 Humans EPC Monogamy

81 MAMMALS and Monogamy? Female mammals have mammary glands nurse young. Males may have little or no role in early nutrition. Meanwhile, males continue to produce hundreds of millions of sperm per day what should a potent male do??

82 Polygyny Red Deer: Male Male contests lead to winners. The prize is a harem.

83 Polygyny: Male & Female Perspectives

84 Polygyny Example: LEKS in birds Leks are aggregations of males for the sole purpose of displaying to females Male Black Grouse

85 Black Grouse: Male Mating Success Most Successful Males Over 5 Years # copulations

86 Humans are Reproductive Outliers Other primates: copulate around ovulation copulate to reproduce Humans are biologically inappropriate copulaters - copulate recreationally - during pregnancy which makes no sense - after menopause which makes no sense - only after birth control is in place makes no sense

87 Strange Human Practices The Pill Morning after pill Spermicides Condoms Abortion Vasectomy Tubal ligation Adoption Infanticide In vitro fertilization Foster mothers Caesarians Pre-school

88 Interspecific Brood Parasitism Birds lay eggs in another species nest!! Brilliant: transfers the task of parenting to the host 1% of all bird species lay their eggs in another species nest. Examples: Honeyguides, cuckoos, finches, cowbirds.

89 Cowbird (a brood parasite) Cowbird Egg

90 Cuckoo female removing host egg in preparation of laying her own egg

91 Brood Parasite (European Cuckoo) begging foster parent for food!! More Please Reed Warbler Foster parent

92 09-12 Warbler Feeding Cuckoo Chick.mpg

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96 PC How long should it last? Parent-Offspring Conflict?

97 Parent-Offspring Conflict Model

98 12-02 Siblicide by Cattle Egret.mpg need disk

99 LAB ASSIGNMENT Goal: Explore human male-female relationships in terms of Mate choice Partner expectations Commitment levels Evolutionary theory

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108 Dungfly males: It s good if you. * are the last male * can copulate for a long time

109 Dungflies SECOND Male Fertilizing Success More Sperm?

110 Sneaker Male (females don t do this sort of thing!!)

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