Fascinating World of Sexual Reproduction in Nature

1. Sexual Reproduction

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3. Sexual & asexual reproduction • Asexual • offspring all have same genes (clones) • no variation • Sexual • gametes (sperm & egg)  fertilization • mixing of genes  variation

4. Parthenogenesis • Development of an unfertilized egg • honey bees • drones = males produced through parthenogenesis  haploid • workers & queens = females produced from fertilized eggs  diploid queen worker drone

5. Different strokes… gay penguins parthenogenesis in aphids “lesbian” lizards sex-change in fish

6. Hermaphrodites • Having functional reproductive system of both sexes earthworms mating flat worm

7. Fertilization • Joining of egg & sperm • external • usually aquatic animals • Development is metamorphosis • internal • usually land animals

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9. Development • External • development in eggs • fish & amphibians in water • soft eggs= exchange across membrane • birds & reptiles on land • hard-shell amniotic eggs • structures for exchange of food, O2 & waste • sharks & some snakes • live births from eggs • Internal • placenta • exchange food & waste • live birth

10. Adaptive advantages? • What is the adaptive value of each type of sexual reproduction • number of eggs? • level of parental of care • habitat?

11. External Fertilization Sperm released into watery environment Eggs released into watery environment. Fertilization occurs in environment. # of sperm released? # of eggs released? Why? Internal Fertilization Sperm released inside female body (vagina). Eggs released into oviduct. Fertilization occurs in oviduct (aka?). # of sperm released? # of eggs released? Why? TONS! TONS! TONS! One (or few)

12. Other really weird organisms! marsupials monotremes

13. Human Reproduction

14. Reproductive hormones LH &FSH • Testosterone • from testes • functions • sperm production • 2° sexual characteristics • Estrogen • from ovaries • functions • egg production • prepare uterus for fertilized egg • 2° sexual characteristics testesorovaries

15. Sex hormone control in males Hypothalamus GnRH Pituitary FSH & LH Testes testosterone Body cells

16. Male reproductive system • Sperm production • over 100 million produced per day! • ~2.5 million released per drop!

17. Male reproductive system • Testicles • produces sperm & hormones • Scrotum • sac that holds testicles outside of body to regulate temperature • Epididymis • where sperm mature • Vas deferens • tubes for sperm to travel from testes to penis • Prostate, seminal vesicles, Cowper’s (bulbourethal) glands • nutrient rich fluid to feed & protect sperm • buffer to counteract acids in vagina

18. Spermatogenesis Testis Epididymis Germ cell (diploid) Coiled seminiferous tubules 1° spermatocyte (diploid) MEIOSIS I 2° spermatocytes (haploid) MEIOSIS II Vas deferens Spermatids (haploid) Spermatozoa Cross-section of seminiferous tubule

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20. Boy Parts & Jobs Testes: Produce Sperm Scrotum: Outer pocket of skin to keep testes cooler for ideal conditions for sperm development. Epididymis: A collection area for mature sperm. Vas Deferens: Carries sperm to the urethra and stores mature sperm Seminal Vesicles: secrete sugars and nutrients Bulbourethral glands: inject mucus Semen: a mix of sperm and nutrient containing fluid.

21. Sperm anatomy tail

22. Female reproductive system

23. Female reproductive system • Ovaries • produces eggs & hormones • Uterus • nurtures fetus; lining builds up each month • Fallopian tubes/oviduct • tubes for eggs to travel from ovaries to uterus • fertilization • Cervix • opening to uterus, dilates 10cm (4 inches) for birthing baby • Vagina • birth canal for birthing baby

24. Female reproductive system

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26. Girlie Parts & Jobs Ovaries: Produce & release mature eggs. Oviduct: carries egg to uterus, fertilization occurs here. Uterus: Site of embryo development. Vagina: Birth canal and site of sperm deposit.

27. LH Menstrual cycle FSH Hypothalamus egg development ovulation = egg release GnRH corpus luteum Pituitary FSH & LH estrogen progesterone Ovaries lining of uterus estrogen Body cells days 0 7 14 21 28

28. Meiosis 1 completed during egg maturation Meiosis 2 completed triggered by fertilization Egg production • Oogenesis • eggs in ovaries halted before Anaphase 1 • Meiosis 1 completed during maturation • Meiosis 2 completed after fertilization • 1 egg + 2 polar bodies unequal division ovulation What is the advantage of this development system?

29. Egg maturation in ovary • Corpus luteum • produces progesterone to maintain uterine lining

30. Menstrual Cycle revisited FSH: Stimulates the follicle to produce an ovum-(pituitary) LH: Causes ovulation (release of ovum)-(pituitary) Estrogen: Prepares the uterine lining-(ovary) Progesterone: Maintains the uterine lining for implantation-(ovary)

31. Negative Feedback

32. Female hormones • FSH & LH • release from pituitary • stimulates egg development & hormone release • peak release = release of egg (ovulation) • Estrogen • released from ovary cells around developing egg • stimulates growth of lining of uterus • lowered levels = menstruation • Progesterone • released from “corpus luteum” in ovaries • cells that used to take care of developing egg • stimulates blood supply to lining of uterus • lowered levels = menstruation

33. Finally, I made it! You got any questions?