1. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-1 Part 4: Animal form and function Chapter 18: Animal reproduction

2. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-2 Reproduction Asexual reproduction –one parent –new individuals genetically identical to parent and to each other Sexual reproduction –two parents –new individuals genetically unique (novel combination of genes from both parents)

3. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-3 Asexual reproduction New individuals produced through mitotic cell division Limited genetic diversity Occurs by: –regeneration –budding –parthenogenesis

4. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-4 Regeneration Production of new individuals –cellular replication by mitosis –differentiation of tissues Reproduction by fragmentation –example: aquatic annelids Regeneration of individuals from body parts –example: starfish

5. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-5 Budding Production of new individuals –outgrowth of body wall of parent Break off to form individual –example: Hydra Remain attached to form part of colony –example: corals

6. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-6 Parthenogenesis Production of new individuals –egg cells develop into embryos without fertilisation –offspring usually female Obligate parthenogenesis –example: Heteronotia binoei (Binoe’s gecko) Cyclical parthenogenesis –example: some species of aphids (cont.)

7. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-7 Parthenogenesis (cont.) Ants, bees and wasps (Hymenoptera) –females produced by sexual reproduction –males produced by asexual reproduction (parthenogenesis) Unfertilised eggs (n) –undergo mitosis –but do not divide into two cells –nuclei fuse to produce a diploid cell (2n) –cell develops as if fertilised

8. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-8 Sexual reproduction New individuals produced through fusion of haploid cells (gametes) from parents –egg (ovum) –sperm (spermatozoon) Increases genetic diversity

9. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-9 Gametes Two types of gametes Similar structure –isogamy Different structure –anisogamy –smaller of gamete pair = male

10. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-10 Male and female Different mating types = sex –male, female Males –produce sperm only Females –produce eggs only

11. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-11 Mating systems Organisms with separate sexes –dioecious Organisms with both sexes in one individual –monoecious or hermaphroditic

12. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-12 Hermaphroditism Hermaphrodites produce male and female gametes Problems of self-fertilisation limited by separation of male and female gametes –anatomy  male and female reproductive tracts separate –behaviour  complex courtship and mating –time  eggs become fertile after sperm are no longer functional  sex change

13. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-13 Changing sex Some species avoid self-fertilisation by sex changes –alternate between male and female at different stages of life cycle Male  female –protandry Female  male –protogyny

14. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-14 Reproductive strategies Developmental strategies vary Indirect development –offspring pass through one or more larval stages before they attain adult form Direct development –offspring hatch or are born resembling miniature adults

15. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-15 Indirect development Many eggs produced –small amount of yolk in each egg –limits time for embryonic development Free-living larval forms Metamorphosis (change in form from larva to adult) –example: butterflies, flies, beetles –example: frogs

16. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-16 Fig. 18.8: Indirect development (a) (b) Copyright © 18.8a D Parer & E Parer-Cook/AUSCAPECopyright © 18.8b Kathie Atkinson

17. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-17 Direct development Few eggs produced –large amount of yolk in each egg –embryo nourished by yolk Embryo develops in egg Hatches/born with adult form –example: land snails, reptiles, birds –example: mammals

18. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-18 Fig. 18.9: Direct development Copyright © 18.9 Jan Aldenhoven/AUSCAPE

19. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-19 Development in mammals Direct development –but eggs have small amount of yolk Young develop in uterus Nutrients provided to developing young –before birth  uterine secretions  placenta –after birth  milk (cont.)

20. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-20 Development in mammals (cont.) Variation in patterns of reproduction –young born at different stages of development Monotremes –lay eggs (oviparous) Marsupials and eutherians –live young (viviparous)

21. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-21 Costs of sexual reproduction Parental investment in reproduction –varies depending on reproductive strategy Includes –production of gametes –increased risk of predation –competition for mates –parental care Cost must not outweigh benefit Caring for young –increases chances of offspring surviving to maturity –reduces ability of one (or both) parents to find food and avoid predators

22. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-22 Gametogenesis Primary sex organs = gonads Male gonad = testis –produces sperm (spermatozoa) Female gonad = ovary –produces eggs (ova) Process of gamete production = gametogenesis –spermatogenesis –oogenesis

23. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-23 Mitotic divisions Primordial germ cells undergo a series of mitotic divisions Give rise to multiple diploid (2n) oogonia/ spermatogonia After the final mitotic division, these cells are termed oocytes/spermatocytes

24. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-24 Meiotic divisions Primary oocyte (product of mitotic divisions) First meiotic division –primary oocyte gives rise to  secondary oocyte  first polar body Second meiotic division –secondary oocyte  ovum (egg)  second polar body –first polar body  polar bodies (cont.)

25. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-25 Meiotic divisions (cont.) Primary spermatocyte (product of mitotic divisions) First meiotic division –primary spermatocyte gives rise to  secondary spermatocytes Second meiotic division –secondary spermatocytes  spermatids

26. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-26 Fig. 18.19a: Oogenesis

27. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-27 Fig. 18.19b: Spermatogenesis

28. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-28 Maturation of gametes Spermatocyte –loss of most of cytoplasm –development of long flagellum (tail) –formation of secretory acrosome at anterior of head section Oocyte –increase in organelles –increase in nutritive materials –development of protective extracellular membranes e.g. vitelline membrane

29. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-29 Fertilisation Fusion of egg and sperm Egg activation –inactive egg is activated by fusion of plasma membranes of egg and sperm –resumes synthetic activity Nuclear fusion –pronuclei of egg and sperm fuse –creates diploid zygote

30. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-30 Methods of fertilisation Methods of bringing egg and sperm together External fertilisation –takes place outside body –examples: corals, frogs Internal fertilisation –takes place inside body –examples: land snails, mammals

31. Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint 18-31 Internal fertilisation Sperm must be transferred to female reproductive tract Intromittent organ –penis, claspers Spermatophore –packet of sperm Injected through body wall –example: leeches