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19-1Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Part 4: Animal form and function
Chapter 19: Animal reproduction
19-2Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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)
19-3Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Asexual reproduction• New individuals produced through mitotic cell
division• Limited genetic diversity• Occurs by:
– regeneration– budding– parthenogenesis
19-4Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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
19-5Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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
19-6Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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
19-7Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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
19-8Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Sexual reproduction• New individuals produced through fusion of haploid
cells (gametes) from parents– egg (ovum)– sperm (spermatozoon)
• Increases genetic diversity
19-9Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Gametes• Two types of gametes• Similar structure
– isogamy
• Different structure– anisogamy– smaller of gamete pair = male
Fig. 19.5a & d: Gametes
19-10Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
19-11Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Male and female• Different mating types = sex
– male, female
• Males– produce sperm only
• Females– produce eggs only
19-12Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Mating systems
• Organisms with separate sexes– dioecious
• Organisms with both sexes in one individual– monoecious or hermaphroditic
19-13Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Hermaphroditism• Hermaphrodites produce both 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
19-14Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Changing sex• Some species avoid self-fertilisation by sex
changes– alternate between male and female at different stages of
life cycle
• Protandry: male female– Example: clownfish
• Protogyny: female male– Example: parrot fish
19-15Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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
19-16Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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)– examples: butterflies, flies, beetles, frogs
Fig. 19.8: Indirect development
19-17Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
19-18Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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
– examples: land snails, reptiles, birds, mammals
19-19Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Fig. 19.9: Direct development
Copyright © 18.9 Jan Aldenhoven/AUSCAPE
19-20Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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
19-21Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Development in mammals (cont.)• Variation in patterns of reproduction
– young born at different stages of development
• Marsupials and eutherians– live young (viviparous)
19-22Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Development in mammals (cont.)• Monotremes
– lay eggs (oviparous)
19-23Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
The 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
Question 1:What benefits of sexual reproduction would outweigh the costs?
a) Increased ability to produce genetic diversity
b) Ability to produce variable offspring which could have a greater chance of success in a new environment
c) Reduction in deleterious mutations having an effect on offspring
d) All of the above
19-24Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
19-25Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Gametogenesis• Primary sex organs = gonads• Male gonad = testis
– produces sperm (spermatozoa)
• Female gonad = ovary– produces eggs (ova)
• Process of gamete production = gametogenesis– spermatogenesis– oogenesis
19-26Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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
19-27Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Meiotic division• Primary oocyte (product of mitotic divisions)• First meiotic division
– primary oocyte gives rise to secondary oocyte first polar body
• Second meiotic division– secondary oocyte gives rise to
ovum (egg) second polar body
– first polar body gives rise to polar bodies
19-28Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Meiotic division (cont.)• Primary spermatocyte (product of mitotic divisions)• First meiotic division
– primary spermatocyte gives rise to secondary spermatocytes
• Second meiotic division– secondary spermatocytes give rise to
spermatids
19-29Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Fig. 19.20a: Oogenesis
19-30Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Fig. 19.20b: Spermatogenesis
19-31Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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
19-32Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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
Fig. 19.25: Fertilisation
19-33Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
19-34Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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
19-35Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Internal fertilisation• Sperm must be transferred to female reproductive
tract• Intromittent organ
– penis, claspers
• Spermatophore– packet of sperm
• Injected through body wall– example: leeches
Question 2:
Which of the following is/are disadvantages of internal fertilisation?
a) gametes and embryo will be prevented from desiccation
b) independence from external water source
c) complicated behaviour must be evolved to bring the male and female into intimate contact
d) the need for an intromittent organ
19-36Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
Summary• Asexual reproduction means having a single
parent• Sexual reproduction requires two parents• Reproduction can be costly• Successful reproduction between male and female
animals requires the proper timing and control of a complex sequence of events
• Animals employ different strategies to maximise their chances of reproductive success
19-37Copyright 2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Biology: An Australian focus 4e by Knox, Ladiges, Evans and SaintSlides prepared by Karen Burke da Silva, Flinders University
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