BIOL10004 Lecture 21 Reproduction 1
Geoff Shaw, Department of Zoology.
Ref:
KLES5: Chapter 20; Chapter 28 esp gonads and HPG axis
section pp 693-695, fig 28.11
KLES4: ch 19; Chap 27, esp p 647-648, Fig 27.10
Two approaches to reproduction are ________________ and _______________
Sexual reproduction needs 2 sexes to make gametes, which involves _____________ cell
division
Males make _______________ that are small and motile
Females make ______________ that are ___________ and ____________
Offspring are a _________________ of the genes of the parents
Reproduction involves mechanisms to get egg and sperm together to ensure ___________
and _________________..
________________ is a specialised form of cell
division where haploid _________________ fuse to
form a new _______________individual
Asexual reproduction relies on _______________ cell
division.
Offspring are genetically _______________ to parents
Examples include ____________, _____________,
____________
Two variations on the theme are H_______________ and P__________________.
Hermaphrodites are animals that can produce both eggs and sperm (not necessarily at the
same time). For example Blue wrasse can change from female to male if the dominant male
in the harem is removed.
Parthenogenesis is a process whereby _______________ eggs can develop into a new
individual. For example aphids use parthenogenetic reproduction to increase in numbers
rapidly in summer, but sexual reproduction in autumn to produce more robust offspring to
survive winter.
Two broad reproductive strategies:
Both strategies work. Circumstances
may make one or the other more
effective for a given species
Costs and benefits in reproduction
Benefits
Mating displays
• attracting mates
Harems
• access to mates
external fertilization • physiology simple
internal fert’n
• make fewer eggs/sperm
viviparity
• high survival of young
post natal care
• high survival of young
Costs
• attracting predators
• male fighting
• high loss of gametes
• complex physiology
• risk to preg. mother
• huge investment by
parents
External vs Internal Fertilization
•
______________ fertilization.
–
•
eg toad – no specialised external genitals needed, but males have
_______________ on forelimbs to help grasp the female in _____________
(see fig 18.25)
_______________ Fertilization
–
requires specialization of the external genitalia to allow sperm transfer, eg
________________.
–
prerequisite to __________________ (ie internal gestation and birth of live
young)
Other Reproductive Organs include…
___________________,
_____________________,
_____________________
Other resources; http://en.wikipedia.org/wiki/Reproductive_system
http://en.wikipedia.org/wiki/Male_reproductive_system,
http://en.wikipedia.org/wiki/Female_reproductive_system,
http://en.wikipedia.org/wiki/Hermaphrodite,
http://en.wikipedia.org/wiki/Parthenogenesis,
http://en.wikipedia.org/wiki/Asexual_reproduction,
http://en.wikipedia.org/wiki/Sexual_reproduction.
Revision Questions
1. List the main differences between sexual and asexual reproduction
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2. List 3 different forms of asexual reproduction, and give an example of a species that
does each one.
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3. Using a simple diagram outline the alternation of haploid and diploid generations that
characterizes meiosis
4. Define a hermaphrodite _________________________________________________
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5. Why do blue wrasse change sex? __________________________________________
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6. Define parthenogenesis _________________________________________________
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7. Write a short paragraph explaining why some animals have lots of young and others
have few.
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8. What are the basic components of a reproductive system?
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9. Draw and label a male reproductive system
10. Draw and label a female reproductive system
11. Compare and contrast internal and external fertilization
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12. List 3 reproductive organs that are not part of the unrogenital tract, and list their main
reproductive functions.
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