BIOL10004 Lecture 22 Reproduction 1 Geoff Shaw, Department of Zoology. Ref: KLES3: ch 18; Chap 25, esp pp 608-9, Fig 25.17 KLES4: ch 19,; Ch ap 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 unfertilized 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.

BIOL10004 Reproduction 1 Geoff Shaw

Two broad reproductive strategies:

Both strategies work. Circumstances may make one or the other more effective for a given species

Costs and benefits in reproductionBenefits• attracting mates• access to mates• physiology simple• make fewer eggs/sperm• high survival of young• high survival of young

Costs• attracting predators• male fighting• high loss of gametes• complex physiology• risk to preg. mother• huge investment by

parents

Mating displaysHaremsexternal fertilizationinternal fert’nviviparitypost natal care

BIOL10004 Reproduction 1 Geoff Shaw

BIOL10004 Reproduction 1 Geoff Shaw

BIOL10004 Reproduction 1 Geoff Shaw

BIOL10004 Reproduction 1 Geoff Shaw

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… ___________________,

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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.

BIOL10004 Reproduction 1 Geoff Shaw

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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BIOL10004 Reproduction 1 Geoff Shaw

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

BIOL10004 Reproduction 1 Geoff Shaw

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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