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REPRODUCTIVE ISOLATION

REPRODUCTIVE ISOLATION. What is reproductive isolation?. Reproductive isolation prevents gene flow between species. A reproductive isolating mechanism prevents individuals of different species from reproducing successfully together.

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REPRODUCTIVE ISOLATION

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  1. REPRODUCTIVE ISOLATION

  2. What is reproductive isolation? • Reproductive isolation prevents gene flow between species. • A reproductive isolating mechanism prevents individuals of different species from reproducing successfully together.

  3. Barriers to gene flow prevent interbreeding between groups of organisms of the same species resulting in reproductive isolation.

  4. Gene flow is the transfer of alleles or genes from one population to another. • Interbreeding is to breed within a closed population. • Inbreeding is the reproduction from the mating of two genetically related parents.

  5. Why is there reproductive Isolation? • Reproductive barriers reduce or directly impede gene flow between individuals of different species, allowing the conservation of each species’ characteristics.

  6. Types of Barriers. • The barriers which can cause reproductive isolation can be • Geographical/environmental • Ecological • Behavioural • Structural (mechanical) • Give examples of each of these (without research)

  7. Text book work. • Read ch 23 pages 588 to 591. • Define each type of barrier and give examples of organisms which have these types of isolating mechanisms. • Go to Biozone Reproductive Isolation and continue with examples.

  8. Geographical or environmental barriers. • Geographic isolation refers to a situation where a species, or a population of a species, becomes separated by a physical barrier (a lake, ocean, mountains, etc.) • eg

  9. Ecological Isolation. • Is the isolation of two related species of organisms made possible by differences in food resources, habitat use, activity period, or geographical range of each species. • eg.

  10. Eucalyptus verrucata.

  11. E. baxteri • Eucalyptus baxteri.

  12. Behavioural Isolation. • Is a form of reproductive isolation in which two populations have differences in courtship rituals or other types of behaviour that prevent them from interbreeding. • eg

  13. Behavioural • Each species may use different signals for attracting a mate. • The mating behaviour of male jumping spiders is an elaborate dance in which they shake their legs and wave their palps. • Females of different species do not respond to the dance.

  14. Jumping Spiders.

  15. Different species of bowerbird construct elaborate bowers and decorate them with different colours in order to woo females.

  16. The Satin bowerbird builds a channel between upright sticks, and decorates with bright blue objects, while the MacGregor’s Bowerbird (right) builds a tall tower of sticks and decorates with bits of charcoal.

  17. Structural Isolation. • Structural isolation, (mechanical) or structural differences in reproductive organs, can prevent copulation. • Examples.

  18. Structural • As a result of the complex shape of the penis in certain arthropod species, many closely related species cannot interbreed with them. • Similarly, the shape of floral features in many plants can affect the transfer of pollen; orchids exhibit a variety of complex features of this type.

  19. Pollen sacs in a lady’s slipper orchid become attached to an insect, but they are not removed by any other kind of flower

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