06 speciation
- 1. Speciation
- 2. Speciation Biological Species: all members of a population that can breed under natural conditions and produce fertile offspring. (With some exceptions: there are some animals of different species that can have fertile offspring)
- 3. Speciation Reproductive isolating mechanism: The term given to an obstacle that prevents inter-species breeding.
- 4. Think. Pair. Share. Think of as many reasons are you can to explain why animals of different species would be unable to breed. Ex. Why wouldn't the following animals have offspring? Dog and Cat Housefly and Fruitfly Spider and Scorpion Raspberry and Blueberry Salmon and Trout Moose and deer Cardinal and Bluejay
- 5. Reproductive Isolating Mechanisms There are 2 types: 1) Prezygotic (preventing egg fertilization) 2) Postzygotic (zygote unable to reproduce)
- 6. Reproductive Isolating Mechanisms 1) Prezygotic isolating mechanisms include: i) Behavioural Isolation: Differences in courtship.
- 7. Reproductive Isolating Mechanisms 1) Prezygotic isolating mechanisms include: ii) Temporal Isolation: Different breeding times/seasons. The western and eastern spotted skunks breed at different times of the year (fall and late winter).
- 8. Reproductive Isolating Mechanisms 1) Prezygotic isolating mechanisms include: iii) Ecological Isolation: Organisms have different habitats. While similar, these kingfishers rarely leave their habitats for a chance to meet the other kingfishers.
- 9. Reproductive Isolating Mechanisms 1) Prezygotic isolating mechanisms include: iv) Mechanical Isolation: Incompatible anatomies. This beetle penis has spikes on it - a mechanical barrier to reproduction with other species.
- 10. Reproductive Isolating Mechanisms 1) Prezygotic isolating mechanisms include: v) Gametic Isolation: Male gametes are unable to fertilize the egg because they do not recognize it. In some species the females lay unfertilized eggs. The male must then cover them with its sperm.
- 11. Reproductive Isolating Mechanisms 2) Postzygotic isolating mechanisms include: i) Zygotic Mortality: The fertilized egg can not develop properly.
- 12. Reproductive Isolating Mechanisms 2) Postzygotic isolating mechanisms include: ii) Hybrid Inviability: Hybrid organism dies before birth or can not survive to maturity. A leopon (lioness and leopard) or lipard (lion and leopardess) is sterile and has a very short life span. None have grown to maturity.
- 13. Speciation 2) Postzygotic isolating mechanisms include: iii) Hybrid Infertility: Hybrid organism healthy but sterile. Beefalo (domestic cow and buffalo)
- 14. Speciation Speciation is the creation of a new species. The new species evolved from an already existing species. There are many different species of fruit flies.
- 15. Speciation This may occur in 2 main ways: 1) Allopatric Speciation: Physical separation of members of a species will place different selective pressures on each population.
- 16. Speciation This may occur in 2 main ways: 1) Allopatric Speciation: Different traits will be selected for survival and the populations will evolve independent of each other.
- 17. Speciation This may occur in 2 main ways: 2) Sympatric Speciation: Species of a single population my be selected for their extreme traits, such as colour or behaviour (disruptive selection).
- 18. Speciation This may occur in 2 main ways: 2) Sympatric Speciation: These extreme traits become the basis for 2 different populations with different selective pressures as they grow apart. The hawthorn fly species (left) gave rise to apple maggot flies (right) , which prefer to eat apples instead of hawthorn fruits
Editor's Notes
- #4: Grolar (Pizzly) Bear