1. 5.4 Evolution
IB Biology

2. Evolution
The cumulative change in the heritable characteristics of a population
Cumulative – small changes over time (many generations)
Heritable – gene-controlled factors/traits
Population – not an individual
Life on Earth is unified by its common origins
Species can evolve
New species arise from preexisting ones

3. Charles Darwin Father of Evolution The Origin of the Species, 1859
HSM Beagle
Studied finches in Galapagos islands

4. Evidence for Evolution – TOK Link

6. Evidence for Evolution

7. Evidence for Evolution
Fossil Record
Remains of extinct species provide evidence that species are continuously evolving
Shows a change in species over time

9. Evidence for Evolution
Homologous Structures
Structures that may look different and perform a different function, but have a “unity” in structure (eg. bone position)
Common ancestry
Look different because they have adapted to perform different functions (adaptive radiation)

10. Pentadactyl limb
(five digits)
Pentadactyl limb
(five digits)

12. Vestigial Structures Darwin called them “rudimentary organs”
Reduced structures that serve no function
Lost function and are gradually being lost
Appendix in humans
Used to be larger sac to digest cellulose
Pelvic bone in baleen whales
Support upright weight
Walking

13. Evidence for Evolution
Selective Breeding
Humans have selected desirable traits in domesticated animals for centuries
Farmer notices a favourable trait, individual allowed to breed
May also influence other characteristics
Farmer notices a negative characteristic, not allowed to breed
Called artificial selection
Eg. Cows
Jersey - milk
Angus - beef

14. Evolution Video
Great Transformations

15. Comparative Embryology

16. Homework Page 184: DBQ Page 189: Thinking about science
(cover the answers on the side)

17. Populations
Populations tend to produce more offspring than the environment can support
Consequence of overproduction of offspring is a struggle to survive
Think back factors that limit population growth

18. Variation
Variation -
A marked deviation from the typical form or function

19. Variation Crossing Over (prophase I) Random Assortment (metaphase I)
Creates new combinations of alleles on a chromosome
Recombination
Random Assortment (metaphase I)
How chromosomes line up at the equator
↑ chromosome number = ↑possibilities
2n = 223= 8, 388, 608 possibilities
Random Fertilization
Any sperm cell can randomly fertilize the egg cell
Faster swimmer!!

21. Evolution in response to environmental change
Antibiotic Resistance in Bacteria
Environmental change: methycillin antibiotic (drug)

22. Antibiotic resistance in bacteria
Methycillin

23. Antibiotic resistance in bacteria
Methycillin resistant
Methycillin susceptible

24. Antibiotic resistance in bacteria
Take your prescription until the very end!!!

25. Worms Activity

26. Evolution in response to environmental change
Peppered Moth (Biston betularia)
Environmental change: soot from pollution, industry
typica stood out
Predation
Population declines
carbonaria camoflauged
Little predation
Survive to pass on trait and population increases
Reversing because of clean air acts

27. Evolution in response to environmental change
Galapagos finches
Darwin visited Galapagos islands in 1853
Observed the size and shape of beaks many species of finches
Finches on each island had different selection pressures, and over the years had adapted to suit own island – own species
Common ancestry
Environmental change:
Food supply

28. Natural Selection Variation produces different traits
give an advantage or disadvantage
Inherited characteristics affect the likelihood of an organisms survival and reproduction
Traits that give an advantage are passed on to the next generation
adaptations
Over time, the proportion of the population with the advantageous trait will increase (and those with a disadvantage will decrease)
“Survival of the fittest”

29. Evolution Video Evolution: Evolutionary Arms Race
Fill in questions on Handout

30. Opposing Viewpoints Published in The Economist, 2009
Friends:

31. HW: IB Questions
Explain evolution of a species by natural selection in response to evolutionary change (8 min)
Explain two examples of evolution in response to environmental change (9 min)
Optional: Evolution extra credit assignment
Read the Survival of the Sneakiest comic on Edline.
Explain it in one paragraph using ecology vocabulary