Understanding Macroevolution and Microevolution: Key Concepts and Examples

2. 2 types of evolution Macroevolution Microevolution Changes within a gene pool Examples: Kettleworth moths Insect resistance Drug resistance • Changes beyond the species • Examples: • Biogeography • Fossil record • Homology • Biochemical similarities • Chromosomal similarities

3. Let’s do Macroevolution first

4. 1. Biogeography: the geographic distribution of species • Why does the Arctic have polar bears and Antarctica penguins?

5. Why are most of the species on islands more closely related to species on the nearest mainland. • The answer is that modern species are where they are because they evolved from ancestors that inhabited those regions. • In the case of island species, inhabitants must have migrated from the original, mainland area where the species originated.

6. On a global scale, we now know that the distribution of species is based upon continental drift.

7. 2. Fossils How are fossils formed? • Preservation in sap • Mineral replacement • Preservation in ice • Traces e.g. footprints • Molds

8. I. Fossils • Fossils are the preserved remains of ancient organisms.

9. The succession of fossil forms is congruent with the theory of descent with modification. • Ex. Extinct intermediate forms in whale evolution.

10. Ambulocetus natans in action. A reconstruction of an early close cousin of whales.

11. Other intermediate forms present in the fossil record:

13. Why is it true that fossil fishes predate fossil amphibians which predate fossil reptiles which predate fossil mammals?

14. 3. Comparative Anatomy

15. a. Homologous Structures

16. b. Vestigial organs • Vestigial organs are remains of a structure that was functional in some ancestor but is no longer functional in the organism in question. • For example, humans have a tail bone (the coccyx) but no tail. The presence of vestigial structures is explained by the common descent.

17. Why does a whale have a pelvic structure?

18. 4. Comparative Embryology: • A comparison of the early stages of their embryonic development may show similarities that suggest a common ancestry.  • For example, the early embryos of fish, birds, pigs and humans closely resemble one another.

19. Comparative Embryology

20. 5. Molecular Biology/Biochemical Similarities • DNA, RNA, amino acids and proteins have all been used to determine evolutionary relationships between organisms • For example: Cytochrome C (in ETC) is used by organisms ranging from yeast to humans • The greater the differences in the DNA bases that code for the cytochrome C enzyme, the longer the time since two organisms shared a common ancestor.

22. Human beta chain 0 Gorilla 1 Gibbon 2 Rhesus monkey 8 Dog 15 Horse, cow 25 Mouse 27 Gray kangaroo 38 Chicken 45 Frog 67 Lamprey 125 Sea slug (a mollusk) 127 Soybean (leghemoglobin) 124 An example of molecular homology. • The numbers is equal to the number of amino acid differences between human hemoglobin and others.

23. A phylogenetic "tree of life" constructed by computer analysis of cyochrome c molecules in the organisms shown

24. Chromosomal Similarities

25. Examples of Microevolutionch 13 section 7

26. Why don’t pesticides work very long? Entomologists say 500 crop pests have already evolved resistance to conventional insecticides.

27. Insecticide Resistance • Currently over 500 pests are resistant to 1 or more common insecticides • Through mutations the insect does not produce enzyme which interacts with the poison

28. Drug Resistance • H1N1, MRSA, HIV drug resistance • Caused by decades of excessive and unnecessary use of antibiotics In 1943, penicillin was introduced as an antibiotic to protect against Staphylococcus infections. By 1946, a number of strains of Staphylococcus demonstrated resistance to penicillin. Today, as many as 80% of Staphylococcus aureus are resistant to penicillin.

29. Kettleworth – BistonBetularia

30. Prior to the industrial revolution, there was a much higher frequency of the light variety of the peppered moth, which, were adapted to the light colored lichen on tree bark. • However, industrial pollution in the 1800’s began to kill the lichen, turning the tree bark into a dark color. • Now, the number of dark variety of peppered moth increased i.e. were naturally selected.

31. So how fast can you mutate? • Animals and plants are about 1/100,000 mitotic cells • Bacteria reproduce by binary fission and mutate about the same….but they multiple every 20 minutes!!! A single bacteria can reproduce so fast that after 36 hrs, there would enough bacteria to cover the Earth 1 foot deep.

32. Sexual Reproduction • Genetic variation in sexual reproduction increases • No way to estimate amount of genetic variation • Sexual reproduction promotes genetic variation

33. The genetic structure of a population. Some basic definitions: • A population is a group of individuals belonging to the same species. • A species is a group of populations whose individuals can successfully interbreed. • A gene pool is the total genes in a population a any one time. It consists of all alleles at all gene loci in all individuals of the population.