1. CHARLES DARWIN proposed natural selection to explain evolution
published On the Origin of Species in 1859
13.1

2. VARIATION within a population

3. A varied population is a POLYMORPHIC population
Not here
Yes!
Why are the jaguars
varied, but not the
bacteria?

4. BELL CURVE shows the frequency of a variation in a population

5. • Genetic variation reflects mutations in the DNA
Variation is visible & measureable
Observe & measure
phenotypic variation

6. Observe and measure variation at the gene level
Heterozygotes express some
sickling, but have malaria resistance

7. Observe & measure variation at the nucleotide level
via genome sequencing

8. OVER-REPRODUCTION
creates competition
toad tadpoles
spiders
fish roe

9. ENVIRONMENTAL CHANGE creates competition

10. VARIATIONS may have differential success

11. REPRODUCTIVE SUCCESS for the ‘most fit’
causes microevolution

12. Antibiotic Resistance
Methicillin-resistant Staphylococcus aureus,
(MRSA) is bacterium that can infect open
wounds, blisters and skin lesions. Resistant
to most of the drugs traditionally used to
fight the bacteria,
Antibiotic Resistance

13. FITNESS?
Fit = most offspring
Not literally ‘fit’

14. Quantify microevolution via changes in frequency
(allelic, phenotypic, etc) P F1 F2 F3 F4 F5
1.0
0.33/0.33/0.33
0.5/0.5
0.5/0.25/0.25
0.4/0.6

15. Microevolution can lead to macroevolution in time Speciation results
One ancestor,
many descendants
Adaptive radiation
The adaptive radiation
of the Galpagos finches

16. AntibioticResistance Protein
Geology PesticideResistance Geomorphology ComparativeBiochemistry DNA ComparativeEmbryology ComparativeAnatomy FossilRecord Chapters 21/22 Protein
Geography AntibioticResistance Geology Protein EVIDENCE Geomorphology ComparativeBiochemistry DNA ComparativeEmbryology ComparativeAnatomy SelectiveBreeding Geography FossilRecord
AntibioticResistance Protein
Geology