1. Natural Selection Developed by Charles Darwin in 1859
Mechanism by which better adapted organisms survive to produce a greater number of viable offspring
Improve chances of survival
Variation
Individuals in a population vary in phenotype which also means their genotype
Some variations are better suited for survival and are inherited
Overproduction
Populations tend to produce more offspring than are needed

2. Neo-Darwinism Refined version Darwin’s theory
Combines Mendel’s genetics
Evolution is driven by chance
2 ways
Small scale mutations (single nucleotide polymorphisms)
Large scale mutations (recombination)
Creates new DNA by lucky accidents

3. Gene Pools
Total genetic information (alleles) in the gametes of all individuals in any given population

4. Population
Group of organism’s of one species that interbreed and live in the same place at the same time

5. Factors that Affect Gene Pools
Mutation
Emigration
Geographical Barriers
Non-Random Mating
Genetic Drift
Bottleneck effect, founder effect
Gene Migration
Speciation
Selection Pressure
Adaptive Radiation

6. Factors Contribute to Fitness of Individual
Measure of how well suited an organism is to survive in its habitat and its ability to maximize the numbers of offspring surviving to reproductive age
How successful an organism is at passing on its genes
Natural selection tends to lean towards individuals who have specific traits that favour them in the environment

7. Allele Frequency (Gene Frequency)
Proportion of a particular allele (variant of a gene) among all allele copies in a specific gene pool
Hardy-Weinberg principle is used to determine allele frequency:
p² + 2pq + q² = 1
“p” and “q” represent frequency of alleles
“p” added to “q” always equals one (100%)

8. Mutation Random occurrences which change the genome of the organism
Increase genetic diversity
Advantageous mutations are favoured by natural selection
Disadvantageous mutations are phased out

9. Geographical Barriers
Isolates the gene pool and prevents regular gene flow between populations

10. Non-Random Mating
Members of gene pool seek out particular phenotypes increasing frequency of particular alleles
Decreases genetic diversity
Also known as selective breeding
Humans breed livestock and plants for particular traits (favourable)
Can lead to in-breeding depression caused by deleterious recessive alleles (cause abnormalities or death)

11. Genetic Drift Species of same population split into groups
Geographical barriers do not allow members of same gene pool to reproduce with one another increasing genetic diversity
Founder Effect
New population is started by few members of original population
Contains reduced genetic variation
Non-random samples of genes
Bottleneck Effect
Population size is reduced for at least one generation
Reduces genetic variation

12. Gene Migration Immigration Gene Flow Emigration
Populations gain alleles from other gene pools
Dependent on difference in allele frequencies between gene pools
Gene Flow
Members from one gene pool mate with members of another gene pool leading to alteration of allele frequencies
Emigration
Population loses alleles from gene pool

13. Speciation
Genetic variation among population is so different that members can no longer reproduce with one another
New species is formed

14. Selective Pressure
Environmental factors reducing reproductive success among members of a population
Contribute to evolutionary change or extinction through process of natural selection
Include
Competition, predation, disease, parasitism, land clearance, climate change, pollutants

15. Antibiotic Resistant Bacteria
Microorganisms show resistance to an antimicrobial drug that was originally effective for treatment
Conjugation
Transfer of genetic material between bacterial cells
Creates genetic diversity
Antibiotic resistance

16. Adaptive Radiation
Species from a common ancestor have successfully adapted to their environment via natural selection
Less competition in population
New ecological niches established (organisms function in environment)
Darwin’s finches

17. Types of Natural Selection
Occur with or without environmental change
Effect a population
Stabilizing Selection
Constant environment
Maintain status quo
Directional Selection
New variation arises in constant environment
Disruptive Selection
Changing environment
Variations that result in better fitness in environment are favoured

18. Stabilizing Selection
Favours the average individuals in a gene pool
Selects against extreme phenotypes of gene pool
Favours majority of population in gene pool
Diversity is decreased
Human birth weight
Infants with average birth weight have increased chance of survival

19. Directional Selection
Favours one extreme phenotype over another extreme phenotype
Phenomena is observed in environments that have changed over time (climate change, food availability)
Population bell curve shifts to left or right
Fewer average individuals when compared to stabilizing selection
Beak length of Galapagos finches
Influenced by human interaction (hunting)

20. Disruptive Selection
Average individual in a population is not favoured
Extreme phenotypes are observed
Lead to speciation (new species)
Diversity increased
Influence by human interaction (environmental pollution)
London’s peppered moths

21. Sexual Selection Special case of natural selection
An organism’s ability to successfully copulate with a mate
Usually female chooses among males
2 ways
Female choice
Male competition

22. Female Choice Intersexual selection between sexes
Females choose males based on specific characteristics or behaviours

23. Male Competition Intrasexual selection
Males compete against other males for territory or mating rights with females
Lead to intense battles

24. Evidence of Evolution Fossil record of change in earlier species
DNA/protein homologies
Geographic distribution of related species
Recorded genetic changes in living organisms over many generations

25. DNA/Protein Homologies
All living things on earth share the ability to create complex molecules out of carbon and a few other elements
All plants and animals inherit their specific characteristics from a combination of genes
Protein is made from DNA made up mostly of only 20 kinds of amino acids