1. Natural Selection = mechanism for evolution
Change in environment?
Asexual: all die/survive
Sexual: some die/survive
Variation within populations
Variation and success
Variation in traits helps determine success rate (survival to reproductive years)
Asexual reproduction lead to little/no variation
Sexual reproduction leads to wide variety of offspring
Based on frequency of alleles/multiple alleles

2. Mechanism of Variation:
Mutations:
Lead to genetic diseases – detrimental affect on survival
Advantageous characteristic – beneficial affect on survival
Neither useful nor harmful
Only few genes mutate – weak source for variation in a population

3. Mechanism of Variation:
Meiosis:
Four genetically different haploid cells produced
Large numbers of possible genetic combinations due to:
Random orientation
Crossing over

4. Mechanism of Variation:
Asexual Reproduction
Sexual Reproduction
Variance in population = some individuals better adapted
Leads to more possible outcomes:
Survive with no adverse effects
Negative affect but survives
Little to no genetic variance  all die/survive
Negative affect and dies
Potato blight
Type of trait is based off chance – what sperm will find what egg

5. Adaptations
Characteristics that are well adapted for an environment – organism is fit
Better adapted to reach high leaves
Mutation leading to short neck = disadvantage
High fitness
Low fitness
More likely to survive
More likely to die
Cannot pass on its mutation – allele disappears from population

6. Natural variation – genetic differences
Most species produce too many offspring
Poorly adapted traits – less success at accessing resources  less chance at surviving to reproductive years
Increases chance of some survival
Increases probability of genes being passed on
Supply and demand for resources
Well adapted traits – more success at accessing resources  higher chance at surviving to reproductive years
Creates competition (struggle for survival)
More fit – increase chance at passing on successful traits – not guaranteed
Over generations – accumulation of changes = evolved species

7. Spray pesticide
Natural variation – few rats survive
Immunity is acquired within lifetime of individual
Resistance – change that evolves in a population over generations
Resistant trait has been selected for
Re-spray pesticide
Characteristics must be heritable not acquired

8. Antibiotic Resistance in Bacteria
Mutations – rare due to asexual reproduction
Examples:
Plasmid Transfers
Syphilis – multiple resistance
Tuberculosis– resistant to 9 different antibiotics
MRSA
New antibiotics are temporary solution
Reduce use of antibiotics
Allow immune system to do its job
Vaccinations