Lecture Notes - Fri Jan 15 starting with artificial selection

Artificial Selection
Breed animals for traits we want
Humans control what genetic traits are most prevalent in populations of domesticated animals and plants
Restricting breeding to those with most desired
Killing those with least desired traits
Phenotype vs genotype
Phenotype – set of observed/physical traits
Genotype – set of genes (DNA)
Phenotype and genotypes aren’t always the same because of recessive genes in organisms with more than 1 set of chromosomes (humans)
Selection for friendliness
Select animal for friendliness, its coat and skin color will change

Most fit organism is the one that survives long enough to pass genes onto next generation

Natural Selection
Observation: all organisms produce more offspring than needed to maintain population if all those offspring survived
Observation: But populations of organisms, aren’t, generally, increasing exponentially
Observation: This is because huge numbers of organisms die before they can reproduce

Darwin/Wallace insight
Hypothesis: which organisms survive to reproduce and which ones die is not just a matter of chance
Organisms that are better able to compete in a given habitat will be more likely to reproduce
Competition for: limited resources, hiding places, mates
This is analogous to artificial selection

Hardy-Weinberg equilibrium
Based on organisms with dominant and recessive traits
Way of calculating how many organisms survive with no mutations and no evolution – only survived by random chance
There ARE mutations
Mutations to cells’ DNA occur every time a cell divides
Most of these mutations are neutral; some affect phenotype of organism
Mutations occur randomly and very rarely at same site in DNA in one organism
Mutations are NOT usually bad

Examples of natural selection
Antibiotic resistance (Flu is a virus – antibiotics kill bacteria)

Falsifiable – can be falsified by gathering empirical data

29 colonies on 10^8 plate
29 * 10^8 in .1 mL of original sample
10 mL of original broth
approxiamately 29 *10^10 bacteria/ original tube

Hey thanks! I actually didn't have that one. Thanks again!

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