In the spoons game, what represented genetic variation?
- the different cards with traits each person received (inherited) Section 4 Genes & Variation What 2 major gaps existed in Darwin’s theory of evolution?
- Didn’t know how traits were passed on
- No idea how variations appeared
What scientist’s work was able to fill these gaps? Mendel
What are two sources of variation? mutation, gene shuffling
What is a mutation? any change in the DNA sequence
What causes mutations? An error in replication, or outside influences such as radiation, or chemicals
When does gene shuffling happen (2) times: crossing over, independent assortment, 50% DNA from each parent
Does natural selection work on the genotype or phenotype? phenotype
Section 5 Evolution as Genetic Change Where is the area of high fitness in directional selection? one end of the curve
Where is the area of high fitness in stabilizing selection? the middle of the curve
Where is the area of high fitness in disruptive selection? the extreme ends of the curve
An average weight baby is the most likely to survive. This is stabilizing selection.
Longer bird beaks gather food better. This is directional selection.
Both small and large bird beaks are well adapted to survive. This is disruptive selection.
What type of selection can result in 2 new subgroups? disruptive
What type of selection favors the average individual? stabilizing
What type of selection favors one extreme trait over the middle and other end? directional
Label each graph disruptive, directional, or stabilizing selection. Then draw the curve for the new graph!
directional stabilizing disruptive
In what size of a population is genetic drift observed? small
What is genetic drift? a random change in allele frequency
What can cause genetic drift? bottleneck effect, founder effect
Explain an example of genetic drift. - Small Amish population had a higher rate of dwarfism and 6 fingers because they only reproduce with a small population
- Many cheetahs were killed so the remaining cheetahs have very little genetic variation among them