Download Week 7: Genetics, Natural Selection, Evolution

3/18/2017
https://www.britannica.com/science/heredity-genetics
Chromosome ‐ a single piece of coiled DNA containing many genes, regulatory elements, and other sequences
• Located in the nucleus of the cell
• Nearly all mammals are diploid
• Cells have two copies of each chromosome • One set from the mother and one from the father
1
3/18/2017
Alleles are alternate forms of the same gene
Example: Flower Color (White and Red alleles of a single gene)
Gregor Mendel (1822‐1884)
2
3/18/2017
3
3/18/2017
Coloration provides an advantage within the population
4
3/18/2017
Mowing (or grazing) selects for the shortest flowers
Domestic dogs evolved from wolves – humans “artificially” selected favorable traits
Most modern crops have been derived from wild plants
Corn was selectively bred beginning about 10,000 years ago in Mexico from several species of grass called teosintes
5
3/18/2017
1.
Selection by fishing
2.
• Only smaller fish escape the net
3.
4.
Population has evolved
•
Now has a smaller average body size
5.
6
3/18/2017
7
3/18/2017
Bluegill (North America)
Cichlid (Africa)
River otter (aquatic)
Weasel (terrestrial)
8