Download Variation Lecture

Day 4
Objective: Explain how biological evolution is the consequence of the interactions
of genetic variation, reproduction and inheritance, and natural selection and
time.
Agenda:
1. Stamps
2. Variation Lecture
3. Variation Lab
This is an example of variation in dogs. List
examples of variation within other
species.
Darwin’s Ideas
• Heritability – traits passed from parents to offspring
• Variation – differences within a species
• Natural selection – some traits are favorable
Heritability
• Heritable traits: differences in appearance due to genes.
Examples:
• Non-heritable traits: differences in appearance not due to genes.
Examples:
Where does genetic
variation come from?
1. Sexual reproduction: crossing over
2. Mutations: mistakes in DNA replication or environment
How do we observe variation?
Monogenetic trait: only
two possible
appearances
Polygenic trait:
many possible appearances
Exit Ticket
1. What type of trait is
shown in these
graphs?
2. Do individuals or
populations evolve?
Defend your
answer.
How Many Chromosomes?
•
Human: __________
•
Chimpanzee: ______
•
Dog: __________
Butterfly: __________
Mosquito: __________
Pine tree: __________
•
Cat: __________
•
Cow: __________
Cucumber: __________
Record for least # chromosomes: ________
•
Trout: __________
Record for most # chromosomes: ________
Conclusions?