1. A review!
In two sentences or fewer, explain what’s going on here

2. Natural selection review!
In order for natural selection to favor a trait, what does it need to “do” for the organism that possesses it?
What kinds of traits support survival?

3. How do you explain this?

4. Why?

5. Sexual selection
Sexual dimorphism: Noticeable differences between males and females within a species.
These traits are not directly associated with reproduction or survival
“Sexual” in this context =
Difference between two sexes
Relating to reproduction

6. Bird of Paradise video
What kind of sexual dimorphism do you see in the bird of paradise?
Do any of the behaviors remind you of things performed by humans?

7. Sage Grouse video Why are females often the sex that is “choosy”?
How many eggs do females produce at a time? How much sperm does a male produce?

8. Mate choice
Mate choice: Individuals of one sex are “choosy” in selecting their mate.
Females are usually choosy because they produce fewer eggs (relative to male sperm)

9. Alligator video
Does the behavior by the alligators have any survival benefits?
If not, what does the behavior “say” about the males? (What’s the point of the behavior?)

10. What’s the point of mating displays?
“Good genes”: Features associated with mating displays are often correlated to good male health
For example: bright beaks, colorful feathers, physical combat

11. A sexual selection summary (so far)
Males and females of a species may exhibit sexual dimorphism
(examples?)
Male bowerbirds create display areas to attract female birds.
When a female bird has entered the structure, he performs a dance.

12. A sexual selection summary (so far)
Growing your investment!
One way that sexual selection happens is mate choice
The females (usually) of a species choose which males to mate with
Females can only produce a limited number of offspring
Females need to maximize the “return” on the energy that they “invest” in reproduction

13. A sexual selection summary (so far)
Another way that sexual selection happens is competition
The males (usually) of a species compete for access to females
Examples: Fighting, showy displays (out-performing another male)

14. A sexual selection summary (so far)
Why do seemingly-useless (or even dangerous) traits end up being selected for?
(examples?)
Features associated with mating displays are often correlated to good male health.

15. Sexual selection and “good genes”
Example: Long-tailed widowbirds
Long tails make it difficult to survive because they cost more energy to produce and maintain
Therefore, only males with good genes have enough resources to produce them.
Long tails = good genes
Females who choose males with long tails will have healthier offspring

16. Background Early cloning methods Artificial embryo twinning
Some of the first cloned organisms came from using a piece of hair to split embryos

17. Cloning by nuclear transfer
Take a nucleus from a donor cell and place it in an unfertilized egg cell
Dolly was the first clone to be grown using the nucleus from an adult cell, instead of an embryo cell

18. Embryonic Stem Cells Unique and essential cells
Continually reproducing and renewing tissue
Less differentiated than adult cells
Differentiation = becoming more specialized