Warm Up 6 3/6 Just copy onto warm up. If an individual dies without reproducing, it does not contribute its alleles to the population’s gene pool. If an individual produces many offspring, its alleles stay in the gene pool and may increase in frequency. Evolution is a change in the relative frequency of alleles in a population.

Warm Up 6 3/6 Your own opinions. Is it better to be a big, small, or average size cat? Explain. Would you rather be extremely short, average, or very tall (over 6’5). Would you rather live somewhere very cold with snow, average like LA or very warm all the time?

Single-Gene Traits Natural selection leads to changes in allele frequencies and thus to evolution

Natural Selection on Polygenic Traits

1. Directional selection When individuals at one end of the curve have higher fitness than individuals in the middle or at the other end. Ex: extinct dog size horse vs. modern horse

2. Stabilizing selection When individuals near the center of the curve have higher fitness than individuals at either end. Ex: Human infant weights.

3. Disruptive selection When individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle.

Warm Up 6 3/5 1. (single-gene or polygenic) traits are represented by the graph below. 2. Looking at the graph, the majority of North American men are what height? 3. Very little number of people are of these heights. Vocab words 4. The combined genetic information of all the members of a particular population 5. The number of times an allele occurs in a gene pool (expressed in a %)

4. Define natural selection in your own words. 5. Can natural selection lead to changes in relative frequencies and thus to evolution?