Exams returned W 2/13----Bonus #1 due F 2/15

As DNA changes; traits change. DNA Traits

Changes to groups, not individuals. Evolution: changes in DNA as information transmitted O O O Bacteria with mutation causing resistance O O O O O O O O Changes to groups, not individuals.

Changes to groups, not individuals. Evolution: changes in DNA as information transmitted O O O Bacteria with mutation causing resistance O O O O O O O O Changes to groups, not individuals. Apply antibiotic O Continues to replicate X X X O O O X X X O O O O O O O X X X X O O O O O O O O Kills most bacteria. Except if some have mutation that allow them to be resistant. O O O O Population of resistant bacteria

Evolution: A species’ genetic component changes as the individuals reproduce. These changes are based on how the DNA changes and who reproduces.

Natural Selection: Individuals that are most successful at reproducing will pass on more of their genetic information.

Reproductive success = evolutionary success

Are genes the only replicators?

Memes: transmissible ideas Ideas can act similarly to genes Contain information Replicate with imperfect fidelity

Mutations

Memes: transmissible ideas Ideas can act similarly to genes or viruses Contain information Replicate with imperfect fidelity

Memes: transmissible ideas Ideas can act similarly to genes or viruses Contain information Replicate with imperfect fidelity Evolve: most successful replicators become most abundant

Contrasts between memes and genes Slow replication High copy fidelity Universal in organisms Memes Rapid replication Low copy fidelity Limited to some organisms Only humans can transmit complex memes?

Selection of memes and genes can be at odds Evolution of memes and genes Selection of memes and genes can be at odds NvN chpt 8

Humans can pass on genes and/or memes

Do memes make humans unique?

Human Population Growth

Natural Selection: Individuals that are most successful at reproducing will pass on more of their genetic information.

Artificial Selection: Individuals chosen by humans will reproduce and pass on their genetic information.

from Teosinte Maize By artificial selection that began ~10,000 years ago.

Wild Brassica oleracea: small side buds Artificial selection Number of Individuals Size of buds (cm) 1 2 3 1. Select individuals that have the largest side buds and breed them. 2. Of the offspring, select individuals that have the largest side buds and breed them. 3. Of the offspring, 4. After several generations, bud size increases dramatically. Figure: 1.3a Caption: (a) This plant is a wild member of the mustard family. It is the progenitor of broccoli, Brussels sprouts, and other domesticated plants. Brussels sprouts: extremely large side buds

Selection only works if there is variability in the population Wild Brassica oleracea: small side buds Selection only works if there is variability in the population Artificial selection Number of Individuals Size of buds (cm) 1 2 3 1. Select individuals that have the largest side buds and breed them. 2. Of the offspring, select individuals that have the largest side buds and breed them. 3. Of the offspring, 4. After several generations, bud size increases dramatically. Figure: 1.3a Caption: (a) This plant is a wild member of the mustard family. It is the progenitor of broccoli, Brussels sprouts, and other domesticated plants. Brussels sprouts: extremely large side buds

Different foods from one species of plant. Created by artificial selection. CB 22.10

Individuals are selected… But populations evolve via changes in DNA during reproduction.

Evolution can only occur when both of these conditions are met: Genetic diversity gives rise to individuals with different traits and Not all individuals can reproduce CB 22.9

Variation of a trait within a species CB 23.11 Variation of a trait within a species

Three basic types of selection… Directional Stabilizing Disruptive

Directional Selection CB 23.12 Directional Selection

Directional Selection has led to an increase in swallow size

Stabilizing Selection CB 23.12 Stabilizing Selection

Human birth weight has been stably selected

CB 23.12 Disruptive Selection

Disruptive Selection in blackbellied seedcrackers

The three different types of selection CB 23.12 The three different types of selection

Evolution: A species’ genetic component changes as the individuals reproduce due to… Non-random changes (natural selection) Random changes (genetic drift/bottleneck) Mutations add new alleles or genes

Exams returned W 2/13----Bonus #1 due F 2/15