Exams returned W 213 Bonus 1 due F

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

As DNA changes; traits change. DNA Traits

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

Evolution: changes in DNA as information transmitted O O O O Bacteria with mutation causing resistance O O O Apply antibiotic Changes to groups, not individuals. O O O X X X X X O O O Continues to replicate O O O O Kills most bacteria. Except if some have mutation that allow them to be resistant. O 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 Genes Memes • Slow replication • Rapid replication • High copy fidelity • Low copy fidelity • Universal in organisms • Limited to some organisms – Only humans can transmit complex memes?

Evolution of memes and genes Selection of memes and genes can be at odds Nv. N 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.

Artificial selection 1. Select individuals that have the largest side buds and breed them. Number of Individuals Wild Brassica oleracea: small side buds 2. Of the offspring, select individuals that have the largest side buds and breed them. 3. Of the offspring, select individuals that have the largest side buds and breed them. 4. After several generations, bud size increases dramatically. 0 Brussels sprouts: extremely large side buds 1 2 Size of buds (cm) 3

Wild Brassica oleracea: small side buds Selection only works if there is variability in the population Artificial selection Number of Individuals 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, select individuals that have the largest side buds and breed them. 4. After several generations, bud size increases dramatically. 0 Brussels sprouts: extremely large side buds 1 2 Size of buds (cm) 3

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

CB 23. 11 Variation of a trait within a species

Three basic types of selection… • Directional • Stabilizing • Disruptive

CB 23. 12 Directional Selection

Directional Selection has led to an increase in swallow size

CB 23. 12 Stabilizing Selection

Human birth weight has been stably selected

CB 23. 12 Disruptive Selection

Disruptive Selection in blackbellied seedcrackers

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