Semester 2, Day 11

Other Mechanisms of Evolution

Agenda Review for Natural Selection Quiz Turn in Homework Take Quiz on Natural Selection Lecture on Other Mechanisms of Evolution Reading/Work Time

Review for Quiz

Genotype, Zygosity, and

Phenotype

Define phenotype and

genotype

Which does natural selection

work upon and why?

Define the four conditions for

natural selection

Define artificial selection

Define natural selection

Understand examples of

each of the following

TYPES of natural

selection:

Directional selection

Disruptive selection

Sexual selection

Stabilizing selection

What is “fitness”?

Homework Due Cornell Notes:

Pages 392-397 (stop BEFORE “Adaptations: Evidence for Evolution”)

Pages 404-409 (stop BEFORE “The Evolution of Species”)

Questions: 15.1 #1, 5 15.2 #1 Chapter 15 Assessment #2, 6, 9, 11, 16, 18-20

Quiz Silently complete quiz Keep eyes on your own paper Flip quiz over when complete

Recall: Evolution Change in a group of organisms over many

generations

CANNOT OCCUR IN AN INDIVIDUAL!

5 Mechanisms of Evolution: Natural Selection Mutations Gene Flow Genetic Drift Nonrandom Mating

Evolution

Mutations: change in DNA that results in a change in

the gene expression

Recall Central Dogma:

3 types of mutations:

Beneficial: benefit organism = HIGHER fitness

Ex. faster runner can survive and reproduce more

Neutral: no effect of fitness

Ex. Eye color doesn’t necessarily help you to survive and reproduce

more

Harmful: hurt organism = LOWER fitness

Ex. People with Huntington’s disease may not survive and reproduce.

DNA mRNA Protein (Gene Expression)

Evolution

How are mutations related to natural selection?

Recall: Natural selection has four conditions:

Variation: differences

Heredity: parent to child

Overproduction: too many offspring

Reproductive Advantage: those able to survive & reproduce pass

on their traits MORE.

Mutations are INHERITED, lead to VARIATION, and can

provide ADVANTAGES

Without mutations, there would be no differences in organisms,

which means no evolution could occur

Evolution

Gene Flow

Movement of

organisms to different

populations

Immigration: enter

area

Emigration: leave area

Results:

MORE variation IN

population

LESS differences

BETWEEN populations.

Evolution Genetic Drift

Taking a small population from a larger one LOSE SOME VARIATION.

Founder Effect: Individuals leave to

start a population ina new area

Bottleneck Effect: Catastrophic event reduces

population

Evolution

Genetic Drift: Founder Effect

Genetic Drift: Bottleneck

Variation of INDIVIDUALS: ensures some INDIVIDUALS

in a species will survive a catastrophic event

Recall: Biodiversity of SPECIES: ensures some SPECIES will

survive a catastrophic event

Evolution

Nonrandom Mating: probability of mating with some

individuals higher than with others

Higher chance of mating with those nearby

Higher chance of mating with those who look similar

Nonrandom mating can lead to INBREEDING:

Continued breeding of closely related individuals

Happens in nature: cheetah bottleneck

Happens artificially: breeding dogs for certain traits

Less Variation = Higher Risk for Disease!!!

Reading/Work Time Cornell Notes on 14.3 and 14.4 Questions:

14.3 #1-3 14.4 #1-5 Chapter 14 Assessment #3, 4, 6, 10-14, 16, 20,

22a, 22c