Chapter 4.1

How does sexual reproduction and change in the genetic information result in variation within populations?

How can we measure variations in a population?

Describe how mutations may improve an individual organisms chance for survival and reproduction?

What is “Natural Selection”?

An adaptation is a structure, behavior or physiological process

These help an organism to survive and

reproduce in particular environment

Example: camouflage

Can you find the “hidden organisms” in the following slide?

Complete Launch Lab – page 113

“Could Cockroaches Rule the Earth?”*Complete the analysis questions 1-4

Biochemical and Body Processes

Hibernation in ground squirrel

Structural AdaptationSharp talons and excellent vision of owl

Thick leaves of buffalo berry that help to reduce the water loss on hot summer days

They are a result of a gradual change of characteristics over time

A variation that helps an individual in a population is likely to be passed on from survivor to survivor

Some variations help and some do not, not all variations become adaptations!

Question: Are there measureable differences in sizes among individuals of a species?

As a class, each measure your thumb and your middle finger

Take the class data and graph this information

Use a data table and a graph that best suits the data gathered

Conclude what you see with this data

A group of reproductively compatible populations

How does variation within a species

occur?

Organisms that reproduce sexually have a blueprint from both parents

Through this reproduction, particular traits are passed on to the new organisms

Mutations are genetic changes that happen in DNA

Occur from mistakes that happen when DNA is being copied

For example: Your DNA has about 175 mutations compared to your parents.

Sometimes you notice mutation, other times it has no effect

Evolution observed at the molecular scale

Down Syndrome: a genetic disorder caused by the presence of all or part of an extra 21st chromosome

Often Down syndrome is associated with some impairment of cognitive ability and physical growth as well as facial appearance

Klinefelter's syndrome: Affected males have an extra X sex chromosome. The principal effect is abnormal testes development and reduced fertility.

Sickle Cell Anemia: A genetic disorder passed on when BOTH parents have the trait or are carriers for the trait

The blood no longer flows easily through the body. Many times the blood starts to clot in the veins and arteries – not allowing regular blood flow to the organs in the body!

Sometimes a mutation allows for a trait that has benefits especially in a changing environment – it will select which organisms will survive

A population will change in its ability to survive as the abiotic conditions around it will select those suitable to survive in the environment

Mutations may provide a new selective advantage

A Housefly with resistance to DDT A California ground squirrel that has a factor in their blood

that helps them combat rattlesnake venom when bitten

Depends on reproductive successOperates on a population, NOT on an

individualDynamic between genetic change and the

changing environmentEnvironment exerts Selective Pressure:

environmental conditions that select for certain individuals and select against others

Natural Selection can take time or can happen quickly

eg: Bacteria vs. Finches

Complete the Thought Lab 4.1 – omit procedure

Complete the Though Lab 4.2

Complete Section 4.1 Review Q’s 1-9