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 Adaptation  Sharp 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 21 st 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 success  Operates on a population, NOT on an individual  Dynamic between genetic change and the changing environment  Environment 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