SPECIES VARIATION CHANGES OVER TIME YOU ALREADY KNOW: SPECIES - A GROUP OF SIMILAR ORGANISMS THAT CAN MATE WITH EACH OTHER AND PRODUCE FERTILE OFFSPRING Members of a species have a shared “gene pool”. GENE POOLall of the alleles of all individuals in a population VARIATION- ANY DIFFERENCE BETWEEN INDIVIDUALS OF THE SAME SPECIES CHANGES IN GENE POOLS CAN BE CAUSED BY : • Climate changes • Landforms • Interactions between species • Mutations DEFINITIONS ARE IMPORTANT – QUICK LAB • Take 1 minute and write on the back of your notes the definition of “home”. • Swap your definition with the person sitting closest to you. • Are your definitions exactly the same? • Why do you think it’s important for us to make sure we all have the same understanding of the words we are using? WHAT CHANGE ARE WE TALKING ABOUT? Change over time Evolution Microevolution Evolution Macroevolution MICROEVOLUTION Changes occur in gene pool Causing more variation in individuals Causing more variations in individuals Causing more changes in the gene pool MICROEVOLUTION the process that occurs over time where changes in gene pools causing more variation in individuals, causing more changes in the gene pool and so forth. QUICK REVIEW: 1. True/False: The word “evolution” always means the same thing to everybody. False 1. A gene pool is all of the ____________ of all the individuals in a population. Alleles 1. Changes in gene pools can be caused by what 4 things: 1. Climate changes 2. Landforms 3.Interactions between species 4.Mutations QUICK REVIEW 2 1.The process of small changes taking place in gene pools over time is known as: ____________ Microevolution 2.Can individuals evolve? No. Only populations can evolve. CHANGES IN GENE POOLS CAUSED BY CLIMATE CHANGES A change in the climate can affect an organism’s ability to survive. Ex: Wood frogs in shady ponds vs. sunny ponds CHANGES IN GENE POOLS CAUSED BY LANDFORMS Landforms are features on the Earth's surface like mountains and plains CHANGES IN GENE POOLS CAUSED BY INTERACTIONS BETWEEN SPECIES The changes caused by interactions of species in the same community. Example: Asian shore crabs & blue mussels CHANGES IN GENE POOLS CAUSED BY MUTATIONS Mutations are random changes in the DNA DDT resistance in insects ANOTHER QUICK REVIEW Name the 4 factors that can cause changes in a gene pool: • Climate changes • Landforms • Interactions between species • Mutations ANOTHER QUICK REVIEW 2 1. Turn to your classmate closest to you and take 1-minute turns explaining how climate change might cause species change. Jot down any questions you have as you discuss it. 2. Turn to a different classmate and take 1-minute turns explaining how landforms might cause species variation. REVIEW 3 1. Turn to a person you have not shared with and take turns explaining to each other how species interacting with each other might cause species variation. 2. Turn to a person you have not shared with yet (3rd person of the day) and take 1 minute each to explain how mutations might cause species variation. SO WHAT IS CONSIDERED EVIDENCE OF SPECIES VARIATION? 1. The fossil record over geologic time 2. Rapid bacterial mutations due to environmental pressures FOSSILS Preserved remains of once-living organisms HOW DO FOSSILS FORM? • Water • Sediments • Pressure • Time FOSSIL RECORD The sum total of all fossils collected by scientists and the information they give. THE GEOLOGIC TIME SCALE A “calendar” of Earth’s history based on information interpreted from the study of fossils. The lower a fossil is found in the layers of earth, the older it is believed to be. BUT THAT’S THE PAST, WHAT IS CONSIDERED EVIDENCE OF SPECIES VARIATION TODAY? Rapid bacterial mutations due to environmental pressures In other words, bacteria changing quickly because of factors in their environment threatening to destroy them. BACTERIAL MUTATION: HOW FAST IS IT?! HOW BACTERIA BECOME RESISTANT TO ANTIBIOTICS SO WHAT DOES THIS HAVE TO DO WITH SPECIES VARIATION? SCIENTISTS BELIEVE THIS MODERN BEHAVIOR OF BACTERIA SHOWS THAT SPECIES VARIATION MAY HAVE OCCURRED THE SAME WAY IN THE PAST. THE LAST QUICK REVIEW 1. What are the 2 pieces of “evidence” of species variation? • The fossil record over geologic time • Rapid bacterial mutations due to environmental pressure 2. What are the characteristics of bacteria? • Unicellular (one-celled) • Prokaryotes • Live everywhere THE LAST QUICK REVIEW 2 1. Antibiotics kill bacteria not viruses. 2. Mutations help bacteria to survive. 3. Only the strongest bacteria survive an antibiotic and the strong bacteria multiply rapidly passing on those antibiotic-resistant genes.