Evolution of populations Big Q: What are the sources of genetic variation? Big Q: What is genetic drift? Big Q: What types of isolation lead to the formation of new species?

Engage- Mimicry Watch the video clip on mimicry and write down the main idea. How does mimicry help a species survive?

Explain - Genetics in Evolution Gene Pool - all the alleles that are present in a population Allele Frequency - the number of times an allele occurs in the gene pool Evolution in a genetic sense involves a change in allele frequency in the gene pool

Elaborate - Genetic Drift Genetic Drift - random change in allele frequency Two types: 1. Bottleneck Effect - change in allele frequency following a dramatic reduction in population size 2. Founder Effect - allele frequencies change as a result of the migration of a small subgroup of population

Elaborate- genetic Equilibrium Genetic Equilibrium - when evolution does not occur due to no changes of allele frequency in the gene pool Hardy Weinberg Principle - calculates the possibilities for changes in a population by predicting: 1. Nonrandom Mating - sexual selection of mates based on traits 2. Small Populations - genetic drift 3. Emigration or Immigration - changing genes in the gene pool 4. Mutations - introduce new genes 5. Natural Selection - changing the fitness

Explain - Speciation Speciation - forming a new species This is caused by isolation: 1. Reproductive Isolation - species cannot interbreed 2. Behavioral Isolation - courtship ritual differences 3. Geographic Isolation - separation by geographic barriers 4. Temporal Isolation - two or more species reproduce at one time

Elaborate - Darwin’s Finches Called adaptive radiation Changes in the gene pool and types of isolation led to speciation across the Galapagos

Explain - Dating Earth’s History Fossils - preserved remains of ancient life commonly found in sedimentary rocks Index Fossil - distinctive fossils used to compare rock age for relative dating Radioactive Dating - uses radioactive isotopes to identify remains based on an element’s half-life

EXplain - rate of Evolution Gradualism - evolution occurs at a slow and steady pace Punctuated Equilibrium - evolution is interrupted by brief periods of rapid change

Elaborate - Types of Evolution Convergent Evolution - production of distantly related organisms with similar structures and characteristics Coevolution - two species evolve in response to changes in each other over time

Evaluate - Genes Complete your exit ticket