EVIDENCE FOR EVOLUTION: 1. Fossils show change over time scientists can ___________________ & use them to support the _______________________________ ________________________________________________________ Anatomy of living species also shows relatedness 2. Homologous Structures _____________________________ because they share a common ancestor: ______________________________ Ex: human arm, dog front limb, horse leg, whale 3. Analogous structures Distantly related species have _______________________________ but are ________________ in structure _________________________ Ex: wing of butterfly & bird 4. Vestigial structures Structures ________________ & often ____________________ ___________________ of functional structures ________________________________ Ex: leg & hip bones in pythons & whales 5. Molecular Evidence Also called ______________________ evidence Compares ____________________ (ex DNA, amino acid sequences) between organisms Related organisms have more of the same molecules in common How do new species form? 1. Geographic Isolation When members of a population are separated Ex: polar, grizzly, & black bears 2. Reproductive Isolation When members of a population can’t breed even though they live nearby Ex: different mating seasons or different mating calls 4 Different Types of Evolution 1. Divergent Evolution -___________________ populations evolve ______________________ Ex: polar & grizzly bears changed independently due to different habitats 2. Convergent Evolution -Unrelated species become _________________ because they live in ___________________ Ex: shark & dolphin 3. Coevolution - Species that _____________________ adapt to ________________ Ex: flowers & hummingbirds 4. Adaptive Radiation - Evolution of ____________________________ from _________________common ancestor Ex: ________________________________________ Population Genetics: Evolution at the Gene Level Population: o Natural Selection: o 4 Steps of Natural Selection: 1. 2. 3. 4. Allele Frequency: o o Example: 1. If 100 individuals make up a population and 50 are homozygous dominant, 25 are heterozygous, and 25 are recessive, what is the allele frequency of the dominant allele? You try! If 300 individuals make up a population and 150 are homozygous dominant, 100 are heterozygous, and the rest are recessive, what is the allele frequency of the recessive trait allele? How does natural Selection affect allele frequency? • Mutations provide the raw material on which natural selection can act. • Evolution depends on ___________ because this is the only way that _____________ among organisms are created • Evolution acts on populations not ________________. Survival of the Fittest: o If individuals having certain genes are better able to produce mature offspring than those without them, the frequency (number #) of those genes will increase. o Survival: o Fitness: Different Lines of Evidence: • Wolf Lineage: • Darwin’s Finches: • Whale DNA: Genetic Drift: o • Example: __________________________________ -- a rare form of dwarfism that includes extra digits -- in the Amish population of eastern Pennsylvania, which has intermarried over many generations. • Example: ____________________________________was changed when U.S. Soldiers had children with Vietnamese women during the Vietnam war. Gene Flow: o Founder Effect: • • The population then will contain only those genes the initial individuals brought with them. • Example: Bottleneck Effect: • • Example: __________________________________________ the population has rebounded from this population bottleneck to some 100,000 animals today. However, these animals are homozygous at every one of the gene loci that have been examined. Types of Natural Selection: Stabilizing Selection: • • example is Directional Selection: • Individuals at either end of the distribution curve are favored. ________________________________________________________ __________________________________________________ • Example: Diversifying (Disruptive Selection) • • Cladistics • A Cladogram is a _______________________ that depicts species divergence from ______________________ • They show the ________________distribution and origins of ___________________________. • Cladograms are _________________________________ of phylogenetic relationships.