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Evolution • Biology Honors • By Gail Mayes • Foothill High School Biology Honors Objectives The Theory of Evolution Click on Tortoise for Intro Evolution • A. The process by which modern organisms have descended from ancient organisms. • 1. Charles Darwin (1809-1882) sailed on the HMS Beagle to the Galapagos Islands. • 2. This voyage sparked a curiosity about how organisms came to be different and survive on each of the islands. Darwin’s Journey Darwin’s Studies • A. Studied to find out why species change over time. Malthus stated that human populations tend to grow faster than Earth’s food supply. Individuals struggle to compete in changing environments. • • • • Compete for food and space Escape from predators Find mates Locate shelter Natural Selection Evidence for Evolution • A. “Adaptation”=Species survived because they were better able to adapt to their environment. • Mole rats that live underground their whole lives are blind. They have adapted to their environment. Can you find the katydid? Lizard Adaptations Video • Lizards have adapted to their environment over time. Click on the lizard to find out how: Mimicry- An adaptation that enables one species to resemble another. Camouflage- Species blend with their environment. They can’t be easily seen by predators. • CAMOUFLAGE Find out more about snakes: • Snakes Click on the octopus to find out how long they have survived through evolution: Vestigial structures- A body structure in a present-day organism that no longer serves its original purpose, but was probably useful to an ancestor. (blind fish in the dark deep sea). Population Genetics and Evolution A. How can a population’s genes change over time? 1. Gene pool- All of the alleles of the population’s genes together on one pool. 2. Allelic frequency- The percentage of any specific allele in the gene pool. 3. Genetic equilibrium- Alleles remain over generations. a. If a population is in equilibrium it is not evolving. b. Mutations results in favorable changes in a species. Hardy Weinberg Video Evolution of Species • A. Speciation- The evolution of new species is called speciation. – 1. Occurs when members of a similar populations no longer interbreed to produce fertile offspring within their natural environment. Speciation • Convergent Evolution- Evolution in which distantly related organisms evolve similar traits. • Different species can look alike: Evolution Quiz Link • http://www.unitedstreaming.com/stude ntCenter/index.cfm?cdCode=8518D92B Conclusion • Evolution is a theory. There is evidence that evolution has occurred. Speciation occurs at a much quicker time scale and is evident in bacterial mutations.