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Patterns of Evolution Extinction Speed and Path of Evolution Adaptive Radiation Convergent Evolution Coevolution Speciation Central Questions • What are gradualism and punctuated equilibrium? • What are adaptive radiation and convergent evolution? • Give a possible example of coevolution not explained in class. • What is speciation and how does it usually happen? Extinction • Extinction generally means the species no longer has living members, but an exact definition is kind of tricky • 99% of all species that have lived on this planet are now extinct! • Species go extinct for a variety of reasons. • Mass extinctions have happened many times in Earth’s history, resulting in large changes in numbers and types of species. Speed and Path of Evolution • Gradualism- evolutionary change is slow and gradual • Punctuated Equilibrium- long periods of stability interrupted by brief periods of major change Adaptive Radiation • A single original species evolves into many forms that live in different ways. • AKA Divergent Evolution Convergent Evolution • Different, unrelated species evolve to live similar lives. These plants aren’t related but both have similar structure because it works well. Coevolution • Evolution of different species are connected based on their ecological interactions • Evolution of flowers and their pollinators are good examples Speciation • Speciation is the development of new species • Usually starts when groups from same species are separated –Separated groups cannot interbreed –Lack of interbreeding results in new species forming Why? Isolating Mechanisms • Behavioral Isolation- population is separated because of what they do • Geographic Isolation- separated by where they live (new obstacle may cause this) • Temporal Isolation- separated by when they are active and breed Population Genetics • An alternate definition of evolution is “change in the frequency of alleles in a population”. What does that mean? • As the relative amounts of each allele changes, that means the population’s genetics are changing. Central Questions • What are gradualism and punctuated equilibrium? • What are adaptive radiation and convergent evolution? • Give a possible example of coevolution not explained in class. • What is speciation and how does it usually happen?
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