2 Levels of Evolutionary Study Microevolution: examines changes to the genes (alleles) within populationsPopulation Genetics: studies the changes in the numbers & types of alleles in a populationExamines evolution within a species.Small changes that do not lead to new species, but can lead to new variations.Macroevolution: examines the evolutionary changes that create new speciesSpeciation: the formation of new species over time
3 MacroevolutionSpecies: a group of organisms that can interbreed and produce fertile offspringSpeciation: the evolution of new speices (by genetic change or change in form)Occurs when members of a similar populations can no longer interbreed!
5 Methods of SpeciationGeographic Isolation: physical barriers divide a population and prevent interbreedingBeetles in Grassland Become GreenBeetles in Woody HabitatBecome Brown
6 Methods of SpeciationReproductive Isolation--occurs when formerly interbreeding organisms can no longer mate & produce fertile offspringGenetic: genetic differences are too great to breed successfullyBehavioral: mating behaviors or mating seasons don’t allow for matingChromosome NumbersPolyploidy: any species with extra sets of chromosomes. Common in plants.Can interbreed or self-fertilize, forming separate speciesHybridization: when two closely related species attempt to mateUsually results in sterile offspringEx: donkey + horse = mule
7 Speed of Speciation Gradualism Punctuated Equilibrium Idea that species originate thru a slow, gradual change of adaptations over long periods of timePunctuated EquilibriumIdea that species can remain stable for long periods of time until environmental changes cause many new species to appearSpeciation occurs in less than 10,000 years!
8 Patterns of Macroevolution Divergent EvolutionConvergent EvolutionCoevolution
9 Divergent EvolutionSpecies diverge or become increasingly distinct from one ancestral speciesEx: Darwin’s finchesAlso called adaptive radiation
10 Convergent EvolutionProcess by which unrelated species become similar as they adapt to similar environmentsOstrichRheaEmuAustraliaSouthAmericaAfrica
11 CoevlutionWhen species who live in close contact evolve adaptations to one another’s existence.
12 Extinction!When all the members of a species die off or fail to reproduceEstimated that 99% of all species that ever lived have become extinctMost extinctions are theresult of environmentalchange, can cause welladapted species to becomepoorly adapted!If the environment changesfaster than a species can adapt,extinction can result!
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