Presentation on theme: "Macroevolution: Evolution of a New Species. Levels of Evolutionary Study Microevolution: examines changes to the genes (alleles) within populations –Population."— Presentation transcript:
Macroevolution: Evolution of a New Species
Levels of Evolutionary Study Microevolution: examines changes to the genes (alleles) within populations –Population Genetics: studies the changes in the numbers & types of alleles in a population Examines 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 species –Speciation: the formation of new species over time
Species: a group of organisms that can interbreed and produce fertile offspring Speciation: the evolution of new speices (by genetic change or change in form) –Occurs when members of a similar populations can no longer interbreed! Macroevolution
Methods of Speciation Geographic Isolation: physical barriers divide a population and prevent interbreeding Beetles in Grassland Become Green Beetles in Woody Habitat Become Brown
Methods of Speciation Reproductive Isolation--occurs when formerly interbreeding organisms can no longer mate & produce fertile offspring –Genetic: genetic differences are too great to breed successfully –Behavioral: mating behaviors or mating seasons dont allow for mating Chromosome Numbers –Polyploidy: any species with extra sets of chromosomes. Common in plants. Can interbreed or self-fertilize, forming separate species –Hybridization: when two closely related species attempt to mate Usually results in sterile offspring Ex: donkey + horse = mule
Speed of Speciation Gradualism –Idea that species originate thru a slow, gradual change of adaptations over long periods of time Punctuated Equilibrium –Idea that species can remain stable for long periods of time until environmental changes cause many new species to appear Speciation occurs in less than 10,000 years!
Patterns of Macroevolution Divergent Evolution Convergent Evolution Coevolution
Species diverge or become increasingly distinct from one ancestral species Ex: Darwins finches Also called adaptive radiation Divergent Evolution
Convergent Evolution Process by which unrelated species become similar as they adapt to similar environments Ostrich Africa Emu Australia Rhea South America
Coevlution When species who live in close contact evolve adaptations to one anothers existence.
Extinction! When all the members of a species die off or fail to reproduce –Estimated that 99% of all species that ever lived have become extinct –Most extinctions are the result of environmental change, can cause well adapted species to become poorly adapted! –If the environment changes faster than a species can adapt, extinction can result!