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Macroevolution: Evolution of a New Species

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1 Macroevolution: Evolution of a New Species

2 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

3 Macroevolution 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!

4 Methods of Speciation Geographic Isolation Reproductive Isolation
Genetic Isolation Behavioral Isolation Chromosomal Polyploidy Hybridization

5 Methods of Speciation Geographic Isolation: physical barriers divide a population and prevent interbreeding Beetles in Grassland Become Green Beetles in Woody Habitat Become Brown

6 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 don’t 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

7 Speed of Speciation Gradualism Punctuated Equilibrium
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!

8 Patterns of Macroevolution
Divergent Evolution Convergent Evolution Coevolution

9 Divergent Evolution Species diverge or become increasingly distinct from one ancestral species Ex: Darwin’s finches Also called adaptive radiation

10 Convergent Evolution Process by which unrelated species become similar as they adapt to similar environments Ostrich Rhea Emu Australia South America Africa

11 Coevlution When 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 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!

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