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!