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Change in genetic structure of a population of organisms over time
Group of the same species that occupies a given area
Group of organisms with similar characteristics that can interbreed and produce viable offspring
The difference in reproductive success of individuals based on genetic traits
Where do traits come from?
Random changes in DNA from mating/mutations
Darwin's observations (2)
- Closely related organisms in different environments are different
- Unrelated organisms in similar environments are similar
Darwinian Evolution (4)
- Heritable Natural Variation
- Limited resources
- Those with traits best able to take advantage of resources are more likely to reproduce
- Species related by common descent
What does natural selection lead to over time (generations)?
Leads to new adaptations and species
What Darwin did NOT do:
- Understand HOW traits were passed on
- "Survival of the fittest"
Evidence of Evolution (6)
- Homologous Structures
- Comparative embryology
- Vestigial Structure
- Analogous Structures
- Field Studies
Parts of the body that are the same but take on different forms/ functions in different animals
Old structures that remain in organisms (human tail), evidence of past evolution
Analogous Structures (2)
- Structures that do not come from related organisms but they look similar
- Arise more than once
Importance of evolution (4)
- Medical Purposes
- Human Interactions
- Natural Resources
- Changes in gene frequencies in a population
- Shorter time periods
What causes microevolution? (3)
- Natural Selection
- Gene flow (migration)- moving in and out of a population
How does Microevolution work?
It works by changing a population "directionally"
- Longer time period
- Forms new species
Populations diverge from each other over time
What causes Allopatric Speciation?
Vicariance & Founder Events
Due to climate, geology, physical changes to habitat
Dispersal to new habitats, common on islands
Sympatric Speciation (3)
- No geographic isolation, but reproductive barriers form
- Specialization to specific foods, habitats
- Changes in behavior
How does evolution occur? (3)
- Change in numbers
- "forced" breeding
- "natural" breeding