1. Life Changes Over Time

2. Today’s Objectives
To investigate and understand how populations change through time, including:
How variation of traits, reproductive strategies, and environmental pressures impact on the survival of populations
Recognizing how adaptations lead to natural selection
How new species emerge

3. Charles Darwin On the Origin of Species Sailed with the HMS Beagle
Observations made in the Galapogos Islands
These observations helped him form the theory of how species change over time called natural selection

4. What is Natural Selection?
Natural selection is governed by the principles of genetics.

5. Types of Adaptations Protective Coloring Physiological Adaptations
Camouflage
Mimicry
Physiological Adaptations
Reproductive Changes
Other changes
Behavioral Adaptations

6. Evidence for Evolution
Fossil record
Anatomy
Homologous structures
Analagous structures
Vestigial structures
Embryology
Molecular biology (DNA differences)

7. What is a Population?
Populations evolve over many generations, individuals don’t
Populations are groups of interbreeding individuals that live in the same place at the same time
Individuals in a population compete for resources with each other

8. How Does Evolution Work?
Populations produce more offspring than the environment can support
The unequal ability of individuals to survive and reproduce leads to the gradual change in a population over many generations

9. Mechanism for change in a population of organisms
Animals who have greater fitness survive in environment and live to reproduce
Random changes (mutations) can lead to greater or less fitness
Adaptations allow an organism to survive better in their environment

10. Mutations & Variety Produced by Sexual Reproduction Allow for Diversity within a Population
Genetic drift (caused by chance)
Bottleneck
Founder effect
Genetic equilibrium
Hardy-Weinberg law
In H-W equilibrium, does not occur

11. Adaptations Can arise in response to environmental pressures
Temperature
Antibiotic resistance in bacteria
Pesticide resistance
Morphological changes in peppered moths

12. Types of Selection Directional Stabilizing Disruptive
Extreme form favored by natural selection
Stabilizing
Middle form most successful
Disruptive
Two extreme forms successful in separate environments

13. How are new species created?
Geographic isolation
Reproductive barriers
Change in chromosome numbers
Adaptive radiation

14. Types of Evolution Convergent evolution Divergent evolution
Dolphins & fishes
Wings of bees & bats
Divergent evolution
Darwin’s finches
Adaptive radiation

15. How fast does evolution occur?
Gradualism
Species change slowly over time
Punctuated Equilibrium
--Species can make rapid “leaps” in evolution
Modern Synthesis
Parts of both are correct