1. Chapter Ten: Principles of Evolution

2. Section One: Early Ideas About Evolution
The process of biological change by which descendants come to differ from their ancestors
Scientists Involved
Linnaeus: developed a classification system
Species: a group of organisms so similar to one another that they can reproduce and have fertile offspring
Buffon: proposed that species shared ancestors
Erasmus Darwin: proposed that all living things came from a common ancestor
Lamarck: said changes in the environment could change an organism’s behavior and thus change its genetics

3. Section One: Early Ideas About Evolution
The fossil record set the stage for the theory of evolution
Fossil: traces of organisms that existed in the past
The fossil record also led to other theories
Catastrophism: says natural disasters such as floods and volcanic eruptions have happened often during the history of Earth
Gradualism: changes in landforms are a result of slow changes over a long period of time
Uniformitarianism: the geologic processes that shape Earth are uniform through time

4. Section Two: Darwin’s Observations
Charles Darwin
Observed variation among traits in similar animals
Variation: the difference in the physical traits of an individual from those of other individuals in the group to which it belongs
Said species somehow adapted to their surroundings
Adaptation: a feature that allows an organism to better survive in its environment
Can lead to genetic change in a population over time

5. Section Two: Darwin’s Observations
Charles Darwin
Found fossil evidence of species changing over time
He found fossils of marine animals in the mountains suggesting geological changes through time also

6. Section Three: Theory of Natural Selection
Insights to Natural Selection
Artificial Selection: the process by which humans change a species by breeding it for certain traits
Heritability: the ability of a trait to be passed down from one generation to the next

7. Section Three: Theory of Natural Selection
A process by which individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals
Observed in populations
Population: all the individual of the same species that live in the same area
Thomas Malthus added that availability of resources also had an effect on species survival

8. Section Three: Theory of Natural Selection
Helps to explain how evolution can occur
Variation
Overproduction: having many offspring raises the chances of survival but also increases competition
Adaptation
Descent with modificaton: descending from the same organism but with some changes
Fitness: the measure of the ability of an organism to survive and reproduce

9. Section Three: Theory of Natural Selection
Acts on existing variation
If an organism’s environment changes, natural selection will cause a change in the organisms
Adaptations do not make an individual perfectly suited for its environment

10. Section Four: Evidence of Evolution
Evidence for Evolution
Fossils
Geography
Migration of individuals from mainland to islands
Biogeography: the study of the distribution of organisms around the world
Embryology
Embryos of different kinds of animals can sometimes be hard to tell apart
Adds to the idea of common descent

11. Section Four: Evidence of Evolution
Evidence for Evolution
Anatomy
Homolgous Structures
Features that are similar in structure but appear in different organisms and have different functions
Ex: forelimbs of certain animals
Analogous Structures
Structures that perform similar functions
Ex: bat wings and wings of a fly
Vestigial Structures
Remnants of organs or structures that had a function in early ancestors
Ex. Pelvic and hind limb bones in snakes

12. Section Four: Evidence of Evolution

13. Section Five: Evolutionary Biology Today
Paleontology: the study of fossils or extinct organisms
DNA sequencing
Pseudogenes: like vestigial structures
Homeobox genes: control development of specific structures
Protein comparison