evolution is a theory! a theory is a well supported explanation of a phenomena that has occurred in...
TRANSCRIPT
Evolution is a Theory!• A theory is a well
supported explanation of a phenomena that has occurred in the natural world
• A theory in science is a well tested, well supported hypothesis, not just a guess
Evidence of Evolution
1. Fossil Record
2. Geographic Distribution of Living Species
3. Homologous Body structures
4. Similarities in Embryology
Evidence of Evolution
Fossil Record provides evidence that living things have evolved
Fossils show the history of life on earth and how different groups of organisms have changed over time
Fossil Formation
1. Ammonite is alive and swimming 2. Ammonite dies and sinks into the sediments
3. Soft body decays, leaving shell (or bones)
4. Minerals gradually replace the bone/shell
Relative vs. Absolute Dating
Relative Dating
• Can determine a fossil’s relative age
• Performed by estimating fossil age compared with that of other fossils
• Drawbacks – provides no info about age in years
Absolute dating
• Can determine the absolute age in numbers
• Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remain
• Drawbacks - part of the fossil is destroyed during the test
Carbon-14 Dating
Primate Fossils
Australopithecus Homo erectus Homo sapien
Primate Brain
Capacity
Primate Bone structure
Human Relatives
Australopithecusafarensis
Homo habilis = handy human1.5 to 2 mya
Homo erectus1.6 mya
bipedal
Neanderthals35,000 to 100,000 ya
Cro-Magnon35,000 to 40,000 ya
2. Geographic Distribution of Living Species
Similar animals in different locations were the product of different lines of descent
Evidence of Evolution
Adaptive Radiation
Turtle
Alligator
Bird
Homologous Body StructuresStructures that have
different mature forms but develop from the same embryonic tissues
e.g. Wing of bat, human arm, leg of turtle
Evidence of Evolution
Homologous Body Structures
Vestigial Organs
– traces of homologous organs in other species
– Organ that serves no useful functione.g. Appendix
Evidence of Evolution
Similarities in Embryology
– In their early stages of development, chickens, turtles and rats look similar, providing evidence that they shared a common ancestry.
Mechanisms for evolution
• Do populations or individuals evolve?
• What is a gene pool?
• How do populations change?
Mechanisms for evolution
• Do populations or individuals evolve?
• What is a gene pool?
• How do populations change?
• Would these types of change effect a large or small population more?
WHAT IS SPECIATION?A single species becomes multiple species.A single species becomes multiple species.
Can result from:Can result from:
- Geographical isolation- Geographical isolation
SPECIATION• GEOGRAPHIC GEOGRAPHIC
ISOLATIONISOLATION
• REPRODUCTIVE REPRODUCTIVE ISOLATIONISOLATION
Coevolution
• Organisms evolve in response to each other.– For every defense mechanism a prey species
develops, a predator develops a way around it.– Pollinators become more and more specialized
to the plants that they pollinate.
Convergent evolution
Unrelated organisms evolve similar structures.
What were these structures called?!?
Homologous structures
Form Fits Form Fits FunctionFunction
Organisms will change Organisms will change over time to become more over time to become more and more efficient. Their and more efficient. Their physical structures will physical structures will
become increasingly become increasingly suited to their specific suited to their specific
tasks. tasks.
Evolution