Evolution
Evolution: Hypothesis or Theory
Hypothesis
A hypothesis is an informed or educated assumption
- It provides a solution to a problem
- It provides an explanation of a specific phenomenon
It is based on scientific evidence and research
It can be tested by experiments or repeated observation
- Depending on the results it is either rejected or accepted
Theory
A theory is a well-substantiated explanation or hypothesis
- It makes sense of a natural phenomenon
It is based on scientific evidence
- It can be tested and confirmed by independent researchers
It is developed and changed or replaced as new evidence is observed
Evolution is a theory
- It is based on a series of hypotheses
- It has been tested and verified over time
, Evolution
Evidence of evolution
Fossil record
- Indicates the climate and environment from the past
- Few individuals fossilise
o Very specific conditions are needed for fossilisation
- Earlier, simpler fossils are found in deeper, older rock
o Recent, complex fossils are found in upper, newer rock
o This indicates the order in which evolution occurred
- Older rock has less biodiversity than new rock
o This indicates biodiversity increased over time
- The fossil record contributes to the complete compilation of
the geological timescale
Modification by descent
- Modification of limbs to adapt to environment
- Modification can occur within a species or within
relatives of a species
o Can result in speciation
ANALOGOUS STRUCTURES
, Evolution
Homologous structures (Divergent evolution)
- Same body plan with different functions
- Can be traced back to a common ancestor
- Develop independently
o Suited to a specific habitat
Analagous Structures (Convergent evolution)
- Same function but different structure
- Adapted to similar environments
- No common ancestor
Evolution: Hypothesis or Theory
Hypothesis
A hypothesis is an informed or educated assumption
- It provides a solution to a problem
- It provides an explanation of a specific phenomenon
It is based on scientific evidence and research
It can be tested by experiments or repeated observation
- Depending on the results it is either rejected or accepted
Theory
A theory is a well-substantiated explanation or hypothesis
- It makes sense of a natural phenomenon
It is based on scientific evidence
- It can be tested and confirmed by independent researchers
It is developed and changed or replaced as new evidence is observed
Evolution is a theory
- It is based on a series of hypotheses
- It has been tested and verified over time
, Evolution
Evidence of evolution
Fossil record
- Indicates the climate and environment from the past
- Few individuals fossilise
o Very specific conditions are needed for fossilisation
- Earlier, simpler fossils are found in deeper, older rock
o Recent, complex fossils are found in upper, newer rock
o This indicates the order in which evolution occurred
- Older rock has less biodiversity than new rock
o This indicates biodiversity increased over time
- The fossil record contributes to the complete compilation of
the geological timescale
Modification by descent
- Modification of limbs to adapt to environment
- Modification can occur within a species or within
relatives of a species
o Can result in speciation
ANALOGOUS STRUCTURES
, Evolution
Homologous structures (Divergent evolution)
- Same body plan with different functions
- Can be traced back to a common ancestor
- Develop independently
o Suited to a specific habitat
Analagous Structures (Convergent evolution)
- Same function but different structure
- Adapted to similar environments
- No common ancestor
