8. Evidence of Evolution
Some evidence of evolution are homologies
and vestigial organs
Homologies are structural likenesses between
parts of different organisms.
• Examples: arm = flipper = wing.
Vestigial organs are any part of an organism that
no longer serves a useful function.
• Example: human appendix
10. Charles Darwin (1809-1882)
Charles Darwin
English scientist advanced
the theory of evolution
Proposed natural
selection.
Conducted his primary
research on the
Galapagos Islands.
11. What is this idea called
Natural Selection?
Certain physical traits help animals survive
eventually become the dominant trait
The better “fit” species lives longer and passes
their helpful physical traits on to offspring
Thus the struggle for existence results in the
“survival of the fittest”
13. What can trigger these changes?
Mutations
Random Genetic Drift
Gene Flow
14. Mutations
A sudden change in the make-up of the
gene or chromosome that brings a new
trait into existence.
Can be helpful or harmful.
Very rare to actually help a species
15. Random Genetic Drift
When a group passes on it’s genetic code to the
next generation not all genes are passed on…
More genetic combinations than offspring...not all
genes are passed on
16. Gene Flow
The transfer of hereditary
characteristics from one breeding group
to another.
Within Population
Across Population
Editor's Notes
Complex species have developed from simpler species because organisms are always striving to better adapt themselves to their physical surroundings
A species is a distinct classification of a plant or animal
Our Place…taxonomy
Evolution governed by natural laws.
Evolution based on the acquisition of acquired traits.
Giraffe has a long neck because it needs to stretch to reach food.
Didn’t believe that the population died off (natural selection)
His two most famous books were “On the Origins of Species” and “The Descent of Man”
Animals with certain physical characteristics that help them to survive in their given environment will live longer and produce more offspring. This will lead to that certain characteristic becoming a dominant trait of that species
Animals with good “survival equipment” are better “fitted” to live in their physical environment. They will live long and pass this “equipment” on to other members of the species
Random acts sometimes you win…sometimes you lose…
How our genes are passed on.
Peppered Moth…polluted areas vs. unpolluted areas.
Within a population:It can introduce or reintroduce genes to a population, increasing the genetic variation of that population.
Across populations:By moving genes around, it can make distant populations genetically similar to one another, hence reducing the chance of speciation. The less gene flow between two populations, the more likely that two populations will evolve into two species.
