Evidence for Evolution
An adaptation is anything that gives an organism a better chance of survival. Structural and physiological adaptations are considered direct evidence of evolution. Most of the evidence to support evolution is indirect.
Direct Evidence
Camouflage - being able to hide or disguise one's self from veiw of something or someone else.
Mimicry- Act of portraying another one's actions
Mimicry- Act of portraying another one's actions
![Picture](/uploads/8/8/7/7/88774156/04-walking-leaf-walkingstick-mimicry-indonesia.jpg?250)
This is a drip-tip katydid mimicking a leaf.
(example of mimicry)
(example of mimicry)
![Picture](/uploads/8/8/7/7/88774156/acanthops-tuberculata-03.jpg?250)
This boxing mantis portrays dead leaves.
(example of mimicry)
(example of mimicry)
![Picture](/uploads/8/8/7/7/88774156/cheetah.jpg?250)
This cheetah uses its spotted skin to blend in with the dry grassland of Africa.
(example of camouflage)
(example of camouflage)
![Picture](/uploads/8/8/7/7/88774156/animal-camouflage-4.jpg?250)
This owl uses its patterned body to blend in with tree bark.
(example of camouflage)
(example of camouflage)
Indirect Evidence
Indirect evidence comes from fossils, anatomy, biochemical, and embryology.
- Fossil Evidence-
![Picture](/uploads/8/8/7/7/88774156/real-layers.gif?266)
Fossil age is determined by carbon dating. The farther the layer from the top layer, the older the fossils within that layer are. The closest layer to the top layer of sediment, the younger the fossils within that layer are. The oldest layer in this picture is the Proterozoic layer. (hence its position from the top layer) The youngest layer in this picture is the Cenozoic Layer. (hence its position from the top)
2. Anatomical Evidence-
Homologous Structures- organisms having similar body
structures show that they have descended from similar ancestors. (represented by the 1st picture) Analogous Structures- organisms having similar functions but different basic structure. (represented by the 2nd picture) Vestigial Structures- organisms having structures that don't have a function but appear to have had a purpose in its ancestral kin. (represented by the 3rd picture) |
3. Embryological Evidence-
![Picture](/uploads/8/8/7/7/88774156/embry.jpg?471)
The two most closely related organisms are the fish and the salamander.
Natural Selection
Charles Darwin was born on Febuary 12th, 1809, in Shewsbury, England. He was the secong youngest of six children. His father and grandfather were doctors. After recieving a bachellors degree at Christ's College, Darwin set off on a 5 year voyage around the world, recommended by a botany proffessor, John Stevens Henley. Darwin boarded the ship, the HMS Beagle, commanded by Captain Robert Fitzroy. Out of his whole trip, the Pacific Islands, Galapagos Archipelago, and South America, were his main points of interest. He collect a variety of specimens from the trip. He created a theory based off of the slight adaptations, or changes, in certain species that appeared to decend from the same ancestors. He said that species changed their traits in order to survive in their environment. This theory was called Natural Selection.
Natural Selection- "Survival of the fittest", when organisms with the strongest traits survive and reproduce.
Effects of natural selection on polygenic traits
Directional Selection- individuals at EITHER END has higher fitness than individuals near the MIDDLE. Disruptive Selection- individuals at UPPER AND LOWER ENDS have higher fitness than individuals near the MIDDLE. Stabilizing Selection- individuals NEAR THE CENTER of a curve have higher fitness than individuals at EITHER END. |
Artificial Selection is the selection of certain animals and livestock to breed in order to produce more meat or better tasting foods.