Evidence for Evolution презентация

EVOLUTION
OF BIRDS
EVOLUTION
OF HORSES
5.1 EVIDENCE FOR EVOLUTION

THE THEORY OF EVOLUTION
5.1 EVIDENCE FOR EVOLUTION
“First” proposed by Charles Darwin.
Based on data collected from 1831-1836 as a naturalist on HMS Beagle.
Darwin did not publish his theory, fearing hostile reactions.

WE SHOULD THANK ALFRED WALLACE…
5.1 EVIDENCE FOR EVOLUTION
In 1858 Wallace sent Darwin a letter outlining his theory on evolution.
Darwin was surprised that Wallace’s basic arguments were the same as his.
Spurred Darwin to publish his theory in his book in 1859
The theory should really be referred to as the Darwin-Wallace Theory!
Video biography of Wallace and Darwin

ANALYSING THE EVIDENCE
5.1 EVIDENCE FOR EVOLUTION
Most biologists accept the theory of evolution based on evidence from:
Fossils ? sequence of preserved organisms matches expectations. Patterns can be seen.
Selective Breeding ? artificial selection can occur
Homologous Structures ? similar structures derived from a common ancestor that may now serve different functions
Patterns of Variation ? examples of gradual divergence across a geographical range
Ross & Phoebe debate evolution

FOSSILS
Rocks are deposited in
layers ? older rocks
lower down
Older fossils found
lower down
Now supported by radioisotope dating
Sequence of fossils matches expectation
5.1 EVIDENCE FOR EVOLUTION

5.1 EVIDENCE FOR EVOLUTION
FOSSILS
Bacteria ? Algae ? Fungi ? Worms ? Fish ? Amphibians ? Reptiles ? Birds ? Mammals
Ecology ? Plant fossils appear before animals; Plants on land appear before animals on land

FOSSILS
Sequences of fossils found linking together current species with likely ancestors
5.1 EVIDENCE FOR EVOLUTION

2. SELECTIVE BREEDING
Artificial selection
Repeatedly select & breed individuals
with desired characteristics
Produced breeds often very different
to the wild species
Short amount of time
+ Selection can cause evolution
- Doesn’t prove evolution occurs naturally
5.1 EVIDENCE FOR EVOLUTION

2. SELECTIVE BREEDING
5.1 EVIDENCE FOR EVOLUTION
Auroch
from Asia
Belgian
Blue

3. HOMOLOGOUS STRUCTURES
Structures that:
Look different
Perform different functions
But have the same origin
? an evolutionary ancestor
They have changed due to
adaptive radiation
Makes them specialised for
a specific function
Example of divergent evolution
5.1 EVIDENCE FOR EVOLUTION

3. HOMOLOGOUS STRUCTURES
Pentadactyl Limb
Same arrangement of bones
Look different as they serve different functions
5.1 EVIDENCE FOR EVOLUTION
Worksheet
Activity

3. HOMOLOGOUS STRUCTURES
Vestigial organs
Reduced structures that serve no function
Difficult to explain without evolution
Evolution = structures that no longer have a function so are being gradually lost
5.1 EVIDENCE FOR EVOLUTION

3. HOMOLOGOUS STRUCTURES
Analogous Structures
Similarities in structure
Different origins/ancestors
Become similar as they
perform similar functions
Convergent evolution
5.1 EVIDENCE FOR EVOLUTION

4. BIOGEOGRAPHIC
Speciation
2 populations become separated
Cannot interbreed
Natural selection acts differently
Characteristics diverge
After time look recognizably different
If populations merge again may not be able to interbreed
They have evolved into separate species
5.1 EVIDENCE FOR EVOLUTION
https://www.youtube.com/watch?v=Egl-Bcbu5Ow
https://www.youtube.com/watch?v=tRc9DawVHaU

5.1 EVIDENCE FOR EVOLUTION

4. BIOGEOGRAPHIC
Endemic Species
Only found in one geographical location
Common on islands
Mainland species migrates
Then diverges (e.g. lava lizard on Galapagos Islands)
5.1 EVIDENCE FOR EVOLUTION