Evidence of EvolutionBy Madalyn Incognito

The 5 evidences of evolution:

Fossils Biogeography Comparative embryology Comparative anatomy Comparative DNA (Biochemistry)

Fossils A fossil is a remnant or trace of a once

living organism How are fossils formed:

The animal dies Soft parts of the animal are eaten or decay;

the bones remain The bones or hard parts are covered in dust

and soil Bones are buried in layers of soil The layers of soil turn to stone. The remains

turn to stone and form a fossil Fossils show that life forms found in fossils

from millions of years ago have similar characteristics to modern life forms. It proves they originated from a common ancestor.

Dating of Fossils The age of rocks can be determined using radioactive

dating The age of rocks can also be determined by correlating

the fossils found in them with rocks of know age The oldest sedimentary rocks contain no fossils; no

evidence of life Older fossils are from organisms which were:

Simple Water living

Younger fossils are from organisms which were: Both simple and complex Both water and land living

Biogeography Biogeography is the study of living things

in relation to geographical regions Darwin and Wallace used biogeography as

evidence of evolution. They noticed that species living in the same area

were more similar to each other than to species living in similar habitats far apart

This shows that species evolved due to the selective pressure of their own habitats

Biogeography tells us that organisms migrate from a place of origin and evolve into new species.

Emu-Australia

Ostrich-Africa

Rhea-South America

Comparative Embryology Comparative Embryology is the branch of

Embryology that compares and contrasts embryos of different species.

Comparative Embryology determines that relatedness of species. Organisms withsimilar structures are argued to have acquired their traits from a common ancestor.

Comparative anatomy The anatomy of different species can be

compared to look for evidence of evolution from a common ancestor.

Homologous structures: Structures found in plants or animals that

have the same origin, but not necessarily exactly the same form or the same function

Example: Pentadactyl limb of vertebrae animals (mammals, reptiles and amphibians)

All vertebrae animals have limbs with five digits (finger-like structures) which have the same basic structural plan but have altered to different environments and lifestyles

This suggests that all these groups of animals originated from a common ancestor

Comparative DNA sequencing Comparison of the DNA sequences allows organisms to

be grouped by sequence similarity and as a result allows the construction of evolutionary trees

Comparative DNA sequencing shows that we all come from a common ancestor

We all have the same bases in our DNA, they are just arranged in different order

The more closely related the animals are the more similar their DNA sequence is

Example: If 2 new species evolved from a common ancestor, their DNA

and protein molecules would change and become different. The number of differences is proportional to the time since they separated