Evidence of Evolution

By 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

Emu-Australia Ostrich-Africa Rhea-South America Biogeography tells us that organisms migrate from a place of origin and evolve into new species.

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 with similar 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