The main lines of evidence of evolution are:

1. Fossil Record2. Homologous Structures3. Vestigial Structures4. Embryology5. Similarities in DNA

Fossil Record It is possible to find

out how a particular group of organisms evolved by arranging its fossil records in a chronological sequence

Provides evidence of changes in species over time

Formation of Fossils Fossils form when an organism dies and Fossils form when an organism dies and

becomes buried in sedimentbecomes buried in sediment With a lack of oxygen, the organism does With a lack of oxygen, the organism does

not decay and the minerals in the sediment not decay and the minerals in the sediment replace the organic materials of the replace the organic materials of the organismorganism

This turns the dead organism into solid This turns the dead organism into solid rockrock

Also why fossils are almost always only Also why fossils are almost always only found in layers of sedimentary rockfound in layers of sedimentary rock

Molds and CastsMolds and CastsMost commonMost commonMolds leave Molds leave hollow hollow impressionimpressionCasts are a Casts are a solid copy of the solid copy of the organismorganism

Types of Fossils

Petrified FossilsPetrified FossilsMinerals Minerals replace part or replace part or all of the all of the organismorganismEx- petrified Ex- petrified woodwood

Types of Fossils

Trace FossilsTrace FossilsProvide Provide evidence of a evidence of a once living once living organismorganismEx- footprints, Ex- footprints, burrows, dunburrows, dun

Types of Fossils

Preserved Preserved RemainsRemainsA process that A process that preserves an preserves an organisms with organisms with little of no changelittle of no changeEx- amber, ice, Ex- amber, ice, tartar

Types of Fossils

Homologous Structures Similar structures in Similar structures in

different organisms different organisms that develop from that develop from the same embryonic the same embryonic tissuetissue

Provides evidence of Provides evidence of a common ancestora common ancestor

Vestigial Organs A structure in an A structure in an

organism that has lost organism that has lost all or most of its all or most of its original function over original function over the course of evolution.the course of evolution.

Provides evidence of Provides evidence of changes in a species changes in a species over timeover time

Comparative Embryology The study of similarities The study of similarities

and differences in the and differences in the early development of early development of plants and animalsplants and animals

Similarities (like tails Similarities (like tails and gill slits of and gill slits of vertebrates) provides vertebrates) provides evidence of a common evidence of a common ancestorancestor

Similarities in Early Development

Similarities in DNA Species that are Species that are

closely related closely related have very similar have very similar sequences in sequences in DNADNA

Provides evidence Provides evidence of a common of a common ancestorancestor

So........ we have the evidence,we know species adapt,we know nature selects those that are most fit to survive,but how does a species change?

One mutation at a time!

A mutation is a change in the DNA base sequence of a gene.

Changes in DNA may change an organism’s physical appearance.

Mutations Harmful mutations hurt the success of the individual. Harmful mutations hurt the success of the individual.

Provide an example of a harmful mutation.Provide an example of a harmful mutation. Beneficial mutations help the success of the individualBeneficial mutations help the success of the individual

Provide an example of a beneficial mutation.Provide an example of a beneficial mutation. Neutral mutations do not help or harm the success of Neutral mutations do not help or harm the success of

the individual.the individual.

Provide an example of a neutral mutation.Provide an example of a neutral mutation.

Speed of Evolution

Gradualism- evolution Gradualism- evolution happens gradually over happens gradually over many generations and many generations and long periods of timelong periods of time

What types of events or circumstances do you think would make gradual changes in a species?

Speed of EvolutionPunctuated Equilibrium- Punctuated Equilibrium-

evolution that happens evolution that happens quickly over just a few quickly over just a few generationsgenerations

What types of events or circumstances do you think would make quick changes in a species?

The End