Evolution- “Change Over Time” All of the changes that have occurred in living things

since the beginning of life on Earth

History of the Earth

4.5 bya •Earth forms

3.5 bya•1st PROKARYOTES

2.1 bya •1st EUKARYOTES

Three important points… Evolution occurs over MANY generations Evolution occurs within POPULATIONS

(NOT individuals) Evolution involves genetic changes in a

SPECIES– (Members of a species interbreed to produce

healthy, fertile offspring)

Evidence for Evolution

FOSSIL EVIDENCE-Provides TRANSITIONAL LINKS

Archaeopteryx- links reptiles and birds

Therapsids- mammal-like reptiles

Anatomical EvidenceHOMOLOGOUS STRUCTURES

structures that are similar because they were inherited from a COMMON ANCESTOR

ANALOGOUS STRUCTURES

similar in function, but NOT inherited from a common

ancestor

NOTE: similar structure, but NOT always function!

NOTE: similar FUNCTION, but not STRUCTURE

In other words…

Sometimes we see structures in two species that are similar…some of them are:– Homologous (they are similar because of a

common ancestor)– Analogous (they are similar because althouth

they do NOT share a recent ancestor, they live in similar environments and have adapted to them similarly)

2 types of Evolution

More Anatomical Evidence:Vestigial Structures

Vestigial Structures are undeveloped structures that were functional in some ancestor, but are no longer needed in that organism.

EMBRYOLOGY- suggests common ancestors

BIOGEOGRAPHICAL EVIDENCE

When we study the distribution of plants and animals on the planet, we notice:– Animals evolved differently in each of the

biogeographical regions– We see evidence that as the continents drifted,

organisms were separated and evolved.

BIOCHEMICAL EVIDENCE

Almost all living things use the same biochemical molecules– DNA, Protein, ATP

Vast diversity came about by only slight differences in the same genes

The more closely “related” the organisms are, the more similar their DNA

Other Evidence…

1. Mimicry and Camoflauge

2. Antibiotic Resistance