evidence what evidence do we have to support the idea of evolution by natural selection?

WHAT EVIDENCEEVIDENCE DO WE HAVE TO SUPPORT THE IDEA OF EVOLUTION BY NATURAL SELECTION?

FOSSILSFOSSILS any remains of life from

an earlier time and the most abundant evidence for evolution

Sedimentary rock contains the most fossils and is formed from mud, sand, and other fine particles

How do scientists figure out how old something is?

Relative Dating —looking at where the rock is located. Older layers are deeper than the layers above. This method only provides an estimated age of a fossil.

How do scientists figure out how old How do scientists figure out how old something is?something is?

Radioactive Dating —measuring how a radioactive element in the fossil (like Carbon or Uranium) has decayed. They compare the amount of stable rock to amount of radioactive element still present.

Not the same kind of dating… Not the same kind of dating…

http://www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html

Fossils document how organisms changed over time, but much of the fossil record is missing or incomplete (like a book with pages ripped out)!

Fossil Hunting on the Galapagos

THERE ARE DIFFERENT KINDS OF FOSSILS…AND DIFFERENT WAYS THAT FOSSILS CAN FORM…

Amber Fossils

Prehistoric termites trapped in amber

Lizard in Amber

Frog in Amber

Fossils that are hardened in tree sap…

Woolly Mammoths

Bones…

Frozen in ice or permafrost…

When do humans “show up” on the planet?

Fossils by Brainpop

Fossils Adv. by Brainpop

Geologic Time by Brainpop

Additional Video ClipsAdditional Video Clips

HOMOLOGOUS STRUCTURESHOMOLOGOUS STRUCTURES

body parts that are similar in origin and structure.

Example: arms, dolphin fin, bat wing, bird wing

VESTIGIAL STRUCTURESVESTIGIAL STRUCTURES

A body part that is reduced in size and does not seem to have a function.

Examples: human appendix,

wisdom teeth and muscles that are for moving the ears.

EMBRYOLOGYEMBRYOLOGY study of the development of

embryos (an organism in its earliest stages of development).

ExamplesExamples: gills and tailbones in humans

What similarities do you see between these embryos?

COMPARING DNA CODESCOMPARING DNA CODES the closer the DNA sequences are in

organisms, the more closely related they are.

Example: DNA has shown that dogs are the closest relatives of bears. Human’s closest relatives are from the ape family.

Cousins?

Example: Humans are most closely related (99.9%) to chimpanzeeschimpanzees.

http://www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html

Other Video Clips

Elephant Evolution

Woolly Mammoths

WHAT CONCLUSIONS CAN BE DRAWN FROM THESE CONCEPTS?

DIVERSITYDIVERSITY over millions of years, the

process of natural selection has created all the different life forms on Earth. Scientists estimate anywhere from 5 million to 100 million species on the planet, but have only identified about 2 million.

DIVERSITYDIVERSITY

CLICK HERE FOR A BIODIVERSITY INTERACTIVE MAP:http://www.biodiversityhotspots.org/xp/Hotspots/pages/map.aspx

RELATEDNESSRELATEDNESS since species evolve from one to the

other, there is always a degree of similarity between them. Generally, the more closely related they are, the more recently they evolved or separated into distinct species. All species are connected on earth because they all share some level of DNA.

RELATEDNESSRELATEDNESS

RELATEDNESSRELATEDNESS

TREE OF LIFE WEB PROJECT: http://tolweb.org/tree/

EXTINCTIONEXTINCTION occurs when an entire species dies

out Due to a change in the

environment without time to adapt/evolve to survive in it

EXTINCTION BY BRAINPOPEXTINCTION BY BRAINPOP