Evidence of EVOLUTION
Evolution: Genetic change in a population through time
Charles Darwin On his journey around the world, Darwin found evidence of GRADUAL CHANGE (evolution) He cited evidences he found in Fossil records Geographic distribution Homologous structures
Evidences of Evolution Today, most evidences of evolution are grouped into 5 main categories: 1. Fossil record 2. Biochemical 3. Comparative anatomy 4. Biogeography 5. Observable events
Fossil Record Paleontology: the study of fossils Fossil: remains or traces of an organism that lived long ago Remains of an organism are things like bones, teeth, or shells Traces of an organism are things like burrows, footprints, or imprints #1
NEW Most fossils are found in layered sedimentary rock Oldest fossils are on the lowest layer Comparing fossils shows: Life on Earth has changed over time An increased number of life forms OLD #1
Biochemical The genetic code Triplets of DNA nitrogen base sequences that code for specific amino acids The amino acid triplet is the same in almost all organisms #2
The similarity of triplet DNA codes making up amino acids shows: A probable common ancestor for all life on Earth Universal genetic code: from organism to organism, genes code for the same amino acids #2
Amino acid sequencing: the amino acid sequence in a particular protein is compared between organisms Amino acid sequencing shows: closeness of relationship a probable common ancestor Number of differences from human hemoglobin Amino acid sequencing is probably the STRONGEST evidence for relationships among organisms #2
Cladogram: diagram that shows the evolutionary relationship among a group of organisms #2
Which organism belongs at each branch? Where does the common ancestor belong? Species AA Difference Gorilla 1 Rhesus Monkey 8 Mouse 27 Chicken 45 Frog 67 Lamprey 125 #2
Comparative Anatomy Homologous structures: structures with similar structure but DIFFERENT FUNCTION ex: turtle, alligator, bird, mammal Homologous structures show: similar genes descent from a common ancestor #3
Analogous structures: body parts of organisms that do NOT have a common evolutionary origin but are similar in function Analogous structures don t illustrate evolutionary relationships; they do provide evidence for evolution #3
Vestigial structures: organs so reduced in size that they are nonfunctioning remnants of similar organs in other species ex: human tailbone, appendix, whale pelvis Vestigial structures show: an organism s evolutionary past a common ancestor with species that have similar structures that are still functioning #3
Embryology: the study of embryos Embryos of different species may appear similar in early stages of development ex: vertebrate development Comparison in similarities in embryos can show: Relationship to a common ancestor #3
Biogeography Geographic distribution of organisms Organisms living widely apart (even different continents) may be similar because they share a common ancestor Biogeography shows: a common ancestor #4
Observable Events Some changes in species have been observed and studied: Peter & Rosemary Grant s study of beak size shift in Darwin s finches H. Kettlewell s study of peppered moth color shifts Observable events show that evolution is an ongoing process #5
Summary 1. Fossil records show that life on Earth has changed, and that there is an increased number of life forms. 2. Biochemical evidence shows that there s a probably common ancestor for all life on Earth. Amino acid sequencing is the strongest evidence for relationships among organisms 3. Comparative anatomy shows similar genes and descent from a common ancestor. 4. Biogeography shows common ancestry. 5. Observable events show that evolution is an ongoing process.
Works Cited Miller, Kenneth and Levine, Joseph. (2004). Biology. Prentice Hall.