Evidence supporting Evolution

Six main lines of evidence that supports the theory of evolution Fossil Evidence Homologous Structures Vestigial Structures Geographic Distribution of organisms Embryology DNA Evidence

Fossils How Fossils Form Fossils can be very large complete skeletons, or very small items such as a tooth Most fossils form in sedimentary rock The formation of fossils only occurs under certain conditions & therefore the fossil record is an incomplete record of life & evolution

Fossil Record Fossil of a fish: perch

Formation of a Fossil Water carries small rock particles to lakes and seas. Dead organisms are buried by layers of sediment, which forms new rock. The preserved remains may later be discovered and studied.

What we can conclude from the fossil record? The fossil record provides evidence about the history of life on Earth. It also shows how different groups of organisms have changed over time 99% of all living things that have lived on the Earth are now extinct

What the fossil record show us Organisms that went Extinct Example: Ammonite

What the fossil record show us

What the fossil record show us Example: Dinosaur tracks

What the fossil record show us The fossil record shows us how animals have changed over time o Examples: Skulls of Australopithecus and Homo erectus

The fossil record shows us how animals have changed over time Examples: Fossils of Skeletons of horse ancestors shows the evolution of the modern horse

Fossils of Skeletons of horse ancestors shows the evolution of the modern horse

Figure 25.1h Mammoth tusks

Figure 25.1c Petrified trees

Figure 25.1a Dinosaur National Monument

Figure 25.1d Leaf impression

Geographic Distribution of Organisms The distribution of living things on the globe provides information about the past histories of both living things and the surface of the Earth. Example: Fossils of marsupials found in the Antarctic as well as in South America and Australia

Geographic Distribution of Organisms Closely related species tend to be found close together suggesting that they evolved in on place and then spread.

Homologous Structures Traits that are similar in different species, share a common ancestor Examples: arm in a human, flipper a seal, wing of a bat all have the same bone structures, but serve different functions The species then adapted to a different niche

The bones in a bat's wing, human's arm, penguin's flipper are the same (homologous), but the function is different

What can we conclude from similarities in bone Structure? Common Ancestors

Analogous Structures Similar in function, differ in structure, not inherited from a COMMON, ancestor For example, the wing of a bird and the wing of an insect are classified as being analogous structures since their structures are unrelated (next slide) Evolved independently

Vestigial Structures Structures that are inherited but no longer used by the organism They are ancestrial remnants that once had a purpose, but now have no functional pupose Example: Small hind leg bones (pelvis & femur) of a whale

Example: Our appendix has no functional purpose, but our herbivore ancestors used it to help them digest plant material

Embryology Vertebrates embryos pass through a series of similar stages in early development.

Human Chicken Pig

Biochemical Evidence of Evolution Similarities between living things: All use DNA as their genetic material All use the same 20 amino acids in their proteins All use ATP to store chemical energy. All do similar cellular respiration to access energy from food (chemical energy)

DNA Evidence Comparing DNA sequences between living organism show close similarities between organisms of different species.

Example: Humans and chimpanzees have 95-99% identical DNA sequence This suggests a recent common ancestor.

ALL LIVING THINGS USE DNA Similarities between living things: All use DNA as their genetic material Suggesting common ancestry.

All proteins in living things are made of the same 20 amino Similarities between living things: All use the same 20 amino acids in their proteins Suggesting common ancestry.

Similar Proteins in all vertebrates All vertebrates, including fish, reptiles, amphibians, birds, mammals use the protein hemoglobin to transport oxygen in blood. Suggesting common ancestry.

Similarities between living things: D.5.2 Explain the biochemical evidence provided by the universality of DNA and protein structure for the common ancestry of living organism Similarities between living things: All use left, and not right-handed amino acids Suggesting common ancestry.

ATP All living things use the molecule Adenine Triphosphate for energy. Suggesting common ancestry.