Why do so many different animals have the same structures, the arm bones in a human are the same bones as a flipper in a whale?

Why are there bones and fossil evidence of creatures that no longer exist? What happened to these creatures?

Why do organisms have structures they no longer use, like the appendix in a human? Non functioning wings in penguins?

Evolution

These questions and others can be answered by EVOLUTION The Theory of Evolution is considered a Unifying Theory of Biology, because it answers many of these questions and offers and explanation for the data.

Charles Darwin born in Shrewsbury, England, in 1809 studied medicine at Edinburgh University (1825-1827) where the sight of blood and surgery without anesthetics repulsed him studied to become a clergyman at Cambridge University (1827-1831)

He sailed aboard the Beagle for 5 years, working as a naturalist. After Cambridge, Charles was recommended for a surveying trip on the HMS Beagle. He sailed aboard the Beagle for 5 years, working as a naturalist.

Darwin noticed that everywhere he went on his voyage, the animals and plants differed vastly. Patterns in the species suggested that the species had changed over time and had given rise to new and different species.

Many of Darwin’s conclusions were based on observations of wildlife in the Galapagos Islands. The Galapagos Islands lie 500 miles west of Ecuador in the Pacific Ocean, directly on the equator. “Galapagos” means turtle.

Darwin noticed on these islands, there were several types of finches. Galapagos finches Darwin noticed on these islands, there were several types of finches. What it must have been like to be Darwin…

Galapagos finches In particular, Darwin observed something odd about the finches: they all looked like a bird he had seen on the South American continent.

Darwin wondered if the birds and other animals had been created to match their environment, why didn’t these birds look like the birds of the African continent, since the environments of both the Galapagos and Africa were similar.

Once on the islands, the birds must have changed over the years. Darwin guessed that some of the birds from South America migrated to the Galapagos. Once on the islands, the birds must have changed over the years.

This would explain the numerous species of birds present. large ground finch woodpecker finch cactus finch This would explain the numerous species of birds present.

evolution Darwin called this… descent with modification or (change in species over time)

Darwin extended these principles to biology, which helped him form his theory of… Natural Selection …or Survival of the Fittest.

Five basic components of Natural Selection

1. All species have genetic variation. Every species is different, even within itself. Look around you…are you all the same?

2. The environment presents challenges to survival. There is a constant struggle for survival. Examples are: Drought Fires Floods Snowstorms Hurricanes Tornadoes Other natural disasters

3. Organisms produce more offspring than can survive 3. Organisms produce more offspring than can survive. Competition (struggle for existence) exists WITHIN and AMONG species. Within a Species Among a Species food food space space mates

Organisms who possess favorable traits will leave more offspring. 4. Survival of the fittest. Some organisms are more suited to their environment as a result of variation in the species. Fitness: the ability of an individual to survive and reproduce in its specific environment. Fitness is a result of adaptation Organisms who possess favorable traits will leave more offspring. In other words, he who spreads the most genes wins! 1st

5. Decent with modification 5. Decent with modification. Living species today are descended with modifications from common ancestral species. Characteristics of fit individuals increase in a population over time. Over time, genes for less favored characteristics will be eliminated from the gene pool. Example: giraffes and their long necks.

Natural Selection: Survival of the Fittest An adaptation is any inherited characteristic ( a genetic variation ) that can increase an organism’s chance of survival. An organism does not change because of need or desire to survive. The organism either already has the variation that enables it to survive or it dies

Adaptations Adaptations are evidence of evolution Structural adaptations Mimicry – enables 1 species to look like another Yellow jacket wasp Harmless syrphid fly

Adaptations Camouflage enables organisms to blend in with their environment

Evidences of Evolution Today most evidences for evolution are grouped into five main categories: Fossil Record Biochemical Comparative Anatomy Biogeography Observable Events

COMPARATIVE ANATOMY HOMOLOGOUS STRUCTURES structures with similar structure but different function (ex: turtle, alligator, bird, mammal) Turtle Alligator Bird Mammal

COMPARATIVE ANATOMY Homologous structures show Similar genes Descent from a common ancestor Turtle Alligator Bird Mammal Ancient lobe-finned fish

COMPARATIVE ANATOMY VESTIGIAL STRUCTURES organs so reduced in size that they are nonfunctioning remnants of similar organs in other species ex: human tailbone, appendix, whale pelvis Whale pelvis diagram by cbray

COMPARATIVE ANATOMY ANALOGOUS STRUCTURES Body parts that do not have common evolutionary origins but are similar in function

COMPARATIVE ANATOMY EMBRYOLOGY Embryos of different species may appear similar in early stages of development Embryo drawings by cbray ex: vertebrate development

COMPARATIVE ANATOMY Comparison of similarities in embryos can show: Relationship to a common ancestor Embryo drawings by cbray

FOSSIL RECORD Paleontology Fossil – remains or traces of an organism that lived long ago Remains: ex. bone, tooth, or shell Traces: ex. burrow, footprint, or imprint Photos by cbray

FOSSIL RECORD Most fossils are found in layered sedimentary rock Oldest fossils are on the lowest layer Layers diagram by cbray

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. Genetic code table by cbray