Evolution and Darwin. Evolution processes earliest forms diversityThe processes that have transformed life on earth from it’s earliest forms to the vast.

EvolutionEvolutionandand

DarwinDarwin

EvolutionEvolution

• The processesprocesses that have transformed life on earth from it’s earliest formsearliest forms to the vast diversitydiversity that characterizes it today.

• A changechange in the genes!!!!!!!!genes!!!!!!!!

Old Theories of EvolutionOld Theories of Evolution

• Jean Baptiste LamarckJean Baptiste Lamarck (early 1800’s) proposed:

““The inheritance of acquired characteristics”The inheritance of acquired characteristics”

• He proposed that by using or not using its body parts, an individual tends to developdevelop certain characteristicscharacteristics, which it passespasses on to its offspringoffspring.

““The Inheritance of Acquired The Inheritance of Acquired Characteristics”Characteristics”

• Example:Example:

A giraffe acquired its long neck because its ancestor stretched higher and higher into the trees to reach leaves, and that the animal’s increasingly lengthened neck was passed on to its offspring.

Charles DarwinCharles Darwin

• Influenced by Charles LyellInfluenced by Charles Lyell who published “Principles of Geology”.“Principles of Geology”.

• This publication led DarwinDarwin to realize that natural forces gradually change Earth’s surface and that the forces of the past are still operating in modern times.

Charles DarwinCharles Darwin

• Darwin set sail on the H.M.S. BeagleH.M.S. Beagle (1831-1836) to survey the south seas (mainly South America (mainly South America and the Galapagos Islands)and the Galapagos Islands) to collect plants and animals.

• On the Galapagos Islands, Galapagos Islands, Darwin observed species that lived no where else in the world.

• These observations led Darwin to write a book.

Charles DarwinCharles Darwin

• Wrote in 1859Wrote in 1859: “On the Origin of Species by “On the Origin of Species by Means of Natural Selection”Means of Natural Selection”

• Two main points:Two main points:

1.1. Species were not created in their present Species were not created in their present form, but evolved from ancestral species.form, but evolved from ancestral species.

2.2. Proposed a mechanism for evolution:Proposed a mechanism for evolution: NATURAL SELECTIONNATURAL SELECTION

Natural SelectionNatural Selection• IndividualsIndividuals with favorablefavorable traitstraits are more

likely to leave more offspring better suited for their environmentenvironment.

• Also known as “Differential Reproduction”“Differential Reproduction”

• Example:Example:

English peppered moth (English peppered moth (Biston betularia))

- light and dark phases- light and dark phases

Artificial SelectionArtificial Selection

• The selective breedingselective breeding of domesticated plants and animals by man.

• Question:Question:

What’s the ancestor of the domesticated dog?

• Answer:Answer: WOLFWOLF

Evidence of EvolutionEvidence of Evolution

1.1. Biogeography: Biogeography:

Geographical distribution of species.Geographical distribution of species.

2. Fossil Record:2. Fossil Record:

Fossils and the order in which they Fossils and the order in which they appear appear in layers of sedimentary rock in layers of sedimentary rock (strongest (strongest evidence).evidence).

Eastern Long Necked Turtle

Evidence of EvolutionEvidence of Evolution

3. Taxonomy:3. Taxonomy:

Classification of life forms.Classification of life forms.

4. Homologous structures:4. Homologous structures:Structures that are similar because Structures that are similar because

of of common ancestry common ancestry (comparative (comparative anatomy)anatomy)

Evidence of EvolutionEvidence of Evolution

5. Comparative embryology:5. Comparative embryology:

Study of structures that appear Study of structures that appear during during embryonic development.embryonic development.

6. Molecular biology:6. Molecular biology:

DNA and proteins (amino acids)DNA and proteins (amino acids)

Convergent EvolutionConvergent Evolution

• SpeciesSpecies from different evolutionary branchesevolutionary branches may come to resemble one another if they live in very similar environments.very similar environments.

• Example:Example:

1.1. Ostrich (Africa) and Emu (Australia).Ostrich (Africa) and Emu (Australia).

2.2. Sidewinder (Mojave Desert) andSidewinder (Mojave Desert) and

Horned Viper (Middle East Desert)Horned Viper (Middle East Desert)

CoevolutionCoevolution

• Evolutionary changeEvolutionary change, in which one species act as a selective forceselective force on a secondsecond species, inducing adaptations that in turn act as selective force on the firstfirst species.

• Example:Example:

1.1. Acacia ants and acacia treesAcacia ants and acacia trees

2.2. Humming birds and plants with Humming birds and plants with flowers flowers with long tubeswith long tubes

Fossils• How do Fossils form?

• Fossils form when the bodies of dead plants and animals are covered in sediment

Fossils

• Petrified Fossils – Fossils that are filled with dissolved minerals and become rock

• Molds and Casts – the fossil dissolves over years and what’s left is filled with sediment

• Preserved Remains – entire organism is whole preserved by ice or tar

Fossils

Dating Fossils

• Scientists can determine the age of a fossil in two ways– Relative Dating

• Fossils are compared to surrounding soil and an approximate age is determined

– Carbon Dating• Scientists measure the amount of Carbon 14

left in the fossil, which is radioactive.

Fossils

• What can we learn from fossils?

• What do fossils prove?

• How old is the Earth?– 4.6 Billion Years old– Largest block of time the Precambrian Era

(4 billion years)

Questions about Evolution

• What happened to the Dinosaurs?– 6 million years ago the Cretaceous period

ending, killing all the dinosaurs– Why?

• Gradualism – evolution occurs slowly but surely

• Punctuated Equilibria – Species evolve in short, quick time periods

Let’s Make our own Fossils!!• Fossils are most commonly found in limestone, shale, and

sandstone, all relatively soft rock that erodes more easily than most rocks do. As the rock gradually wears away, the fossil layers within it are exposed. One enjoyable way of demonstrating how fossils are made is to make fossil "casts" or prints out of plaster.

• 1.   Start with a clean tuna can or styrofoam bowl and fill it to a depth of about 1" with modeling clay. Then press a plastic animal, rock, or other object halfway into the clay. Remove the object, leaving a clean imprint in the clay. 2.   Next, mix 1/4 to 1/2 cup plaster of paris with water until the consistency is similar to pancake batter. Pour the plaster into the can over the clay, filling the imprint and covering the bottom of the can to a depth of about 1". Let the plaster dry for at least 24 hours before removing it from the can. Separate any remaining clay from the plaster and you have a "fossil" of the object.