The fossil recordThe fossil record

What is a fossil?What is a fossil?

A trace from a long dead A trace from a long dead organism.organism.

Biogeography – study of the Biogeography – study of the geographical distribution of fossils geographical distribution of fossils and living organisms. and living organisms.

How fossils formHow fossils form Hard parts such as shells, bones, or Hard parts such as shells, bones, or

teeth, are long-lasting and may teeth, are long-lasting and may become preserved as fossils. become preserved as fossils.

Under the right conditions, minerals Under the right conditions, minerals dissolved in groundwater seep into dissolved in groundwater seep into the tissues of a dead organism and the tissues of a dead organism and replace its organic material. The replace its organic material. The remains become petrified—they turn remains become petrified—they turn to stone. to stone.

What types of fossils What types of fossils are there?are there?

Mold – an imprintMold – an imprint

Cast- molds that are eventually filled Cast- molds that are eventually filled with minerals. with minerals.

Dating fossils: Relative Dating fossils: Relative AgesAgesLaw of superimpositionLaw of superimposition – sucessive layers – sucessive layers of rock and soil are layered on top of one of rock and soil are layered on top of one another. another.

The lowest stratum (layer) would have The lowest stratum (layer) would have the oldest fossils. the oldest fossils.

Dating fossils: Absolute Dating fossils: Absolute AgesAges

Radiometric datingRadiometric dating - method most - method most often used to determine the absolute often used to determine the absolute ages of rocks and fossils. ages of rocks and fossils.

Based on the measurement of Based on the measurement of certain radioactive isotopes in certain radioactive isotopes in objects.objects.

What we can learnWhat we can learn

Species that existed and then became Species that existed and then became extinct. extinct.

There were several mass extinctions – There were several mass extinctions – brief periods where large number of brief periods where large number of species disappeared. species disappeared.

EvolutionEvolution

All the changes that have All the changes that have transformed life over an transformed life over an immense time.immense time.

LamarckLamarck

Proposed that life evolves of Proposed that life evolves of changes.changes.

Adaptation – an inherited Adaptation – an inherited characteristic that improves an characteristic that improves an organism’s ability to survive and organism’s ability to survive and reproduce in an environment.reproduce in an environment.

Voyage of the BeagleVoyage of the Beagle

When: December 1831When: December 1831 Mission: Chart unmapped Mission: Chart unmapped

stretches of South America’s stretches of South America’s coastline.coastline.

Charles Darwin was on this trip to Charles Darwin was on this trip to study the geology and plant and study the geology and plant and animal life encountered.animal life encountered.

UniformitarianismUniformitarianism

Earth’s geological structure Earth’s geological structure results from observable processes results from observable processes that cycle.that cycle.

Darwin: Modification of Darwin: Modification of environment is a very slow environment is a very slow process. process.

What did Darwin see?What did Darwin see?

Plants in South America were quit Plants in South America were quit distinct from the plants in Europe.distinct from the plants in Europe.

Fossils found were distinct – Fossils found were distinct – appeared to be gigantic versions appeared to be gigantic versions of modern animals.of modern animals.

Supported the thought that species Supported the thought that species living on the continent were decedents living on the continent were decedents from ancestral species that used to from ancestral species that used to live on the continent. live on the continent.

Darwin’s Main Points: Darwin’s Main Points: Descent with Descent with ModificationModificationToday’s species descended from Today’s species descended from ancestral species. Depending on where ancestral species. Depending on where the modern species ended up they the modern species ended up they adapted to that environment. adapted to that environment.

Modification with Modification with Natural SelectionNatural Selection

Individuals with more favorable Individuals with more favorable characteristics leave more offspring characteristics leave more offspring than other individuals. than other individuals.

Adaption to Adaption to environmentenvironment

The number of favorable The number of favorable characteristics in an organism characteristics in an organism increasesincreases

An organism’s contribution to next An organism’s contribution to next generation – fitness. generation – fitness.

Your taskYour task Take this animal and Take this animal and

draw how it would draw how it would adapt to one of the adapt to one of the following climates. following climates. You must include 5 You must include 5 adaptations – label adaptations – label and explain:and explain:– SwampSwamp– DesertDesert– Tropical forestTropical forest– North PoleNorth Pole– MarsMars– Your choiceYour choice

What are homologous What are homologous structures?structures?

Structural similarities found in Structural similarities found in more than one species that share more than one species that share a common ancestor. a common ancestor.

Explain how these homologous Explain how these homologous structures suggest a common structures suggest a common ancestor. ancestor.

Homologous structures show how Homologous structures show how different animals can use their different animals can use their very similar forelimb bones in very similar forelimb bones in different ways. different ways.

This suggests a common ancestral This suggests a common ancestral species whose forelimb bone species whose forelimb bone structure was modified as those structure was modified as those forelimbs took on new functions. forelimbs took on new functions.

Contrast the size and shape of Contrast the size and shape of the bones of the whale flipper the bones of the whale flipper and the bat wing.and the bat wing.

The whale bones are thick and flat The whale bones are thick and flat which provide a paddle like which provide a paddle like surface.surface.

The bones of the bat are thin and The bones of the bat are thin and light which is a necessary light which is a necessary adaptation for flight.adaptation for flight.

Analogous StructuresAnalogous Structures

Structures that serve the same Structures that serve the same function but do not share a function but do not share a common ancestor.common ancestor.

Vestigial StructuresVestigial Structures

remnant of a structure that may remnant of a structure that may have had an important function in have had an important function in a species' ancestors, but has no a species' ancestors, but has no clear function in the modern clear function in the modern species species

Similarities in Similarities in EmbryologyEmbryology

Which one of the four species do the Which one of the four species do the cytochrome cytochrome cc data suggest is most data suggest is most closely related to humans? The closely related to humans? The hemoglobin data? hemoglobin data?

MONKEYSMONKEYS

Which one of the four species do Which one of the four species do the cytochrome the cytochrome cc data suggest is data suggest is least related to humans? The least related to humans? The hemoglobin data? hemoglobin data?

FROGSFROGS

More evolution More evolution EvidenceEvidence Similarities in macromolecules:Similarities in macromolecules:

– DNA & amino acid sequencesDNA & amino acid sequences

The more similar the proteins are The more similar the proteins are in 2 organisms, the closer related in 2 organisms, the closer related they are.they are.

Patterns in EvolutionPatterns in Evolution

CoevolutionCoevolution Convergent EvolutionConvergent Evolution Divergent EvolutionDivergent Evolution

CoevolutionCoevolution

2 or more species changing 2 or more species changing togethertogether

Convergent EvolutionConvergent Evolution

The environment The environment selects similar selects similar phenotypes. phenotypes.

Ancestors are Ancestors are very different.very different.

Divergent EvolutionDivergent Evolution

2 or more related 2 or more related populations/species become more populations/species become more and more differentand more different

Adaptive Radiation – related species Adaptive Radiation – related species evolve from a common ancestorevolve from a common ancestor

Artificial selectionArtificial selection