LIFE OVER TIMELIFE OVER TIME

What processes have created diverse species & adaptations

throughout history?

What processes have created diverse species & adaptations

throughout history?

Theories of Evolution began when scientists began asking these questions…

What is a Scientific Theory?

Fact: An observation that has been repeatedly confirmed with not dispute. For example, there are 23 pairs of chromosomes in human cells.

Law: A descriptive generalization about how some aspect of the natural world behaves under stated circumstances. For example, one of Newton's laws of motion that states that for every action, there is an equal and opposite reaction.

Hypothesis: A testable statement about the natural world that explains why something occurs.

Theory: A well-supported explanation of some aspect of the natural world that can incorporate facts, laws, and tested hypotheses. For example, the cell theory states that cells are the basic unit of all living organisms and that all new cells arise from the division of pre-existing cells.

What is Evolution?What is Evolution?

Evolution = a series of gradual or rapid changes in living & nonliving things through time

Evolution of Stars Evolution of the Earth System (water, landforms, atmosphere)

Evolution of Living ThingsEvolution of Scientific ideas

Theories of EvolutionTheories of Evolution

Theories of Evolution are…Theories of Evolution are…

• attempts to explain changes & diversity in living things through time

• supported by a great deal of research & study

Theories of Evolution are Not…Theories of Evolution are Not…• attempts to explain the origins & purpose of life!

• a religion or belief system

• Law of Use & Disuse - organisms respond to changes in their environment by developing new organs or changing the structure/function of old organs. . . .

• Theory of Inheritance of Acquired Characteristics these acquired characteristics were then passed on to the organism's offspring. . . .

Giraffes Long Necks

Early Theories of EvolutionEarly Theories of Evolution

Jean-Baptiste de Lamarck (1744-1829) Jean-Baptiste de Lamarck (1744-1829)

The Basis for Modern Theories of EvolutionThe Basis for Modern Theories of Evolution

Charles Darwin (1809-1882) Charles Darwin (1809-1882)

• Artificial Selection - selective breeding in pigeons

• Natural Selection - organisms with certain variations survive, reproduce & pass on these traits to their offspring

Galapagos Island Animal Species

An Intro to Modern TheoryAn Intro to Modern Theory

http://evolution.berkeley.edu/evosite/evo101/IIntro.shtml

http://evolution.berkeley.edu/evosite/evo101/IIntro.shtml

How Does Evolution Happen?How Does Evolution Happen?Fundamental to the process of evolution

is genetic variation within populations upon which selective forces can act in order for long term change to occur.

Fundamental to the process of evolution is genetic variation within populations upon which selective forces can act in order for long term change to occur.

Genetic Drift (Random) Genetic Variation Change in Populations (Evolution) Natural Selection (Non-random)

What Causes Genetic Variation?

What Causes Genetic Variation?

Mutations Mutations

Gene Flow (Migration) Gene Flow (Migration)

Sex Sex

Genetic DriftGenetic Drift

Change in the genetic makeup of a population by chance events (random!)

It does NOT work to produce adaptations!

Change in the genetic makeup of a population by chance events (random!)

It does NOT work to produce adaptations!

Examples:

1. Ellis-van Creveld syndrome in Amish

2. Stepping on a bug!

3. A bird left on an island - Galapagos

Examples:

1. Ellis-van Creveld syndrome in Amish

2. Stepping on a bug!

3. A bird left on an island - Galapagos

Natural SelectionNatural Selection

1. There is Genetic Variation1. There is Genetic Variation

2. There is Selective Pressure - environmental conditions

2. There is Selective Pressure - environmental conditions

3. There is Survival of Some3. There is Survival of Some

4. There is Reproduction by the Survivors

4. There is Reproduction by the Survivors

5. Adaptations Show5. Adaptations Show

How Do New Species Form?

How Do New Species Form?

Species = Species = Group of similar organisms that can interbreed & produce fertile offspring

Group of similar organisms that can interbreed & produce fertile offspring

Speciation = Speciation = Evolution of a new speciesEvolution of a new species

Causes of SpeciationCauses of Speciation

1. Geographic Isolation = when a physical barrier divides a population

1. Geographic Isolation = when a physical barrier divides a population

Each population adapts to its environment thru natural selection & develops its own gene pool. Over time the separate groups become so different they can no longer interbreed! (Galapagos Animals)

Each population adapts to its environment thru natural selection & develops its own gene pool. Over time the separate groups become so different they can no longer interbreed! (Galapagos Animals)

2. Reproductive Isolation = when organisms no longer mate & produce fertile offspring

2. Reproductive Isolation = when organisms no longer mate & produce fertile offspring

Mating times change to different parts of the year for groups in different areas (Tree frogs)

Mating times change to different parts of the year for groups in different areas (Tree frogs)

Mutations in chromosomes occur to make breeding difficult (Plants - crops)

Mutations in chromosomes occur to make breeding difficult (Plants - crops)

How Fast is Speciation?How Fast is Speciation?

1. Gradualism = species originate through a gradual change in adaptations (10,000+ yrs)

1. Gradualism = species originate through a gradual change in adaptations (10,000+ yrs)

2. Punctuated Equilibrium = species originate in rapid bursts (10,000 yrs or less) with long periods of equilibrium in between

2. Punctuated Equilibrium = species originate in rapid bursts (10,000 yrs or less) with long periods of equilibrium in between

Fossils show camels evolved slowly & steadily over time (pg 408)

Fossils show camels evolved slowly & steadily over time (pg 408)

Fossils show that higher temps & competitive species caused rapid changes in isolated populations - elephants!

Fossils show that higher temps & competitive species caused rapid changes in isolated populations - elephants!

EVIDENCE OF EVOLUTION

EVIDENCE OF EVOLUTION

1. Adaptations - a structure or behavior that helps an organism better survive in its environment (arose from Natural Selection)

1. Adaptations - a structure or behavior that helps an organism better survive in its environment (arose from Natural Selection)

A. Mimicry

B. Camo

C. Physiological - antibiotic resistance in bacteria = superbugs

EVIDENCE OF EVOLUTION

EVIDENCE OF EVOLUTION

2. Fossil RecordA. Give clues to what ancient organisms

looked likeB. Compare to organisms today to see

relationshipsC. A link to show change over time

2. Fossil RecordA. Give clues to what ancient organisms

looked likeB. Compare to organisms today to see

relationshipsC. A link to show change over time

EVIDENCE OF EVOLUTION

EVIDENCE OF EVOLUTION

3. Comparative Anatomy3. Comparative Anatomy

A. Homologous Structures = body structures on diff. organisms that are similar in structure/function - evidence of common ancestor

B. Vestigial Structures = body structures in an organismthat no longer serve a purpose but may have in an ancestor - show what used to be

4. Embryos = all vertebrates look similar as embryos - suggests all related

4. Embryos = all vertebrates look similar as embryos - suggests all related

EVIDENCE OF EVOLUTION

EVIDENCE OF EVOLUTION

5. DNA Similarities

5. DNA Similarities

EVIDENCE OF EVOLUTION

EVIDENCE OF EVOLUTION

Examples of Recent Evolution (Change): Examples of Recent Evolution (Change):

EVIDENCE OF EVOLUTION

EVIDENCE OF EVOLUTION

1. Natural Selection in Action - Peppered Moths

2. Artificial Selection - Crops, Dogs - People?

The EndThe End

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.