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
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