Intro to Evolution – Ch 15Objective: 3.05 Examine the development of the theory of evolution by natural selection including: development of the theory; the origin and history of life;
The Fossil RecordChapter 15.1
Objective: Examine the development of the theory of evolution by natural selection including: fossil and biochemical evidence; mechanisms of evolution; applications (pesticide and antibiotic resistance)
Why use fossils? Scientists have used the fossil record to
construct a history of life on Earth. Earth’s life forms appeared 3.5 billion years ago Fossil record is not complete, but pretty good for
general information
Fossils Trace of long-dead organism Formed in sediment – dust, sand, mud – by
wind or water Hard body parts frozen in time Minerals replace soft tissue > rocks
Types of fossils Mold – imprint of organism Cast – imprint replaced with minerals – looks
like a model Evidence of behavior – footprints/tracks Insects petrified and frozen in amber
Dating Fossils Relative Dating
Rock layers are put down in order Oldest on bottom, youngest layers on top
Radiometric Dating Use Carbon-14 for ages 50,000 years or less Half-life is 5730 years
Nicolaus Steno Law of superposition – successive layers of
rock or soil were deposited on top of one another by wind or water
Stratum (lowest layer) – or layer in cross section is the oldest, top layer is youngest
Earth’s age ~ 4.6 billion years Relative age – age by comparison
e.g. I am older than you by comparison yet you don’t know my exact age
E.g. the cement in the foundation of the building is older than the roof by comparison yet I don’t know the exact age in years of the building
Absolute age – age in years by radiometric dating (carbon -14)
Succession of forms Extinct – disappeared from existence Mass extinctions – large numbers of species
disappeared – drastic environmental change like volcanic
activity, collisions with asteroids
First organisms begin with prokaryotes in Precambrian era (540 mya)
Biogeography – study of the geographical distribution of fossils
Indicates that organisms arise in areas where similar body forms lived suggesting that they are the new-improved model! A modified version
Theories of EvolutionChapter 15.2
Objective: 3.05 Examine the development of the theory of evolution by natural selection including: development of the theory; the origin and history of life;
Processes of science vs. processes of faith
Science:
Observe Ask questions Propose hypotheses Conduct Investigation Alter hypotheses
Faith:
Religious faith is a belief; Faith is not altered to fit evidence I ask students to learn theory of evolution – they don’t
have to “believe” in it just understand it. I will not teach creationism nor intelligent design – they
are not science
Evolutionary TimelineEvolutionary Timeline
Jean Baptiste de LaMarck inheritance of acquired traits – characteristic passed
to offspring; not determined by genes repeated use or disuse of body part during their
lifetime was then passed down to offspring or inherited
E.g. webbed feet of duck
Related fossils to living organisms based on similar appearance
1st to say organisms change over time
Use & Disuse - Organisms Could Change The Size Or Shape Of Organs By Using Them Or Not Using Them
Blacksmiths & Their Sons (muscular arms)
Giraffe’s Necks Longer from stretching)
Inheritance Of Acquired TraitsTraits Acquired During Ones Lifetime Would Be Passed To Offspring
Clipped ears of dogs could be passed to offspring!
Charles Darwin & Alfred Wallace Independently propose that species were modified
by natural selection – when organisms with traits well suited to the environment reproduce more successfully than other organisms
Published Origin of the Species Sailed on HMS Beagle to Galapagos Islands, west
of S. America
What is the Theory of Evolution by Natural Selection?
Populations would grow exponentially if there were unlimited resources
Environmental factors limit reproductive capacity Organisms compete for resources There is variation within populations and those with useful
adaptations survive The survivors reproduce and pass on their genes The new generation will have a greater frequency of the
adaptive traits Over a long period of time, the differences are so great that
the result could be a new species
HMS Beagle voyage
Naturalist Read Principles of Geology by Charles Lyell
Uniformitarianism – geological cycles observed today are the same processes from long ago
e.g. volcanoes erupt the same today as millions of years ago
Darwin sailed on the Beagle for 5 years making observations as the ship’s naturalist.
He studied: tortoises, finches & more Island species varied from mainland species
AND from island-to-island species Each island had long or short neck tortoises
Finches: Finches on the islands resembled mainland finch More types of finches appeared on the islands
where the available food was different (seeds, nuts, berries, insects…)
Finches had different types of beaks adapted to their type of food gathering
Evolved from a common remote ancestor phylogenetic tree - shows evolutionary relationships
Phylogenetic Tree or Ancestral Tree showing proposed evolution
Darwin’s 2 theories: Descent with modification
Newer organisms in fossil record are modified descendants of older species
All species descended from original type of life Modification by natural selection
Organisms with favorable traits have more offspring than others without them– adaptive advantage
Can adapt to environment therefore more fit
Survival of the Fittest Fitness
Ability of an Individual To Survive & Reproduce
Adaptation Inherited Characteristic That Increases
an Organisms Chance for Survival
Survival of the Fittest Adaptations Can Be:
Physical Speed, Camouflage, Claws, Quills, etc.
Behavioral Solitary, Herds, Packs, Activity, etc.
Survival of the Fittest Fitness Is Central To The Process Of
Evolution Individuals With Low Fitness
Die Produce Few Offspring
Survival of the Fittest AKA Natural Selection
Survival of the Fittest
Key ConceptOver Time, Natural Selection Results
In Changes In The Inherited Characteristics Of A Population. These Changes Increase A Species Fitness In Its Environment
Descent With Modification Takes Place Over Long Periods of
Time Natural Selection Can Be Observed As
Changes In Body Structures Ecological Niches Habitats
Descent With Modification Species Today Look Different From
Their Ancestors Each Living Species Has
Descended With Changes From Other Species Over Time
Descent With Modification
EVIDENCE for EVOLUTION Evidence from fossils.
The Geographical Distribution of Living Species
Homologous Structures of Living Organisms
Similarities In Early Development
Homologous Body Structures Structures That Have Different Mature Forms
But Develop From The Same Embryonic Tissues
Homologous Body Structures Scientists Noticed Animals With Backbones
(Vertebrates) Had Similar Bone Structure May Differ In Form or Function Limb Bones Develop In Similar Patterns
Arms, Wings, Legs, Flippers
Homologous Body Structures Not All Serve Important Functions
Vestigial Organs Appendix In Man Legs On Skinks
Similarities In Early Development
Embryonic Structures Of Different Species Show Significant Similarities
Embryo – early stages of vertebrate development
Similarities In Embryonic Development
Evidence from genetics. All organisms share the same basic
mechanism of heredity (DNA/RNA) E.g.: mtDNA evidence for human evolution
A branching tree radiating from a common ancestor – phylogenetic tree
We can conduct research on other species to understand our own genes.
Similarities in DNA SequenceSimilarities in DNA Sequence
Evolution in action. Many bacterial pathogens (origin of feeling –
what started the disease) have evolved resistance to antibiotics
In the case of HIV, which causes AIDS, significantviral evolution occurs within the course of infection of a single patient
Evolution of drug-resistance in HIV
•Many agricultural pests have evolved resistance to chemicals that farmers have used for only a few decades.
•Moreover, scientists can perform experiments to study evolution in real time using bacteria and fruit flies that reproduce quickly.
Evolution Evolution of pesticide of pesticide resistance resistance in response in response to selectionto selection
