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Evolution. Ms. Luaces. Quick Review: Theory vs. Law. Theory: A well-tested explanation to make accurate predictions They can be changed!. Law: A generalized way of explaining things, but doesn’t necessarily say why Law of gravity Can’t be disproven. Earth’s Early History – 19.3.

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Ms. Luaces

quick review theory vs law
Quick Review: Theory vs. Law
  • Theory: A well-tested explanation to make accurate predictions
    • They can be changed!
  • Law: A generalized way of explaining things, but doesn’t necessarily say why
    • Law of gravity
    • Can’t be disproven
earth s early history 19 3
Earth’s Early History – 19.3
  • What do scientists hypothesize about early Earth and the origin of life?
  • What theory explains the origin of eukaryotic cells?
  • What is the evolutionary significance of sexual reproduction?
the mysteries of life s origins
The Mysteries of Life’s Origins
  • Earth was struck by a large object and heated
    • Eventually cooled down enough to form oceans
  • It’s atmosphere had very little oxygen
the mysteries of life s origins1
The Mysteries of Life’s Origins
  • Miller and Urey’s experiment suggested how mixtures of organic compounds necessary for life could have arisen
    • Not entirely accurate… more recent experiments have been done
    • First formations were thought to be proteinoid microspheres that had some characteristics of living things – NOT CELLS!
the mysteries of life s origins2
The Mysteries of Life’s Origins
  • “RNA World” hypothesis states that RNA came before DNA… do you think this is possible?
the mysteries of life s origins3
The Mysteries of Life’s Origins
  • First forms of live evolved to live in an oxygen free world – anaerobic prokaryotes
  • Eventually, photosynthetic bacteria came around which produced _________. This allowed aerobic organisms to evolve.
origin of eukaryotic cells
Origin of Eukaryotic Cells



Have nucleus

Have membrane-bound organelles

Have mitochondria

No nucleus

Very few membrane-bound organelles

origin of eukaryotic cells1
Origin of Eukaryotic Cells
  • The endosymbiosis theory suggests that a __________ relationship evolved between eukaryotes and prokaryotes
    • Created the mitochondria and the chloroplasts we know today
origin of eukaryotic cells2
Origin of Eukaryotic Cells
  • In support of this hypothesis:
    • Mitochondria and chloroplasts contain their own DNA which is similar to bacteria DNA.
    • Have their own ribosomes
    • Replicate like bacteria (binary fission)
sexual reproduction
Sexual Reproduction
  • Important in our evolutionary history because it introduces genetic diversity / variation.
  • Genetic variation increases the likelihood of a population adapting to new or changing environmental conditions.
evidence of evolution 16 4
Evidence of Evolution – 16.4
  • How does the geographic distribution of species today relate to their evolutionary history?
  • How do fossils help to document the descent of modern species from ancient ancestors?
  • What do homologous structures and similarities in embryonic development suggest about the process of evolutionary change?
  • How can molecular biology be used to trace the process of evolution?
  • What does recent research on the Galapagos finches show about natural selection?
evidence of evolution
Evidence of Evolution
  • Darwin hypothesized that animals evolved because of natural selection… what is that??
  • Patterns in the distribution of living and fossil species tell us how modern organisms evolved from their ancestors.

Closely related but different

Distantly related but similar

Alike species with different traits

Different species with same traits (similar environment)

age of earth fossils
Age of Earth & Fossils
  • Radioactive data shows Earth to be 4.5 billion years old – supporting Darwin’s theory (lots of time for evolution)
  • Recent fossil records are filling the gaps, showing that modern species evolved from extinct ancestors.
comparing anatomy embryology
Comparing Anatomy & Embryology
  • Evolutionary theory explains the existence of homologous structures adapted to different purposes as the result of descent with modification from a common ancestor.
comparing anatomy physiology
Comparing Anatomy & Physiology



Similar structure

Similar function

comparing anatomy embryology1
Comparing Anatomy & Embryology
  • Vestigial structures aren’t necessary, but don’t harm the function of the organism and so they remain
  • Appendix!
comparing anatomy embryology2
Comparing Anatomy & Embryology
  • Similar patterns of embryological development provide further evidence that organisms have descended from a common ancestor.
genetics molecular biology
Genetics & Molecular Biology
  • At the molecular level, the universal genetic code and homologous molecules provide evidence of common descent
  • Most of the DNA and RNA used from bacteria to humans is the same. We must have come from a common ancestor!
genetics molecular biology1
Genetics & Molecular Biology
  • Homologous proteins are shared from bacteria to humans – how we make insulin from bacteria for our use.
  • Homologous genes exist between flies and humans – these same genes direct our head-to-tail development and limbs
testing natural selection
Testing Natural Selection
  • The Grant’s were able to test Darwin’s hypothesis by:
    • Analyze that there was enough heritable variation in the traits for natural selection
    • There were enough differences in beak size and shape to produce differences in fitness
testing natural selection1
Testing Natural Selection
  • Dry weather = more survival of large beak birds
  • Their data confirmed that competition and environment drive natural selection
hominine evolution 26 3 pg 767
Hominine Evolution – 26.3 (Pg. 767)
  • What adaptations enabled later hominine species to walk upright?
  • What is the current scientific thinking about the genus Homo?
hominine evolution
Hominine Evolution
  • We separated to create hominines and chimpanzees
  • The skull, neck, spinal column, hip bones, and leg bones of early hominine species changed shape in ways that enabled later species to walk upright – bipedal.
hominine evolution1
Hominine Evolution
  • Bipedal allowed us to free our hands for tools – developed opposable thumbs
    • Also developed larger brains (cerebrums)
  • Figure 26-16 gives major differences between humans and gorrillas
hominine evolution2
Hominine Evolution
  • Fossils date back to 7 million years old – not all findings are ancestors, they may be relatives
  • Research suggests bipedalism evolved before larger brains
  • Oldest hominine: 2002, Sahelanthropus
  • Best studied:1974, Australopithecus afarensis or Lucy
hominine evolution3
Hominine Evolution
  • Recent research shows our human evolution isn’t straight forward – more like several branches and several trunks
    • Homo habilis: “handy man”, probably our ancestor
    • Homo ergaster: bigger brain, downward-facing nostrils
hominine evolution4
Hominine Evolution
  • Our genus originated in Africa and migrated from there to populate the world
    • Homo habilisin Turkey
    • Homo Erectus in Asia
hominine evolution5
Hominine Evolution
  • Multiregional hypothesis says we evolved independently in various parts of the world
  • “Out-of-Africa” model suggests we migrated and colonized the rest of the world about 200,000 years ago
    • More supported theory by mitochondrial DNA evidence
hominine evolution6
Hominine Evolution
  • Modern humans may or may not have coexisted with Neanderthals… something made Neanderthals go extinct and Homo sapiens remain the only hominine clade.
    • Both used stone tools, lived in complex social groups, controlled fire, and had rituals to bury their dead.
the brain pg 902 903
The Brain (Pg. 902-903)
  • Split into 5 major components:
    • Cerebrum
    • Limbic System
    • Thalamus and Hypothalamus
    • Cerebellum
    • Brain Stem
the brain
The Brain
  • Cerebrum: largest region of the brain responsible for voluntary (conscious) activities
    • Intelligence, learning and judgment are stored here
    • The part that grew the most in our ancestors
the brain1
The Brain
  • The Cerebrum is split up into right and left hemispheres
    • Left hemisphere controls right-side of the body and vice versa
  • Also into four lobes
    • Frontal (planning, judgments)
    • Temporal (hearing and smell)
    • Parietal (reading and speech)
    • Occipital (vision)
the brain2
The Brain
  • The Cerebrum also has two layers
    • The cerebral cortex (topmost layer, aka grey matter) which has many of the neurons responsible for all the activities
    • White matter (innermost layer) which makes connections between different brain areas
the brain3
The Brain
  • Limbic System: mostly associated with emotions, behavior, and long-term memory
the brain4
The Brain
  • Thalamus: receives messages from sensory neurons and sends them to the right place
  • Hypothalamus: helps to know and analyze hunger, thirst, fatigue, anger, and body temperature
the brain5
The Brain
  • Cerebellum: second largest region of the brain which deals with coordinating the body’s actions
the brain6
The Brain
  • Brain stem: the oldest part of the brain which connects the brain to the rest of the body
    • Also controls important functions like blood pressure, heart rate, breathing, and swallowing
    • What keeps you breathing while you sleep
let s practic e
Let’s Practice
  • From Activity workbook B: I will assign you a study buddy to work with and complete the following:
    • 31.2, pages 480-481
    • 1 separate sheet of paper for each group of 2 for Workbook B: Questions and answers (including the brain diagram).
    • Pages 86-89 #4 from your EOC Coach workbook.
    • Each one is to complete #4 in their EOC coach workbook
    • Due today
darwin s voyage of discovery 16 1
Darwin’s Voyage of Discovery – 16.1
  • Darwin developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent from common ancestors
  • Darwin was born in 1809 and began his journey in 1831 on the HMS Beagle
observations aboard the beagle
Observations Aboard The Beagle
  • Darwin didn’t just observe species, he thought about them in scientific ways and noticed
    • Species vary globally
    • Species vary locally
    • Species vary over time
    • Different species inhabit separate, but ecologically similar habitats
observations aboard the beagle1
Observations Aboard The Beagle
  • Darwin also noticed that different, yet related animal species occupied different habitats within a local area
  • All his observations were conducted between Australia, South America, and Africa (and of course, the Galapagos)
observations aboard the beagle2
Observations Aboard The Beagle
  • Darwin also noticed that some fossils of extinct animals were similar to living species – the Glyptodont and the Armadillo
  • All of this evidence suggested that species are not fixed, but that they change by some kind of natural process which we know today as ________________.
let s practice
Let’s Practice!
  • Find your study buddy
  • Study Workbook B – Pgs. 236-237. And pg. 86 “The Brain” #4. Question AND Answer. One sheet of paper for both of you
ideas that shaped darwin s thinking 16 2
Ideas that shaped Darwin’s thinking – 16.2
  • Hutton and Lyell, two geologists, concluded that Earth is extremely old and the processes that changed Earth in the past are still operating in the present
    • Went against the idea that Earth was only a few thousand years old
an ancient changing earth
An Ancient, Changing Earth
  • Hutton introduced deep time: our planet’s history is older than we can imagine. He reached this conclusion by his observations of:
    • The layers of rocks in mountains, valleys, and even volcanic molten lava
    • Rain, wind, heat and cold take a long time to shape rock
an ancient changing earth1
An Ancient, Changing Earth
  • Lyell believed in uniformitarianism – laws are constant over time (what happens now, happened then)
    • Darwin read Lyell’s book and observed an earthquake push rock from the sea out – if Earth was old, and the same things happened, could life have changed too?
lamarck s evolutionary hypothesis
Lamarck’s Evolutionary Hypothesis
  • Lamarck suggested that species decide what part of themselves to use / not use, and these traits were passed on to offspring
    • Published the year Darwin was born, 1809
lamarck s evolutionary hypothesis1
Lamarck’s Evolutionary Hypothesis
  • He suggested that if we wanted longer legs, we simply had to wish or stretch for them and it would happen – acquired characteristics
  • Then, we passed then on to our children – inherited acquired characteristics
  • Crazy ideas! But he was the first to suggest we changed according to our environment – essential for people like Darwin to come up with evidence!
population growth
Population Growth
  • Malthus had suggested that we can’t grow unchecked because there won’t be enough space for everyone – we were limited by war, famine and disease
  • Darwin linked this to other organisms and reasoned this must be the reason why only certain individuals survive and reproduce
artificial selection
Artificial Selection
  • Variations cause some animals to be more productive than others – we choose the best and breed those to make sure those variations become permanent.
  • Darwin didn’t understand where these variations came from, but he knew this would cause changes in the species
let s practice1
Let’s Practice!
  • Study Workbook B – Pg. 238
  • On your own individual sheet of paper – you will use this to study for your test next week! Q&A!!!
  • You can work in pairs to find the answers
darwin presents his case 16 3
Darwin Presents His Case- 16.3
  • Darwin did not publish his ideas immediately for fear of being ridiculed, until he found out Wallace was about to publish something very similar
evolution by natural selection
Evolution by Natural Selection
  • The struggle for existence: more are born than can survive, and must compete for resources
    • Those with the best adaptations (body part, color, function or behavior) survive and reproduce – have high fitness
evolution by natural selection1
Evolution by Natural Selection
  • Natural selection occurs in any situation in which
    • More individuals are born that can survive (survival of the fittest)
    • There is natural heritable variation (variation and adaptation)
    • There is variable fitness among individuals (survival of the fittest)
evolution by natural selection2
Evolution by Natural Selection
  • Natural selection doesn’t make “perfect” organisms- just good enough to survive in their environments
    • If the environment changes, adaptations can change also… so long as it’s not too fast of a change
common descent
Common Descent
  • As generations progress, we get species evolving into new species – descent with modification
  • The principle of common descent is that all living and extinct species are descended from ancient common ancestors
    • The tree of life
evolution as genetic change in populations 17 2
Evolution as Genetic Change in Populations – 17.2
  • What does the book tell us about pesticide use?
  • Pesticide resistance?
  • How does this change the insect population over many years?
prior knowledge
Prior Knowledge
  • Genotype: what your DNA says
  • Phenotype: what you see (what your DNA codes for)
  • Allele: alternate forms of a gene (hair color can be red, brown, blonde, black, etc)
  • **Natural selection acts on the phenotype, not the genotype**
prior knowledge1
Prior Knowledge
  • Dominant: the allele that is stronger – the phenotype you see
  • Recessive: the allele that is weaker – can be masked
  • Heterozygous: different alleles (Bb)
  • Homozygous: same alleles (BB, or bb)
single gene vs polygenic traits
Single Gene vs. Polygenic Traits

Single-Gene Trait

Polygenic Trait

Atrait controlled by only one gene

Ex: Hair color

A trait controlled by many genes

Ex: Height

  • Please read 17.1 as background information and review these concepts on your own! If you need help, come and see me before / after school!
how natural selection works
How Natural Selection Works
  • Evolutionary adaptation comes from an increased ability of an individual to pass on their particular genes, or alleles
  • Natural selection on single-gene traits can lead to changes in allele frequencies, and thus, to changes in phenotype frequencies
how natural selection works1
How Natural Selection Works
  • Natural selection on polygenic traits can affect the relative fitness of phenotypes and thereby produce one of three types of selection
    • Directional selection
    • Stabilizing selection
    • Disruptive selection
directional selection
Directional Selection
  • Individuals at one extreme of the curve have higher fitness than individuals in the middle or other end
    • Ex: Big beak birds survived and overtook the population in our Gizmo during drought… at the end of the 5 years, all birds were big beak!
stabilizing selection
Stabilizing Selection
  • Individuals at the center of the curve have higher fitness than individuals at either end
    • Ex: During normal rainfall, middle size beaked birds survived most in our Gizmo
disruptive selection
Disruptive Selection
  • Individuals at both ends of the curve have higher fitness than individuals in the middle
    • Ex: If only very small and very large seeds are left, birds with small and large beaks will be the only ones left – almost creates two different species
genetic drift
Genetic Drift
  • In small populations, individuals that carry a particular allele may leave more descendants than other individuals leave, just by chance.
  • We know this random change in allele frequency to be genetic drift
genetic drift1
Genetic Drift
  • Bottleneck effect: a dramatic change (usually due to a disaster) that leaves very few individuals behind with little genetic diversity
    • Ex: Disease
genetic drift2
Genetic Drift
  • Founder effect: a small population with limited allele frequencies migrates to a new habitat
evolution vs genetic equilibrium
Evolution vs. Genetic Equilibrium
  • If the individuals are not evolving, then the allele frequencies are not changing
    • Sexual reproduction may reshuffle genes, but won’t introduce anything new
evolution vs genetic equilibrium1
Evolution vs. Genetic Equilibrium
  • The Hardy-Weinberg principle predicts that 5 conditions can disturb genetic equilibrium and cause evolution:
    • 1. Nonrandom mating
    • 2. Small population size
    • 3. Immigration / Emigration
    • 4. Mutations
    • 5. Natural Selection
evolution vs genetic equilibrium2
Evolution vs. Genetic Equilibrium
  • Nonrandom Mating: if the individual is choosing a mate based on sexual selection (size, strength, or color) then there will be evolution
  • Small Populations: Founders effect and Bottleneck effects
  • Immigration / Emigration: introduces new alleles into the gene pool
  • Mutations: also introduces new alleles
  • Natural Selection: favors different phenotypes, and therefore, genes
let s practice2
Let’s Practice!
  • Study Workbook B Pgs. 254-258
  • You must write on your own individual sheet of paper, QUESTION AND ANSWER
  • You may work with a buddy to find the answers
the process of speciation 17 3
The Process of Speciation – 17.3
  • Different circumstances can lead to speciation:
    • Reproductive isolation – either through behavioral, geographic, or temporal separation
isolating mechanisms
Isolating Mechanisms
  • Behavioral isolation typically happens because courtship rituals are different
    • Ex: Birds with different mating calls
isolating mechanisms1
Isolating Mechanisms
  • Geographic isolation occurs when a natural disaster or landmark separates two species – such as mountains or rivers
isolating mechanisms2
Isolating Mechanisms
  • Temporal isolation occurs when two species reproduce at different times
speciation in darwin s finches
Speciation in Darwin’s Finches
  • Speciation in Galapagos finches occurred by founding of a new population, geographic isolation, changes in the new population's gene pool, behavioral isolation, and ecological competition
let s get creative
Let’s Get Creative!
  • Pg. 412 in the textbook – Thinking Visually
  • With a partner, draw out the concept map and fill in the missing words. Then draw a picture that represents each of the words in the bubbles based on what we’ve learned!