Evolution

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Evolution

• Earths History

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Formation of the Earth

• Sun formed first
• Earth
• Formed through accretion
• Many collisions, much heat
• Basically a liquid ball

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Earth

• Age
• gt 4 billion years
• Have only recorded history for 1/700,000 of this
  time period
• How do we determine what happened long ago
• Geologic History (sedimentary rock)

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Dating the earth

• Radiometric dating
• Use rate of decay of radioactive isotopes of
  certain elements (halflife)
• C-14 vs. C-12 5,230
  years
• (this ratio is known for living animals and is
  stable)
• Good for up to 60,000 years
• Uranium 235 704,000,000 years
• Potassium 40 1,250,000,000 years
• Uranium 238 4, 500,000,000 years

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Other ways to date rock

• Rock Layers
• Each rock layer and structure records an event
  (uplifting, deposition, erosion)
• Sedimentary rock is deposited horizontally
• Oldest on bottom, youngest on top
• Fragments within a rock (clasts) are older than
  material surrounding it.
• Igneous intrusions and geologic structures
  (faults, folds

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Other ways to date rocks

• Index Fossils
• Life forms evolve in a definite and non-repeating
  order
• Index fossils
• Use to age date rock from different regions
• Widely distributed, short geologic lifespan,
  preservable hard parts.

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Why are fossils important?

• Fossils are among the most valuable sources of
  information about the Earth's history. They tell
  us about the organisms that lived on Earth from
  the time of the oldest fossils, about 3.8 billion
  years ago, to the present. By studying fossils we
  can learn not only about the creatures and plants
  of the distant past, but how they grew, what they
  ate, how they interacted, and many aspects of
  their behavior.

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Economic Use of Fossils

• Fossils are one of the most useful aids to
  finding oil, because oil tends to accumulate in
  the pores of particular rock layers.
• Rocks of different ages contain different
  fossils. Study of microscopic fossils brought up
  in chips of rock during drilling of wells has led
  to many major oil and gas discoveries.
• Also, the oil itself is derived from fossil
  remains of ancient organisms.

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Additional Benefits

• Knowledge about how life evolved on earth and
  about diseases, both ancient and modern.
• Understanding of past climates, including ice
  ages and warm periods
• Study of the catastrophic extinction of the
  dinosaurs and many other life forms provide new
  insight into the impact of ET organisms to
  evolution
• Physical and chemical changes in fossils that
  lived during times of drastic climatic change
  helps us understand the implications of the
  changes (ie global warming) we are causing in our
  own environment.

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What was the environment

• All elements present, but what compounds had
  formed?
• Oparin and Haldane 1920s
• NH3, H2, water, methane (CH4)
• More complex molecules formed due to heat and
  lightning and UV radiation

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How were organic compounds made?

• Miller and Urey 1950s
• Closed glass apparatus that formed a continuous
  system
• In this simulated system amino acids formed
• But..what about life?

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Making Life

• Cell like structures
• Microspheres
• Coacervates
• Droplet groups containing aa, lipid and sugars
• Have some life qualities, but no heritability

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Origin of Heredity

• Cech- 1980s
• RNA takes on many forms
• RNA can act as a catalyst (like protein)
• Ribozymes
• Theory.
• May have started life in an RNA world

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Ribozymes

• Can as a catalyst
• To speed up other reactions
• For their own replication
• Competition
• Different RNA molecules compete for the same
  resources (bases)
• Some better than others at linking
• Efficiency ? survival of the fittest
• Self replicating systems of RNA have been created

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From RNA to life

• Mineral templates to which organic molecules
  attach
• Replicating RNA evolve inside microspheres or
  coacervates
• RNA might act to direct assembly of structures

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The First Cells

• NO DIRECT EVIDENCE, only inferences
• Little or no O2,
• Size and shape of procaryotes
• Environment full of small organic molecules
  (food)
• THEREFORE.. Anaerobic, heterotrophic, prokaryotes

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THEN WHAT

• Organic molecules become scarce due to growing
  population of heterotrophs
• RESULT autotrophs would have the advantage
• BUT first autotrophs did NOT use the sun.

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First Autotrophs

• Archaea
• Most likely model for first autotrophs
• Unicellular
• Thrive in harsh conditions
• Many are chemosynthetic
• CO2 - carbon source
• Sulfur energy source

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Photosynthesis/Aerobic Respiration

• Cyanobacteria
• 3 billion years ago
• geologic evidence of traces of photosynthetic
  activity -? Oxygen
• Unicellular or Colonial
• Oxygen was toxic to many organisms at first
• Ozone formed from oxygen ? UV protection
• Ozone layer REQUIRED for existence of life on land

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Oxygen The good and the bad

• Damaging to many
• Bonding with a compound neutralized it
• Start of aerobic respiration
• Formed ozone layer
• Shield against UV
• Allowed new forms of life to form

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The First Eukaryotes

• Margulis
• Theory of Endosymbiosis
• Large prokaryotes ate smaller prokaryotes
• ? chloroplasts and mitochondria
• Chloroplasts and Mitochondria ingested
• Replicate independently
• Have their own DNA

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Theory of Evolution (Chapter 15)

• Development of new organisms from existing
  organisms
• Theory well supported explanation that
  incorporates observations, inferences, and tested
  hypotheses

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Ideas of Darwins Time

• Beginning to suspect that the earth was older
• 1800s Rock strata studied
• Fossils found
• Cuvier Catastrophism
• Sudden catastrophes causes mass extinctions
• Lyell Uniformitarianism
• Process in the past similar to now

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Ideas in Darwins Time

• Lamarck
• Simple organisms could arise from non-living
• Inheritance of acquired characteristics
• Darwin and Wallace
• Descent with modification
• Both had travelled throughout the world
• Saw similarities and differences

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Galapagos

• Great place to study evolutionwhy?
• Isolated islands
• Rapid adaptation
• Different climates on each island ? different
  vegetation
• Small populations
• Limited immigration/emigration
• NATURAL SELECTION CAN BE SEEN!

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Theory of Natural Selection

• Is the mechanism for descent with modification
• Reasoning Key forces that cause evolution over
  time

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What are the key forces

• Overproduction ? limiting environment
• Genetic variation ? individual variation
• Variations can have strength depending on
  conditions
• Struggle to survive ?
• some variations more successful than others
• Competition for resources
• Differential reproduction ? those with better
  adaption have more offspring
• Nature changes species by selecting favorable
  traits

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Fitness

• A measure of an individual s hereditary
  contribution to the next generation
• Adaptation can be short term or long
• Those traits that increase the fitness of
  individual will become more prevalent
• Change in a population over time (long term)

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Where do we find evidence ?

• Fossil Record
• Biogeography
• Anatomical evidence
• Embryological evidence
• Biochemical evidence (DNA)

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Evidence of Evolution

• The Fossil Record
• Location of fossils determines age
• Absolute age of a rock radiometric dating
• Distribution of fossils
• Transitional species ? evolving forms

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Evidence of Evolution

• Biogeography
• Study of location of organisms around the world
• Closely related organisms are on different
  continents (monkeys in Africa and SA)
• Unrelated animals had similar adaptations in
  similar environments (even if organisms were in
  distant locations)
• EXAMPLES
• Most mammals in Australia are marsupials but can
  have characteristics similar to cats, mice and
  moles

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Evidence of Evolution

• Anatomical Evidence
• Homologous structures
• Related structure, different function
• Human, penguin, alligator, bat (forelimb)
• Analogous structures
• Unrelated structure (bat wings and butterfly
  wings) but similar function
• Vestigial structures
• Tailbone (humans)
• Pelvic bone (whales)
• Appendix

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Evidence of Evolution

• Embryological Evidence
• Stages of development look like other animals.
  Change as further development occurs (pharygeal
  slits, flippers, tail, etc)

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Evidence of Evolution

• Biochemical Evidence
• Similarity in DNA sequences
• Same Bases
• Many similar basic proteins
• MAJOR DETERMINING FACTOR NOW

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Modern Synthesis of Evolutionary Theory

• Integration of
• Theory of Natural Selection
• Genetics
• Phylogeny modeled based on the combination of
  these two
• Shown in Cladograms or Phylogenetic trees.

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Evolution in Action

• Case Study Anole Lizards
• Evolution is ongoing
• Patterns of evolution repeat in different times
  and places
• Interactions between species (including humans)
  affect their ongoing evolution

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Anole Lizards

• Different body types
• Correspond to the habitat in which the species
  lives
• Trees (long legs, thick bodies, long tails)
• Grass dwellers ( slender body, long tail)
• Twig dwellers ( thin bodies, short legs and
  tails)
• Did one evolve from the second (divergent
  evolution) or
• Did they evolve independently, but similarly
  (convergent evolution)?

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Anole Lizards

• Twig dwellers are on each island
• HOWEVER Each is a unique species
• Hypotheses
• Ancestral anole species living on one island
  migrated to the others (common ancestor)
• Each twig-dwelling species evolved independently
  from a distinct ancestral anole species

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Anolis cybotes
Anolis insolitus
Anolis pulchellus
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How do you test?

• Compare DNA from various species
• RESULT
• DNA evidence supports independent development on
  each island
• Each tree dweller arose from different species
  but evolved similar adaptations used for similar
  habitats
• CONVERGENT EVOLUTION different species evolve
  similar traits

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Convergent Evolution

• Australianvs. mainland
• Placental vsmarsupial

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Divergent Evolution

• Descendants of a Single ancestor diversify into
  species that each fit a different part of the
  environment
• One body type survives in one habitat (branches),
  but not another.

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Adaptive Radiation

• Divergence in high gear
• Adaptive Radiation
• New population in a new environment
• Divergent evolution to fill many parts of the
  environment (Darwins Finches)

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Adaptive Radiation
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Artificial Selection

• Domestication
• Choose a preferred trait and breed for the
  trait.
• Color, ear length, coat, leg length, head shape,
  etc.
• Dog and Cat Breeds
• All dog breeds descend from East Asian wolves
• Started 15,000 years ago.

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Domestication of the Dog

• 14,000 150,000 years ago
• From the wolf (ves)
• Different interbreeding lines contributed
• Indian or Asian Wolf
• Pug, mastiff, bloodhound
• Chinese Wolf
• Many Toy breeds
• NA wolf
• Husky, Alaskan malamute

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Domestic characteristics

• Ear shape and length
• Snout shape
• Leg length
• Coat length
• Sickle tail (all domestic dogs)
• As compared to straight brush tail of wolf
• Retain Juvenile characteristics
• Bark, soft coat, large head, ears that hang down,
  guarding (staying with pack), hunting dogs
  (intermediate behavior)dont lead but follow
• Basenjihunts like a peer,

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Co-Evolution

• Two or more species have evolved adaptations to
  each others influence
• Pollen-carrying
• Camouflage
• Antibiotic resistance

Coevolution between the yucca moth and the yucca
plant. (Top) A female yucca moth (Tegeticula
yuccasella) pushing pollen into the stigma tube
of the yucca flower while visiting the flower to
deposit her eggs. (Bottom) Yucca moth larvae
feeding on seeds in the yucca fruit.
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Population Genetics (Chapter 16)

• Study of evolution from a genetics viewpoint
• Microevolution change in the collective genetic
  material of a population
• Population smallest unit in which evolution
  occurs. Individuals DONT evolve!!!

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Observable Variation in Traits

• Size of Fish
• Count frequency of size of mature fish
• Fin length, fin shape, tail shape, coloration
• Quantitative traits (height, weight, length) tend
  to show variation in a bell curve (normal curve)

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Causes of Variation

• Environmental factors
• Amount and quality of food
• Hereditary variation
• Mutation random change in gene
• Recombination reshuffling of genes due to
  crossing over and independent assortment
• Random pairing of gametes

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Gene Pool

• Total genetic information available in a
  population
• Each generation is dependent upon the gene pool
  of the breeding population.
• Also dependent on allele frequency
• number of a certain allele/total number of all
  alleles for that gene

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Phenotype Frequency

• Individuals with a particular phenotype
• All individuals of all phenotypes
• Our lab was an example of determining frequency
  of phenotypes and then determining new allele
  frequency
• The frequency of all expected phenotypes sums to
  1

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Hardy Weinberg Genetic Equilibrium

• While frequencies CAN change from generation to
  generation, they will remain the same IF
• 1. No net mutations occur (alleles remain the
  same)
• 2. Individuals neither enter nor leave the
  population
• 3. The population is large
• 4. Individuals mate randomly
• 5. Selection does not occur.

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True Equilibrium is theoretical

• What disrupts equilibrium?
• Go back and look at the list

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Disruption of Genetic Equilibrium

• Mutation
• Geneflow
• genes moving from one population to another
• (immigration and emigration)
• Genetic Drift
• Change in allele frequencies due to random events
• In a small population, this can occur when ONE
  individual doesnt reproduce (or thrives)
• Non-random mating
• Geography, assortative mating (mate picked based
  on similar traits), sexual selection (males
  chosen based on certain traits)

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Natural Selection

• Generally is absent.
• Stabilizing Selection
• Average form has highest fitness
• Disruptive
• Extremes have greater fitness the average form
• Directional Selection
• Individuals with an extreme form of a trait
  (one-sided) have greater fitness
• Anteater with long tongue

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Continental Drift

• First proposed in 1915 by Wegener
• Idea Earth drifts atop a liquid core
• Supported by fossil record
• Same fossils on different continents
• Same strata (rock) on different continents

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How did it happen

• Pangaea
• ? Laurasia
• North America, Asia, Europe
• ? Gondwana
• South America, Africa, India, Australia, New
  Zealand, Madagascar

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Speciation
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Speciation

• What is a species?
• The Process of Speciation
• Models of Speciation
• Interesting examples of Speciation

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Speciation

• What is a species?
• The Process of Speciation
• Models of Speciation
• Interesting examples of Speciation

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What is a species?

• Morphological Species Concept
• Biological Species Concept
• Modern Species Concepts

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Morphological Species Concept

• Linnaeus invented the system of classifying
  organisms in the 1800s
• Classification of a species by appearance
  (structure and function ie phenotype)

Domain
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Issues with Morphologic Concept

• Phenotypic variation within a species can be
  huge (the dog)
• Small phenotypic variation between species
  (anole) exists

Looks CAN be deceiving!
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Different phenotypes same or different species
Hydrangea
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Same or Different?
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Same or different?
Western Meadowlark
Eastern Meadowlark
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Same or different?

• CONVERGENT EVOLUTION
• Same or different ancestor?

Cacti (Americas)
Euphorbia (Africa)
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Cladograms and speciation.
Common ancestor
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Defining species is complicated

• Phenotypic variation within species may make us
  think that there is more than one species
• Different species may look remarkably similar

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Evolution ? Speciation!

• A population can evolve without forming a new
  species
• Example smaller size or smaller beak from year
  to year (like the beak size within a bird species
  from year to year)
• In this case due to food availability

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Biological Species Concept

• Most widely accepted concept.
• Species defined in terms of ability to
  interbreed
• DEFINITION
• Interbreeding natural populations that are
  reproductively isolated from other such groups

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However, Biological Concept not always
appropriate

• Must revert to Linnaeus (morphological) system
  for
• extinct organisms
• asexual organisms
• some distinct species that can still interbreed
  and produce viable offspring (e.g., coyotes,
  wolves, and dogs)

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Modern species concepts

• If gt 5 of amino acids are different, then
  consider two organisms to be of different species

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Speciation

• What is a species?
• The Process of Speciation
• Models of Speciation
• Interesting examples of Speciation

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The Process of Speciation
One species (set of interbreeding organisms)
Genetic variant spreads through part of the
species bearers of this variant must mate only
with other bearers of the same variant
Two species. Further phenotypic, behavioural and
ecological differences may evolve
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What causes this to happen

• 1. Geographic Isolation
• Canyons, mountains, water, deserts, migration
  (accidental)
• More common in land animals than in flying or
  fish animals
• Leads to Allopatric (different homelands)
  Speciation

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What causes this to happen?

• 2. Reproductive Isolation
• A barrier arises to prevent breeding between
  population groups in the same area.
• Can lead to Sympatric (within the same homeland)
  Speciation

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How Speciation occurs
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Evidence exists for both types of speciation

• BUTmostly allopatric
• Sympatric flowers (2-4)

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Allopatric speciation

• SPACE SEPARATION
• The Grand Canyon squirrels cant fly

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Chance events influence evolution
Migration Catastrophe Penal colony
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Founder effect occurs
Due to migration of a non-representative
small population
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Sympatric speciation polyploidization
Polyploid can self fertilize? New species!
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Chromosome evolution Fused chromosomes
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Barriers to interbreeding(sympatric speciation)

• Two species have been formed if breeding is
  prevented
• 1) Before fertilization E.g. cant interbreed,
  wrong time for pollination
• 2) After fertilization E.g. offspring are
  inviable or sterile (e.g., in polyploid vs.
  diploid species or mule vs. donkey)

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WHAT CHANGES

• Time of breeding (day or night)
• Location of breeding (specific flower species or
  island)
• Preference to specific colors
• Differences in habitat (often beside each other)

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Speciation

• What is a species?
• The Process of Speciation
• Models of Speciation
• Interesting examples of Speciation

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Models of Speciation

• Gradualist Model
• Darwin thought species arose gradually and slowly
• Punctuated Equilibrium Model
• speciation occurs in quick bursts followed by
  long periods of no change
• Fossil record supports this model but is
  incomplete

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Gradualism vs. Punctuated Equilibrium
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Speciation

• What is a species?
• The Process of Speciation
• Models of Speciation
• Interesting examples of Speciation

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Adaptive radiation of Darwins finches
Single ancestral species arrived from mainland S.
America millions of years ago, radiated into 13
species with specialized feeding habits
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Ring Species Diverge and converge
Ensantina salamanders
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Co-speciation of host and parasite
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A different look at Geology

• The rest of the slides deal with the formation of
  the earth and life, and are fairly similar to
  previous slides, but show some nice pictures and
  talk about ongoing environmental changes.
• Be sure to check out the slide set on line
  dealing with Classification especially DNA
  clocks!

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Changing Environments and Evolution
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Changing environments and Evolution

• Early Earth and the Origin of Life
• Major events in the history of life
• Continental drift and life as we know it
• Present day environmental changes

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Changing environments and Evolution

• Early Earth and the Origin of Life
• Major events in the history of life
• Continental drift and life as we know it
• Present day environmental changes

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Early Earth

• Earth was formed 4,500,000,000 yrs ago
• Earth was very hot and constantly bombarded by
  meteor showers from space
• At this point there was no liquid water, life was
  impossible
• About 3,900,000,000 yrs ago, Earth was solidified
  enough and cool enough for liquid water
• Life apparently arose shortly thereafter

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Formation of ingredients for life

• 1950s Miller and Urey found that the input of
  electrical energy could spur the creation of
  organic compounds from inorganic compounds and
  ocean water

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The transition from molecules to life

• the step from amino acids to replicating life is
  still a mystery
• biochemical clues suggest that there may have
  been life on the planet as early as 3.8 billion
  years ago
• First fossils are 3.5 billion years old (resemble
  modern day bacteria)

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Environment for early life forms

• Essentially no atmospheric O2
• Highly corrosive, destroys molecules
• Highly energetic
• Lightning, volcanic activity, UV radiation high
• Provide energy for chemical reactions

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Could life originate elsewhere?

• As our understanding of our own solar system has
  increased, the hypothesis that life is not
  restricted to Earth has received more attention.
• Europa (a moon of Jupiter)
• may have liquid water beneath the surface and
  may support life
• Mars
• is cold, dry, and lifeless today, but was
  probably relatively warmer, wetter, and had a
  CO2-rich atmosphere billions of years ago
• Mars subsurface may still be capable of having
  life
• Many scientists see Mars as an ideal place to
  test hypotheses about Earths prebiotic chemistry

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Where did first life forms evolve?

• Previously assumed to be on the surface of the
  ocean
• Now, it is thought that life evolved in
  hydrothermal vents in the deep ocean where no
  photosynthesis takes place
• sulphide-rich water and heat provided the
  necessary elements for lifes reactions

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Deep Sea vents
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Changing environments and Evolution

• Early Earth and the Origin of Life
• Major events in the history of life
• Continental drift and life as we know it
• Present day environmental changes

• Early Earth and the Origin of Life
• Major events in the history of life
• Continental drift and life as we know it
• Present day environmental changes

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A clock analogy for Lifes History

• Major events are
• Photosynthesis
• Multicellularity
• Invasion of land
• Humans (come into the picture a few minutes to
  1200)

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The Evolution of Photosynthesis

• Photosynthesis Using sunlight to create
  carbohydrate from CO2
• First photosynthetic organisms used Hydrogen
  sulphide (combination of old and new) and
  created sulphur as a by-product
• Modern day photosynthesis uses only CO2 and water
  and produces O2 as by-product

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Oxygen changed the world

• Over the next 3 billion years, the oceans became
  saturated with O2
• organisms that could not tolerate O2 went extinct
  (or became very rare and restricted to O2-free
  environments)
• 800 million years ago, O2 starts seeping into
  atmosphere creating the ozone layer

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Ozone layer allows life on land

• By 400 million years ago, O2 levels were
  approximately at modern levels
• Ozone layer blocks the UV radiation, which causes
  mutations, allowing organisms to invade land

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Early changes in the environment
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Cambrian Explosion of multicellular organisms

• Earliest known fossils of multicellular
  organisms, 600 mya
• 540-505 mya huge diversity of organisms present
  in the fossil record
• Best fossils displaying Cambrian explosion are in
  the Burgess Shales in the Canadian Rockies

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Determining the Earths History
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Fossils of Early life forms

• microscopic
• found in 3.4 billion year-old rock

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Cambrian fossils
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Other well-preserved fossils
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Other well-preserved fossils
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Other well-preserved fossils
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Changing environments and Evolution

• Early Earth and the Origin of Life
• Major events in the history of life
• Continental drift and life as we know it
• Present day environmental changes

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Continental Drift

• continents ride across the surface of Earth,
  propelled by powerful volcanic forces
• explains some basic patterns of similarity and
  dissimilarity of flora and fauna

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Pangaea

• Until 200 mya, all continents were clustered
  together at tropical latitudes
• As plates of Pangaea broke off, each plate
  carried a different set of life forms

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The Drifting of Continents
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Australia and Antarctica

• Have been isolated from the other continents for
  the longest time
• Resulted in them having the most unique flora and
  fauna
• e.g., marsupials

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Unique flora and fauna of Australia
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Changing environments and Evolution

• Early Earth and the Origin of Life
• Major events in the history of life
• Continental drift and life as we know it
• Present day environmental changes

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Recent Ozone changes

• Human activities have
• increased ozone in the troposphere
• decreased ozone in the stratosphere

Good ozone (protects Earth from UV radiation)
Bad ozone (reactive gas)
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Increases in tropospheric ozone

• By-products of burning fossil fuels (e.g., oil.
  gas) react with oxygen to make O3
• O3 reacts with chlorophyll in plants, detrimental
  to growth

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Decreases in stratospheric ozone

• CFCs, HCFCs and other chemicals react with O3
  to make O2
• decrease in O3 increases UV radiation ? higher
  rates of cancer (in humans and other mammals),
  reproductive failure in birds and lizards, damage
  to plants, etc.

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Summary

• Life began on Earth 3.5 bya
• The evolution of photosynthetic organisms
  resulted in the formation of the ozone layer,
  paving the way for life on land
• Continental drift has played a large part in
  shaping the modern day distribution of organisms
• Changes in the environment are happening today at
  a rapid pace

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Classification of Organisms

• Based on natural similarities
• Structure
• Function
• DNA and RNA
• TAXONOMY
• Science of describing, naming and classifying
  organisms

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Classification - History

• Linnaean system
• Based on form and structure
• Seven levels
• K,P,C,O,F,G,S
• Binomial Nomenclature
• Genus species or Genus species
• InitiallyTWO kingdoms
• Plantae and Animalia

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Kingdoms and Domains
The three-domain system
Bacteria
Archaea
Eukarya
The six-kingdom system
Bacteria
Archaea
Protista
Plantae
Fungi
Animalia
OLD KINGDOMS
The traditional five-kingdom system
Monera
Protista
Plantae
Fungi
Animalia
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Systematics

• Evolutionary Classification
• Combines
• Fossils
• Comparative homologies
• Comparative sequencing of DNA/RNA
• Cladistics
• Molecular clocks

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What does each provide

• Fossils
• Time context
• Changes in life through sedimentary rock
• Eras defined by changes in fossils
• Comparative Homologies
• Feature shared due to common ancestor
• MUST be tested (could be convergent)

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What does each provide?

• Cladistics
• Evolutionary relationships
• Primitive (common to all) characteristics
• Derived (appear in some but not all members)
• Derived provide the clues!
• Principle of Parsimony
• Molecular clocks
• Average time for a set number of mutations is
  predictable
• Allows estimation of time

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Phylogeny

• Phylogenies trace patterns of shared ancestry
  between lineages
• Similarly, each lineage has common ancestors.

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Clades and Cladograms

• Grouping that includes a common ancestor and all
  the descendants (living and extinct) of that
  ancestor.
• Using a phylogeny, it is easy to tell if a
  group of lineages forms a clade.

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Nested Hierarchies

• Groups of related organisms share sets of similar
  characteristics
• The number of shared traits increases with
  relatedness.

• Snakes and lizards more closely related to one
  another than to the other animals represented.
• However, at a more inclusive level, snakes,
  lizards, birds, crocodiles, whales, camels,
  chimpanzees and humans all share some common
  traits since they have a common ancestor.

145
Dichotomous Keys

• Dichotomous keys versus evolutionary
  classification
• Dichotomous keys contain pairs of contrasting
  descriptions.
• After each description, the key directs the user
  to another pair of descriptions or identifies the
  organism.
• Example 1. a) Is the leaf simple? Go to 2
  b) Is the leaf compound? Go to 3
• 2. a) Are margins of the leaf jagged? Go to 4
  b) Are margins of the leaf smooth? Go to 5

146
Archaebacteria vs. Eubacteria

• Bacteria
• Archaebacteria
• Cell wall
• RNA polymerases resemble eucaryotic enzymes
• Have introns in some genes
• Eucaryota
• Protista (Protoctista)
• Not Animalia (no blastula)
• Not Plantae (embryo within maternal tissue)
• Not Fungi (no spores) and have cilia and flagella
• Not Monerans (have nucleated cell, live in water,
  formed from symbiogenesis

147
SO
  I.  Bacteria (19) Most of the Known Prokaryotes Division (Phylum) Proteobacteria N-Fixing Bacteria Division (Phylum) Cyanobacteria Blue-Green Bacteria Division (Phylum) Eubacteria True Gram Posive Bacteria Division (Phylum) Spirochetes Spiral Bacteria Division (Phylum) Chlamydiae Intracellular Parasites
 II.  Archaea (16) Prokaryotes of Extreme Environments Kingdom Crenarchaeota Thermophiles Kingdom Euryarchaeota Methanogens Halophiles Kingdom Korarchaeota Some Hot Springs Microbes
III.  Eukarya (35) Eukaryotic Cells Kingdom Protista (Protoctista) Kingdom Fungi Kingdom Plantae Kingdom Animalia
148
What are viruses???

• Not in any kingdom
• No membrane-bound organelles
• No ribosomes (organelle site of protein
  synthesis),
• No cytoplasm (living contents of a cell),
• No source of energy production of their own.
• No self-maintenance metabolic reactions of living
  systems. Viruses lack cellular respiration,
  ATP-production, gas exchange, etc.
• Do reproduce, but at the expense of the host
  cell. Only capable of reproduction within living
  cells.

149
Phylogenetic Diagram
150
Phylogenetics

• Evolutionary history

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