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EQ’s 1-4

1. What happened at the Cambrian Explosion?2. What happened at the K-T Boundary?3. What were the first type of organisms on

Earth?4. What does the endosymbiont theory?

Land Conditions: Earth was molten lava to start. Gravity started pulling elements together. Crust started to form

Atmosphere conditions: Probably were gases expelled from volcanoes (water, CO2, sulfur dioxide)

MODERN EVIDENCE OF EARLY LIFEFossils- Any preserved evidence of

an organism by mineral replacement, molds/casts, ice mummies or amber.

How does a fossil form? Organism must die and be covered in sediment quickly (near moving water).

On what parts of the Earth do we find fossils? Areas that were moving, shallow water when those organisms lived.

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Steps to Fossils1. Organism dies near/in water2. Quickly covered in sediments

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3. Flesh decays, more sediments4. Minerals harden in the bones

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5. Bones decay, only minerals are left

HOW OLD ARE THESE FOSSILS?Relative Dating- Method used to

determine the age of rocks by comparing them with other layers.

Radiometric dating- Uses the decay of radioactive isotopes to measure the age of a rock.

Half-life- the known amount of time it takes for half of the original isotope to decay (Uranium238 to Lead 206)

How is the time scale organized?It expresses the major geological

and biological events in Earth’s history.

Eon- Time is split into PreCambrian and Phanerozoic.

Era- The next largest division (Dinosaurs=Mesozoic)

Period- the divisions of an era.

Precambrian Era- The first 4 billion years on Earth, prokaryotes 1st then multicellular eukaryotes.

Paleozoic Era- Major diversification of body plans and # of species. Life in oceans 1st, then moved to land. 2 mass extinctions.

Mesozoic Era- Early mammals 1st, then dominated by reptiles (dinosaurs). 1st flowering plants and birds.

Cenozoic Era- Mammals are dominant life-form, diversified quickly

Cambrian Explosion- When ancestors of most animal groups diversified.

K-T Boundary- Layer between Mesozoic and Cenozoic eras. Evidence of impact event (iridium).

Plate Tectonics- Movement of large continental plates.

Origins of EarthSpontaneous Generation- Idea

that life arises from non-life. Example- mice came from damp hay and corn

Theory of Biogenesis- Only living organisms can produce other living organisms.

How did complex molecules join together?

Primordial Soup Hypothesis- If early Earth had mix of gases, organic cmpds could be made by reactions in the oceans.

Deep-Sea Vents- Some believe that these reactions began here, where sulfur forms the base of the food chain.

Order of Organic Molecule Organization

1. The first organic molecules originated

2. Formation of proteins3. Genetic code that could

produce these proteins.

4. Formation of membranes, molecules become cells

Cellular Evolution1. 1st cells were prokaryotes

(bacteria), very simple with no nucleus or cell parts. Similar to archaea bacteria (thermophiles)

2. Photosynthesizing Prokaryotes- Archaea used sulfur for food, next organisms used light (photosynthesis)

3. Endosymbiont Theory- Ancestors of eukaryotes lived in association with prokaryotes. Explains DNA in chloroplasts and mitochondria.

Evolution- Idea that organisms CHANGE OVER TIME as a result of “genetic variations” enabling them to ADAPT to changing environments.

Evolution explains…..a. How living things develop from

ancestors

b. How Earth came to be populated by species

Evidence for evolution can be seen in….

a. Cell similarities in all lifeb. Similar proteins in all cells

c. Many species disappearing from Earth

d. Living species being different from ancestors

• Organisms being suited to environments

• Extinction- When a species that once lived on the Earth no longer exists. Death rate is higher than birth rate

• In 1859, Charles Darwin published his book On the Origin of Species on evolution. Darwin was a naturalist on the HMS Beagle, a ship that sailed around South America into the Pacific Ocean.

• On his trip, Darwin collected many different samples of organisms. From these, Darwin made observations and thoughts on evolution (change).

One Important Stop: Galapagos Islands

a. Location of islands- far enough from South America to make it difficult for organisms to get there from mainland.

• b. Islands are separated from each other, keeping them isolated.

• c. Numerous number of finch species with differences in beak shape.

People who affected Darwin’s Work

a. Charles Lyell- Described the processes of how landforms are formed. He believed these processes took millions of years.

b. Alfred Russell Wallace- Developed his own theory of evolution, which was similar to Darwin’s.

• c. Thomas Malthus- Mathematician who explained how the human population had the potential to reach huge numbers in a short time period.

DARWIN’S CONCLUSIONSStruggle for Existence: The

struggle of all organisms in the environment to fulfill ALL of their survival needs.

What needs do organisms fight for?

a. Foodb. Spacec. light

d. Watere. Mineralsf. oxygen

# of ParentsAsexual=1 Sexual=2

TraitsAsexual- same as parent’s traitsSexual- mixture of DNA from both

parents

Less or Greater VariationAsexual- lessSexual- greater

• Mutation: A sudden change that occurs in the genetic material of an organism. This change may produce a small or large change in the organism

Types of Genetic Variation:1. structural/anatomical change2. Physiological change3. Behavioral change

4. Chromosomal/gene change5. Molecular change

Most Important Types of Genetic Variation

a. Chromosomalb. Molecular

• Why? These variations are changes in genetic code

• What drives evolution? Changes in genetic code.

Darwin’s Two Clear Facts1. There is a struggle for existence,

which limits the number of surviving offspring.

• 2. There are differences among offspring due to individual variations.

• What determines which individuals survive to reproduce and thus become the parents of the next generation? The individuals whose genetic variations allow them to compete for their needs the best.

• Natural Selection: The process by which organisms that have the best adaptive traits for an environment are more likely to survive and reproduce (survival of the fittest).

• Adaptations: Special characteristics that make an organism well suited for a particular environment.

***WRITE THIS ON BOTTOM***Natural Selection- environment

chooses the best traits.

How do organisms evolve the adaptations that enable them to survive so well in a particular environment?

Adaptations randomly occur due to random changes in genetic material

• Selective Breeding: The breeding of organisms by humans to produce a specific trait. HUMANS SELECT TRAITS, NOT ENVIRONMENT

Examplesa. Dogsb. Cattlec. vegetables

d. Fruite. horses

• What happens to undesirable traits? They are selected to be removed by humans and replaced with desirable traits.

Genetic VariationReproduction: fusion of gametes

that leads to small differences between the offspring and it’s parents.

Genetic Variation: The small differences in a trait of a species that allows it to adapt to environmental changes.

• Overproduction: The production of offspring that are too numerous to live. They die due to: disease, predation, environmental factors. EX.-sea turtles

• Competition- Struggle between individuals of the same or different species to fulfill their own needs by obtaining limited available resources.

What other factors add to the struggle for existence for individual species?

a. Predatorsb. parasites

c. Diseasesd. Climate extremes (hot/cold)e. Floodf. drought

What 2 things are explained in Darwin’s book, On the Origin of Species?

1. how natural selection might operate

• 2. Provides evidence that evolution occurred

• What is a theory? It provides an explanation for how some aspect of the natural world operates.

• What does the theory of evolution state? It states that all organisms on Earth have descended from a common ancestor.

• In Darwin’s theory of Natural Selection, what aspect of evolution could Darwin not explain? Sexual reproduction /genetic basis for variation

• Why could he not explain this aspect? DNA was not discovered as the genetic material until the next century.

Evidence of Evolution1. Fossil Record- Provides a record

of species that lived long ago so we can compare old species with new ones.

• 2. Comparative Anatomy- Similar parts of different species have different functions but are constructed similarly.

• 3. Comparative Embryology- Comparing different species’ embryos to find similarities/differences.

• 4. Comparative Biochemistry- Comparing DNA, enzymes and other molecules for similarities/differences

• 5. Geographic distribution- Species will have more similarities to species that are on the same continent.

• Homologous structures- Features in different species that have the same evolutionary origin, but may perform different functions at the present time.

• Convergent Evolution- Process where unrelated species evolve similar characteristics that help them survive in similar environments.

• Analogous structures- Features in different species that have different evolutionary origins but serve similar functions (ex. Wings of fly vs. bird)

Primitive trait- a trait that evolved in an early, common ancestor

Examples: five digits on feet

Advanced trait: A trait that is modified by evolution to be different from the primitive trait it evolved from.

Example: hooved animals

• Fossils- traces or remains of dead organisms, preserved by natural processes.

• What parts of an organism are usually fossilized? Bones and other hard parts of their bodies

What organisms/parts are found in these examples?

a. Amber- insects, leaves, small lizards

• Ice- wooly mammoths

• c. Mineral replacement in sedimentary rocks- Once buried in sediment, its tissues are replaced by minerals.

• d. Mud impressions- mud hardens, plant/animal remains

• What type of rock do you find fossils in? sedimentary

• Where does this rock need to develop near in order to create fossils? Stream, river, lake (sedimentation)

• What has to happen to the carcass quickly in order to create fossils? It must be buried in sediments

• What type of sediment layers would you find fossils in? Sandstone or mudstone

• Vestigial Structures: Structure with little/no function in an organism, but is clearly related to a more developed structure in another organism

Examples of Vestigial Structuresa. Human appendixb. Snake’s tiny leg bonesc. Cave salamander’s eyes

Embryology: the study of organisms at very early developmental stages to find similarities/differences in species.

How do organism similarities in both anatomy and embryology provide evidence for evolution? Similarities in species’ anatomy and embryology shows how they changed from a common ancestor

Biochemistry-Studying the molecules that make up organisms (DNA, proteins, enzymes, hormones)

Examples: studying protein interactions with antibodies, comparing hemoglobin of apes/man

Microevolution: Change in species with adaptations best suited for the environment over a SHORT TIME and on a SMALL SCALE

Macroevolution: Change in species to the environment over a LONG TIME on a LARGE SCALE.

Peppered Moth Story:Before Industrial revolution- gray

colored moths favored for camouflage on tree bark.

After Industrial revolution: Tree bark is now darker from soot, darker colored moths become favorable

Were dark colored peppered moths always present? yes

Why were there more dark colored moths in the population after industrialization? They “fit” the environment better

What was the selective agent for this change? The color of the tree bark

Industrial Melanism: When populations near polluted areas evolve to have darker (more protective) coloring than those in less polluted areas.

***Write this on the bottom***Light colored moths will still be

born because that trait is still in the DNA.

Biogeography: Comparing the distribution of plants and animals on one continent to another continent.

Example:1. The South American mara compared to the European rabbit. They do not have similar ancestor.

2. How did species of plants or animals reach the Hawaiian Islands? Either Asia or North America

Best Example for Darwin: Comparing animals on the East coast of South America to the animals on the West coast.

• Adaptation- small changes in the same trait of an organism

• Of the five types of evolution evidence, what was not available to Darwin? Biochemistry, no genetic basis

Fitness- measure of a trait’s relative contribution to the following generation.

Camouflage- adaptations that allow an organism to blend into their surroundings.

Mimicry- 1 species evolves to resemble another 1 for protection.

Antimicrobial resistance- humans use antibiotics that kills most bacteria. Resistant bacteria breed and cause outbreaks.

Speciation: Process of evolution where new species form that are better suited to a changing environment.

Morphology: The changing of shape and/or structure of an organism in response to a changing environment.

Example: Leavesa. Desert b. Deciduousc. Taiga d. Tropical

Physiology: The way an organism and it’s internal parts function at a cellular level (cells, tissues, organs)

SpeciationSpecies: A group of related

organisms that can breed and produce fertile offspring.

Reproductive Isolation: When 1 population of a species is prevented from breeding another population. Can lead to speciation.

How does a population of organisms change? As genetic traits common to the population change.

Genetic Drift: The process by which allele frequencies change over time due to changes in the environment.

Founder Effect: When a population has a very different gene pool from it’s parent population because it descends from only a few ancestors.

Bottlenecks: Process where a genetic makeup of a population changes because all but a few individuals have been eliminated.

Gene Flow: Movement of alleles into and out of a population as individuals move in and out of a population

Geographic Isolation: Reproductive isolation that is caused by a geographic barrier keeping 2 populations of a species apart.

Name physical barriers:a. Mountain topsb. Isolated lakesc. Forests between grasslandsd. islands

What leads to different beaks on the finches of the Galapagos Islands? Variations in food sources on different islands.

If a seed-eating finch lives on an island with only insects to eat, what are his choices for survival?

Move to another island or starve**some might have beak

adaptation to stay**

Divergent EvolutionAdaptive Radiation: Process by

which several species evolve from parent species, adapting to different ecological niche

Examples: reptiles to turtles, lizards, crocodiles, dinosaurs and eventually to birds

Convergent EvolutionParallel Evolution: Where 2 or

more species evolve separately, but in similar ways

Examples: birds and flying insects

Coevolution: Process by which two or more species evolve in response to each other.

Example: many insects and flowers (pollination)

Gradualism: Process by which species evolve at a continuous, slow, steady pace

Punctuated Equilibrium: When species undergo little or no change for long periods of time, then evolve via sudden changes

Stabilizing selection- when organisms with extreme forms of a trait are removed.

Directional selection: population shift towards extreme version of a trait

Disruptive selection: when average traits are removed, creating 2 populations of extremes

• Sexual Selection: change in frequency of trait based on competition for a mate.

ExtinctionWhy does this happen? a. Death rate higher than birth

rate

b. Diseasec. More predators

Mass Extinction: When a high percentage of species die out at the same geological time period.

When was the last two mass extinctions?

a. End of Permian Period-240 millions years ago

b. End of Cretacious Period-65 million years ago

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