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EQs 1-4

What happened at the Cambrian Explosion?

What happened at the K-T Boundary?

What were the first type of organisms on Earth?

What does the endosymbiont theory?

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

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

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MODERN EVIDENCE OF EARLY LIFE

Fossils- Any preserved evidence of an organism by mineral replacement, molds/casts, ice mummies or amber.

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

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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 Fossils

Organism dies near/in water

Quickly covered in sediments

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Flesh decays, more sediments

Minerals harden in the bones

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5. Bones decay, only minerals are left

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HOW OLD ARE THESE FOSSILS?

Relative Dating- Method used to determine the age of rocks by comparing them with other layers.

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

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

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How is the time scale organized?

It expresses the major geological and biological events in Earths history.

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Eon- Time is split into PreCambrian and Phanerozoic.

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Era- The next largest division (Dinosaurs=Mesozoic)

Period- the divisions of an era.

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

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

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

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

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Cambrian Explosion- When ancestors of most animal groups diversified.

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

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Plate Tectonics- Movement of large continental plates.

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Origins of Earth

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

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

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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.

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

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Order of Organic Molecule Organization

1. The first organic molecules originated

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Formation of proteins

Genetic code that could produce these proteins.

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4. Formation of membranes, molecules become cells

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Cellular Evolution

1. 1st cells were prokaryotes (bacteria), very simple with no nucleus or cell parts. Similar to archaea bacteria (thermophiles)

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

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

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

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Evolution explains..

How living things develop from ancestors

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b. How Earth came to be populated by species

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Evidence for evolution can be seen in.

Cell similarities in all life

Similar proteins in all cells

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Many species disappearing from Earth

Living species being different from ancestors

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Organisms being suited to environments

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

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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.

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

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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.

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

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

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

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People who affected Darwins Work

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

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

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

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DARWINS CONCLUSIONS

Struggle for Existence: The struggle of all organisms in the environment to fulfill ALL of their survival needs.

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What needs do organisms fight for?

Food

Space

light

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Water

Minerals

oxygen

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# of Parents

Asexual=1Sexual=2

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Traits

Asexual- same as parents traits

Sexual- mixture of DNA from both parents

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Less or Greater Variation

Asexual- less

Sexual- greater

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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

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Types of Genetic Variation:

structural/anatomical change

Physiological change

Behavioral change

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Chromosomal/gene change

Molecular change

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Most Important Types of Genetic Variation

Chromosomal

Molecular

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Why? These variations are changes in genetic code

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What drives evolution? Changes in genetic code.

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Darwins Two Clear Facts

1. There is a struggle for existence, which limits the number of surviving offspring.

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

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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.

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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).

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

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***WRITE THIS ON BOTTOM***

Natural Selection- environment chooses the best traits.

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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

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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

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

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Examples

Dogs

Cattle

vegetables

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Fruit

horses

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

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Genetic Variation

Reproduction: fusion of gametes that leads to small differences between the offspring and its parents.

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

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

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

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

Predators

parasites

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c. Diseases

Climate extremes (hot/cold)

Flood

drought

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What 2 things are explained in Darwins book, On the Origin of Species?

1. how natural selection might operate

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2. Provides evidence that evolution occurred

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

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

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

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

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Evidence of Evolution

1. Fossil Record- Provides a record of species that lived long ago so we can compare old species with new ones.

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

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

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

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

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

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

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

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

Examples: five digits on feet

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

Example: hooved animals

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

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

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What organisms/parts are found in these examples?

a. Amber- insects, leaves, small lizards

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Ice- wooly mammoths

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

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

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

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What type of rock do you find fossils in? sedimentary

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

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

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

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

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Examples of Vestigial Structures

Human appendix

Snakes tiny leg bones

Cave salamanders eyes

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

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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

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

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

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

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

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Peppered Moth Story:

Before Industrial revolution- gray colored moths favored for camouflage on tree bark.

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

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Were dark colored peppered moths always present? yes

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

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

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

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***Write this on the bottom***

Light colored moths will still be born because that trait is still in the DNA.

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

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

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

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

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Adaptation- small changes in the same trait of an organism

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

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Fitness- measure of a traits relative contribution to the following generation.

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

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

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

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

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

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Example: Leaves

Desertb. Deciduous

c. Taigad. Tropical

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

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Speciation

Species: A group of related organisms that can breed and produce fertile offspring.

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

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

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

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

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

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

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

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Name physical barriers:

Mountain tops

Isolated lakes

Forests between grasslands

islands

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

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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**

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Divergent Evolution

Adaptive Radiation: Process by which several species evolve from parent species, adapting to different ecological niche

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

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Convergent Evolution

Parallel Evolution: Where 2 or more species evolve separately, but in similar ways

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Examples: birds and flying insects

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

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Example: many insects and flowers (pollination)

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

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

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

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Directional selection: population shift towards extreme version of a trait

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

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

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Extinction

Why does this happen?

a. Death rate higher than birth rate

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Disease

More predators

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

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When was the last two mass extinctions?

a. End of Permian Period-240 millions years ago

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b. End of Cretacious Period-65 million years ago