Evolution and Extinction

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DNA

composed of two strands of sugar-phosphate backbone bound to nucleic acids

2%

the approximate percentage of the human genome codes for proteins

tRNA

are used by the ribosome to read the messenger RNA

Replication and transcription

the two main central dogma processes that occur in the nucleus

Introns

are removed during splicing and stay in the nucleus

Three Domains of Life

Archea, Bacteria, and Eukarya

Prokaryotes(bacteria)

the true owners of our world

Oxygen

it wasnt present before the evolution of photosynthesis on this planet.

2.5 Billion years old

the age of the oldest Eukaryote fossil

Four lines of evidence for endosymbiosis theory

1. size of organelles nearly identical to size of free-living prokaryotes
2. organelles of eukaryotes have their own DNA, RNA, and ribosomes
3. organelles reproduce separately during division of eukaryotic cell
4. mitochondria are susceptible to antibiotics

Inside of stars

where all elements heavier than He are produced

During Supernovae Explosion

where all elements heavier than Fe are produced

Why there is extra iron in the universe

because it is the end product of normal stellar nucleosynthesis

Age of Earth

4.45 billion years old

Two key things we learn from meteorites

composition of the inner planets and age of the Earth/Solar system

Ring Species

species that have interbreeding populations with range endpoints that do not interbreed.

Homologous Species

a structure derived from a common ancestor and can be modified for different uses in different lineages

Its Size

why mars has so much less atmosphere than Earth and Venus

Sedimentary Rocks

where a huge amount of C02 is tied up on earth

Four Steps to build a habitable planet

1.) Raw material
2.) heavy construction
3.) Modifications
4.) make it comfortable

Cuvier

The main proponent of the reality of extinction

Cretaceous mas extinction

the mass extinction that caused the end of the dinosaurs

99%

percentage of animals to have ever lived that are now extinct

Permian mass extinction

Largest of the mass extinctions

Marine Biota

the type of biota most affected by the permian extinction

Generation

the timescale most relevant to measuring evolutionary rates

Three things required for natural selection to occur

Variation
Heritability
Differential Reproduction

3 ways groups of organism may become reproductively isolated

Geographic barriers; different mating/flowering seasons (timing); different mating displays/phermones; different pollinators in plants; sterile hybrids; unviable embryos

Faunal Succession

discovered before natural selection theory, can be used to order and subdivide geologic time, and forms the basis of biostratigraphy

Directional Selection Followed by stabilizing selection

a population starts out on the slope of adaptive landscape with only one fitness peak that is static over time; this is the expected type of selection of the population, assuming that that natural selection can act on the relevant traits

Haldane

change in standard deviations per generation

how imperfect are paleontological collections

2% globally, locally it can be quite complete 0-100%

Edmond Halley

used the saltiness of the ocean to determine the age of the earth

The Erosion of the Weald

the erosion of a landscape in england used to measure the age of the earth

The accumulation of sediment

measuring the thickness of sedimentary rocks used to estimate age of earth

William Thompson

lord kelvin. Laws of Thermodynamics to explain how the universe works.
earth cooled from original molten mass
mixing achieves equilibrium
center solidifies firs
no other energy inputs
end result is sphere of uniform temperature

Kants nebular hypothesis

solar system formed by gravitational collapse of dust and gas in planetary nebula
gravitational contraction resulted in increase in temperature; impacts of asteroids into other bodies converted kinetic energy to heat
given open system of solar system and law of conservation, system must cool down; time required can be calculated

Radioisotopic Decay

chemical elements are defined by the number of protons (+) in there nucleus. Isotopes are atoms with the same number of protons but different numbers of neutrons (neutral charge). some isotopes are unstable and will spontaneously decay into new stable elements, most these process give off high-energy particles that can be measured

Oldest Rock from Earth

4.03 Ga up in canada eh

Oldest Mineral from Earth

4.40 Ga

Oldest Objects on Earth

4.55 Ga meteorites

Oldest Visible prokaryote fossil

3.465 Gyr

When oxygen accumulates in the atmosphere

2,300,000,000 2.3 Ga

Oldest eukaryote fossil

2.5 Ga

Earth freezes over "snowball earth"

710,000,000 710 Ma

Oldest Multicellular animal fossil

600,000,000 yr 600 Ma

Cambrian Explosion of animals

542,000,000 yr 542 Ma

First Archosaurs

240,000,000 yr

Why there is extra iron in the universe

because that is the end product of normal stellar nucleosynthesis

Sun

rather small start, it does not have enough mass to go supernova, it barely has enough mass to burn He, made up of H, and He, 2nd generation

When will the sun burn out

In 5 Ga our sun will run out of H fuel and will begin to collapse; this will heat up outer shell, expands to engulf earth; ultimately core will cool to a white dwarf

Moon

soon after earth formation a mars-sized early planet is believe to have impacted earth
material ejected from earth/impactor eventually coalesced to form the moon

Two key things that plate tectonics does that are important to evolution

1.) move continents around
2.) recycle/release material at earths surface

What controls planet's temperature

1) luminosity of star
2) distance from star
3) reflectivity of surface
4) composition of atmosphere

Water on earth

Most water on the earth derives from degassing of the mantle

where a lot of CO2 is tied up in

Sedimentary rocks - active tectonics and liquid H2O permits this

chemolithotrophs

use inorganic compounds as an energy source; e.g., iron oxidizing, sulfide oxidizing, and hydrogen oxidizing

photolithotrophs

use light as an energy source in photosynthesis; normal photosynthesis releases O2, but photosynthesis can be anoxygenic

Key elements of bacteria/archea

1) Barrier to external environment (cell wall and phospholipid bilayer)
2) DNA/RNA
3) Ribosomes

Rusting of the planet to accumulate free O2

before evolution of photosynthesis, there was no free oxygen in atmosphere: its way too reactive
when no oxygen was present in atmosphere, elements like Fe were soluble in water; in order for O2 to build up in atmosphere, oceans had to rust!

~2.4 Ga

Economically important precambrian iron: superior province banded iron formation

Origin of eukaryotes believed to be the "enclosure" of some prokaryotic cells by another larger prokaryotic cell

1) size of organelles within eukaryotic cells is nearly identical to the size of free-living prokaryotes to which they are metabolically similar
2) organelles of eukaryotes (mitochondria, chloroplasts) have their own DNA, RNA, and ribosomes; sequences are similar to prokaryotes
3) Organelles have their own independent mechanisms of reproduction during division of eukaryotic cell
4) Mitochondria are susceptible to antibiotics

The Middle Cambrian

Trilobite Evolution

What Caused the Cambrian Explosion

Biological Factors
-Devlopmental Trigger: the evolution of HOX genes and the differentiation and patterning of animal body plans
-Ecological Trigger: the evolution of predators and an evolutionary arms race
Physical Factors
-Oxygen Trigger: O2 threshold reached, permitting evolution of large bodied animals w/ active lifestyles
-Snowball Earth: the deepfreeze of earth "did something" to prompt the evolution of animals with shells

The "Great Unconformity"

1.5 Ga of missing piece

Problems getting onto land

Gravity and water. Must have structural features to support body. must have structural features to prevent desiccatioin

Arthropods

First animal to get on land, have exoskeleton

Causes of Extinction

-Out-competed by other organisms
-Environmental Change
-Evolution
-Stochastic (Random)

Normal "Background" Extinction

extinction due to many different taxon specific causes (e.g., predation, competition) and to chance; continuously happening; accounts for MOST extinctions

Mass Extinctions

Wholesale elimination of many unrelated taxa on a global scale; extinction rate is significantly higher than normal; the "rules" of who lives/dies change; constitutes a small proportion of total extinction over time, but have disproportionate effects; usually thought to be drieven by unusual/rare events

Big Five major mass extinctions

Permian/Triassic: ~95% species loss on land and in sea
Ordovician/Silurian: ~85% species loss in sea, too few land metazoans to make any estimates
Triassic/Jurassic: ~80% species lost, land and sea
Cretaceous/Paleogene: 76% of all species went extinct; non-avian dinosaurs go extinct
End-Devonian: estimates vary... this one has been discounted

How dinosaurs went extinct

Mammals out compete "inferior" dinosaurs
Smoking Gun

Siliciclastics

High nutrient, soft substrates

Carbonates

Low nutrient, firm substrates

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