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Evolution and Extinction

STUDY
PLAY
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