Unit 11: Evolution

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Evolve

Change

Microevolution

Any change in allele frequency in the gene pool of a population

Macroevolution

An accumulation of many small genetic changes that result in the formation of a new species from a pre-exsiting species

What are the two theories to how Earth formed?

1. Intelligent design/ creationism (God created)
2. The Big Bang Theory

What is The Big Bang Theory?

* All matter in entire universe condensed in one location
* Explodes, everything/particles goes flying
* Gases and reactions following explosion forms galaxies, planets, suns, ect.
* Earth was super hot from explosion and cooled to form a crust
* Earth has solid iron core and has magma under crust

When does The Big Bang Theory say Earth was formed?

4\.5 billion years ago

When does intelligent design say Earth was formed?

12,000 - 200,000 years ago

Where does Oparin’s Hypothesis say CHNO (part of SCHNOP) came from?

Simple gas molecules

Where does Oparin’s Hypothesis say carbon (C) came from?

Methane gas (CH4)

Where does Oparin’s Hypothesis say hydrogen (H) came from?

Hydrogen gas (H2)

Where does Oparin’s Hypothesis say nitrogen (N) came from?

Ammonia gas (NH2)

Where does Oparin’s Hypothesis say oxygen (O) came from?

Water vapor (H2O)

What is Oparin’s Hypothesis?

* Methane gas, hydrogen gas, ammonia gas, and water vapor collided and reacted with each other because of all the energy present where eventually organic molecules formed
* They rained down into the seas (“Organic soup”) while continuing reacting with each other
* Lots of time passes then 1st cells are made

What are examples of energy present that caused organic molecules to form?

* Heat
* Light
* Radiation
* Lightning
* Volcanic eruptions

What is Miller’s test?

* Tested Oparin’s hypothesis


* Uses distillation apparatus (made of glass tubing)
* Created water cycle
* Let experiment run for 24 hours

What were the results of Miller’s test?

Second time run: 2 amino acids (Glycine & Alanine)

How many years ago is Earth said to have been created according to the Big Bang Theory?

4\.5 billion years ago

How many years ago were the 1st cells said to have been created according to the Oparin’s hypothesis?

3\.5 billion years ago

How many years ago were the 1st cyanobacteria said to have been created?

2\.5 billion years ago

Why is the appearance of the 1st cyanobacteria important?

They photosynthesize and bring oxygen into the air

How many years ago were the 1st eukaryote cells said to have been created?

1\.5 billion years ago (took 2 billion years to develop)

What are the first cells according to Oparin’s hypothesis?

* Cell membrane
* Cytoplasm
* RNA
* Ribosomes

What are the traits of the first cells according to Oparin’s hypothesis?

* Anaerobic (no oxygen in air)
* Aquatic (formed in water)
* Glycolysis (1st respiration process)
* Smaller
* Divided A-sexually by fission
* Heterotrophs (ate each other)
* Chemosynthesis (ate inorganic food)
* Did not photosynthesize

What are fossils?

Remains of past life

What are the different kinds of fossils?

1. Could be an imprint (perfect impression)
2. Could be cast (stone replica)

What can be learned from fossils?

How the organism died, what lived with it (past life)

What are the methods of fossilization?

1. Tar pits
2. Ice caves
3. Amber
4. Volcanic ash
5. Peat bog
6. Sedimentary rock

What is amber?

Crystalized tree sap

What does amber fossilize?

Small animals/insects

What is a peat bog?

Muddy swamp like quicksand that is acidic

What is the most common method of fossiliztion?

Sedimentary rock

What is relative dating?

Comparing the age of fossils by observing how deep they are in the rock layer

What is absolute dating?

Using radioactive isotopes to find age

Is it better to have long or short half life for absolute dating?

Longer

What is half life?

The time it takes for half of radioactive material to decay

How do you use absolute dating?

* Guess the measurement of grams of radioactive isotope at death
* Calculate grams to half life of radioactive isotope till get 1 gram

Why isn’t absolute dating perfect or always accurate?

* Number of grams is only an estimate
* Measured assuming constant half life rate

What is the geologic time scale?

The entire history of Earth (includes history of life)

What is the geologic time scale divided up into?

Four eras of time

What are eras divided up into?

Periods

What are periods divided up into?

Epoch

What are the four eras of time?

1. Precambrian
2. Paleozoic
3. Mesozoic
4. Cenozoic

When was the Precambrian era?

4600-543 years ago (4 billion years long)

When was the Paleozoic era?

543-245 years ago (250 million years long)

When was the Mesozoic era?

245-65 million years ago (180 million years long)

What is considered to be the age of dinosaurs?

Triassic, Jurassic and Cretaceous periods in the Mesozoic era

What is our current era?

The Cenozoic era

When was the Cenozoic era?

65 million years ago - current time

What is the trend that ends an era?

Mass extinction of life (though some survive)

Why are eras getting shorter?

Change is happening faster

What should be seen in the fossil record?

Lots of gradualism, small steady changes over time to get to modern species

Why isn’t the fossil record not perfect evidence of macroevolution?

* Not seen in most species
* Record is incomplete, can miss species
* Not always interpreted correctly
* No way to know if correct
* Can’t always go off DNA or appearance
* So much unknown

What are homologous structures?

Has similar bone/internal structure/pattern, don’t have same function

What is an explanation for homologous structures?

Common ancestor

What are vestigial structures?

Left over/extra reminate body parts no one of species uses

What is an explanation for vestigial structures?

Had a common ancestor that once used the body part

Can you live without a vestigial body part?

Yes

What are examples of vestigial structures?

* Human coccyx (tailbone)
* Human appendix

What are homologous vertebrate embryos?

When all vertebrate (backboned) at some point goes through stage when embryo

What are physical traits of being homologous vertebrate embryos?

* Curved spine, ends at tail
* Big eyes
* 4 limb buds
* Gill slits

What is an explanation for homologous vertebrate embryos?

Common ancestor

What is the most important difference between species that beats all others?

Developmental (homologous vertebrate embryos)

What are homologous molecules?

2 main molecules compared between species: DNA gene sequence and proteins

What is an explanation for homologous molecules?

Common ancestor

What is Lamarck’s theory?

1. Inheritance of acquired characteristics (wrong- anything you inherit must come from DNA)
2. Vestigial organs go away if we decide we don’t need them anymore (wrong- not choice, though over time could possibly disappear)
3. Organisms have an innate desire to change (wrong- change isn’t a choice)

Who is Charles Darwin?

Considered the father of modern evolution

What is Darwin’s story on the Galapagos Islands?

* Found 13 different kinds of finch (only 1 kind in Ecuador)
* Guess original had children with different beak mutations, had to find new food
* Kept alive because no predators, no competition
* Don’t reproduce together by choice

What are Darwin’s observations?

1. There is variation within a population
2. More organisms are produced than the environment can support
3. Population size remains constant over time
4. The Earth is slowly but constantly changing

What is Darwin’s theory of macroevolution?

1. There is fierce competition for resources
2. Natural selection
3. What is considered fit to survive is constantly changing as environment is constantly changing

What is fitness?

* Whatever helps you survive better
* Lives long enough to pass fit trait, reproduce
* Adaptations are fit traits
* Eventually everyone in population will have fit trait, those without had died

What is natural selection?

* Main mechanism for change
* Nature/environment determines fitness

How much life has gone extinct? Why?

95%, couldn’t mutate and change with environment

What is speciation?

The making/forming of new species from a pre-existing species

What are species (only applies to animals)?

* Must naturally mate/reproduce in wild
* Offspring viable (they must be able to reproduce when they grow up)
* Both criteria must be met to be determined as the same species

What is allopatric specation?

* Geographic barrier causing split in species
* Reproductive isolation
* Each population gets different mutations till becoming different species

What is sympatric speciation?

* In same location
* A group gets mutation
* Can still reproduce together
* Mutated and normal group may choose to reproduce separately, eventually becoming a new species

What is adaptive radiation?

When one species enters a new territory and quicky radiates out into multiple species (all shares common ancestor)

Why is adaptive radiation possible?

* No competition, no preators in new area
* Can adapt to different environments predators to fill different niches in area

What is an example of adaptive radiation?

Darwin’s finches

What is convergent evolution?

Two different unrelated species in different locations evolve similarly, has similar adaptations

Why is convergent evolution possible?

* They live in similar environments
* Natural selection is similar

What is an example of convergent evolution?

Sugar glider (Australia) & flying squirrel (North America)

What are analogous structures?

* Similar adaptations to different species
* Looks similar outwardly
* Has same function
* Different origin
* Different inside
* Exact opposite of homologous structures

What is gradualism?

Small gradual changes in species over time (very rare)

What is equilibrium?

Species doesn’t change at all, living fossils (species millions of years old that still exist today: sharks)

What is punctuated equilibrium?

Short burst of rapid change (most common)

What could cause rapid change in punctuated equilibrium?

* Big natural disasters
* New species migrated

What are the 5 conditions of Hardy-Weinberg equilibrium (no change in allele frequency of a gene pool)?

1. No mutations (can’t create new allele or change allele)
2. No natural selection (everyone must be equally fit, has equal chance of survival)
3. No migration in or out
4. Large population size (couple losses won’t change allele frequency, smaller populations change faster as affected more by loss)
5. Random mating (no selectiveness, everyone is equal)

What was Hardy-Weinberg’s conclusion?

Can’t meet all 5 conditions for prolonged periods of time, therefore change in allele frequency is inevitable (must happen)

What are the equations to calculating allele frequencies?

p^2 + 2 pq + q^2 = 1

p+q=1

What does “p” represent?

Frequency of dominate allele (A)

What does “q” represent?

Frequency of recessive allele (a)

What does “q^2” represent?

Frequency of homozygous dominate genotype (AA)

What does “pq” represent?

Frequency of heterozygous genotype (Aa)

What does “p^2” represent?

Frequency of homozygous recessive genotype (aa)