4 steps in origin of life

1.     Building blocks formed, nucleotides and amino acids
Environment: no oxygen, UV radiation, lightning 
2.     Polymers formed: monomers-->polymers 

            Catalyzed by clay surfaces with charged ions 

3.     Protocell: membranes enclosed polymers
            Characteristics: boundary, contain information (RNA), enzymatic function, rudimentary self-replication

4. Cellular properties - metabolism, replication

Evolution of protocell to bacterium:

1.     External skin (liposome)

2.     Ribozymes support membrane and reproduce

3.     Chance mutations: ribozymes start metabolism

4.     RNA sequencing chains code for proteins

5.     Proteins: enzymes, support

6.     DNA: better stability

7.     Complex organisms=bacteria 

1.     traits vary within a population

2.     some traits are heritable

3.     some individuals survive to produce viable offspring

4.     survival depends on individual’s traits 

Describe 5 examples of evidence of evolutionary change 

1.     Fossil record: tiktaalik 

2. Biogeography: Endemic species: species naturally found in specific location

3.     Selective breeding: human influence on genetic traits

4.     Homologous evolution
Homologous traits, vestigial structures, developmental homology, molecular homology

5.     Convergent evolution: natural selection in traits due to environmental need (curling tails seahorses and monkeys)

6.     Ecological field studies: gal’apogos finches – different beak sizes 

Harvey Weinberg Equilibrium

p2 + 2pq + q2 = 1

total population equilibrium  

Natural Selection: 

directional 

stabilizing 

disruptive 

balancing 

Directional selection: favor ONE extreme mutation

Ex. Black peppered moth

Stabilizing selection: favor middle, select against extremes

Ex. Bird clutch size

Disruptive selection: favor BOTH extremes, diverse environment
Ex. Two mimic pops of butterflies, two species?

Balancing selection: balanced polymorphism, two traits equally favored

Ex. Sickle cell anemia 

Explain genetic drift, founder effect and bottleneck effect

Genetic drift: random allele frequency NOT related to environmental pressures, reduces genetic variation

Bottleneck effect:extreme factors reduce pop indiscriminately (flood), different allele frequencies due to smaller pop

Founder effect: small population founds new larger population, low diversity due to few alleles brought to pop (ex. Amish)

movement of individuals to different population groups 

Biological species concept: able to breed successfully - ligers, mules, doesnt work with asexual bacteria.

Morphological species concept: different phenotypes – but what characteristics to consider important?    

Ecological species concept: ecological niche – two species cannot occupy same niche

Evolutionary/phylogenic concept: molecular evidence using DNA, requires DNA 

List, explain and give examples of at least 3 prezygotic isolating mechanisms and 2 postzygotic isolating mechanisms

Prezygotic: prevents fertilization
- Habitat isolation
- temporal isolation
- Behavioral isolation: different mating rituals
- Mechanical isolation: different genitalia
- Gamete isolation: different proteins on gametes

 Postzygotic: factors after fertilization (less common)
- reduced viability: different gametes impair development (stillbirth)
- reduced fertility: sterile hybrid (mules, ligers)
- hybrid breakdown: decreased viability in subsequent generations 

Sympatric vs allopatric speciation 

Allopatric speciation: geographical separation causes new species

Topographical changes (earthquake)

Adaptive radiation: species adapt to different behaviors

Sympatric speciation: something other than geography affects species

Polyploidy: nondisjunction causes errors in chromosomes

New niches create new species