Topics 4-6

Question 1

What is genetic and phenotype variation?

Answer 1

genetic: diversity of alleles in a population
phenotype: variety in visible expression of “types”

Question 2

List five factors that can changes allele frequency? ( aka the causes of evolution )

Answer 2

1. natural selection
2. sexual selection
3. mutations
4. gene flow
5. gentic drift
   * make sure to review each individually*

Question 3

What is the difference between the founder effect and the bottleneck effect?

Answer 3

founder effect: is when small part of a population seperates from the main group and starts a new population
bottleneck effect: a catastrophic event wipes out a lot of the population, rare alleles are more likely to be lost

Question 4

What are the main details of directional selection?

Answer 4

• extreme phenotype favoured
• response to steady change in the environment
• loss of gene variation
• directional shift in the mean of the population

Question 5

What are the main details of distruptive selection?

Answer 5

• extremes are favoured
• results in polymorphism
• maintains genetic variation ( loss of phenotype )

Question 6

What are the main details of stabilizing selection?

Answer 6

• common phenotype favoured
• selection AGAINST the extremes
• average conditions stay the same
• little or no evolutionary change

Question 7

What is negative frequency - dependant selection & heterozygote advantage?

Answer 7

neg freq - dependant: rare genotypr has the advantage

heteo advantage: ex) sickle-cell anemia, the heterozygous allele has the advantage

Question 8

What is mircoevolution?

Answer 8

evolutionary change below the species level ( occurs mainly through selection or drift )

Question 9

What is macroevolution?

Answer 9

evolutionary change above the species level
( mass extinctions, speciation, apperance of higher taxa )
note: ‘game changers’ aka the big events

Question 10

What is the Biological Species Concept?

Answer 10

” consists of a group of actually or potentially interbreeding individuals that are reproductively isolated from other such groups “

Question 11

Define pre-reproductive and list the prezygotic isolation mechanisms

Answer 11

prevents two individuals from forming a zygote

• ecological ( habitat selection )
• temporal ( different time of day/season )
• behavioral ( courtship patterns )
• mechanical ( anatomically incompatiable )
• gamete isolation ( sperm & egg can’t fuse )

Question 12

Define post-reproductive and list the postzygotic isolation mechanisms

Answer 12

occur after a zygote has formed

• zygote death
• hybrid infertility ( offsrping can’t reproduce )
• hybrid inviability ( lower fitness )

Question 13

What is speciation?

Answer 13

the formation of new & distinct species in the course of evolution

Question 14

What is the difference between cladogeneis &anagenesis?

Answer 14

cladogeneis: branching or spiltting of a lineage
anagenesis: evolutionary change within a lineage, resulting in differences between sister lineages

Question 15

What is the difference between allopatric and sympatric speciation?

Answer 15

allopatric: population sibdivided by a geographical barrier
sympatric: subgroups formed within a continous habitat, the subgroup can stop mating with the original pop. and the possibility of a new species could occur

Question 16

What is gradualism?

Answer 16

slow differentiation by natural selection over any generations ( Darwin )

Question 17

What is punctuated equilibrium?

Answer 17

speciation happens rapidly followed by relatively long periods of stasis ( then no change )

Question 18

What is abiogeneis?

Answer 18

idea that life arose from non-life more than 3.5 billion years ago, note: the first life forms were simple and through a gradual process became increasingly complex

Question 19

A fossil is most likely to be fossilized if…?

Answer 19

• has a hard body
• was aquatic
• closer to inshore
• decomposing organisms are absent

Question 20

What is the difference between relative and radiometric dating?

Answer 20

relative: stratigraphy
- can’t tell specific date it was fossilized
- can tell which came first, second, third, wtc
radiometric: focuses on looking closely at C-12 and C-14 which is then converted to N-14 as the organisms began to decay

Question 21

Explain continental drift?

Answer 21

the land masses drifting on plates “floating” on hot mantle, the tectonic boundaries are locations for sites of earthquakes and volcanoes

Question 22

What are the four steps that formed life?

Answer 22

1. inorganic compounds
2. organic monomers
3. polymers
4. membrane enclosed compartment

Question 23

Describe Step 1

Answer 23

inorganic atmospheric gases ( CO2, N2, H, methane )
—> huge amounts of energy ( lightning, deep sea thermal vents and collisions )
organic molecules ( sugar, lipids )

Question 24

Describe Step 2

Answer 24

organic acids ( nitrogenus bases, sugars ) ---> proteins ( enzymes, nucleic acid ) 
- RNA monomers produced spontaneously from simple molecules

Question 25

Describe Step 3

Answer 25

• life reproduces: DNA molecules carry genetic info
• life requires energy: metabolism
• needs to seperate it self from the environment ( cell membrane )
  Protocells = spontaneous formation of hollow lipid cells ( bi-layered structure )

Question 26

Describe Step 4

Answer 26

first genetic matieral: RNA

- single stranded, fragile, self-replicating 
- can catalyze many different reactions 
- favoured by natural selection ( RNA World )  

genetic matieral of all living organisms today: DNA
- double helix
- very stable structure
- more accurately replicated ( also favoured by
natural selection

Question 27

Where did life originate?

Answer 27

hot, mineral ruch deep sea vents & clay

- where many of the earliest derivate prokaryotes live

Question 28

What are some alternative theories?

Answer 28

• extraterrestial origin

- special creation

Question 29

What did Miller mimick in his experiment?

Answer 29

tried to replicate conditions from early earth ( can’t reproduce the exact conditions ) but created the basic building blocks