Unit 2: Evolution and Adaptations

Question 1

Thomas Malthus provided Darwin with a mechanism for understanding

Answer 1

natural selection

Question 2

carry capacity

Answer 2

• limiting factors in nature such as food resources stay constant in nature or grow arithmetically
• when the carrying capacity is reached limiting factors in populations begin to take place
• a population cannot exceed the carrying capacity without ramifications

Question 3

Populations tend to grow [–] if uncontrolled

Answer 3

exponentionally

Question 4

Competition for resources ensures

Answer 4

that not all individuals recieve everything required to reproduce at high capacity

Question 5

Reproductive Success

Answer 5

• the measure of ability to contribute DNA to future generations
• # of generations that are raised to reproductive age

Question 6

Fitness

Answer 6

strategies and adaptations that produce more offspring are likely to remain and thrive in the population and become the norm

Question 7

What are the three prerequisites or “ingredients” for evolution by natural selection

Answer 7

1. variation among the individuals in a population for a particular trait
2. variation must be heritable - it must have a genetic basis
3. variation in the trait must have consequences for the fitness of individuals, resulting in differences in survival + reproductiive success

Question 8

The gene pool is

Answer 8

shared by all the individuals within the population

each individual has their own subset

Question 9

what is a gene pool

Answer 9

all traits that could potentially get passed on

Question 10

population

Answer 10

all the individuals of the same species that can interbreed

Question 12

consequences

Answer 12

some versions are more successful and some are not successful

Question 13

Bottleneck Effects can lead to

Answer 13

decrease in diversity and eventual population decline

could be due to disease or natural disaster

Question 15

Bottleneck Effect

Answer 15

sharp reduction in size of population due to environmental events

Question 16

Founder Effect

Answer 16

• When a small group of individuals form the gene pool for a new population
• move and don’t replicate original diversity
• not representative of original population

think of colonization

Question 16

Selection can change the frequency of traits in 3 ways

Answer 16

• stabilizing
• directional
• disruptive

Question 17

stabilizing selection

Answer 17

• outliers are unsuccessful
• becomes more uniform w/ less variation
• leads to a lack of phenotypic diversity over time

Question 18

Directional selection

Answer 18

• moves populations toward a current environmental goal
• shift towards one trait
• variations of traits that allow organisms to survive shift graph
• as food availability changes, increased beak size is advantageous

Question 19

Disruptive selection

Answer 19

• when more than one phenotype is adaptive within the environment
• intermediate traits don’t survive the best
• extremes survive
• two successful traits

Question 20

What happened during the 1970 drought

Answer 20

• resulted in large birds
• large strong, beaks

Question 20

Why did average beak depth in Darwin’s finches changes

Answer 20

• changes in seed size and hardness due to environmental changes
• strong selection pressure

Question 21

What happened during the 1980

Answer 21

• resulted in small birds
• small beaks
• soft seeds
• due to El Nino influence

Question 22

The direction of selection may not be the same as that of

Answer 22

overal evolution

Question 23

What are the driving forces for changes

Answer 23

selection osciallations

Question 24

Random mutation can lead to

Answer 24

evolution

Question 25

Hardy-Weinberg Equilibrium in Allele Frequency Equation

Answer 25

p + q = 1

Question 26

conditions for hardy-weinberg equilibrium

Answer 26

• random mating
• no emigration
• no immigration
• no mutation

Question 27

mutation rates in humans have been esitmated to be in the order of [–] to [–] per [–] per [–]

Answer 27

mutation rates in humans have been esitmated to be in the order of 10^-4 to 10^-6 per gene per generation

Question 28

the rate of nucleotide substitutions is estimated be 1 in 108 generation, implying that

Answer 28

30 nucleotide mutations would be expected in each human gamete

Question 29

Selective pressure by predators can

Answer 29

drive selection
* example: predators prefer larger amphipod offspring, so small offspring are more likely to survive and reproduce

Question 30

Peppered moths demonstrate allelic frequency shift due to

Answer 30

• a change in environmental conditions (SO2)
• industrial melanism

Question 31

what is industrial melanism

Answer 31

increase in pollution darkens roosting areas

Question 32

Rattites are more closely related to [–] than each other, indicating [–]

Answer 32

Rattites are more closely related to flighted-birds than each other, indicating **a more complex phylogeny **

Question 33

In allopatric speciation, genetic drift can

Answer 33

generate separate species

Question 34

independent evolution due to differing environmenal forces results in

Answer 34

inability to interbreed

Question 35

allopatric speciation

Answer 35

• occurs when a species separates into two separate groups which are isolated from one another
• A physical barrier, such as a mountain range or a waterway, makes it impossible for them to breed with one another.

Question 36

Sympatric speciation

Answer 36

• occurs when there are no physical barriers preventing any members of a species from mating with another, and all members are in close proximity to one another
• A new species, perhaps based on a different food source or characteristic, seems to develop spontaneously

Question 37

some populations can adapt to [–], which allows rapid [–]

Answer 37

• polyploidy
• sympatric speciation

Question 38

polyploidy

Answer 38

• the acquistion of extra chromosomes
• many species can’t tolerate it, but those who can demonstrate rapid speciation due to inability to interbreed with original cospecies

Question 39

The human genome demonstrates adaptation to a variety of

Answer 39

environmental conditions