Evolution of Populations

Question 1

Evolution occurs in _______ NOT _________

Answer 1

Evolution occurs in populations NOT individuals

Question 2

Genetic basis of evolution

Biological species

Answer 2

group of similar individuals who mate + produce viable fertile offspring

Question 3

Geographic variation

Answer 3

change in the genetic composition of separate populations

Question 4

Population

Answer 4

group of individuals of the same species living in the same geographical area

Question 5

Individuals of a population generally have the same number + type of genes
what’s different?

Answer 5

Some variation due to environment, some due to heredity

Question 6

Population genetics

Answer 6

science that studies the process of microevolution

Question 7

Microevolution

Answer 7

Exchange in the genetic makeup of a population from generation to generation

Question 8

Gene pool

Answer 8

All copies of every type of allele at every locus in all members of the population

Question 9

Allelic frequency

Answer 9

The % of alleles in a gene pool

Question 10

The Hardy-Weinberg Principle:

Compare the scenario with data from a real population

Answer 10

• If there are no differences → real population is not evolving
• If there are differences → suggests real population may be evolving

Question 10

Genotype frequency

Answer 10

the proportion of a particular genotype in the population

Question 11

The Hardy-Weinberg Principle

Answer 11

• One way to assess if natural selection or other factors are causing evolution at a particular locus
• Determine what the genetic makeup of a population would be if it were not evolving at that locus

Question 12

If allele frequency changes over generations → __________

Answer 12

If allele frequency changes over generations → evolution is occurring

Question 13

Factors causing microevolution

(5)

Answer 13

1. Mutations (random mechanism)
2. Sexual recombination (random mechanism)
3. Natural selection (adaptive, non-random)
4. Genetic drift (random mechanism)
5. Gene flow (random mechanism)

Question 14

Mutation

Answer 14

change in the nucleotide sequence of an organism’s DNA

Question 15

where do most mutations occur

Answer 15

• Most mutations occur in somatic cells + lost when individual dies
• Only mutations in gametes can be passed onto offspring

Question 17

Mutation rate

Answer 17

tend to be low in animal in plants + more rapid in microorganism

Question 18

Mutation

Change from generation to generations

Answer 18

Change from generation to generations is very small

Question 19

Sexual recombination importance

Answer 19

In sexually reproducing populations→ sexual recombination is far more important than mutations in producing genetic differences that make adaptation possible

Question 20

Sexual recombination

Change from generation to generation

Answer 20

Change from generation to generation → very small
Mostly reshuffling

Question 21

Genetic drift

Answer 21

random evolutionary change in a population

Question 22

Genetic drift

More likely in a ________ population

Answer 22

More likely in a small population than in a large population

Question 23

# Genetic drift Describes how allele frequencies can ___________

Answer 23

Describes how allele frequencies can **fluctuate unpredictably from one generation to the next**

Question 24

# what am I Alleles may be eliminated from population purely by chance Regardless of beneficial or harmful

Answer 24

Genetic drift

Question 25

# Genetic drift Decreases genetic variation ______ a population Increases genetic differences ________ populations

Answer 25

Decreases genetic variation **within** a population Increases genetic differences **among different** populations

Question 26

The bottleneck effect

Answer 26

* A sudden change in the environment (fire) can drastically reduce side * By chance alone, certain alleles may be overrepresented, others underrepresented

Question 27

# what am I Major factor altering allele frequencies

Answer 27

Genetic drift + Gene flow

Question 28

Genetic drift will continue to change the gene pool until what

Answer 28

Genetic drift will continue to change the gene pool until **the population is large enough to eliminate the effect of chance fluctuations**

Question 29

The founder effect

Answer 29

* Occurs when a few individuals become isolated from a larger population * Small fraction of population establishes a new colony + Bring with them only **small fraction of genetic variability of OG**

Question 30

Gene flow

Answer 30

* Results from the movement of fertile individuals * Migration of breeding individuals → movement of alleles

Question 31

# what am I May cause a population to lose alleles (loose genetic variability) and others to gain some (increase genetic variability)

Answer 31

Gene flow

Question 32

what does gene flow counter

Answer 32

Counters genetic drift and natural selection, and microevolution

Question 33

# what am I Only mechanism that consistently causes adaptive evolution

Answer 33

Natural selection

Question 34

Natural seleciton Can alter the frequency distribution of heritable traits in 3 ways:

Answer 34

1. Directional selection 2. Distributive selection 3. Stabilizing selection

Question 34

Evolution by natural selection is a blend of chance and “sorting:

Answer 34

* Chance → creation of new genetic variation (mutation) * Sorting → favors some alleles over others

Question 34

Directional selection

Answer 34

shifts over makeup of population by factoring variants at **one extreme** of the distribution

Question 35

Natural selection = _________

Answer 35

Natural selection = **adaptive evolution**

Question 36

Distributive selection

Answer 36

favors variants at **both ends** of the distribution

Question 37

Natural selection leads to adaptation, but the process __________

Answer 37

Natural selection leads to adaptation, but the process **does not involve trying**

Question 37

Sexual selection shuffles existing alleles + deals them at random | 3 processes

Answer 37

* Crossing over * Independent assortment * Random fertilization

Question 38

Stabilizing selection

Answer 38

**removes extreme variants** from the population and prevents intermediate types

Question 39

Natural selection and sexual reproduction

Answer 39

In organisms that reproduce sexually → most genetic variation results from the unique combination of alleles that each individual receives

Question 40

natural selection + intentions

Answer 40

NS has **no intentions or senses** → can't sense what a species needs

Question 41

NS cannot fashion perfect organisms | 4 reasons why

Answer 41

1. Evolution is limited by historical constraints 2. Adaptations are often compromises 3. Not all evolution is adaptive 4. Selection mostly only edits existing variations

Question 42

Adaptations are often compromises

Answer 42

* Organisms are often faced with conflicting situations that prevent an organism from perfecting any one feature for a particular situations * Changing one feature for the better might change another for the worse

Question 43

Not all evolution is adaptive

Answer 43

Chance affects the genetic structure of populations

Question 44

Selection mostly only edits existing variations

Answer 44

Selection favors only the fittest variations from those traits that are available **New generations do not arise on demand**