Lec 5-8

Question 1

Define Microevolution

Answer 1

evolutionary processes which drive changes in allele frequencies within a species
Only ONE species

Question 2

Define Macroevolution

Answer 2

evolutionary processes which drive species formation over time
Formation of a NEW species

Question 3

The four microevolutionary processes are

Answer 3

natural selection
genetic drift
mutation
population size/structure changes

Question 4

Define natural selection

Answer 4

process whereby any heritable features than enhance fitness of an organism increase in frequency in the population of succeeding generations

Question 5

Purifying selection is

Answer 5

an allele is removed after selection

Question 6

Positive selection is

Answer 6

an allele becomes the most common variant

Question 7

Balancing selection is

Answer 7

the favoring of a heterozygous variant

Question 8

What is genetic drift?

Answer 8

changes in allele frequency due to random sampling from one generation to next

Question 9

Small populations are ___ susceptible to genetic drift

Answer 9

more

Question 10

How does genetic drift affect the presence of rare alleles in a population?

Answer 10

can cause loss of these alleles

Question 11

The bottleneck effect is

Answer 11

a type of genetic drift where a large population is reduced in size and alleles are lost, variation is reduced.

Question 12

What is the founder effect?

Answer 12

A type of genetic drift that involves the movement of a subset of a population to another area. These individuals start a new population with a different allele frequency than the original population

Question 13

Define effective population size

Answer 13

Ne
measures the amount of drift a population has experienced

Question 14

The smaller the Ne, the ____ the drift

Answer 14

greater

Question 15

What is the molecular clock hypothesis?

Answer 15

Scientists noted that rates of amino acid replacements in animal hemoglobins were proportional to time of divergence

Question 16

Molecular evolutionary substitutions proceed at a ____ rate

Answer 16

constant

Question 17

Why can sequences be used to estimate the times that sequences diverged?

Answer 17

Sequences evolve at constant rates

Question 18

Factors that impact molecular clock rates include

Answer 18

generation time
mutation rate
body size/metabolic rate
DNA repair mechanisms

Question 19

Define heterozygosity. How is it calculated?

Answer 19

Proportion of heterozygotes in the population
measure of genetic variability
1-sum of allele frequencies^2

Question 20

The fixation index

Answer 20

Measures genetic variation within populations
relative to differences between two populations

Question 21

Interpret the following
Fst=1

Fst=0

Fst=0.11

Answer 21

FST = 1
Variation between populations = 100%
Variation within populations = 0%
FST = 0

Variation between populations = 0%
Variation within populations = 100%

FST = 0.11
Variation between populations = 11%
Variation within populations = 33%

Question 22

What is cluster analysis

Answer 22

Places individuals in a population into groups based on shared genetic structure

Question 23

Define phylogenetics

Answer 23

the study of evolutionary
relationships between living and extinct
species.

Question 24

Define phylogeny

Answer 24

A hypothesis of ancestor
descendant relationships.

Question 25

Define phylogenetic tree

Answer 25

a graphical summary of a
phylogeny

Question 26

Molecular phylogenetics begin with

Answer 26

a multisequence alignment of homologous regions of DNA in different species

Question 27

Define a neighbor joining tree

Answer 27

phylogenetic tree that takes as input a distance matrix, specifying distance between each pair of taxa

Question 28

Name the benefits of using a neighbor joining tree

Answer 28

fast, produces one tree
works on large datasets
reduces all sequence information to one distance value

Question 29

Define maximum parsimony

Answer 29

draws a tree based on the least number of evolutionary transitions

Question 30

The maximum parsimony (MP) is based on the… concept

Answer 30

Based on Occam’s Razor concept – states that
when considering competing explanations, the
simpler one, with fewer inferences or transitions,
is preferred.

Question 31

Fission is … while fusion is ….

Answer 31

one chromosome breaks into two

two chromosomes fuse into one

Question 32

Human chromosome two was created from

Answer 32

fusion of two ape chromosomes

Question 33

One challenge in building phylogenetic trees us

Answer 33

different data creating different trees

Question 34

A gene tree is

Answer 34

phylogenetic tree built
using a single gene, reflects the history
of the gene, but not always congruent
with the species phylogeny.

Question 35

The FOXP2 gene is
Mutations result in

Answer 35

a gene required for development of speech and language regions of the brain during embryogenesis.
Mutations result in speech language disorder
Humans and Neanderthals share two mutations on this gene, chimpanzees do not have this

Question 36

MYH16 (Myosin Heavy Chain 16) gene is
it was created by a ___ and may connect with
___MYA

Answer 36

a gene that resulted in the muscle fibers surrounding the human jaw
2bp deletion may connect with evolution of brain expansion
2.4 MYA

Question 37

There are ___ alu insertions within the human lineage compared with ___ in chimpanzee. One disease caused by ALU insertions is

Answer 37

ewing sarcoma

Question 38

Evolution at ‘two levels’ in humans and chimpanzees refers to

Answer 38

differences in gene expression (e.g. protein synthesis) between
humans and chimpanzees