2.2 Evolution

Question 1

Define Evolution

Answer 1

Evolution is the change over time in the proportion of individuals in a population differing in one or more inherited traits

Question 2

How do changes in alelles frequency occur in evolution

Answer 2

Through the non-random processes of natural selection and sexual selection, and the random process of genetic drift

Question 3

Natural selection acts on

Answer 3

Genetically varied populations

Question 4

Variation arises as a result of

Answer 4

Mutations

Question 5

Describe mutations

Answer 5

Mutation is the original source of
new sequences of DNA. These new
sequences can be novel alleles. Most mutations are harmful or neutral, but in rare cases they may be beneficial to the fitness of
an individual.

Question 6

Talk about populations offspring in regards of the environment

Answer 6

Populations produce more offspring than the
environment can support

Question 7

Individuals with variations that are better suited to their environment tend to……

Answer 7

• survive longer
• produce more offspring
• breed to pass on those alleles that conferred an advantage to the next generation

Question 8

What is the result of selection

Answer 8

Selection results in the non-random increase
in the frequency of advantageous alleles and
the non-random decrease in the frequency of
deleterious alleles.

Question 9

Define sexual selection

Answer 9

Sexual selection is the non-random process
involving the selection of alleles that increase
the individual’s chances of mating and
producing offspring

Question 10

Sexual selection may lead to….

Answer 10

sexual dimorphism

Question 11

Sexual selection can be due to

Answer 11

• Male to Male Rivalry
• Female Choice

Question 12

Describe male to male rivalry

Answer 12

Male-male rivalry: large size or weaponry
increases access to females through conflict.

Question 13

Define Female Choice

Answer 13

Female choice involves females assessing
the fitness of males.

Question 14

When does genetic drift occur

Answer 14

Genetic drift occurs when chance events
cause unpredictable fluctuations in allele
frequencies from one generation to the next

Question 15

What type of population is genetic drift more important in and why

Answer 15

Genetic drift is more important in small
populations, as alleles are more likely to be
lost from the gene pool

Question 16

Describe population bottlenecks

Answer 16

Population bottlenecks occur when a
population size is reduced for at least one
generation.

Question 17

Describe Founders Affect

Answer 17

Founder effects occur through the isolation of
a few members of a population from a larger
population. The gene pool of the new
population is not representative of that in the
original gene pool.

Question 18

Why is the gene pool altered by genetic drift?

Answer 18

A gene pool is altered by genetic drift
because certain alleles may be underrepresented or over-represented and allele
frequencies change

Question 19

Where selection pressures are strong, the rate of evolution can be _________

Answer 19

Rapid

Question 20

Define Selection Pressures

Answer 20

Selection pressures are the environmental
factors that influence which individuals in a
population pass on their alleles.

Question 21

Selection pressures can be sorted into two categories

Answer 21

Biotic

• competition
• predation
• disease
• parasitism

Abiotic

• changes in temperature
• changes in light
• changes in humidity
• changes in pH
• changes in salinity

Question 22

The Hardy-Weinberg (HW) principle states
that

Answer 22

In the absence of evolutionary
influences, allele and genotype frequencies
in a population will remain constant over the
generations

Question 23

The conditions for maintaining the HW
equilibrium are:

Answer 23

no natural selection, random
mating, no mutation, large population size
and no gene flow (through migration, in or
out).

Question 24

The HW principle can be used to

Answer 24

determine
whether a change in allele frequency is
occurring in a population over time

Question 25

HW Equation and what it stands for

Answer 25

p^2 + 2pq + q^2 = 1

p = frequency of dominant allele

q = frequency of recessive allele

p^2 = frequency of homozygous dominant genotype

2pq = frequency of heterozygous genotype

q^2 = frequency of homozygous recessive
genotype

Question 26

Changes in HW suggest

Answer 26

evolution is occurring

Question 27

Define Fitness

Answer 27

Fitness is an indication of an individual’s
ability to be successful at surviving and
reproducing

Fitness is a measure of the tendency of some
organisms to produce more surviving
offspring than competing members of the
same species.

Question 28

Relation of fitness and the gene pool of the next generation

Answer 28

It refers to the contribution made to the gene
pool of the next generation by individual
genotypes

Question 29

Two categories of fitness

Answer 29

• Absolute Fitness
• Relative fitness

Question 30

Define absolute fitness

Answer 30

Absolute fitness is the ratio between the
frequency of individuals of a particular
genotype after selection, to those before
selection

Question 31

Absolute fitness Equation

Answer 31

frequency of a particular genotype
after selection

÷

frequency of a particular genotype
before selection

Question 32

Absolute fitness in relation to the values obtained from the equation

Answer 32

If the absolute fitness is 1, then the frequency
of that genotype is stable. A value greater
than 1 conveys an increase in the genotype
and a value less than 1 conveys a decrease.

Question 33

Define Relative Fitness

Answer 33

Relative fitness is the ratio of the number of
surviving offspring per individual of a
particular genotype to the number of
surviving offspring per individual of the most
successful genotype

Question 34

Relative fitness equation

Answer 34

number of surviving offspring per
individual of a particular genotype

÷

number of surviving offspring per
individual of the most successful genotype

Question 35

Define co-evolution

Answer 35

Co-evolution is the process by which two or
more species evolve in response to selection
pressures imposed by each other

Question 36

How does a change in traits of one species affect another

Answer 36

A change in the traits of one species acts as
a selection pressure on the other species

Question 37

Co-evolution is frequently seen in pairs of
species that have __________

Answer 37

symbiotic interactions

Question 38

Define Symbiosis

Answer 38

co-evolved intimate relationships
between members of two different species.

Question 39

Define Mutualism

Answer 39

Mutualism: both organisms in the interaction
are interdependent on each other for
resources or other services. As both
organisms gain from the relationship, the
interaction is (+/+).

Question 40

Define Commensalism

Answer 40

Commensalism: only one of the organisms
benefits (+/0).

Question 41

Define Parasitism

Answer 41

Parasitism: the parasite benefits in terms of
energy or nutrients and the host is harmed as
the result of the loss of these resources (+/-).

Question 42

The red queen hypothesis states that……

Answer 42

in a
co-evolutionary relationship, change in the
traits of one species can act as a selection
pressure on the other species

Question 43

Species in co-evolutionary species must

Answer 43

Adapt to avoid extinction