Evolution

Question 1

Evolution

Answer 1

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

Question 2

What happens during evolution?

Answer 2

Changes in allele frequency occur through the non-random processes of natural selection and sexual selection and the random process of genetic drift

Question 3

Natural selection

Answer 3

Acts on genetic variation in populations.

Question 4

How does genetic variation come about?

Answer 4

Arises as a result of mutation.mutation is the original source of new sequences of DNA, these new sequences can be novel alleles

Question 5

Process of natural selection

Answer 5

Populations produce more offspring than the environment can support, individuals with variations that are better suited to their environment tend to survive lager and produce more offspring, breeding to pass on their alleles that conferred on advantage to the next generation.

Question 6

What does selection result in?

Answer 6

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

Question 7

Sexual selection

Answer 7

The non-random process involving the selection of alleles that increase the individual’s chance of mating and producing offspring

Question 8

What may sexual selection lead to?

Answer 8

Sexual dimorphism

Question 9

What can be factors affecting sexual selection?

Answer 9

Male-male rivalry, female choice

Question 10

Male-male rivalry

Answer 10

Large size or weaponry increases access to females through conflict.

Question 11

Female choice

Answer 11

Involves females assessing fitness of males

Question 12

Genetic drift

Answer 12

Occurs when chance events cause unpredictable fluctuations in allele frequencies from one generation to the next.

Question 13

Why is genetic drift more important in small populations?

Answer 13

As alleles are more likely to be lost from the gene pool.

Question 14

Population bottle necks

Answer 14

Occur when a population size is reduced for at least one generation.

Question 15

Founder effects

Answer 15

Occur through the isolation of a few members ofa population from a larger population.the gene pool of the new population is not representative of that in the original gene pool

Question 16

How is a gene pool altered by genetic drift?

Answer 16

Certain alleles may be under-represented or over-represented and allele frequencies change.

Question 17

Selection pressures

Answer 17

The environmental factors that influence which individuals in a population pass on their alleles,

Question 18

Biotic selection pressures

Answer 18

Competition, predation, disease, parasitism

Question 19

Abiotic selection pressures

Answer 19

Changes in temperature, light, pH, salinity

Question 20

Hardy-weinberg principle

Answer 20

States that in the absence of evolutionary influences, allele and genotype frequencies in a population will remain constant over Te generations.

Question 21

Conditions for maintaining hw principle

Answer 21

No natural selection, random mating, no mutations, large population size, no gene flow (through migration, in or out)

Question 22

How con we use the hw principle?

Answer 22

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

Question 23

Fitness

Answer 23

An indication of an individual’s ability to be successful at surviving and reproducing, it is a measure of the tendency of some organisms to produce more surviving offspring than competing members of the same species.

Question 24

What does fitness refer to?

Answer 24

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

Question 25

Absolute fitness

Answer 25

The ratio between the frequency of individuals of a particular genotype after selection, to those before selection.

Question 26

What does an absolute fitness of one mean?

Answer 26

The frequency of that genotype is stable.

Question 27

What does an absolute fitness value of greater than one mean?

Answer 27

An increase in the genotype

Question 28

What does an absolute fitness value of less than one mean?

Answer 28

A decrease in the genotype

Question 29

Relative fitness

Answer 29

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 30

Co-evolution

Answer 30

The process by which two or more species evolve in response to selection pressures imposed by each other.

Question 31

How does co-evolution work?

Answer 31

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

Question 32

Where is co-evolution frequently seen?

Answer 32

In pairs of species that have symbiotic interactions.

Question 33

Symbiosis

Answer 33

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

Question 34

Mutualism

Answer 34

Both organisms in the interaction are interdependent on each other for resources an other services, both organisms benefit.

Question 35

Commensalism

Answer 35

Only of the organisms benefit

Question 36

Parasitism

Answer 36

The percsite benefits in terms of energy or nutrients and the host is harmed as the result of the loss of these resources.

Question 37

The Red Queen hypothesis

Answer 37

In a co-evolutionary relationship change in the traits of one species can act as a selection pressure on the other species. This means that species in these relationships must adapt to avoid extinction.