2.2 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

How is genetic drift caused?

Answer 2

Genetic drift occurs when chance events cause unpredictable fluctuations in allele frequencies from one generation to the next. More important in small populations as changes in allele frequency will be more significant

Question 3

Bottleneck Effect

Answer 3

Occurs when a population size is randomly reduced for at least one generation, so lowering the range of alleles upon which any subsequent selection pressure may then act

Question 4

Founder Effect

Answer 4

Occurs through the isolation of a few random members of a population from a larger population, so the gene pool of the new population is not representative of that in the original gene pool

Question 5

Fitness

Answer 5

Indication of an individual’s success in surviving and reproducing

Question 6

What does natural selection result in?

Answer 6

The non-random increase in the frequency of advantageous alleles which increase fitness, and the non-random decrease in the frequency of deleterious alleles which can reduce fitness.

Question 7

Sexual Selection

Answer 7

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

Question 8

Male-Male Rivalry

Answer 8

Large size or weaponry increase an individual’s access to females through successful conflict with competing males

Question 9

Female Choice

Answer 9

Involves females assessing the fitness of males through honest signals related to display, colours, plumes, calls and songs

Question 10

Selection Pressure

Answer 10

Measures how strongly a biotic or abiotic factor exerts its effect by influencing which individuals in a population survive and pass on their alleles to the next generation.

Question 11

Hardy-Weinberg Principle

Answer 11

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

Question 12

Absolute Fitness

Answer 12

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

Question 13

Relative Fitness

Answer 13

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 14

Co-Evolution

Answer 14

The process by which two or more species evolve in response to selection pressures imposed by each other. A change in the traits of one species acts as a selection pressure on the other species.

Question 15

Parasitism

Answer 15

The parasite has a positive, beneficial relationship with its host which is negatively affected by the relationship

Question 16

Mutualism

Answer 16

The two species both derive positive benefits, and, in most cases, each species cannot survive without the other

Question 17

Commensalism

Answer 17

One species derives positive benefit and the other in the relationship is neither substantially positively nor negatively affected, so can be described as being neutral

Question 18

Red Queen Hypothesis

Answer 18

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

Question 19

Red Queen Hypothesis in terms of parasites

Answer 19

Hosts that become better able to resist their parasites have greater fitness, putting selection pressure on the parasites to adapt and increase their fitness in terms of virulence.