2a: Drift And Selection

Question 1

Evolution definition

Answer 1

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

Question 2

During evolution, changes in allele frequency occur through the…

Answer 2

• non-random process of natural selection and sexual selection
• random process of genetic drift

Question 3

Is natural selection random or non-random

Answer 3

Non-random

Question 4

Is sexual selection random or non-random

Answer 4

Non-random

Question 5

Is genetic drift random or non-random

Answer 5

Random

Question 6

Variation in traits arises as a results of…

Answer 6

Mutation

Question 7

What does natural selection result in

Answer 7

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 8

Process of natural selection

Answer 8

• population produces ore offspring tan the environment can support
• individuals with variations that are better suited to their environment tend to survive longer
• this produces more offspring, breeding to pass on those alleles that conferred an advantage to the next generation

Question 9

What is sexual selection

Answer 9

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

Question 10

What is sexual dimorphism

Answer 10

Sexual dimorphism describes physical/ structural differences between males and females of the same species

Question 11

What is male-male rivalry

Answer 11

When large size or weaponry (of males) *increases the access to females through conflict. *

Question 12

What is female choice

Answer 12

Female choice involved females assessing the fitness of males.

Question 13

when does genetic drift occur

Answer 13

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

Question 14

Why is genetic drift more important in small populations

Answer 14

Alleles are more likely to be lost from the gene pool

Question 15

What is the bottleneck effect

Answer 15

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

Question 16

What is the founder effect

Answer 16

• occur through the isolation of a few members of a population from a larger population
• the gene pool is not representative of that in the original gene pool

Question 17

What is the impact of a reduced population (bottleneck or founder effect)

Answer 17

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

Question 18

What are selection pressures

Answer 18

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

can be biotic or abiotic

Question 19

Where selection pressures are strong, the rate of evolution ca be…

Answer 19

Rapid

Question 20

What does the Hardy-Weinberg principle state

Answer 20

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

Question 21

Conditions for maintaining the Hardy-Weinberg equilibrium

Answer 21

• no natural selection
• random mating
• no mutation
• large population size
• no gene flow (eg migration in or out)