Natural selection and speciation

Question 1

Genetic and environemntal factors cause ……

Answer 1

Variation

Question 2

What is the primary source of genetic variation?

Answer 2

Mutation

Question 3

Define gene pool

Answer 3

All of the alleles of all of the genes of all the individuals within a particular population at a given time

Question 4

What is intraspecific competition?

Answer 4

competition between individuals of the same species

Question 5

Give 3 reasons why differential survival and reproduction could occur.

Answer 5

Prediation

Disease

Competition

Question 6

An organism has a selecive advantage. What does this mean?

Answer 6

Better adapated for the conditions present.

More likley to survive and reproduce.

Pass on favourable alleles

Question 7

How is genetic variation produced/

Answer 7

Crossing over

Independent segregation/random assortment

random fusion of gametes

Mutation

Question 8

Name 3 types of selection

Answer 8

Stabilising

Directional

Disruptive

Question 9

Describe stabilising

Answer 9

Preserves the average phenotype

Selection against extreme phenotypes.

Occurs when enviornment is stable

Question 10

Give an example of stailising selection

Answer 10

Human birht wieght

Question 11

Give an example of directional selection

Answer 11

Antibioitic resistance in bacteria

Question 12

Give a defition of speciation

Answer 12

Evolution of a new species from an existing one

Question 13

Define a species

Answer 13

Group of similar organisms that breed producing fertile offspring

Question 14

Give the 2 types of speciation

Answer 14

Allopatric and sympatric

Question 15

The effect of genetic drift is greater on which population size - small or large?

Answer 15

small

Question 16

Allopatric speciation occurs when …..

Answer 16

When 2 populations become geographically isolated

Question 17

Give examples of how organims might be geographical isolatied

Answer 17

physical barrier which prevents interbreeding e.g. oceans, rivers, mountains, deserts.

Question 18

Define reproductive separation

Answer 18

when 2 populations can no longer interbreed and produce fertile offspring

Question 19

Example of allopatric speciation

Answer 19

Finches on the Galapagos Islands!

Question 20

Sympatric means

Answer 20

same country

Question 21

Sympatric speciation occurs

Answer 21

within a population of organisms living in the same area (doesnt require geographical isolation)

Question 22

sympatric speciation arises because

Answer 22

they have different breeding seasons, they may inhabit different habitats in the same area so never meet, anatomical differences,

Question 23

Name the type of selection shown

Answer 23

stabilising

Question 24

name the type of selection shown

Answer 24

directional

Question 25

Describe how allopatric speciation occurs

Answer 25

Two populations are geographically isolated

Creates separate gene pools with no interbreeding

Variation due to mutaiton

Different selection prressures

Differential reproductive success

Leeds to change in allele frequencies

Occurs over long period of time

Populations no longer albe to interbreed to produce fertile offspring

Question 26

Name the type of selection shown

Answer 26

Disruptive

Question 27

What does evolution do to the frequency of alleles in a population?

Answer 27

Changes them - increase or decrease

Question 28

What happens to the frequency of the alleles that give organisms an advantage?

Answer 28

Increases

Question 29

What happens to those organisms that are better adapted to the selective pressures in the environment?

Answer 29

Survive, reproduce and pass on favourable alleles

Question 30

What happens to the phenotype during stabilising selection?

Answer 30

Preserves the middle of the range phenotypes

Question 31

Which phenotype is selected for during directional selection?

Answer 31

An extreme phenotype - these are more likely to survive and reproduce

Question 32

What phenotype is preferred in disruptive selection?

Answer 32

BOTH extremes (select against the middle phenotype)

Question 33

Genetic drift can lead to ..

Answer 33

speciation

Question 34

What is genetic drfit?

Answer 34

Chance (not the environment) determines which organisms survive,

reproduce and pass on their alleles

Question 35

Genetic drift has a greater effect on which size population?

Answer 35

Smaller populations

Question 36

Describe Sympatric Speciation

Answer 36

Occurs in the smae population

Mutations cause variation in alleles

Reproductive separation with no gene flow

Different allleles selevted for

Change in allele frequency

Disruptive selection

Differnet specifies formed which cannot interbreed