Evolution may lead to speciation - 3.7.3

Question 1

What causes variation in phenotype?

Answer 1

Genetic and environmental factors

Question 2

What is the primary source of genetic variation ?

Answer 2

Mutations

Question 3

What else introduces genetic variation ?

Answer 3

meiosis and random fertilisation of gametes

Question 4

What results in differential survival and reproduction?

Answer 4

Predation, disease and competition

Question 5

What are organisms with phenotypes providing selective advantages more likely to do?

Answer 5

• Produce more offspring and pass on favourable alleles
• The effect of this is a change in allele frequency in a gene pool

Question 6

What are the different types of selection ?

Answer 6

Stabilising
Directional
Disruptive

Question 7

What is disruptive selection?

Answer 7

• Individuals which contain alleles for either extreme trait are most likely to survive and pass on alleles
• Allele frequency changes and more individuals possess the allele for extreme trait, middling = less frequent

Question 8

What does continued disruptive selection lead to?

Answer 8

Speciation

Question 9

What is speciation ?

Answer 9

The process by which a new species is made

Question 10

When does speciation occur?

Answer 10

When one original population of the same species becomes reproductively isolated.

Question 11

What does isolation mean?

Answer 11

Means that there are 2 populations of the same species but they can’t breed

Question 12

How does isolation create 2 different species?

Answer 12

It results in the accumulation of differences in gene pools to the extent that the 2 populations would be unable to interbreed to make fertile offspring, thus they are 2 species

Question 13

What are the two ways in which populations become reproductively isolated ?

Answer 13

Geographically - allopatric
Due to changes in reproductive mechanisms - sympatric

Question 14

What is allopatric speciation?

Answer 14

When a population becomes geographically isolated over time
It separates the original population into 2 and they can’t reproduce due to the barrier

Question 15

How does allopatric speciation occur?

Answer 15

Both separate populations continue to accumulate different beneficial mutations to help survive
- Due to the accumulation of diff DNA overtime, the 2 become so gen. different, they = unable to interbreed

Question 16

What is sympatric speciation ?

Answer 16

When species become reproductively isolated due to differences in their behaviour

Question 17

How does this occur ?

Answer 17

A random mutation occurs in the population , impacting the reproductive behaviour.
Due to this - individuals don’t reproduce together - no gene flow between them.

Question 18

What is genetic drift ?

Answer 18

A change in allele frequency in a population between generations

Question 19

What does continual, substantial genetic drift result in?

Answer 19

Evolution

Question 20

How does population size affect the allele frequencies ?

Answer 20

• The smaller the population, the bigger the impact allele frequency changes have proportionally , this is why evolution occurs faster in smaller populations

Question 21

Population - define

Answer 21

Group of organisms of the same species living in the same area at the same time that can interbreed to make fertile offspring

Question 22

Habitat - define

Answer 22

Part of an ecosystem where a particular organism lives

Question 23

Community - define

Answer 23

All populations of different species in the same area at the same time

Question 24

Ecosystem - define

Answer 24

A community of living organisms (biotic) interacting with their physical environments and non living components (abiotic)

Question 25

Niche - define How is a niche decided?

Answer 25

An organisms' role in an ecosystem, including its position in the food web and habitat. Each species occupies its own decided by adaptation to abiotic/biotic conditions

Question 26

What is carrying capacity ?

Answer 26

The max population size an ecosystem can support

Question 27

Abiotic factors are ..?

Answer 27

the non living components of an ecosystem

Question 28

What are biotic factors ?

Answer 28

Living organisms in an ecosystem that interact with and influence other organisms and their environment.

Question 29

What factors affect population size ?

Answer 29

Abiotic and biotic factors Inter and Intra specific competition

Question 30

What are some examples of abiotic factors ?

Answer 30

- pH and soil conditions - temperature - oxygen and CO2 concentration

Question 31

How do animals and plants get adapted to abiotic factors ?

Answer 31

through natural selection over many generations

Question 32

How does the severity of abiotic factors affect population size?

Answer 32

The less harsh the abiotic factor, the higher the range of species, thus the higher the population size

Question 33

What is an example of biotic factors?

Answer 33

Inter and Intra specific competition and predation

Question 34

What is interspecific competition ?

Answer 34

When members of different species are in competition for the same resources in limited supply - better adapted = more likely to succeed

Question 35

What is intraspecific competition?

Answer 35

When members of the same species are in competition for resources and a mate

Question 36

Intraspecific competition in relation to mating

Answer 36

- Those who are fitter = more energy to perform a more impressive courtship ritual - or have more fur or feathers - better condition = more attractive

Question 37

What pattern do predator-prey relationships have?

Answer 37

- Size of predator and prey fluctuate - More prey than predators always - Size of the population will always change in prey and then predators (lag time)

Question 38

Why do we use sampling ?

Answer 38

It's more time efficient and if implemented right, can be more accurate.

Question 39

How are samples accurately representative of the population?

Answer 39

- Random sampling in uniform areas - eliminate bias - Line transects to examine changes over distance - By having a large number of samples

Question 40

Quadrat practical

Answer 40

1. Lie two tape measures at a right angle to create a gridded area 2. Use a random number generator (i.e calculator) to generate coordinates 3. Place the quadrat and collect the data 4. repeat at least 10 times

Question 41

When do we use line transects ?

Answer 41

Used to estimate the population size when they are unevenly distributed

Question 42

What are the two types of transect - briefly outline

Answer 42

1. belt transect - quadrat is placed at every position along the tape measure 2. interrupted belt transect - quadrat is placed at uniform intervals along the tape measure

Question 43

Transects - method

Answer 43

1. Place tape measure at right angle to (i.e- shore line) 2. Place the quadrat every 5 metres 3. Collect the data 4. Repeat by placing another 30 transects along the transect line

Question 44

What is mark-release-recapture used to do?

Answer 44

Estimate the size of populations of motile animals

Question 45

Outline a method for mark-release-recapture

Answer 45

1. Initial sample of population is captured, the number caught = recorded 2. These individuals are marked, mark must be weather resistant 3. These marked individuals = released and left for a period of time to allow them to randomly disperse 4. A second sample is captured 5. the total number caught in the second is recorded as is the number recaptured w/ marking 6. Size of population is estimated on the principle that proportion marked in 2nd sample = proportion of marked in population as a whole

Question 46

Equation for the estimated total population

Answer 46

Estimated total pop. = number of orgs initially caught x number of orgs in second sample / number of marked recaptured

Question 47

Ethics with mark-release-recapture

Answer 47

- Mark must be non toxic - Must not increase chance of predation - Must not reduce chances of reproduction

Question 48

Why may the population estimate not be accurate ?

Answer 48

the method goes off assumptions only such as : - Population size is constant 9 no birth/death/migration) - Animals always redistribute evenly (may all huddle near food in reality)

Question 49

What is succession ?

Answer 49

the change in an ecological validity over time

Question 50

what does primary succession begin with ?

Answer 50

a pioneer species colonising their rock or sand

Question 51

Give an example of a pioneer species, what're they adapted to do ?

Answer 51

Lichen Adapted to survive in harsh abiotic factors and through their death and decomposition change abiotic factors - make them less harsh and form a thin layer of soil ( humus )