Selection and speciation

Question 1

Causes of variation

Answer 1

1. mutation
2. meiosis
3. random fertilisation

Question 2

A mutation could:

Answer 2

1. neutral
2. selective advantage
3. selective disadvantage

Question 3

How does the environment influence an organism phenotype

Answer 3

Affects the way genes are expressed
phenotype sets limits for characteristics

Question 4

environmental influences eg

Answer 4

Temp
light intensity
humidity
abiotic/biotic factor

Question 5

What is continous variation

Answer 5

characteristics controlled by more than one gene

Question 6

Define the term natural selection

Answer 6

Process by which organisms better adapted to their environment survive and reproduce in greater numbers, increases frequency of the advantageous allele within population

Question 7

Natural selection

Answer 7

1. Variation due to mutation
2. better adapted individuals are more likely to survive and reproduce
3. These organisms are more likely to pass on their alleles
4. Less adapted fail to survive and reproduce
5. selection pressure due to environment
6. Change in allele frequency over a large period of time
7. Selection pressure can be biotic or abiotic

Question 8

Stabilising selection

Answer 8

Occurs in all population where environment is stable
selection pressure at ends of distribution
Favours average
eliminate extremes
Reduces variability
Reduces opportunity for evolutionary change

Question 9

Directional selection

Answer 9

Mean in population represents optimum phenotype for existing conditions
Environmental change favours an extreme

Question 10

Disruptive selection

Answer 10

Selection pressures favours 2 extremes phenotype
organisms possess the new extreme optimum phenotype
Over time selection means 2 extremes will dominate

Question 11

what does the term speciation mean

Answer 11

Evolution of new species from existing species
Belong to the same gene pool
group with similar characteristic and same genes capable of interbreeding to produce fertile offspring

Question 12

What does natural selection do?

Answer 12

Change in frequency of alleles in a population by which new species can arise

Question 13

if 2 population can interbred……

Answer 13

they will not evolve in 2 distinct species

Question 14

reproductive isolation

Answer 14

Th become genetically distinct via accumulation of mutation and different selection pressure

Question 15

TERM: description and example
- Genetic drift
-Bottleneck

Answer 15

Is the random increase or decrease in allelic frequency
natural disaster
tsunami

Question 16

TERM: description & example

Answer 16

Change in allele frequency due to the migration of fertile individuals
migration

Question 17

Allopatric seciation