speciation and genetic drift

Question 1

what factors lead to the process of natural selection ?

Answer 1

• competition for resources
• disease
• predators

Question 2

why is natural selection possible ?

Answer 2

• because in every population there will be a wide range of variation in phenotypes
• due to genetic and environmental factors

Question 3

what is the primary source of genetic variation ?

Answer 3

• mutation

Question 4

what factors add to the variation ?

Answer 4

• meiosis and random fusions of gametes

Question 5

what is meant by differential reproductive success ?

Answer 5

• not all individuals are as likely to reproduce
• resulting in changes in allele frequencies within a gene pool

Question 6

what are the 3 types of selection ?

Answer 6

• stabilising
• directional
• disruptive

Question 7

what is meant by disruptive selection ?

Answer 7

• when individuals which contain the alleles coding for either extreme trait are more likely to pass on their alleles

Question 8

what does disruptive selection result in regarding the gene pool ?

Answer 8

• the allele frequency changes
• more individuals posses the allele for the extreme trait
• middling trait allele becomes less frequent

Question 9

what can continued disruptive selection lead to ?

Answer 9

• speciation

Question 10

draw the graph for disruptive selection ?

Answer 10

miss esruch

Question 11

what is speciation ?

Answer 11

• the process which results in the creation of a new species

Question 12

when does speciation occur ?

Answer 12

• when the original population of the same species becomes reproductively isolated

Question 13

what does reproductive isolation mean ?

Answer 13

• when the 1 population of the same species splits into 2
• and they cannot breed together

Question 14

what can he reproductive isolation result in ?

Answer 14

• results in the accumulation of differences in their gene pools to the extent that the 2 populations would be unable to interbreed to make fertile offspring
• so classed as 2 different species

Question 15

what are the 2 different ways that a species can become reproductively isolated ?

Answer 15

• allopatric
• sympatric

Question 16

allopatric ?

Answer 16

population is separated geographically

Question 17

sympatric ?

Answer 17

• due to changes in reproductive mechanisms
• differences in their behaviour

Question 18

why does sympatric speciation occur?

Answer 18

• because random mutations within the population could impact reproductive behaviour

Question 19

examples of impact on reproductive behaviour ?

Answer 19

• mutation may cause individuals to peform a different courtship ritual
• or to be fertile at different times of the year ( can be linked to plants)

Question 20

what does it mean if the individuals cannot reproduce together ?

Answer 20

• there will be no gene flow between the 2 groups within the population

Question 21

where is genetic drift only relevant and important in
?

Answer 21

• in small populations

Question 22

what is meant by the genetic drift ?

Answer 22

• the change in the allele frequency within a population between generations

Question 23

will there always be genetic drift between generations ?

Answer 23

yes

Question 24

what kind of genetic drift results in evolution ?

Answer 24

• substantial

Question 25

why does evolution often occur more rapidly in smaller populations ?

Answer 25

- the smaller the population is - the bigger the impact allele frequency changes have proportionally