Genetic diversity and Adaption

Question 1

define allele

Answer 1

one of a number of alternative versions of a gene

Question 2

define population

Answer 2

a group of interbreeding organisms of the same species living in the same place

Question 3

define gene pool

Answer 3

the number of alleles in a particular population at a specific time

Question 4

define genetic diversity

Answer 4

the total number of different alleles in a population

Question 5

define allele frequency

Answer 5

how often a particular allele occurs within a gene pool

Question 6

why is there a great diversity between individuals of the same species?

Answer 6

even though they all have the same genes, there are many different alleles. the characteristics of an individual in a species depends on the combination of alleles it has.

Question 7

what can the genetic diversity of a population be affected by?

Answer 7

• introduction of new individuals
• selective breeding (artificial selection)
• natural disaster and population crash
• isolation

Question 8

why does a greater genetic diversity mean its more likely for individuals in a population to survive an environmental change?

Answer 8

• a wider range of alleles and therefore a wider range of characteristics
• therefore a greater probability that some individuals will possess a characteristic that suits it to the new environmental conditions

Question 9

what is natural selection?

Answer 9

• random mutations result in different alleles of a gene being produced - genetic variation/diversity
• although most mutations are harmful, in a certain environment a selection pressure the new allele may give its possessor a selective advantage over others
• the possessor of these allele will be better able to survive and reproduce successfully, passing on their alleles to their offspring
• offspring in the next generation who possess the advantageous allele are also more likely to survive to reproduce
• over many generations the proportion of individuals in the population with the new allele increases.

Question 10

what are the two types of selection?

Answer 10

• stabilising selection
• directional selection

Question 11

what is stabilising selection?

Answer 11

when the same environmental conditions persist for a long time, selection favours the average individuals since they are well adapted to the environment. any individuals that have characteristics that differ greatly from the average will be selected against.
this preserves the characteristics of the populations, reduces range and standard deviation.

Question 12

what is directional selection?

Answer 12

when/if environmental conditions change, different alleles will be favoured (average individuals are no longer so well adapted to the environmental conditions) selections favours individuals at one of the extremes. changes characteristics of a population.