6. evolution of species

Question 1

what is evolution

Answer 1

the gradual change is species over time which can lead to:

• a change within a new species
• the production of a new species

Question 2

what is a mutation

Answer 2

a random change to an organisms genetic material (DNA). mutations are spontaneous and are the only source of new alleles.

mutations may be neutral, confer an advantage or a disadvantage to survival.

environmental factors (radiation and some chemicals) can increase the rate of mutation

Question 3

describe adaptions (from mutations)

Answer 3

an adaption is an inherited characteristic that makes an organism well suited to survival in its environment/niche

Question 4

describe the evolution process

Answer 4

1) species produce more offspring than the environment can sustain
2) natural selection (survival of the fittest) occurs when there are selection pressures
3) the best adapted individuals in a population survive to reproduce, passing on the favourable alleles that confer the selective advantage
4) these alleles increase in frequency within the population

Question 5

what is speciation

Answer 5

the formation of new species

occurs after part of a population becomes isolated by an isolation barrier, which can be geographical, ecological or behavioural.

(then) different mutations occur in each sub population. natural selection selects different mutations in each group, due to different selection pressures. each sub population evolves until they become so genetically different that they are two different species.

Question 6

what are selection pressures

Answer 6

any factors which can affect the survival or reproduction of an organism

Question 7

describe variation

Answer 7

variation within a population makes it possible for a population to evolve over time in response to changing environmental conditions