Biology- Speciation

Question 1

SPECIATION –

Answer 1

the formation of a new species

Question 2

MICROEVOLUTION –

Answer 2

change in allele frequencies and phenotypic traits within a population and species

Question 3

MODES OF SPECIATION

Answer 3

For speciation to occur, a group of individuals must somehow become ISOLATED (separated) from the rest of the population (reproductive isolation is necessary)

Question 4

REPRODUCTIVE ISOLATING MECHANISM –

Answer 4

any biological factor that prevents individuals of different species from reproducing successfully; occur at 2 points

Question 5

ALLOPATRIC SPECIATION (“other place”) –

Answer 5

• the formation of new species as a result of evolutionary changes following a period of geographic isolation
  -Won’t share mutations that arise, natural selection may favour different traits, genetic drift may alter gene pools  become increasingly less alike over time and will likely have evolved a reproductive isolating mechanism
  E.g. formation of mountain ranges, continental drift, travel to remote islands, human activity (e.g. agricultural expansion, building roads, fragmented habitats)

Question 6

SYMPATRIC SPECIATION (“same place”) –

Answer 6

• the evolution of populations within the same geographic area into separate species
• Some individuals may exploit a new niche in same area (e.g. new diet or behaviour)
• E.g. hawthorn flies laid eggs on fruits of hawthorn trees, BUT once apple trees where introduced, some started laying eggs on apples  disruptive selection favouring mutations where some only feed off hawthorn fruits while others feed only on apples