Speciation

Question 1

Six steps to speciation

Answer 1

1. Geographical isolation
2. Variation(mutation/sexual reproduction)
3. Competition
4. Survival of the fittest
5. Passing on of genes
6. Reproductive isolation, genetic drift of two gene pools, two new species produced

Question 2

What is speciation

Answer 2

Formation of a new species via the process of evolution, become reproductively isolated due to genetic drift of two gene pools and cannot successfully interbreed to produce fertile offspring

Question 3

What is allopatric speciation

Answer 3

Caused by geographical isolation eg mountains and rivers

Question 4

What is sympatric speciation

Answer 4

Caused by reproductive isolation between populations caused by rapid genetic change

Question 5

What is adaptive radiation

Answer 5

When a species becomes adapted to its local environment resulting in changes to allele frequency of each population meaning each population evolves and different species form

Question 6

What are prezygotic barriers

Answer 6

Those that occur before fertilisation eg temporal(differences in mating seasons), behavioural(different mating calls), habitat(different habitats in the same area), morphological

Question 7

What are postzygotic barriers

Answer 7

Those that occur after fertilisation that prevent the organism from developing and mating eg having the wrong number of chromosomes so gametes can’t fuse/embryos won’t develop leading to hybrid sterility

Question 8

Three factors needed for evolution

Answer 8

-variation
-heredity- difs between organisms must be heritable
-selection pressures