Speciation

Question 1

Speciation definition

Answer 1

Production is the production of two or more separate species. It is brought about by isolation, mutation and selection.

Question 2

Species definition

Answer 2

Group of organisms which can interbreed to produce fertile offspring and which does not normally breed with other groups.

Question 3

2 types of speciation

Answer 3

Allopatric speciation and Sympatric species.

Question 4

Allopatric speciation

Answer 4

Occurs when the isolation barrier preventing gene flow and stoping the sub species interbreeding is a geographical barrier - for example rivers, mountain ranges etc.

Question 5

Gene pool definition

Answer 5

Total of all the genomic sequences (alleles) present in the genotypes of the members of a species.

Question 6

Allopatric speciation process pt 1, 2 and 3

Answer 6

1. A large interbreeding population
2. Population becomes split into two ore more isolated sub populations by a geographical barrier which prevents interbreeding and gene exchange
3. Mutations occur at random in each sub population. These mutations are different in each sub population. Results in new variation arising in each group.

Question 7

Allopatric speciation process 4,5 and 6

Answer 7

4. Selection pressures acting on each sub population differ depending on climate, predators, diseases etc. Natural selection affects each group in a different way.
5. Over a long period of time natural selection increases the frequency of new alleles causing the two gene pools to become so altered that groups have become genetically distinct and isolated.
6. If the barrier is removed, they are no longer able to interbreed to produce fertile offspring since their chromosomes cannot make matching pairs. Speciation has occurred and two separate distinct species have evolved.

Question 8

Sympatric speciation process 1,2 and 3

Answer 8

1. Large interbreeding population sharing the same ecological niche.
2. Alternative ecological niche becomes available, some members of the population start to exploit the new niche.
3. The two populations now exploit different resources and no longer interbreed - behaviour has become an isolating barrier.

Question 9

Sympatric speciation 4,5

Answer 9

4. Mutations provide new variation in each group but are not shared by both groups.
   The mutants are better adapted to exploit alternative ecological niche.
5. Genetic sequences for adaptations to alternative ecological niche are favoured by natural selection.
   Two genetically distinct species are formed that are no longer ab,e to interbreed and produce fertile offspring.