Reproductive Separation, Types of Speciation and Genetic Drift Flashcards
When does reproductive separation occur?
When certain alleles and phenotypes of some individuals prevents them from successfully breeding with other individuals of the population.
Name 7 factors that can lead to reproductive separation.
Hybrid Stability
Gametic
Mechanical
Behavioural
Temporal
Ecological
Geographical
Describe how hybrid stability can lead to reproductive isolation.
Hybrids, such as mules formed from the fusion of donkey and horse gametes, are sterile because they cannot produce their own gametes. Therefore, they cannot mate with each other.
How do gametic factors lead to reproductive separation?
Gametes may be prevented from meeting due to genetic or biochemical incompatibility.
How do mechanical factors lead to reproductive separation?
Anatomical differences may prevent mating from occurring.
How do behavioural factors lead to reproductive separation?
Think about how to patterns on males leads to mating.
Mating is often preceded by courtship which is stimulated by the colour or markings of the opposite sex. Any mutations that cause variation in these markings may prevent mating as the opposite sex may not notice them.
How do temporal (seasonal) factors lead to reproductive separation?
Breeding seasons of each population don’t coincide so they do not interbreed.
How does location (ecological factors) affect reproductive seperation?
Populations live in different habitats within the same area, so individuals don’t meet.
How do geographical factors lead to reproductive seperation?
They cause a physical barrier to organisms mating.
What is speciation?
When gene flow between populations has stopped, so they become isolated from each other and form 2 different new species.
Why are speciated organisms no longer able to interbreed?
They evolve independently from each other as a result of different allele frequencies.
How can we be sure that speciation has definitely occurred?
The offspring produced after interbreeding are infertile.
Name 2 types of speciation.
Allopatric
Sympatric
Name the type of isolation that leads to allopatric speciation.
Give an example of how this type of isolation occurs.
Geographical isolation.
Occurs when a physical or man made barrier separates 2 populations, such as water or motorways.
How do gene pools change during allopatric speciation?
The genes in each separate population become isolated from each other as a result of reproductive separation. This means no genetic exchange can happen between populations, creating 2 separate gene pools.
