Topic 7- Types of speciation Flashcards
Define speciation
the formation of new species from pre-existing species over time
Why does speciation occur?
a result of changes to gene pools from generation to generation
What is necessary for speciation?
Genetic isolation between the new population and the pre-existing species population
Why does Allopatric speciation occur
geographical isolation
Which type of speciation is most common?
Allopatric speciation
What is meant by geographic isolation?
when populations of a species become separated from each other by geographical barriers
Give some examples of geographical
Natural- body of water/mountain range
Manmade- a road
What is the result of allopatric speciation?
creates two populations of the same species who are reproductively separated from each other, and as a result, no genetic exchange can occur between them
Why do populations diverge and form separate species
If there are sufficient selection pressures acting to change the gene pools (and allele frequencies) within both populations
What changes does speciation cause?
changes in the alleles/genes of each population will affect the phenotypes present in both populations
Over time, the two populations may begin to differ physiologically, behaviourally and morphologically (structurally)
What are the two things that cause sympatric variation?
-Ecological separation: Populations are separated because they live in different environments within the same area
-Behavioural separation: Populations are separated because they have different behaviours
Why do both allopatric and sympatric variation occur?
Mutations
Why are mutations important for speciation?
- new alleles of genes for selection to act on
-produce the differences in physiology, behaviour and morphology between populations over many generations, eventually leading to speciation
Explain how natural selection leads to evolution.
In geographically isolated populations, differences in selection pressures can lead to changes in allele frequencies, and eventually to speciation
What occurs when chance (instead of environmental selection pressures) affects which individuals in a population survive, breed and pass on their alleles
Genetic drift
