evolution and speciation Flashcards
(25 cards)
What is speciation?
Evolution of new species from existing ones
What is a species?
A group of individuals who are capable of breeding with each other to produce fertile offspring
Why does evolution occur?
As a result of a change in allele frequencies in a population
What does reproductive isolation of two populations cause?
Difference in their gene pools
When do new species arise?
Genetic differences lead to production of infertile offspring
What are the types of speciation?
Allopatric and sympatric
When does allopatric speciation occur?
Mutation and meiosis is split due to geographical differences
What does this result in?
A physical barrier which separates a population
What happens to the population when they are isolated?
There is no gene flow
What will operate to cause selection for different phenotypes?
Different selection pressures
What happens to the frequency of these alleles?
Different allele frequencies occur for each isolated population
What is a result of this over a long period of time?
The frequencies of the separate gene pools become so different they cannot have fertile offspring
When does sympatric speciation occur?
When they are not geographically isolated to become reproductively isolated
What could happen within a population?
Random mutation
What could this reproductive isolation be the result of?
Different flowering or mating seasons
What does sympatric speciation involve?
Disruptive selection
Why are the populations reproductively isolated?
No gene flow between gene pools
What will change due to mutations?
Allele frequency
What will happen over long periods of time?
Allele frequencies will be too different there won’t be fertile offspring
What can genetic drift lead to?
Speciation
What does genetic drift occur by?
Chance
What happens during genetic drift?
The allele of a particular gene is passed in more frequently than others
Where does genetic drift have a bigger impact?
In smaller populations
Why is this?
Smaller diversity
