Evolution Flashcards
What do we call the changes in organisms over generations as a result of genetic variation?
evolution
During natural selection, what happens to the frequency of DNA sequences that increase the chances of survival?
increase
During natural selection, what happens to the frequency of deleterious sequences?
reduce
Is natural selection random or non-random?
non-random
What does deleterious mean?
harmful
Name the 3 types of selection.
stabilising, directional, disruptive
What is selected for in stabilising selection?
an average phenotype
What is selected against in stabilising selection?
the extremes of the phenotype
What is selected for in directional selection?
one of the extremes
What is selected for in disruptive selection?
2 or more phenotypes
What is it called where genes are transferred between individuals of the same generation?
Horizontal gene transfer
What is vertical gene transfer?
Genes are passed from one generation to the next
Which type of cells can carry out vertical and horizontal gene transfer?
Prokaryotes
What is an advantage of horizontal gene transfer?
Rapid natural selection/evolutionary change
What do we call the generation of new biological species by evolution?
speciation
What are the 3 stages (in order!) of speciation?
isolation, mutation, selection
What is a species?
A group of organisms that can interbreed and produce fertile offspring
What type of speciation takes place with geographical barriers?
allopatric
Name the 2 possible barriers involved in sympatric speciation.
ecological and behavioural
Why are isolation barriers so important to the process of speciation?
They prevent gene flow between the sub-populations
