1.7 - Evolution Flashcards
What is evolution?
The changes in organisms over generations as a result of genomic variation.
What is meant by vertical gene transfer?
where genes are transferred from parents to offspring by sexual or asexual reproduction.
What is meant by horizontal gene transfer?
Where genes are transferred between individuals in the same generation.
Which type of gene transfer leads to rapid evolutionary change?
Horizontal Gene Transfer
Which organisms only transfer genetic material by vertical gene transfer?
Eukaryotes
Which organisms can transfer genetic information by both vertical and horizontal gene transfer?
Prokaryotes
What is speciation?
The generation of new species by evolution as a result of isolation, mutation and selection.
What is Natural Selection?
The non-random increase in frequency of DNA sequences that increase survival and non-random reduction in frequency of deleterious sequences.
What is the definition of a species?
A group of organisms which can interbreed to produce fertile offspring.
What is meant by ‘stabilising selection’?
An average phenotype is selected for and extremes of the phenotype range are selected against.
What is meant by ‘disruptive selection’?
Two or more phenotypes are slected for.
What is meant by ‘directional selection’?
One extreme of the phenotype range is selected for.
Summarise natural selection.
Organisms who are better adapted to their environment are more likely to survive to pass on their genes.
What is the importance of isolation barriers?
They prevent gene flow between sub-populations during speciation.
What is meant by sympatric speciation?
Speciation brought about by a behavioural or ecological barrier e.g. different breeding seasons, different mating rituals
