Evolution Flashcards
What is evolution?
The changes in organisms over generations as a result of genomic variations
What is natural selection?
The non random increase in frequency of DNA sequences that increase survival and the non random reduction in deleterious sequences
The changes in phenotype frequency are as a result of what types of selection?
Stabilising
Disruptive
Directional
Describe directional selection?
One extreme of the phenotype range is selected for
Describe disruptive selection?
Two or more phenotypes are selected for
Describe stabilising selection?
An average phenotype is selected for and extremes of the phenotype is selected against
Where is natural selection more rapid?
In prokaryotes
How can prokaryotes exchange genetic material?
They can exchange genetic material horizontally, resulting in faster evolutionary change than in organisms that only use vertical transfer
Describe horizontal gene transfer.
Genes are transferred between individuals in the same generation
Describe vertical gene transfer.
Transfer of genes from parent to offspring as a result of sexual or asexual reproduction
Define a species.
A group of organisms that are capable of interbreeding and producing fertile offspring, and don’t normally breed with other groups
Define speciation.
The generation of new biological species by evolution, as a result of isolation, mutation and selection
Name and give examples of the three types of isolation barriers.
Geographical- mountains, sea, desert
Ecological- ph of soil
Behavioural- female not attracted to male, hibernation/nocturnal etc
What is the importance of isolation barriers during speciation?
The isolation barrier prevents breeding/ gene flow between sub populations during speciation
Describe allopathic speciation.
Involves geographical barriers
