Unit 1 - KA7 - Evolution Flashcards
Changes in organisms over generations as a result of genomic variations.
Evolution
Exchange of genetic material
Gene transfer
Prokaryotes can exchange genetic material in this way and viruses and prokaryotes can transfer genetic sequences into the genome of eukaryotes.
Horizontal gene transfer
Genetic information is passed from parents to offspring via sexual or asexual reproduction
Vertical inheritance / Gene transfer
Non-random increase in frequency of DNA sequences that increase survival.
Natural Selection
Non-random increase in frequency of DNA sequences that increase reproduction
Sexual selection
This type of selection favours the middle characteristics in a range of variation
Stabalising selection
Favours an extreme characteristic away from the middle.
Directional selection
Favours two extreme characteristics at the expense of the middle.
Disruptive selection
Random decrease and increase in frequency of sequences, particularly in small populations.
Genetic drift (old Higher)
Gene frequency changes by mutation but the effect on the phenotype is minor and gives no change or selective advantage.
Neutral mutation - a type of missense
Occurs by chance, a new colonising population has different gene frequencies from the original population (less diverse)
Founder effect (old Higher)
Caused by a phenotype which increases the chances of survival
Selective advantage
The generation of a new biological species as a result of isolation, mutation and selection
Speciation
Isolation occurs due to geographical barriers such as mountains or oceans. This stops the gene flow between populations
Allopatric speciation
