U1:KA7 - Evolutions Flashcards
What is evolution?
Evolution is the changes in organisms over generations as a result of genomic variation
What is vertical inheritance?
Vertical inheritance is when genes are transferred from parent to offspring as a result of sexual or asexual reproduction
What is horizontal gene transfer?
it is gene transfer from one cell to another, not through reproduction
What generations is vertical gene transfer between?
It goes from one generation to the other (parent to offspring)
What generation is horizontal gene transfer between?
The same generation
What is natural selection?
It is the non-random decrease in frequency of deleterious DNA sequences that increase survival
What is stabilising selection?
The average phenotype is selected for, the extremes are selected against
What is directional selection?
One extreme phenotype range is selected for while the average and other extreme phenotype range are selected against
What is disruptive selection?
Two or more phenotypes are selected for whilst others in the phenotype range are selected against
What is a species?
A species is a group of organisms that are capable of interbreeding and producing fertile offspring
What is speciation?
Speciation is the generation of new biological species by evolution
What is the first stage in the process of speciation?
One species exists which interbreeds and shares the same gene pool, the population becomes split by a barrier into 2 sub populations
What is the second stage in the process of speciation?
Mutations occur at random, different mutations occur in each of the populations causing new variation
What is the third stage in the process of speciation?
Over a long period of time the gene pools in the two sub populations become so altered that the groups cannot interbreed
What are the four main stages of speciation?
Isolation by a barrier, mutation, natural selection, formation of seperate species
