Evolution - 1.7 Flashcards
What is evolution?
changes to organisms over time, caused by natural selection
What is vertical inheritance?
genes are transferred from parent to offspring as a result of sexual or asexual reproduction
What is horizontal transfer?
genes are transferred between individuals of the same generation
What is evolution more rapid in and why?
prokaryotes due to horizontal exchange
what type of inheritance is safer and why?
vertical as genes have been “tried and tested”
What is Natural selection?
the non - random increase in frequency of DNA sequences which increase survival and the non - random decrease in harmful sequences
What does having a quantitative trait mean?
-polygenic
-controlled by many genes working together
-measurable phenotype
What are the three types of selection for a quantitative trait?
-stabilising
-directional
-disruptive
explanation of stabilising and what happens to the graph
-average phenotype is selected for, extremes are selected against
-graph gets thinner
explanation of directional and what happens to the graph
-one extreme is selected for
graph moves to the right
explanation of disruptive and what happens to the graph
-two or more phenotypes are selected for
-graph splits
what is a species?
a group of organisms which can interbreed to produce fertile offspring
What is the definition of speciation?
formation of a new species brought about by isolation, mutation, selection
Why are isolation barriers important?
preventing gene flow between sub populations
What is allopatric speciation?
when a population becomes separated due to a geographical barrier
