Evolution Flashcards
What is evolution?
The change over time in the proportion of individuals in a population with one or more differing traits
When does genetic drift occur?
When chance events cause unpredictable fluctuations in allele frequencies from one generation to the next
Does genetic drift have a higher impact in small or large populations? Why?
Small populations as the number of organisms with the same alleles are smaller than in large populations so there is more of a chance for an allele to be completely lost
Is genetic drift random or non-random?
Random
What are 2 examples of the effects of genetic drift?
The bottleneck effect- when a population size is randomly reduced for at least one generation which will then lower the range of alleles
The founder effect- the random isolation of a few individuals causing a new gene pool which is not representative of the whole population’s gene pool
What is the source of new DNA sequences?
Mutations
What are new DNA sequences known as?
Novel alleles
What are the 3 outcomes of a mutation on an individuals fitness?
Harmful- decreasing the fitness
Neutral- having no impact on fitness
Beneficial- improving the fitness
What does selection do to the frequency of individuals which harmful and beneficial mutations?
It increases the number of those who have beneficial mutations by these individuals being able to survive and so reproduce passing down the mutation.
It decreases the number of those who have the harmful mutation as they are less likely to survive and so less likely to reproduce and pass down the mutation.
Is selection random or non-random?
Non-random
What is sexual selection?
The selection for alleles that make an individual more likely to find a mate and produce offspring
Is sexual selection random or non-random?
Non-random
