Lesson 5 - Mechanisms of Evolution Flashcards
What cell can mutations only be passed on?
Only mutations within sex cells can be passed on
What results from mutations?
New alleles
Key Factors Leading to Evolution
When populations are small, chance fluctuations can cause changes in allele frequencies.
When mating is nonrandom, individuals that are preferred mates will pass on more alleles.
Mutations may cause new alleles to be created or changed, causing a change in allele frequency.
Migration will remove alleles from one population and add them to another
Natural selection causes certain alleles to be passed on increasing the relative frequency of alleles in the next generation.
Gradual Evolution
Increment of change is small compared to time
Punctuated Evolution
Increment of change is large compared to time
Stabilizing selection
most common phenotypes within a population are most favoured
Directional selection
environment favours individuals with more extreme variations
Disruptive selection
variations at opposite extremes
Sexual selection
favours the selection for any trait that influences the mating success of the individual
Cumulative selection
small changes accumulate over time because of their selective advantage
Genetic Drift
Changes to allele frequency as a result of chance.
Bottleneck Effect
severe event results in a drastic reduction in numbers
very small sample of alleles survives to establish a new population
Founder Effect
Genetic drift that results when a small # of individuals separate from their original population.
Gene Flow
The movement of alleles from one population to another through the movement of individuals.
Where are traits coded for?
on DNA in units called GENES. Genes are located at specific LOCI
