Chapter 9.2 Evolution Of Populations Flashcards
What is evolution in genetic terms?
A change in the frequency of alleles in a population over time
Define fitness.
How well an organism can survive and reproduce in its environment
What did Darwin believe about fitness?
Only the fittest individuals survive to reproduce and pass on their traits to the next generation
What has to happen to a population for fitness to increase?
Over time, as individual organisms successfully respond to changing conditions in the environment, the population evolves and its fitness increases.
What are four sources of genetic variations that contribute to the evolution of populations?
- Shuffling of alleles during meiosis
- Mutations
- Gene Flow
- Genetic Drift
What is gene flow?
Gene flow occurs when individuals with new alleles physically move from one population to another.
Does gene flow increase or decrease the genetic variation of a population?
Increase
What was one reason for Darwin’s oversimplification of evolution?
He did not know about mutations.
How many new mutations does each human child inherit from their parents on average?
60
Mutations to which type of cell are passed on to offspring and affect their fitness?
sex cells
Do mutations that increase fitness or mutations that decrease fitness become more common in a population?
Mutations that increase fitness become more common
Why do mutations that decrease fitness tend to disappear?
Because the individuals with that mutation die or reproduce less successfully
What creates all the variation among members of a species and accounts for the diversity of organisms on Earth?
Mutations
What is genetic drift?
Random change in a small populations allele frequency.
How are alleles lost to a population?
The only carrier of an allele dies and this is NOT passed to the next generation.
