Natural Selection and Evidence for Evolution Flashcards
Why do individuals in a population show genetic variation?
Because of differences in their alleles.
How do new alleles arise?
Through mutations.
What are selection pressures?
Factors that affect an organism’s chance of surviving and reproducing.
What are examples of selection pressures?
- Predation
- Competition for resources (food, water, mates, etc.)
- Disease
What makes an individual have a better chance of survival and more likely to breed?
Individuals with characteristics that make them better adapted to the selection pressures in their environment.
What will be a result of individuals’ adaptations to their environment when they breed?
The alleles responsible for the useful characteristics are more likely to be passed on to the next generation.
What happens to a species that can’t compete?
They are likely to go extinct.
What is an antibiotic?
A drug designed to kill bacteria or prevent them from reproducing.
How can the allele for antibiotic resistance be passed on to lots of offspring, in a population of bacteria?
The bacterium with the antibiotic resistance allele survives exposure to the antibiotic, and reproduces to pass on the resistance allele to their offspring.
How does antibiotic resistance provide evidence for evolution?
It makes the bacteria better adapted to an environment in which antibiotics (a selection pressure) are present.
As a result, antibiotic resistance becomes more common in a population over time.
What is a fossil?
Any trace of an animal or plant that lived a long time ago (over a thousand years).
Where are fossils most commonly found?
In rocks (generally, the deeper the rock, the older the fossil).
How do fossils provide evidence for evolution?
By arranging fossils in chronological order, gradual changes in organisms can be observed.
