Terms
A group of organisms that can reproduce with one another and produce fertile offspring.
Speices
The process in which organisms with helpful traits are more likely to survive and reproduce.
Natural Selection
Scenario: A drought causes plants to become very hard and dry. Birds with stronger beaks survive better.
Question: What acted as the selection pressure?
The drought / hard food availability
A mutation is a change in an organism’s ________.
DNA / genes
True or False: Individual organisms evolve during their lifetime.
False
A group of the same species living in the same area.
Population
An organism’s ability to survive and reproduce.
Fitness
In snowy environments, white foxes are harder for predators to see.
Question: What is the white fur an example of?
Adaptation
Mutations are important to evolution because they create new ________ in a population.
variation
Evolution acts on individuals, but over time changes occur in the ________.
population
Differences in traits between individuals in a population.
Variation
A change in the traits of a population over generations.
Evolution
Some bugs are faster than others. Birds catch more slow bugs.
Question: Which bugs are more likely to reproduce?
The faster bugs
True or False: All mutations are harmful.
false
If every organism in a population were exactly identical, natural selection would have difficulty occurring. Why?
no variation
A trait that improves an organism’s chances of surviving or reproducing in its environment.
Adaptation
The surroundings and conditions in which an organism lives.
Environment
A species of fish lives in polluted water. Over many generations, fish that tolerate pollution survive and reproduce more often.
Question: What process is occurring in this population?
natural selection
A bird is born with a mutation that gives it slightly larger wings. In a windy environment, the bird can glide more efficiently and escape predators.
Question: Why might this mutation become more common over time?
Birds with the mutation survive and reproduce more successfully
A population of insects contains green and brown individuals. After many generations in a forest, almost all the insects are green.
Question: Why did the population change over time?
The green insects survived and reproduced more successfully in that environment
Anything in the environment that affects survival or reproduction.
Selective Pressure (pressure)
A change in DNA that can introduce new traits.
Mutation
A population of insects is sprayed with pesticide. Most die, but a few survive because they already have a trait that makes them resistant. Over several generations, most of the population becomes resistant to the pesticide.
Question: Did the pesticide CAUSE the insects to evolve resistance?
No -> the resistant insects already existed in the population, and the pesticide selected for them by killing the non-resistant insects
A mutation appears in a rabbit that changes its fur color, but the fur color does not affect survival or reproduction at all.
Question: What will MOST likely happen to this mutation over time?
it may stay, disappear, or spread randomly because it provides no survival advantage or disadvantage
someone says: “Organisms evolve because they try really hard to adapt.”
Question: Why is this statement incorrect?
Individuals do not choose adaptations; beneficial traits already present are selected over generations