Download Natural Selection Student note sheet Artificial selection – explains

Natural Selection
Student note sheet
1. Artificial selection –
______________________________________________________________________________
2. ___________________ explains evolution
a. 1858 Darwin writes “The Origin of Species”, explains evolution through the theory of
___________________ ________________
b. Natural selection – individuals that are better ____________ to their ______________ =
more likely to ______________ and _________________ than other members of the
same species. (“Survival of the Fittest”)
c. ________ steps to natural selection!!
Steps of NATURAL SELECTION:
Step 1: _________________________ – each species makes more offspring than will survive
Step 2: ___________________________ - Any difference between individuals of the same species
- some traits help, some hurt them.
- Some variations are helpful = adaptation
- Different genes = different traits
- Examples: Fast swimmers, better camouflage
Step 3: _________________________________________________________________________
– A natural environment doesn’t have enough resources for everyone, so only some individuals
survive to adulthood.
Step 4: ___________________________________________________________
– the individuals that are well adapted to the environment are more likely to survive and
reproduce. Their genes will be passed on.
**Over a long period of time, natural selection can lead to evolution.**
Peppered moth story:
The case of the English peppered moth is an example of how human actions can
affect natural selection. In the late 1700’s, most English peppered moths were
light gray in color. The light-colored moths had an advantage over black
peppered moths because birds could not see them against the light-gray trees.
Natural selection favored the light colored moths over the black moths.
The industrial revolution began in England in the late 1700’s. People built factories to make cloth and
other goods. Over time, smoke form the factories blackened the trunks of the trees Now the lightcolored moths were easier to see than the black ones. As a result, birds caught more light-colored
moths. Natural selection favored the black moths. By about 1850, almost all the peppered moths
were black.