Download Natural Selection

Variability
Variation within a species is called variability.
Main Idea!!
Why do you think
there is variability
within all species?
What purpose do these
differences serve?
Natural Selection
• Natural Selection occurs when the
environment “selects” which
individuals will survive long enough to
reproduce.
• This is another way that affects the
survival of a species.
Antibiotic resistant bacteria
• This is the ability of bacteria to survive an
attack by an antibiotic and is an excellent
example of natural selection at work. Bacteria
that develop a mutation that allows them to
survive an antibiotic will live long enough to
reproduce and so spread the 'survival' gene
to subsequent generations. Those bacteria
with this gene will survive and become more
numerous in the bacterial population.