Download File - About Ms. Aguilar

STUDY GUIDE: NATURAL SELECTION
Name:______________________________________ per:_______
Define the following terms:
1. Species2. Fitness3. Variation4. Phenotype5. Mutation6. Genetic recombination7. Adaptation-
8. Who was Charles Darwin? What was his contribution to
science?
9. What is meant by the term “common ancestor”?
10. Describe Darwin’s theory of evolution by Natural Selection
AND Give an example from nature:
12. Name two things that cause genetic variation within a species:
1)
2)
13.Why is genetic variation a good thing?
11. Draw a picture of #10:
14. Hummingbirds can have long or short bills. Explain why a longer-billed hummingbird might survive better
in a particular environment. Use scientific language to explain:
THINGS TO REMEMBER:
Be familiar with the Summary of Darwin’s Theory:
o There is genetic variation in every natural population
o Individual organisms differ (are different) and some of this variation is inherited
o Organisms produce more offspring than can survive, and many that do survive do not reproduce
o Organisms compete for resources (struggle for existence)
o Each unique organism has different advantages and disadvantages in the struggle for existence.
Individuals best suited to their environment survive and reproduce
most successfully. These organisms pass their traits to their offspring.
Other individuals die or leave fewer offspring. This process of natural
selection causes species to change over time.
o Species today are descended with modification from ancestral species
that lived in the distant past. All species on earth evolved from an
ancient common ancestor.
Evolution is any change in the relative frequency (percentage) of alleles in a population
 VARIATION IS A GOOD THING!!
DIVERSITY IS A GOOD THING!!
 The greater the variation/diversity, the more likely a species will survive a big change in the environment
(or a disease, or a meteor, or a volcanic eruption, or even a two degree change in temp, etc.)
Natural Selection in the Galapagos:
 Example: Finches on different islands looked so different from one another because natural selection
shaped the beaks of different bird populations as they adapted to eat different foods (in different
habitats).
 Another example: Tortoises on different islands had different neck lengths according to the height of the
vegetation in their habitat.
NATURAL SELECTION ACTS ON THE PHENOTYPE, NOT THE GENOTYPE!!
It only matters how the organisms traits are expressed- nature doesn’t know exactly what the genes are inside,
only what it looks like or acts like
New species are formed through reproductive isolation.
There are 3 types of reproductive isolation:
1. geographic isolation- separated by rivers, mountains, bodies of water, etc
2. behavioral isolation- diff behaviors, mating songs, rituals
3. temporal isolation- mate at different times