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Notes
SPI 0807.5.3
Variation in Populations
Science
Variation in Populations
 Variation refers to a variety or diversity of traits
(different kinds) within any given population.
 Variation occurs due to natural selection and is the
result of the pairing of alleles from parental DNA
(dominant and recessive) and also from mutations.
Example: Look around at the other students. Notice the
unique traits that individuals have such as hair color,
height, eye color, skin color, etc.
This is an example of variation within the student population
 Likewise variations occur in nature in populations of
plants, animals, insects, fish, etc.
4 Phases of Natural Selection
Phase 1
Phase 2
Phase 3
Phase 4
Questions
SPI 0807.5.3
Variation in Populations
Science
Insecticide 2
Note: This in only about insecticide two. Also, this is about
resistance (survival rate) and not about the percentages killed!
 For population two, only 2 % survived, and with population
four, zero % survived. They were the least resistant.
Questions
SPI 0807.5.3
Variation in Populations
Science
Note: Something beneficial happened in 1988 that enabled the
population to increase. One logical explanation is that with
fewer predators, more rabbits survived.
Questions
SPI 0807.5.3
Variation in Populations
Science
Better in the summer
Better in the winter
Note: This charts shows the color variation in the summer.
Brown is dominant in this summer as camouflage.
In a snowy winter, white would be better camouflage.
Questions
SPI 0807.5.3
Variation in Populations
Science
Note: The new predator runs 40 KPH. Therefore the rabbits
that can run faster than this have the best chance of surviving.
Questions
SPI 0807.5.3
Variation in Populations
Science
Note: After 5 generations, genotype Gg is only 5% of the
population. One explanation would be that this type of grass
is producing fewer seeds that the other two types of grass.