Transcript CFA 03- Review Notes

Variation in Populations
Tennessee SPI Objective:
Analyze data on levels of variation within a population to
make predictions about survival under particular
environmental conditions.
 Variation refers to a variety or diversity of traits
(different kinds) within any given population.
Three causes of variation
1) Diversity of genetic traits from sexual reproduction
2) Diversity of genetic traits that result from mutations
3) Changing environmental conditions
Variation in populations
 variations occur in human populations & in populations
of plants, animals, birds, insects, fish, bacteria etc.
Variation in Populations

Thesome
Galapagos
arealocated
in the Pacific
Ocean

pointhas
inIslands
past,
small population
ofand
Finches
 At
Each island
athe
slightly
different
ecosystem,
these
about
600 miles
west
of Ecuador
(see picture
below).
(birds)
blown
from
SouthThis
American
these
islands.
fincheswere
adapted
accordingly.
lead totosignificant
variation in the shapes and sizes of their beaks.
South American Finch
Variation in Populations
 Over time the finches developed different beak shapes and
sizes in order to eat the local food (structural adaptations).
Food Source
Only Bugs
narrow-pointed
beak for eating
insects
Food Source
Nuts & Bugs
Food Source
Only Nuts
Moderately wide beak Very wide beak for
with a sharp point for only eating nuts
cracking nuts and
eating insects
Review Questions
Note: Termination refers to the percentage of bugs that were killed
Review Questions
Review Questions