Download 7.2 Natural Selection

SBI3U – Unit 3: Evolution
Date: ____________________
7.2 Natural Selection
Selective Pressure
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Environmental conditions that _______________ certain characteristics of individuals and
___________________________ other characteristics.

The _______________________ selects which variation survives best.
Natural Selection

The process by which _____________________________________________ over many generations
as organisms with __________________________________________, passing their traits to offspring
Natural Selection does not:

Does NOT _______________________ in the environment nor have any _______________________

A trait that was once advantageous may become ______________________ in the future
Fitness

The relative contribution an individual makes to the next generation by ________________________
_______________________________________________________ (Survival of the Fittest)
Artificial Selection

___________________ - a type of artificial selection

Artificial Selection - when the selective pressure is exerted by __________________
Human desired traits
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______________________
– food crops, food animals
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______________________
– dogs, cats, horses
Results of Selective Breeding for Oil Content in Plants

In the Venn Diagram below, list key difference between natural selection and artificial selection on
each outer circle and the similarities of both in the middle circle.
TO DO LIST:

Section 7.2 p. 307 #7 – 12, p. 311 #1 – 13
•
Read and make notes on ‘Consequences of Artificial Selection’ p. 310