Topic 5

Question 1

Who developed the theory of natural selection?

Answer 1

Charles Darwin

Question 2

What are the two main principles of natural selection?

Answer 2

1. there is variation within a population of organisms and this variation can be inherited
2. individuals with inherited traits that are better suited for growth and reproduction in a given environment can contribute disproportionately to the next generation

Question 3

Who is Georges Cuvier?

Answer 3

• did not believe species changed over time (no evolution)
• after a catastrophe, a different species simply moved into the area (catastrophism)

Question 4

What is natural selection?

Answer 4

a process in which individuals with favorable inherited traits are more likely to survive and reproduce.

Question 5

What is decent with modification?

Answer 5

describes the origin of new species (speciation) from ancestral species.

• natural selection is the mechanism for “decent with modification”

Question 6

What is genotypic variation?

Answer 6

• the difference in DNA among individuals in populations.
• Genotype = genetic makeup of an organism
• genotypic variation is heritable.

Question 6

What are the two observations of evolution by natural selection?

Answer 6

1. members of a population vary in their inherited traits.
2. populations produce more offspring than the environment can support, and many of these offspring fail to survive and reproduce.

Question 6

What is phenotypic variation?

Answer 6

the variability in phenotypes that exist in a population.

• phenotype = an organisms observed characteristics
• an organism’s phenotype is determined by interaction of environmental factors and its genotype.

Question 7

What is a selective agent?

Answer 7

• environmental factors acting on populations to effect the survival and/or reproduction of individuals in the populations

Question 8

What is a selective pressure?

Answer 8

when a selective agent consistently causes differences in survival and/or reproduction in a population

• selective pressures act on individuals, but only populations evolve.

Question 9

consistent selection pressure leads to…

Answer 9

… a directional change in the population, known as natural selection.

• if the selection pressure changes, the direction of natural selection will change.

Question 10

What is an adaptation?

Answer 10

an inherited characteristic of an organism that enhances its survival and reproduction in a specific environment.

Question 11

What does natural selection increase?

Answer 11

The adaptation of populations.

Question 12

Natural selection acts on…

Answer 12

Existing variation. (genetic diversity)

• natural selection does not create new variation.