Unit 6- Lesson 1(Natural Selection)

TRAITS & NATURAL

SELECTION

CLASS EXPLORATION ACTIVITY

Climate change refers to long-term shifts in temperatures and

weather patterns.

In a population of moth, wing color is determined by dominant
grey (G) and recessive blue (g) alleles of a single gene. Bats are a
common predator of the moth species.

Grey moths have the genotype GG or Gg.
Blue moths have the genotype gg.

Example Case Study:

How is the color of the moth relevant to its environment?

Thought Questions

Which of the moths (grey or blue-winged) is likely to be better

adapted to the environment and why?

Starting Population

Let's imagine a starting population that looks like this:

GG

Gg

Gg

GG

gg

gg

gg

gg

GG

Gg

Gg

GG

gg

gg

gg

gg

There are 6 G alleles.

There are 10 g alleles.

There are 16 alleles in total

(Two for each of the 8 moths)

∴

dominant allele = 6/16 = 0.375

(or 37.5%)

recessive allele = 10/16 = 0.625

(or 62.5%)
50% of moths are grey.

50% of moths are blue.

Now, let's
consider the
environment and
what we know.

Therefore, it is likely that blue moths will be spotted and
eaten by bats as they will stand out.

Bats are a common predators of the moth species.
Moths hide using camouflage against trees that are grey
and brown in color.

Surviving Population

Let's imagine the surviving population that looks like this:

GG

Gg

Gg

GG

gg

Most of the blue moths are eaten by bats.

GG

Gg

Gg

GG

gg

There are 6 G alleles.

There are 4 g alleles.

There are 10 alleles in total

(Two for each of the 5 moths)

∴

dominant allele = 6/10 = 0.6

(or 60%)

recessive allele = 4/16 = 0.4

(or 40%)
80% of moths are grey.

20% of moths are blue.

How has the frequency of the alleles changed in the moth

population?

Discussion Questions

What could this change mean for the next generation of moths?