Twenty years ago, about half the population of Darwin's bark spiders in the zoo exhibit had sti
silk, and about half had not sticky silk. Now, almost all the spiders in the population have stick
Explain to the zoo director why and how the distribution of traits in the spider population could
changed. In your explanation, be sure to include the following:
What caused this spider population to have more spiders with the sticky silk trait?

Q&A Education