Quick Quiz
It looks like your students have some questions about Big Issues in evolution. Reflect on what you have just learned and see how well you can respond. Just click on their raised hands!
You could respond:
“Actually, a ‘half an eye’ might be really useful
for distinguishing between light and dark. So there can be an intermediate advantage to the intermediate stages of a complex
feature. And the intermediate stage might have been used for a different function and then co-opted for a more complex one.”
You could respond:
“Punctuated equilibrium is relatively rapid evolution at a speciation event. Gradualism is the slow genetic modification of a population over long periods of time. Probably
both happen. Different populations have different histories.”
You could respond:
“Nice play on words! Actually there are trends in evolution,
though this should not be confused with progress. Trends are changes in a particular direction over long periods of
time—such as the increased height of the crown of horse teeth as grasses changed. Progress is a different matter.
There is no ladder to perfection and progress can be defined in numerous ways. High-crowned teeth is a pretty good thing
for a hungry horse, but would not do much good for a duck.”
You could respond:
“Odd. I don’t have anything in writing about that.”
You could respond:
“A transitional form is a species of living thing that is
in some ways intermediate between the forms that came before and after it. It shows the path of evolution.”
You could respond:
“The first function of feathers wasn’t flight. They may have originally evolved for display, protection, or insulation. Feathers still perform these functions, plus they help most birds fly.”
You could respond:
“Well, who spins a web better: you or a spider? We often define success in ways that make us the winner. But this is self-centered. There are lots of different ways to look at success.”
You could respond:
“Well, for example, if there were a mass extinction or a big change in the environment, it would open up many new niches. If some lineages had the right traits and genetic variation, they might get to take advantage of the opportunity and fill these niches.”
