Approximately 65 million years ago, a mass extinction occurred on planet Earth. Layers of soil dating back to this time contain large amounts of the radioactive element iridium. This indicates that a large asteroid or comet struck Earth, throwing up huge clouds of debris, which would block much of the sunlight. Food became very scarce. Half of the marine species and nearly all of the dinosaur species went extinct during this time. Soon after the cloud settled, the surviving species of mammals rapidly diversified and filled the niches left empty by the dinosaurs. What evolutionary event was represented by this asteroid collision and the resulting cloud?
a. mutation
b. gene flow
c. genetic drift
d. natural selection
Thanks!
Categorized | Affiliate Marketing 101
Approximately 65 Million Years Ago…?
Posted on November 4, 2011.
d. natural selection
Of the choices available, that’s the only one that half way makes sense.
d sound right
Mass extinction event. That’s not one of your choices, so kick your teacher for me.
If I had to pick one of these alternatives, I would choose this one:
c. genetic drift
This was a random occurrence that probably reduced many populations down to a very small number of individuals (that is, the ones that didn’t just go extinct) — which would be a bottleneck, which is a subtopic of genetic drift.