How does variation in a species help it to survive when the environment changes?
Think furry animals for example. When Mount Pinatubo in the Philippines erupted, it threw enough ash into the upper atmosphere that it lowered the average temperature around the globe by a degree for more than a full year after the eruption. Now think the same thing from the super volcano under Yellowstone, where the caldera is over 60 miles in diameter! Ash from THAT kind of eruption will darken the noon sun to where it would be winter all year long. Which furry animals will survive a year round winter? The ones with the long dense fur, of course, will survive in greater numbers than species with short less dense fur. We’re talking step change as opposed to gradual. Gradual change can be accommodated easily with simple natural attrition favoring one more surviving animal per generation, instead of the step change which favors a large specific range as survivable. With the ash cloud winter, the long hairs survive and the short hairs do not. When the 6 mile diameter asteroid landed in t
