18.1 Finding Order in Diversity
18.2 Modern Evolutionary Classification
18.3 Building the Tree of Life
GRIN AND BEAR IT
If you simply looked at a polar bear and brown bear, you would probably never doubt that they are members of different species. Polar bears grow much larger than brown bears, and their paws have adapted to swimming long distances and to walking on snow and ice. Their white fur camouflages them, but the coats on brown bears are, well, brown—and their paws aren't adapted to water.
Clearly polar bears and brown bears are very different physically. But do physical characteristics tell the whole story? Remember the definition of species: “a group of similar organisms that can breed and produce fertile offspring.” Well, polar bears and brown bears can mate and produce fertile offspring. They must be members of the same species, then. But are they? As you read this chapter, look for clues to whether polar bears are a separate species. Then, solve the mystery.
Never Stop Exploring Your World.
Solving the mystery of scientific classification is only the beginning. Take a video field trip with the ecogeeks of Untamed Science to see where the mystery leads.