Biology Ruby-throated hummingbirds migrate 2,000 km every fall. Before migrating, they eat nectar and convert much of the sugar in the nectar to fat. Why is it advantageous for these birds to store energy as fat rather than as glycogen?

The images show two species of tree frogs in a particular region. the gray tree frogs are adapted to the trees of the woodlands, while the green tree frogs can survive in woodlands or grasslands. the gray frog was abundant in the woodlands. because of climatic changes, most of the trees in the region died, and the woodlands changed to grasslands. in such a case, the . the gray tree frog is closely related to the green tree frog genetically, but they have different mating calls. this suggests that speciation occurred because of .