Apply species concepts to biological evidence, using reproductive isolation and shared characteristics to decide whether organisms are classified as the same species in Cambridge A Level Biology questions.
Bears are several species of mammal in the family Ursidae.
Climate change and loss of habitats due to human activity have reduced the size of some bear populations in recent years.
Grizzly bears, Ursus arctos horribilis, and polar bears, Ursus maritimus, are found in North America.
Fig. 8.1 shows a grizzly bear and a polar bear.
Grizzly bears have:
- a varied diet that includes grasses, roots, berries, nuts, rodents, insects and fish
- a habitat of woodland or grassland
- a maximum mass of 270 kg .
Polar bears have:
- a diet that consists of other animals, such as seals
- a habitat of land and sea ice
- a maximum mass of 450 kg .
Climate change has caused populations of grizzly bears to spread further north and populations of polar bears to spread further south. In some areas there is habitat overlap and, on rare occasions, breeding between grizzly bears and polar bears has occurred.
The offspring of grizzly bears and polar bears are known as pizzly bears.
Pizzly bears can breed together in the wild.
Fig. 8.2 shows a pizzly bear.
Fig. 8.2
With reference to three different species concepts, discuss whether grizzly bears and polar bears should be classified as separate species.