The gulf sturgeon was first recognized as a separate subspecies in 1955.

White tigers do not constitute a separate subspecies of their own and can breed with orange ones.

However, others have not observed this subsequently and the consensus is that no separate subspecies are recognized.

It is possible that the population in each ocean represents a separate subspecies.

But other scientists do not recognize any separate subspecies.

It is possible that these variations are separate subspecies, but this is disputed.

The groups had been classified previously as separate subspecies because of differences in body size, horn shape, habitat or behavior.

These differences have led biologists to consider them as separate subspecies.

The difficulties in identifying separate subspecies, or even species, is pronounced.

Within a number of species, separate subspecies have been identified.