This can be a troubling idea, particularly to a biologist who studies species.

They are required reading for anyone who studies species and speciation.

The species has not been studied much in the wild, and little is known of its behaviour.

Yet worldwide only 4,000 species have actually been studied and identified by scientists.

However, more species have been studied in recent years.

Information about the breeding of this family is incomplete, with many species having never been studied.

In studying invasive species, scientists often see a direct effect.

This species was not well studied until the 1960s.

It was not until two weeks later that the new species was studied.

This species is also relatively popular among gardeners and has recently been studied for possible medical uses.