They do not interbreed.
"Introduction to the Science of Sociology" by Robert E. Park
They also frequently interbreed.
"The History of the European Fauna" by R. F. Scharff
The best-known of these so-called species interbreed freely.
"Our Domestic Birds" by John H. Robinson
The flock was allowed to wander at will and to interbreed freely.
"The Black Fawn" by James Arthur Kjelgaard
It will interbreed with the blue hare.
"Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 8" by Various
Many allied species of Cats will interbreed, even two so far apart as the Lion and the Tiger.
"The Cambridge Natural History, Vol X., Mammalia" by Frank Evers Beddard
Polar and brown bears diverged between 4 million and 5 million years ago, but they continued to interbreed when the climate warmed, finds a new study led by the University at Buffalo and Penn State.
Did chimp and human ancestors interbreed .
This is one of the most common Butterflies of the meadows so common that they Just discovered that there is a Type B that looks almost the same but doesn't Interbreeds.
Sub-Saharan Africans only modern humans whose ancestors did not interbreed with them.
The polar bear's origins have been a topic of much discussion in recent years, as the Arctic bears have begun to migrate south and interbreed more frequently with their brown bear cousins.
Most of the squashes can interbreed and many are combinations of more than one species.