It can also backcross with its parental species. Mendel tested his hypothesis with a type of backcross called a testcross. Overall, viability is reduced in these hybrids and they rarely backcross with their parent species. A spontaneous backcross of the grapefruit and sweet orange then resulted in the orangelo. Similarly, a F2 animal bred to an F1 animal creates a F2b backcross. The backcross used a single English Pointer; subsequent breedings have all been to purebred Dalmatians.