Suppose that, in a typical sexual species, a strain of parthenogenetic females arose, producing only daughters like themselves.

She thought that the strain showing in Collier's face arose out of fear for her rather than for himself.

A 1986 paper by Army researchers said the strain did not arise until 1980.

Thus two distinct strains arose, one in France and one in England.

Names now mutate faster than Staphylococcus, and the trendier the name, the more aerobic the pace at which new strains arise.

When a new strain of flu arises, they tend to worry.

Usage declined in the 1980s as piperaquine-resistant strains of P. falciparum arose and artemisinin-based antimalarials became available.

But another question, just as pertinent, would be this: Why do pandemic strains arise so rarely?

For the Mitnauls, strains arise from debt.

If antibiotics are used on such a large scale, it is no surprise that strains of bacteria arise which do not then respond to antibiotics.