Spo11 mutants of the fission yeast Schizosaccharomyces pombe and C. elegans undergo meiotic crossover recombination and proper chromosome segregation when dU:dG lesions are produced in their DNA.

However recombination can be restored to near normal levels by a deletion in rad2, a gene that encodes an endonuclease involved in Okazaki fragment processing (Farah et al., 2005).

The most recent common ancestor of the social amoeba genera Dictyostelium, Polysphondylium and Acytostelium, appears to have lacked the Spo11 gene.

Bloomfield[12] speculated that dormant cells in the soil might be exposed to many kinds of stress, such as desiccation or radiation, that could induce spontaneous DNA damage.

Such damage would make the induction of double-strand breaks by Spo11 redundant for the initiation of recombination during meiosis, and thus explain its absence in this group.