Jp. Randerson et Ld. Hurst, Small sperm, uniparental inheritance and selfish cytoplasmic elements: a comparison of two models, J EVOL BIOL, 12(6), 1999, pp. 1110-1124
It has previously been suggested that small sperm size may be an adaptation
to achieve uniparental inheritance of organelles, and hence to prevent the
spread of selfish cytoplasmic elements. Such an explanation for anisogamy
implies a mechanism whereby the male gamete eliminates its own cytoplasm pr
ior to fusion with the egg. A model has been presented demonstrating the in
vasion and persistence of a modifier that acts gametically to kill its own
organelles. Here we show, however, that this model is far from robust; inde
ed, if any cost is associated with the modifier it cannot persist. We also
show that despite an empirically demonstrated association between anisogamy
and multicellularity, this result also applies if the analysis is applied
in the multicellular case. This class of model contrasts with the majority
of analyses in which the modifier kills off the incoming gamete's organelle
s. We show that these models are highly robust, even if uniparental inherit
ance is imperfect.