Data from: Testing sex ratio theory with the malaria parasite Plasmodium mexicanum in natural and experimental infections

The malaria parasite (Plasmodium) life history accords well with the
assumptions of Local Mate Competition (LMC) of sex ratio theory. Within a
single meal of the blood-feeding vector, sexually dimorphic gametocyte
cells produce gametes (females produce 1, males several) that mate and
undergo sexual recombination. The theory posits several factors drive the
Plasmodium sex ratio: male fecundity (gametes/ male gametocyte), number
and relative abundance of parasite clones, and gametocyte density. We
measured these traits for the lizard malaria parasite, P. mexicanum, with
a large sample of natural infections and infections from experiments which
manipulated clonal diversity. Sex ratio in single-clone infections was
slightly female-biased, but matched predictions of theory for this
low-fecundity species. Sex ratio was less female-biased in clonally
diverse infections as predicted by LMC for the experimental, but not
natural infections. Gametocyte density was not positively related to sex
ratio. These results are explained by the P. mexicanum life history of
naturally low clonal diversity and high gametocyte production. This is the
first study of a natural malaria system that examines all traits relevant
to LMC in individual vertebrate hosts and suggests a striking example of
sex ratio theory having significance for human public health.