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TESTING SEX RATIO THEORY WITH THE MALARIA PARASITE PLASMODIUM MEXICANUM IN NATURAL AND EXPERIMENTAL INFECTIONS
Author(s) -
Neal Allison T.,
Schall Jos. J.
Publication year - 2014
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/evo.12334
Subject(s) - biology , gametocyte , malaria , sex ratio , sex allocation , sexual dimorphism , plasmodium (life cycle) , fecundity , parasite hosting , zoology , oreochromis , evolutionary biology , ecology , genetics , immunology , demography , population , plasmodium falciparum , pregnancy , sociology , world wide web , computer science , offspring , fishery , fish <actinopterygii>
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 one, 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, Plasmodium mexicanum , with a large sample of natural infections and infections from experiments that 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.