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INEXPLICABLY FEMALE‐BIASED SEX RATIOS IN MELITTOBIA WASPS
Author(s) -
Abe Jun,
Kamimura Yoshitaka,
West Stuart A.
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.12451
Subject(s) - biology , sex ratio , sex allocation , mating , competition (biology) , operational sex ratio , assortative mating , inbreeding , sperm competition , zoology , ecology , demography , mating system , population , sociology
The sex ratio behavior of parasitoid wasps in the genus Melittobia is scandalous. In contrast to the prediction of Hamilton's local mate competition theory, and the behavior of numerous other species, their extremely female‐biased sex ratios (1–5% males) change little in response to the number of females that lay eggs on a patch. We examined the mating structure and fitness consequences of adjusting the sex ratio in M. australica and found that (1) the rate of inbreeding did not differ from that expected with random mating within each patch; (2) the fitness of females that produced less female‐biased sex ratios (10 or 20% males) was greater than that of females who produced the sex ratio normally observed in M. australica . These results suggest that neither assortative mating nor asymmetrical competition between males can explain the extreme sex ratios. More generally, the finding that the sex ratios produced by females led to a decrease in their fitness suggests that the existing theory fails to capture a key aspect of the natural history of Melittobia , and emphasizes the importance of examining the fitness consequences of different sex ratio strategies, not only whether observed sex ratios correlate with theoretical predictions.