13 - Fig–associated wasps: pollinators and parasites, sex–ratio adjustment and male polymorphism, population structure and its consequences

Summary

ABSTRACT

Fig–pollinating and fig–parasitizing wasps are integral parts of one of the most fascinating plant–insect interactions known. Moreover, studies of these wasps have been instrumental in developing and refining ideas concerning the influence of population structure and inbreeding on shaping the outcome of kin selection. We present data compiled from six studies spanning five continents that relate brood sex ratios with foundress number in 24 pollinator species. All predictions of local mate competition (LMC) and inbreeding theory are at least qualitatively supported. Additionally, the sex ratios produced by single foundresses of any given species appear to be influenced by brood size and the frequency of multiple foundress broods in that species. We then consider the assumptions underlying the testing of the specific LMC model and consider the relative merits of observational and experimental tests of the theory. Furthermore, we discuss the existing studies of the parasitic wasp species that have addressed the unusual morphological and behavioral polymorphisms for flightlessness and lethal combat that are found in the males of these species. These differences appear to be influenced by the parasites' population structure and density, although other factors are also implicated. Finally, we compare the nature of the support for LMC theory from fig–pollinating wasps with that from the parasitoid wasp Nasonia vitripennis, and suggest future lines of research.