Molecular Phylogenies of Fig Wasps: Partial Cocladogenesis of Pollinators and Parasites

Abstract

Figs (Ficus spp., Moraceae) and their pollinating wasps form an obligate mutualism, which has long been considered a classic case of coevolution and cospeciation. Figs are also exploited by several clades of nonpollinating wasps, which are parasites of the mutualism and whose patterns of speciation have received little attention. We used data from nuclear and mitochondrial DNA regions to estimate the phylogenies of 20 species of Pleistodontes pollinating wasps and 16 species of Sycoscapter nonpollinating wasps associated with Ficus species in the section Malvanthera. We compare the phylogenies of 15 matched Pleistodontes/Sycoscapter species pairs and show that the level of cospeciation is significantly greater than that expected by chance. Our estimates of the maximum level of cospeciation (50 to 64% of nodes) are very similar to those obtained in other recent studies of coevolved parasitic and mutualistic associations. However, we also show that there is not perfect congruence of pollinator and parasite phylogenies (for any substantial clade) and argue that host plant switching is likely to be less constrained for Sycoscapter parasites than for Pleistodontes pollinators. There is perfect correspondence between two terminal clades of two sister species in the respective phylogenies, and rates of molecular evolution in these pairs are similar.

Mutualism favours higher host specificity than does antagonism in plant–herbivore interaction

“…Under such circumstances, both leaf-feeding and flower-infesting moths are provided with multiple available hosts, but the latter are more selective in their host choice owing to a broader range of coevolutionary traits with which they are constrained. The occurrence of multiple co-flowering host species is also the case in figs, for which preliminary analysis of host specificity in pollinating and non-pollinating fig wasps suggested that the former tends to be more host-specific (Weiblen & Bush 2002;Marussich & Machado 2007; but see Lopez-Vaamonde et al 2001;Jousselin et al 2006Jousselin et al , 2008.…”

“…In contrast to their pollinating relatives, each of these cheater species has evolved to use four to six yucca hosts (Pellmyr 1999;Segraves & Pellmyr 2004), suggesting that host specificity in the pollinators may not be determined solely by the herbivorous habit of the moths (Pellmyr 2003). In the fig system, non-pollinating agaonid wasps that are closely related to and co-occur with pollinating fig wasps tend to be less host specific than are the pollinators (Weiblen & Bush 2002;Marussich & Machado 2007; but see Lopez-Vaamonde et al 2001;Jousselin et al 2006Jousselin et al , 2008. In addition, fig herbivores in general are dominated by insects that feed on several locally available fig hosts (Novotny et al 2002(Novotny et al , 2006.…”

Phylogeny and DNA barcoding of inquiline oak gallwasps (Hymenoptera: Cynipidae) of the Western Palaearctic

“…DNA was extracted from a single hind leg of most specimens using a simple Chelexbased protocol (Lopez-Vaamonde et al 2001). Based on prior experience (though not a hard 265 and fast rule), for insects less than 2 mm long we extracted DNA from the whole wasp using the DNeasy Tissue Kit (QIAGEN cat.…”

Coevolutionary Dynamics and the Conservation of Mutualisms

“…Slight cheats that arise by mutation could gradually erode the mutualistic interaction, and lead to dissolution or reciprocal extinction (Roberts and Sherratt 1998;Doebeli and Knowlton 1998). Although cheating has been assumed to be under strict control, recent empirical findings (reviewed by Bronstein 2001b) indicate that cheating is rampant in most mutualisms; in some cases, cheaters have been associated with mutualisms over long spans of evolutionary time (Després and Jaeger 1999;Pellmyr and Leebens-Mack 1999;Lopez-Vaamonde et al 2001). Recent theoretical advances have increased our understanding of the ecological and evolutionary persistence of particular forms of mutualism (e.g., Holland and DeAngelis 2001;Law et al 2001;Yu 2001;Holland et al 2002;Morris et al 2003;Wilson et al 2003).…”