Ability to gall: The ultimate basis of host specificity in fig wasps?

1. Fig trees (Ficus spp.) and their host-specific pollinator fig wasps (Agaonidae) are partners in an obligate mutualism. Receptive phase figs release specific volatiles to attract their pollinators, and this is generally effective in preventing pollinator species from entering figs of the wrong hosts. 2. If entry is attempted into atypical host figs, then ostiole size and shape and style length may also prevent reproduction. In spite of these barriers, there is increasing evidence that fig wasps enter atypical hosts, and that this can result in hybrid seed and fig wasp offspring. 3. This study examines the basis of pollinator specificity in two dioecious fig species from different geographical areas. Kradibia tentacularis pollinates Ficus montana in Asia. Ficus asperifolia from East Africa is closely related but is pollinated by a different species of Kradibia. 4. In glasshouses, K. tentacularis was attracted to its normal host, F1s and backcrosses, but only rarely entered figs of F. asperifolia. Foundresses were able to lay eggs in hybrids, backcrosses, and F. asperifolia, although flower occupancy was lowest in F. asperifolia figs and intermediate in hybrids. 5. The fig wasp failed to reproduce in female F. montana, male F. asperifolia, and male F1s, and most but not all backcrosses to F. montana. This was a result of the failure to initiate gall production. 6. Host specificity in this fig wasp is strongly influenced by host volatiles, but the ability to gall may be the ultimate determinant of whether it can reproduce

Tinkering with the C-Function: A Molecular Frame for the Selection of Double Flowers in Cultivated Roses

International audienc

An extreme case of plant-insect co-diversification: figs and fig-pollinating wasps

It is thought that speciation in phytophagous insects is often due to colonization of novel host plants, because radiations of plant and insect lineages are typically asynchronous. Recent phylogenetic comparisons have supported this model of diversification for both insect herbivores and specialized pollinators. An exceptional case where contemporaneous plant insect diversification might be expected is the obligate mutualism between fig trees (Ficus species, Moraceae) and their pollinating wasps (Agaonidae, Hymenoptera). The ubiquity and ecological significance of this mutualism in tropical and subtropical ecosystems has long intrigued biologists, but the systematic challenge posed by >750 interacting species pairs has hindered progress toward understanding its evolutionary history. In particular, taxon sampling and analytical tools have been insufficient for large-scale co-phylogenetic analyses. Here, we sampled nearly 200 interacting pairs of fig and wasp species from across the globe. Two supermatrices were assembled: on average, wasps had sequences from 77% of six genes (5.6kb), figs had sequences from 60% of five genes (5.5 kb), and overall 850 new DNA sequences were generated for this study. We also developed a new analytical tool, Jane 2, for event-based phylogenetic reconciliation analysis of very large data sets. Separate Bayesian phylogenetic analyses for figs and fig wasps under relaxed molecular clock assumptions indicate Cretaceous diversification of crown groups and contemporaneous divergence for nearly half of all fig and pollinator lineages. Event-based co-phylogenetic analyses further support the co-diversification hypothesis. Biogeographic analyses indicate that the presentday distribution of fig and pollinator lineages is consistent with an Eurasian origin and subsequent dispersal, rather than with Gondwanan vicariance. Overall, our findings indicate that the fig-pollinator mutualism represents an extreme case among plant-insect interactions of coordinated dispersal and long-term co-diversification

Ecologie chimique des interactions ficus-pollinisateurs (fonctions, coût de production et évolution des composés volatils émis par les figues)

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Role of odour compounds in the attraction of gamete vectors in endophytic Epichloë fungi

Grass-infecting Epichloë endophytes (Ascomycota, Calvicipitaceae) depend on Botanophila flies for gamete transfer, while fly larvae feed and develop on the fertilized fungal fruiting structures. Flies are known to be attracted by volatile signals, but the exact mechanisms of chemical communication and the degree of specialization are unknown. Headspace samples collected from five different Epichloë species were analysed with respect to physiologically active substances using Botanophila flies. In field bioassays using synthetic compounds, their attractiveness and the specificity of the Epichloë-Botanophila attraction were investigated. The identification of a new natural product, methyl (Z)-3-methyldodec-2-enoate, attracting Botanophila flies is reported here, and chokol K is confirmed as an attractive compound. Different blends of the two compounds attracted Botanophila flies under field conditions, but the three fly taxa present at the study site showed no preference for specific blends of volatiles. Chemical communication in the Epichloë-Botanophila system relies on a few specific compounds, known as a communication system with 'private channels'. Although ratios of emitted compounds vary in different Epichloë species, this seems not to lead to specialized attraction of Botanophila flies. Low selective pressure for specialization may have maintained a more generalist interaction between fungi and flies