Molecular markers reveal reproductive strategies of non-pollinating fig wasps

1. Fig wasps have proved extremely useful study organisms for testing how reproductive decisions evolve in response to population structure. In particular, they provide textbook examples of how natural selection can favour female-biased offspring sex ratios, lethal combat for mates, and dimorphic mating strategies. 2. However, previous work has been challenged, because supposed single species have been discovered to be a number of cryptic species. Consequently, new studies are required to determine population structure and reproductive decisions of individuals unambiguously assigned to species. 3. We used microsatellites to determine species identity and reproductive patterns in three non-pollinating Sycoscapter species associated with the same fig species. Foundress number was typically 1-5 and most figs contained more than one Sycoscapter species. Foundresses produced very small clutches of about 1-4 offspring, but one foundress may lay eggs in several figs. 4. Overall, the data show poor match to theoretical predictions of solitary male clutches and gregarious clutches with (n-1) females. However, sex ratios are male-biased in solitary clutches and female-biased in gregarious ones. 5. At the brood level (all wasps in a fig), a decrease in sex ratio with increasing brood size is only significant in one species, and sex ratio is unrelated to foundress number. In addition, figs with more foundresses contain more wasp offspring. 6. Finally, 10-22% of females develop in patches without males. As males are wingless, these females disperse unmated and are constrained to produce only sons from unfertilized eggs

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

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

Phylogeny and evolution of life-history strategies in the Sycophaginae non-pollinating fig wasps (Hymenoptera, Chalcidoidea)

<p>Abstract</p> <p>Background</p> <p>Non-pollinating Sycophaginae (Hymenoptera, Chalcidoidea) form small communities within <it>Urostigma </it>and <it>Sycomorus </it>fig trees. The species show differences in galling habits and exhibit apterous, winged or dimorphic males. The large gall inducers oviposit early in syconium development and lay few eggs; the small gall inducers lay more eggs soon after pollination; the ostiolar gall-inducers enter the syconium to oviposit and the cleptoparasites oviposit in galls induced by other fig wasps. The systematics of the group remains unclear and only one phylogeny based on limited sampling has been published to date. Here we present an expanded phylogeny for sycophagine fig wasps including about 1.5 times the number of described species. We sequenced mitochondrial and nuclear markers (4.2 kb) on 73 species and 145 individuals and conducted maximum likelihood and Bayesian phylogenetic analyses. We then used this phylogeny to reconstruct the evolution of Sycophaginae life-history strategies and test if the presence of winged males and small brood size may be correlated.</p> <p>Results</p> <p>The resulting trees are well resolved and strongly supported. With the exception of <it>Apocrytophagus</it>, which is paraphyletic with respect to <it>Sycophaga</it>, all genera are monophyletic. The Sycophaginae are divided into three clades: (i) <it>Eukoebelea</it>; (ii) <it>Pseudidarnes</it>, <it>Anidarnes </it>and <it>Conidarnes </it>and (iii) <it>Apocryptophagus</it>, <it>Sycophaga </it>and <it>Idarnes</it>. The ancestral states for galling habits and male morphology remain ambiguous and our reconstructions show that the two traits are evolutionary labile.</p> <p>Conclusions</p> <p>The three main clades could be considered as tribes and we list some morphological characters that define them. The same biologies re-evolved several times independently, which make Sycophaginae an interesting model to test predictions on what factors will canalize the evolution of a particular biology. The ostiolar gall-inducers are the only monophyletic group. In 15 Myr, they evolved several morphological adaptations to enter the syconia that make them strongly divergent from their sister taxa. Sycophaginae appears to be another example where sexual selection on male mating opportunities favored winged males in species with small broods and wingless males in species with large broods. However, some species are exceptional in that they lay few eggs but exhibit apterous males, which we hypothesize could be due to other selective pressures selecting against the re-appearance of winged morphs.</p

Voyage(s) dans l'immobilité

Performance artist Yann Marussich comments here his own personal itinerary, his experiments, his performances since the early 2000s. He lays out the timeline of his artistic research and provides an overview of his methods, as well as of their foundations. Starting from dance and Body Art, he develops a unique approach centred on apparent immobility and on micro-movements.L''artiste performer Yann Marussich commente ici son propre itinéraire, ses expérimentations, ses performances réalisées depuis le début des années 2000. Il nous livre le parcours chronologique de sa recherche artistique et donne un aperçu de sa méthodologie de travail, comme de ses présupposés. Partant de la danse et du Body Art, il développe une méthodologie singulière, centrée sur l''immobilité apparente mettant en jeu des micro-mouvements.El artista performer Yann Marussich comenta aquí su proprio itinerario, sus experimentaciones, sus performances realizadas desde el comienzo de los años 2000. Nos entrega un recorrido cronológico de su búsqueda artística y da una vision de conjunto de su metodología de trabajo, como de sus presupuestos. Partiendo de la danza et del Body Art desarrolla una metodología singular focalizada sobre la inmovilidad aparente colocando en juego los micro-movimientos.Marussich Yann. Voyage(s) dans l'immobilité. In: Communications, 92, 2013. Performance - Le corps exposé. Numéro dirigé par Christian Biet et Sylvie Roques. pp. 239-251

Rockfall hazard and risk management: an example of a comprehensive approach in northern italy

In the context of slope instability phenomena, the detachment of blocks from steep walls account for 40% of landslides occurences in Alpine areas (Cooco,1991). This phenomenon, also known as rockfall, occours in densely populated area such as the Italian Alps, where the hazard is quite high due to the presence of several buildings and house. We have chosen to assess the risk posed by potential rockfalls in an area hosting a small industrial complex close to a steep limestone slope. To this aim, a comprehensive set o geological, geomorphological and geomechanical surveys were conducted both in detachment and transit zones. The study area is located in the Carnic Alps, in proximity of a small stream - torrent vajont - at a height of 800-1300 m