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International audience; Many insects metamorphose from antagonistic larvae into mutualistic adult pollinators, with reciprocal adaptation leading to specialized insect-plant associations. It remains unknown how such interactions are established at molecular level. Here we assemble high-quality genomes of a fig species, Ficus pumila var. pumila, and its specific pollinating wasp, Wiebesia pumilae. We combine multi-omics with validation experiments to reveal molecular mechanisms underlying this specialized interaction. In the plant, we identify the specific compound attracting pollinators and validate the function of several key genes regulating its biosynthesis. In the pollinator, we find a highly reduced number of odorant-binding protein genes and an odorant-binding protein mainly binding the attractant. During antagonistic interaction, we find similar chemical profiles and turnovers throughout the development of galled ovules and seeds, and a significant contraction of detoxification-related gene families in the pollinator. Our study identifies some key genes bridging coevolved mutualists, establishing expectations for more diffuse insect-pollinator systems.

International audience; Figs and fig wasps are a classic example of an obligate pollination mutualism. Decades of work untangling the ecology and evolution of these organisms has simultaneously contributed to development of the fields of mutualism, coevolution and plant-insect interactions at large. With > 800 species, figs (Ficus, Moraceae) are among some of the larger genera of angiosperms. Phylogenetic studies of Moraceae have supported the clade Castilleae as the sister lineage of Ficus. Compared to Ficus, Castilleae have many fewer species (60 species in 11 genera), suggesting changes in rates of diversification along these two branches. Relatively little is known about Castilleae compared to Ficus, and we argue that defining the clade comprising Ficus and Castilleae, hereafter Involucrata, focuses attention on opportunities for comparative studies of pollination mutualisms and diversification rates. In this study, we define Involucrata and propose a revised classification scheme that accounts for the phylogenetic reconstruction based on the most comprehensive sampling of this group to date. Moving forward, this classification will better guide and support evolutionary, ecological and comparative pollination biology studies of this group. Additional Keyword: Asperae-external transcribed spacer-Involucrata-Mixtiflores-Noyera-paralogy-phylogenetic reconstruction.

Background In brood site pollination mutualisms, pollinators are attracted by odours emitted at anthesis. In Ficus, odours of receptive figs differ among species and the specific pollinators generally only enter figs of their host species ensuring a pre-zygotic barrier to plant interspecific hybridisation. However, field observations recorded that, in Guangdong province in China, Valisia javana hilli, the local pollinator of F. hirta, entered and reproduced successfully in the figs of the closely related F. triloba on a regular basis. We propose that closely related Ficus species produce similar receptive fig odours. Under particular contexts of odours locally present, the receptive fig odours of non-host figs of a Ficus species may become attractive to pollinators of closely related Ficus species. We used the headspace technique to collect in situ receptive fig odours of F. triloba in a series of locations in China. Under controlled conditions, we tested the attraction of fig pollinating wasps from F. hirta and F. triloba to host figs and non-host figs in Y tube experiments. Results Receptive fig odours of F. triloba though different from those of F. hirta, were mainly composed of a same set of volatile organic compounds. When given the choice between receptive fig odours and air, the pollinating wasps were only attracted by their host’s odours. However, when given a choice between host and non-host figs the pollinators of F. hirta were equally attracted by the two odours while the pollinators of F. triloba tended to be more attracted by their host’s fig odours. Conclusions Receptive fig odours vary geographically within species and the differentiation of receptive fig odours between closely related Ficus species is often incomplete. This allows localised or occasional pollinator sharing following different modalities. Cross stimulation when wasps are exposed simultaneously to odours of host and non-host species may be important. While occasional pollinator sharing may play a marginal role when wasp populations are robust, it may ensure the provisioning of new pollinators from the closest relative of a Ficus species if its pollinators go extinct.

International audience; Finding a mate is a crucial step in sexual reproduction. The mutualism between figs and their pollinators is exploited by many figwasps that develop within their galls and attain sexual maturity simultaneously. Male pollinators carry the specific burden of detecting and opening mating holes in galls containing conspecific females before mating with them. The mating behaviourand antennal sensilla of male pollinators associated with Ficus semicordata was investigated to understand mate recognition. Male Ceratosolen gravelyi located female-containing galls from a distance, but only attempted to chew a mating hole after antennal contact with the gall surface was made. They showed similar responses to females and body extracts but failed to respond to washed female bodies. This behaviour indicates that unidentified chemicals present on the body surfaces of females are sufficient to elicit olfactory attraction and tactile confirmation. Multiporous plate sensilla are candidates for olfactory reception from a distance while basiconic sensilla may be involved in contact chemoreceptor. All of the sensilla are highly localised, on the distal part of the terminal flagellomere, suggesting a response to selection for strong directionality in the complex odour environment of the fig in which messages produced by hundreds of females may confuse precise mate localisation.

Mutualism is ubiquitous in nature and probably all species in the world are involved in some form of such ecological interaction. The evolution of mutualisms is often envisioned in a framework where individual selection leads to reciprocal exploitation that results in net benefits to all the interacting parties, i.e. in a framework in which individual selection intrinsically destabilises the mutualistic association. However, mutualisms are stable, and rarely turn into parasitism. At a macroevolutionary scale, mutualisms have been a source of major evolutionary innovations and have benefited all the species involved. Indeed, complementary traits of the partners enable them to colonise new ecological niches. In this chapter we discuss mutualism as a source of evolutionary innovation, using some insect-plant associations as examples. Firstly, we dedicate a topic to theoretical aspects and hypotheses on evolutionary forces stabilizing mutualisms (and their pitfalls). We present some examples of mutualisms that allowed insects and/or plants to expand their ecological niches. Finally, we focus on fig tree – animal interactions that, putatively, allowed this plant lineage to diversify in subtropical and tropical ecosystems and to form a group of keystone species for the functioning of many forest ecosystems.

International audience; The synstigma is a structure formed by clusters of two to several stigmas, whether in the same or between different flowers. Although rare in angiosperms, synstigmas are found in c. 500 out of the c. 750 Ficus spp. (Moraceae). This floral structure is associated with fig-fig wasp pollinating mutualism. The synstigma structure and pollen tube pathways were studied in six Ficus spp. from Ficus section Americanae to test the hypothesis that the synstigma allows pollen grains deposited on a stigma to emit pollen tubes that can grow laterally and fertilize surrounding flowers. Syconia containing recently pollinated stigmas were collected and dissected, and the stigmas were processed for analyses with light and scanning and transmission electron microscopy. The arrangement of the synstigmas across species can be spaced or congested, with the number of stigmas per synstigma ranging from two to 20. Contact between the stigmas in a synstigma occurs by the intertwining of the stigmatic branches and papillae; their union is firm or loose. The pollen tube grows through live cells of the transmitting tissue until reaching the ovule micropyle. Curved pollen tubes growing from one stigma to another were observed in five out of the six species studied. The curvilinear morphology of pollen tubes probably results from competition by pollen between the stigmas composing a synstigma via chemotropic signals. The synstigma appears to be a key adaptation that ensures seed production by flowers not exploited by the fig wasps in actively pollinated Ficus spp. Additional keywords: active pollination-Ficus-Moraceae-pollen grain-pollen-pistil interaction-pollen tube-ultrastructure.

Background and Aims Moraceae, the family of mulberry and fig trees, displays small homogeneous flowers but extremely diverse inflorescences ranging from simple and branched to complex and condensed. Inflorescences also vary in flower organization in the receptacle, in the degree of flower condensation and in receptacle shape. Thus, the objective of the present study was to compare the inflorescence morphogenesis of Moraceae species, to investigate whether clades with a similar pollination mode share the same patterns of inflorescence development and the developmental stages at which we observe the key changes resulting in the diversified inflorescence architecture that culminates in the Ficus syconium. Methods Inflorescences at different developmental stages were sampled from Brosimum gaudichaudii, Castilla elastica, Clarisia ilicifolia, Ficus pertusa, Maclura tinctoria and Morus nigra and processed for surface and anatomical analyses. Key Results The inflorescence morphogenesis of the studied species is highly variable. The shape of the inflorescence meristem (bulging, hemispheric or elongated), the initiation order and arrangement of flowers along the receptacle and the occurrence of bracts vary between related species. This diversity originates early during inflorescence development. Brosimum gaudichaudii, C. elastica and F. pertusa have flowers enclosed or immersed within the receptacle, although inflorescences begin their development as flat and open structures, as occurs in the other three study species. Conclusion Comparison of the inflorescence morphogenesis in Moraceae species allows us to infer that evolutionary ontogenetic changes driven by pollinators culminate in the enclosure of flowers inside the receptacle, as occurs in the Ficus syconium.

Plants, phytophagous insects and their parasitoids form the most diverse assemblages of macroscopic organisms on earth. Enclosed assemblages in particular represent a tractable system for studying community assembly and diversification. Communities associated with widespread plant species are especially suitable as they facilitate a comparative approach. Pantropical fig-wasp communities represent a remarkably well-replicated system, ideal for studying these historical processes. We expect high dispersal ability in non-pollinating fig wasps to result in lower geographical turnover in comparison to pollinating fig wasps. The ability of non-pollinating wasps to utilise a number of hosts (low host specificity) is a key determinant of overall geographical range, with intraspecific competition becoming a constraining factor should diet breadth overlap among species. Finally, we expect conserved community structure throughout the host range. We aim to test these expectations, derived from population genetic and community studies, using the multi-trophic insect community associated with Ficus hirta throughout its 3,500 km range across continental and insular Asia. We collect molecular evidence from one coding mitochondrial gene, one non-coding nuclear gene and multiple microsatellites across 25 geographical sites. Using these data, we establish species boundaries, determine levels of host specificity among non-pollinating fig wasps and quantify geographical variation in community composition. We find low host specificity in two genera of non-pollinating fig wasps. Functional community structure is largely conserved across the range of the host fig, despite limited correspondence between the ranges of non-pollinator and pollinator species. While nine pollinators are associated with Ficus hirta, the two non-pollinator tribes developing in its figs each contained only four species. Contrary to predictions, we find stronger isolation by distance in non-pollinators than pollinators. Long-lived non-pollinators may disperse more gradually and be less reliant on infrequent long-distance dispersal by wind currents. Segregation among non-pollinating species across their range is suggestive of competitive exclusion and we propose that this may be a result of increased levels of local adaptation and moderate, but regular, rates of dispersal. Our findings provide one more example of lack of strict codiversification in the geographical diversification of plant-associated insect communities.

International audience; Flower odor is often essential for attracting pollinators, and this is especially true for species-specific mutualism such as the one between Ficus species and their pollinating wasps. Receptive figs emit a stage and species specific odor composed of a mix of volatile organic compounds (VOC) that is attractive to their pollinators. Histological studies suggest that the ostiolar bracts are the main locus of fig floral VOC synthesis. To confirm a major role of the ostiole in VOC synthesis, detect the genes involved in VOC synthesis and analyze differences between closely related species, we compare the transcriptomes of pre-receptive and receptive figs of two closely related species, F. hirta and F. triloba. The two species presented similar numbers of expressed genes and similar annotation, classification results, and their upregulated unigenes belonged to similar biosynthetic pathways. However, phenylpropanoid and terpene synthesis were the main enriched VOC pathways in receptive figs of F. hirta while terpene and jasmonate synthesis were the main enriched VOC pathways in F. triloba. The shift in gene expression between pre-receptive and receptive figs was much more marked in the ostiolar bracts than in the flowers of F. hirta, and in the fig wall, confirming an important role of the ostiole in receptive fig odor emission. Only one unigene directly involved in VOC synthesis presented signatures of positive selection, further supporting that the source of interspecific receptive fig odor differentiation is based on gene regulation rather than on gene differentiation. Regulation based receptive fig odor differentiation between species suggests a potential for rapid evolution of this interspecific barrier

Despite their ecological and evolutionary importance as key components of tropical ecosystems, the phylogeny of fig trees is still unresolved. We use restriction-site-associated DNA (RAD) sequencing (ca420kb) and 102 morphological characters to elucidate the relationships between 70 species ofFicusrepresenting all known subgenera and sections and five outgroups. We compare morphological and molecular results to highlight discrepancies and reveal possible inference bias. We analyse marker and taxon properties that may bias molecular inferences, with existing softwares and a new approach based on iterative principal component analysis to reduce variance between clusters of samples. For the first time, with both molecular and morphological data, we recover a monophyletic subgenusUrostigmaand a clade with all gynodioecious fig trees. However, our analyses show that it is not possible to homogenize evolutionary rates and GC content for all taxa prior to phylogenetic inference and that four competing positions for the root of the molecular tree are possible. The placement of the long-branched sectionPharmacosyceaas sister to all other fig trees is not supported by morphological data and considered as a result of a long branch attraction artefact to the outgroups. Regarding morphological features and indirect evidence from the pollinator tree of life, the topology that divides the genusFicusinto monoeciousversusgynodioecious species appears most likely. Active pollination is inferred as the ancestral state for all topologies, ambiguity remains for ancestral breeding system including for the favored topology, and it appears most likely that the ancestor of fig trees was a freestanding tree. Increasing sampling may improve results and would be at least as relevant as maximizing the number of sequenced regions given the strong heterogeneity in evolutionary rates, and to a lesser extent, base composition among species. Despite morphological plasticity and frequent homoplasy of multiple characters, we advocate giving a central role to morphology in our understanding of the evolution ofFicus, especially as it can help detect insidious systematic errors that tend to become more pronounced with larger molecular data sets.

In Madagascar, biodiversity, local livelihoods and agroecosystems are increasingly threatened. It is critical to understand and support local social-ecological systems that sustain livelihoods and value biodiversity. This study investigates why Betsileo communities in Ambendrana and Sahabe protect isolated individuals and clusters of Ficus species in their rural landscapes. Ficus trees have multiple values and sustain webs of ecological interactions that favor biodiversity. We show that spontaneous seedlings of Ficus are protected and that people also actively propagate Ficus by stem cuttings. Their multiple values and uses and the distribution patterns of each species, are linked to social-ecological dynamics and to the historical construction of local landscapes. Both past and present uses associated with each Ficus species define how they are protected. Different sets of practices associated with each species are governed by both material and symbolic considerations. Ficus reflexa, a boundary marker of zebu corrals, has a symbolic role in protecting humans and livestock and checks erosion; F. lutea is a marker of residences of ancient noble classes and F. tiliifolia is a remnant of swidden agriculture and a marker of the memory of ancestors, but its numbers are shrinking. Ficus trees are protected but there is no strict taboo against cutting them when they hinder crop production. Their potential role for biodiversity conservation is linked to these social-ecological dynamics. Based on these findings, we propose some rules of thumb for developing collaborative approaches which consider synergies between local and scientific knowledge.

Background While the communities constituted by phytophageous insects and their parasites may represent half of all terrestrial animal species, understanding their diversification remains a major challenge. A neglected idea is that geographic phenotypic variation in a host plant may lead to heterogeneous evolutionary responses of the different members of the associated communities. This could result in diversification on a host plant by ecological speciation in some species, leading to geographic variation in community composition. In this study we investigated geographic variation of inflorescence receptacle size in a plant, Ficus hirta, and how the hymenopteran community feeding in the inflorescences has responded. Our predictions were:Inflorescence size variation affects wasp species differently depending on how they access oviposition sites.In some affected lineages of wasps, we may observe vicariant, parapatric species adapted to different inflorescence sizes. Results We show that fig (the enclosed inflorescence of Ficus) wall thickness varies geographically. The fig-entering pollinating wasp was not affected, while the parasites ovipositing through the fig wall were. Two parapatric species of Philotrypesis, exhibiting strikingly different ovipositor lengths, were recorded. One species of Sycoscapter was also present, and it was restricted, like the shorter-ovipositor Philotrypesis, to the geographic zone where fig walls were thinner. Conclusions Previous work on fig wasps suggested that parapatric geographic ranges among congenerics were due to adaptation to variation in abiotic factors, complemented by interspecific competition. Our results show that parapatric ranges may also result from adaptation to variation in biotic factors. Within an insect community, differences among species in their response to geographic phenotypic variation of their host plant may result in geographically heterogeneous community structure. Such heterogeneity leads to heterogeneous interaction networks among sites. Our results support the hypothesis that plant geographic phenotypic variation can be a driver of diversification in associated insect communities, and can complement other diversification processes. Electronic supplementary material The online version of this article (10.1186/s12862-018-1239-5) contains supplementary material, which is available to authorized users.

International audience; A comparison was performed of the antennal sensilla of females of four chalcid wasp species Ceratosolen emarginatus Mayr, 1906, Sycophaga sp., Philotrypesis longicaudata Mayr, 1906, and Sycoscapter roxburghi Joseph, 1957, which are specific and obligatory associated with Ficus auriculata (Lour, 1790). The four species exhibit different oviposition strategies in the fig ovules where their offspring hatch and develop. Antennal sensilla morphology was evaluated using scanning electron microscopy. Females of the four species present 11 morphologically similar types of sensilla: trichoid sensilla, sensilla obscura, chaetica sensilla 1 and 2, which all have mechanosensory functions; uniporous basiconic sensilla, which are presumably contact chemosensilla; basiconic capitate peg sensilla, coeloconic sensilla 1, multiporous basiconic and placoid sensilla, which may be regarded as olfactory sensilla, and coeloconic sensilla 2 and 3, which are presumed to be proprioreceptors or pressure receptors. The four species have significant differences in the abundance and arrangement of trichoid sensilla and chaetica sensilla 1 on the flagellum. The coeloconic sensilla and sensilla obscura only occur on the antennae of C. emarginatus that enter figs. The chemosensilla which are presumably involved in host discrimination, i.e., basiconic sensilla, multiporous placoid sensilla and basiconic capitate peg sensilla, are similar in shape and configuration, although they present some differences in abundance. These findings provide practical information on the adaptations of fig wasps and the relationship between multisensory antennae and functions in fig wasp behaviour.

A listagem de especies de Ficus para o Mato Grosso do Sul foi obtida da revisao mais recente para o Brasil extra-amazonico e complementada pelo exame de materiais depositados em herbarios. Foram registrados 12 especies de Ficus para o estado, sendo 10 pertencentes a secao Americanae e duas a secao Pharmacosycea. Destacamos a ocorrencia de uma especie endemica ao Pantanal (F. carautana L.J. Neves & Emygdio). O presente estudo provavelmente lista a maioria das especies de Ficus ocorrentes no Mato Grosso do Sul. No entanto, o maior esforco de amostragem em regioes com baixos indices de coletas certamente contribuira para o registro de novas ocorrencias para o genero.

International audience; The ways that plant-feeding insects have diversified are central to our understanding of terrestrial ecosystems. Obligate nursery pollination mutualisms provide highly relevant model systems of how plants and their insect associates have diversified and the over 800 species of fig trees (Ficus) allow comparative studies. Fig trees can have one or more pollinating fig wasp species (Agaonidae) that breed within their figs, but factors influencing their number remain to be established. In some widely distributed fig trees, the plants form populations isolated by large swathes of sea, and the different populations are pollinated by different wasp species. Other Ficus species with continuous distributions may present genetic signatures of isolation by distance, suggesting more limited pollinator dispersal, which may also facilitate pollinator speciation. We tested the hypothesis that Ficus hirta, a species for which preliminary data showed genetic isolation by distance, would support numerous pollinator species across its range. Our results show that across its range F. hirta displays clinal genetic variation and is pollinated by nine parapatric species of Valisia. This is the highest number of pollinators reported to date for any Ficus species, and it is the first demonstration of the occurrence of parapatric pollinator species on a fig host displaying continuous genetic structure. Future comparative studies across Ficus species should be able to establish the plant traits that have driven the evolution of pollinator dispersal behaviour, pollinator speciation and host plant spatial genetic structure.

International audience; PREMISE: Variation in pollen-ovule ratios is thought to reflect the degree of pollen transfer efficiency—the more efficient the process, the fewer pollen grains needed. Few studies have directly examined the relationship between pollen-ovule ratio and pollen transfer efficiency. For active pollination in the pollination brood mutualisms of yuccas and yucca moths, figs and fig wasps, senita and senita moths, and leafflowers and leafflower moths, pollinators purposefully collect pollen and place it directly on the stigmatic surface of conspecific flowers. The tight coupling of insect reproductive interests with pollination of the flowers in which larvae develop ensures that pollination is highly efficient.METHODS: We used the multiple evolutionary transitions between passive pollination and more efficient active pollination to test if increased pollen transfer efficiency leads to reduced pollen-ovule ratios. We collected pollen and ovule data from a suite of plant species from each of the pollination brood mutualisms and used phylogenetically controlled tests and sister-group comparisons to examine whether the shift to active pollination resulted in reduced pollen-ovule ratios.RESULTS: Across all transitions between passive and active pollination in plants, actively pollinated plants had significantly lower pollen-ovule ratios than closely related passively pollinated taxa. Phylogenetically corrected comparisons demonstrated that actively pollinated plant species had an average 76% reduction in the pollen-ovule ratio.CONCLUSIONS: The results for active pollination systems support the general utility of pollen-ovule ratios as indicators of pollination efficiency and the central importance of pollen transfer efficiency in the evolution of pollen-ovule ratio.

Most plants are pollinated passively, but active pollination has evolved among insects that depend on ovule fertilization for larval development. Anther‐to‐ovule ratios (A/O ratios, a coarse indicator of pollen‐to‐ovule ratios) are strong indicators of pollination mode in fig trees and are consistent within most species. However, unusually high values and high variation of A/O ratios (0.096–10.0) were detected among male plants from 41 natural populations of Ficus tikoua in China. Higher proportions of male (staminate) flowers were associated with a change in their distribution within the figs, from circum‐ostiolar to scattered. Plants bearing figs with ostiolar or scattered male flowers were geographically separated, with scattered male flowers found mainly on the Yungui Plateau in the southwest of our sample area. The A/O ratios of most F. tikoua figs were indicative of passive pollination, but its Ceratosolen fig wasp pollinator actively loads pollen into its pollen pockets. Additional pollen was also carried on their body surface and pollinators emerging from scattered‐flower figs had more surface pollen. Large amounts of pollen grains on the insects' body surface are usually indicative of a passive pollinator. This is the first recorded case of an actively pollinated Ficus species producing large amounts of pollen. Overall high A/O ratios, particularly in some populations, in combination with actively pollinating pollinators, may reflect a response by the plant to insufficient quantities of pollen transported in the wasps’ pollen pockets, together with geographic variation in this pollen limitation. This suggests an unstable scenario that could lead to eventual loss of wasp active pollination behavior.

International audience; Parasitoids contribute to controlling phytophagous insect populations. Their action on a host is often measured by numbers of emerging adult parasitoids. However, parasitoid oviposition attempts may lead to host mortality and sometimes both host and parasitoid die during larval development. Therefore, establishing the effect of parasitoids on host populations requires estimating total effect of parasitoids. The communities of wasps developing in figs (the closed inflorescences of Ficus) have become a model system to investigate micro-hymenopteran interaction networks. A galled ovule produces either a single galling wasp or a single parasitoid providing a simple way to measure costs. However, some galled flowers produce no wasps. We show that about one quarter of galled flowers fail to produce pollinator offspring in the absence of parasitoids. In the presence of parasitoids, the number of empty galls is increased. For each emerging parasitoid, 1.9 pollinator larvae were killed. Hence, host mortality induced by parasitoids is much larger than actual parasitoid production, a feature documented in some other host-parasitoid interactions and that may be pervasive in nature

International audience; The mutualism of figs and their pollinating fig wasps is widely regarded as a model for coevolved mutualism. A high degree of host specificity is ensured by female wasps only being attracted by their specific fig tree species through the volatile organic compounds (VOCs) released by the figs when they are ready to be pollinated. However, very little is known about the molecular mechanisms underlying the production of VOCs and how pollinators respond to these VOCs. Here we present transcriptome sequencing data from VOC-treated fig wasps and control fig wasps. Using Illumina paired-end sequencing, approximately 6.47 Gbp and 6.48 Gbp high quality reads were generated for fig wasps that had been exposed or not to VOCs of their host fig. After read trimming, the de novo assembly of both types of reads produced 58,192 unigenes with an average length of 817 bp. Then functional annotation and GO enrichment analysis was performed by aligning all-unigenes with public protein databases including NR, SwissProt, and KEGG. Differentially expressed genes (DEGs) were investigated using the RPKM method. Overall, 16 up-regulated genes and 13 down-regulated genes were identified. We further performed GO enrichment and metabolic pathway enrichment analyses. One gene involved in the synoptic vesicle cycle and two genes coding for odorant binding proteins (OBP) are likely to have potential impacts on the response of fig wasps to the VOCs emitted by their host figs. This is the first transcriptome sequencing of a fig wasp in the presence of VOCs of its host figs using the next-generation sequencing technology. Our studies suggest that the expression of some genes in the olfactory neural system of the fig wasps is affected by the VOCs released from the figs. This suggests the presence of a dynamic molecular system of detection and hence response to host plant VOCs. As such our findings provide indications for further mechanistic studies on the fig-fig wasp interactions.

International audience; Humans have favored the presence of Ficus species within anthropogenic landscapes and near human settlements throughout the planet due to a number of beliefs and for practical purposes. An intimate or mutualistic relationship between Ficus spp and human societies has been suggested but explanations about the motivations of these proximities between humans and Ficus remain very fragmentary. The case study presented in this paper, which was conducted in the sacred hills located in the surroundings of an urban area, Antananarivo, capital city of Madagascar, inhabited by the Merina, aims at finding some answers to the following two questions. To what extent are Ficus species integrated into the ecologies of human groups, understood here as interactions between humans (social, political and economic dimensions)? 2) Do humans introduce Ficus species into new habitats, potentially offering new ecological opportunities? This study builds on initial work conducted in Madagascar in the region of Fianarantsoa in Betsileo rural communities. Results shown in this paper suggest that: 1) the kings of Imerina, the region located in the north-eastern part of the High Plateau of Madagascar, have planted Ficus species abundantly, especially Ficus lutea Vahl and Ficus. polita Vahl, to claim ownership upon new territories of the Imerina and symbolically establish their political hegemony. Marriages with women from non-Merina cultural groups, such as the Sakalava inhabiting the Western Coast, and the use of Ficus species as symbols of power has contributed, with other activities, to the unification process of Madagascar; 2) The ecological distribution of F. lutea has been substantially manipulated by people from Imerina by planting this species quite abundantly in the sacred hills surrounding Antananarivo, an area where this species is at its ecological limit of distribution and also in faraway places such as the Western coast where the tree is not naturally distributed.

International audience; The stigma plays several roles such as pollen hydration and selection, and pollen tube nutrition. In the Ficus-fig wasp mutualism, stigmata have an additional, almost unknown, function by representing a physical interface for both plant and wasp reproduction. We used light and electron microscopy to compare the detailed morphology of the stigmata of nine Ficus species of different sections and with different pollination modes and sexual expressions. Figs were collected at the stage when the stigmata were receptive for pollination. Stigmata in actively pollinated monoecious species have well developed papillae concentrated on the adaxial surface exposed towards the fig cavity. Conversely, the passively pollinated monoecious species have the whole surface of the stigmata covered by somewhat smaller papillae. In both actively and passively pollinated monoecious species these features are consistent, irrespective of style length. In all actively pollinated gynodioecious species, the stigmata of pistillate flowers were tubular or infundibuliform whereas in almost all actively pollinated monoecious species (except F. racemosa) the stigmata were filiform, with one branch or two asymmetric branches. In gynodioecious species the short-styled flowers in “male” figs show a limited receptive surface with small papillae, while the stigmata of long-styled flowers in “female” figs are covered by papillae that extend down the sides of the style, increasing the stigmatic surface. In actively pollinated species, stigmata are cohesive, forming a common surface for pollen tube germination (= synstigma). The synstigma arrangement was quite variable: lax, cohesive or very cohesive, with entanglement by stigmatic papillae and stylar trichomes. Entanglement by stylar trichomes is common in gynodioecious species. The synstigma arrangement did not correlate with phylogeny or breeding system. This study is the first to report a very loose synstigma in actively pollinated monoecious Ficus species. Our analyses revealed that, in Ficus, the synstigma is functionally analogous to an extra-gynoecial compitum. Comparative studies will be required to test further hypotheses about the evolutionary determinants of such variation.

International audience; Plant leaves host species rich communities of foliar endophytic fungi (FEF). Compared to the other compartments of the plant microbiome, FEF diversity is poorly known. Here we document the communities of FEF associated with the endemic Corsican pine Pinus nigra subsp. laricio at three sites across its natural range and examine the effect of forest site, tree age and light exposure on FEF composition. Metabarcoding using next-generation sequencing provided 8,243,608 Ascomycota ITS2 sequences clustered into 642 FEF operational taxonomic units (OTUs). FEF communities did not differ in species richness across sites and tree cohorts, but differed in composition among forest patches and according to tree age. FEF community composition did not correlate with needle location (shade vs full light). Results are robust against the various options of the bioinformatic pipeline specifically developed. This study provides the first picture of FEF diversity in a Mediterranean island and underlines the complementarity of forest massifs for fungal conservation.

International audience; The high adaptive success of parasitic Hymenoptera might be related to the use of different oviposition sites, allowing niche partitioning among co-occurring species resulting in life history specialization and diversification. In this scenario, evolutionary changes in life history and resources for oviposition can be associated with changes in ovipositor structure, allowing exploitation of different substrates for oviposition. We used a formal phylogenetic framework to investigate the evolution of ovipositor morphology and life history in agaonid wasps. We sampled 24 species with different life histories belonging to all main clades of Agaonidae including representatives of all described genera of non-pollinating fig wasps (NPFW). Our results show an overall correlation between ovipositor morphology and life history in agaonid fig wasps. Ovipositor morphologies seem to be related to constraints imposed by features of the oviposition sites since ovipositor morphology has experienced convergent evolution at least four times in Sycophaginae (Agaonidae) according to the resource used. Nongalling species have more distantly spaced teeth with uneven spacing, as opposed to the observed morphology of galling species. Our results suggest that the ancestral condition for ovipositor morphology was most likely the presence of one or two apical teeth. Regarding life history, ovary galling species that oviposit in receptive figs possibly represent the ancestral condition. Different ovipositor characteristics allow exploitation of new niches and may be related to resource partitioning and species coexistence in the fig-fig wasp system.

International audience; Insects show a multitude of symbiotic interactions that may vary in degree of specialization and structure. Gallinducing insects and their parasitoids are thought to be relatively specialized organisms, but despite their ecological importance, the organization and structure of the interactions they establish with their hosts has seldom been investigated in tropical communities. Non-pollinating fig wasps (NPFW) are particularly interesting organisms for the study of ecological networks because most species strictly develop their offspring within fig inflorescences, and show a multitude of life history strategies. They can be gall-makers, cleptoparasites or parasitoids of pollinating or of other non-pollinating fig wasps. Here we analysed a set of non-pollinating fig wasp communities associated with six species of Ficus section Americanae over a wide area. This allowed us to investigate patterns of specialization in a diverse community composed of monophagous and polyphagous species. We observed that most NPFW species were cleptoparasites and parasitoids, colonizing figs several days after oviposition by pollinators. Most species that occurred in more than one host were much more abundant in a single preferential host, suggesting specialization. The food web established between wasps and figs shows structural properties that are typical of specific antagonistic relationships, especially of endophagous insect networks. Two species that occurred in all available hosts were highly abundant in the network, suggesting that in some cases generalized species can be more competitive than strict specialists. The Neotropical and, to a lesser extent, Afrotropical NPFW communities seem to be more generalized than other NPFW communities. However, evidence of host sharing in the Old World is quite limited, since most studies have focused on particular taxonomic groups (genera) of wasps instead of sampling the whole NPFW community. Moreover, the lack of quantitative information in previous studies prevents us from detecting patterns of host preferences in polyphagous species.

© 2017 The Authors Tropical rainforests harbour much of the earth's plant diversity but little is still known about how it evolved and why a small number of plant genera account for the majority. Whether this success is due to rapid turnover or constant evolution for these hyper-diverse plant genera is here tested for the species-rich genus Ficus L. (figs). The pan-tropical distribution of figs makes it an ideal study group to investigate rainforest hyper-diversification patterns. Using a recently published, dated and comprehensive phylogenetic hypothesis, we infer that figs are an old lineage that gradually accumulated species and exhibits very low extinction rates, which corresponds to the ‘museum model’ of evolution. Overall, no major significant shifts in evolutionary dynamics are detected, yet two shifts with lower probability are found. Hemi-epiphytism, monoecy, and active pollination are traits that possibly are associated with the hyper-diversity found in figs, making it possible for the plants to occupy new niches followed by extensive radiation over evolutionary time scales. Figs possess unique diversification patterns compared to other typical rainforest genera. ispartof: ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY vol:90 pages:4-11 status: published

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Aim Using a dated phylogenetic hypothesis with nearly complete species-level sampling of Ficus subsect. Urostigma with several samples per species, spatio-temporal diversification patterns are clarified, and alternative hypotheses for repeated Palaeotropical intercontinental disjunctions (PIDs) are revisited. Location (Sub)tropics of Africa, Madagascar, Asia and Australia. Methods Estimates of divergence times were obtained using a Bayesian relaxed clock analysis via the program beast with three calibration points. The output was used to analyse the historical biogeographical patterns via the program rasp (S-DIVA option). The results were compared with existing geological knowledge. Results The subsection probably originated in Madagascar or Madagascar and India, and dispersed once (or twice) to Africa and once to Asia (1st PID). From Asia the taxa dispersed all over Southeast Asia and finally to the west Pacific. Wallace's Line was relatively recently crossed several times independently by widespread species. One dispersal event back from Asia to Africa is inferred (2nd PID). Main conclusions The combination of dates and area optimizations for the ancestral nodes of Ficus subsect. Urostigma agree with the tectonic history of the various areas and divergence dates published for Ficus. The first PID is explained by species rafting on India to Asia, after which the majority of species evolved in Asia-Australia. The second PID probably involved dispersal from India via south Asia and Arabia to Africa in the early Miocene before the world-wide climate cooled down and areas became drier. Dispersal over Wallace's Line is by widespread species from which only a few local endemics in east Malesia-Australia developed. The biogeographical history of F. subsect. Urostigma supports a complex picture of several crossings of PIDs and it confirms that the route between Asia and Africa via south Asia and Arabia is often favoured. This route was available during a long period from Oligocene to mid-Miocene and perhaps even up to 2 Ma.

PREMISE OF THE STUDY Fig trees (Moraceae) have remarkable enclosed inflorescences called figs or syconia. The flowers are pollinated by host-specific fig wasps that enter the fig to lay their eggs. This nursery pollination system is one of the most studied of tropical mutualism interactions, but the source of the volatiles that attract fig wasps to their specific host figs has not been confirmed. The fragrance is the basis of host selection and, therefore, of reproductive isolation among sympatric Ficus species. This study locates and characterizes the glands likely to be responsible for pollinator attraction and also protection from herbivory in the figs of nine Ficus species representing all the major lineages within the genus. METHODS Figs with receptive pistillate flowers were examined using light and scanning electron microscopy. Tests for histolocalization of substances were employed to detect glandular activity throughout the figs. KEY RESULTS A great diversity of glands is found throughout the fig, and for the first time, the sites producing fragrances are identified. Scent glands are present on the ostiolar bracts and the outer layers of the fig receptacle. Laticifers and phenolic-producing idioblasts, epidermis, and trichomes associated with fig protection occur on the ostiolar bracts, the fig receptacle, and floral tissues. CONCLUSIONS The volatiles produced by glands on the ostiolar bracts are candidate sources for the long-distance attraction of pollinator fig wasps. Scent glands on the outer layers of the receptacle may also play a role in chemical perception of the figs or may be related to their protection. The high cost to the plants if the figs are eaten and the temperature conditions required for nursery pollination are likely the factors that led to the selection of phenolic glands and laticifers during the group's evolution.

The food webs consisting of plants, herbivorous insects and their insect parasitoids are a major component of terrestrial biodiversity. They play a central role in the functioning of all terrestrial ecosystems, and the number of species involved is mind-blowing (Nyman et al. 2015). Nevertheless, our understanding of the evolutionary and ecological determinants of their diversity is still in its infancy. In this issue of Molecular Ecology, Sutton et al. (2016) open a window into the comparative analysis of spatial genetic structuring in a set of comparable multitrophic models, involving highly species-specific interactions: figs and fig wasps. This is the first study to compare genetic structure using population genetics tools in a fig-pollinating wasp (Pleistodontes imperialis sp1) and its main parasitoid (Sycoscapter sp.A). The fig-pollinating wasp has a discontinuous spatial distribution that correlates with genetic differentiation, while the parasitoid bridges the discontinuity by parasitizing other pollinator species on the same host fig tree and presents basically no spatial genetic structure. The full implications of these results for our general understanding of plant-herbivorous insect-insect parasitoids diversification become apparent when envisioned within the framework of recent advances in fig and fig wasp biology.

Pollinator fig wasps (Hymenoptera: Agaonidae) display numerous adaptations linked to their obligate association with fig trees (Ficus). Ceratosolen fig wasps pollinate figs that often fill temporarily with liquid, and one clade has males with unusually long hind legs. We investigated their morphology and behaviour. Scanning electron microscopy (SEM) revealed that the cuticle of their hind legs is highly modified and covered with numerous hydrophobic setae and microtrichia that can prevent blockage of the wasps' large propodeal spiracles by liquids. In deep liquid, the males floated on the surface, but when only a thin layer of liquid was present, the legs allowed males to access females without the risk of drowning. Access to females was facilitated by an air bubble that forms between the hind legs and maintains a column of air between the spiracles and the centre of the figs. Sexual selection should favour males that can gain earlier access to mates, and the modified legs represent an adaptation to achieve this. Convergent adaptations are known in some unrelated non-pollinating fig wasps that develop in similar liquid-filled figs, but these species have enlarged hydrophobic peritremata at the ends of their metasoma to protect the spiracles located there. Unlike non-pollinating fig wasps, pollinator males need to insert their metasoma deep into females' galls during mating. This difference in mating behaviour has constrained the extent of convergence.

Flowers are a remarkable component of everyday life. Their diversity of shape, colour and fragrance witnesses the importance of the joint evolutionary processes resulting from the interactions between plants and their insect pollinators. Indeed, pollination mutualisms with insects are key factors that have allowed the evolutionary success and diversification of flowering plants (McKey & Hossaert-McKey, 2008). This diversification of plants has led to an even more impressive diversification of insects. This chapter retraces the main steps of the past history of diversification of pollination interactions with the emergence of some major pollinator groups of insects and proposes some insights into the selective processes acting on the evolution of the entomophilous pollination.

Fig wasp communities constitute a model system to analyse determinants of community complexity and to investigate how biological interaction networks are maintained. It has been suggested for monoecious figs, that fig pollinating wasps avoid ovipositing in flowers located close to the fig wall because of strong parasitic pressure by wasps ovipositing through the fig wall. This behaviour could help explain why mainly seeds are produced in flowers located close to the fig wall, thus stabilizing the fig-pollinating wasp mutualism. In this contribution we explore, for dioecious figs, whether ovipositor length of parasitic species may really be limiting. In dioecious figs, functionally male figs produce pollinating wasps and pollen while female figs produce only seeds, facilitating selection of traits favouring pollinator reproduction in male figs. We show in Ficus erecta that fig walls are thicker in male figs than in female figs. Male figs presenting thick walls, thicker than the length of the parasites' ovipositors, went unparasitized while male figs presenting thinner walls were systematically parasitized. Hence, in F. erecta , ovipositor length of the parasites is limiting access to some figs. However, we also show that in another dioecious species, Ficus formosana , presenting thin walled male figs, no fig is protected against oviposition by its two parasites. Hence in dioecious as well as in monoecious figs, in some Ficus species, ovipositors of the parasites are limiting access to ovules, while in other Ficus species all ovules are exposed to parasitism.

While Ficus present a series of traits often associated with dioecy, the prevalence of dioecy in Ficus is atypical. In Asian floras, dioecious Ficus species generally outnumber monoecious ones. Further this is also true in relatively northerly locations for Ficus such as the island of Taiwan. Ficus are pollinated by species-specific wasps that use fig flowers as breeding sites. In dioecious fig species, pollinators develop only in the inflorescences of male fig trees. In this study, we investigated the reproductive phenology of four dioecious Ficus species with distinct ecologies in several locations in northern and southern Taiwan. The two first species (Ficus erecta and Ficus septica) were investigated in four locations. Reproductive phenology was quite different among sites, even within a single species. For example, F. erecta presented well-defined crops at the population level in its usual high-elevation habitat but continuous fig production at low elevations, especially in South Taiwan. The two other fig species (Ficus pedunculosa var. mearnsii and Ficus tinctoria subsp. swinhoei), are shrubs growing together along seashores in exposed locations on coral reef remnants. These two species presented quite different traits allowing the survival of pollinating wasp populations. Ficus pedunculosa var. mearnsii produced figs continuously so that fresh receptive figs were always available for the pollinating wasps while F. tinctoria subsp. swinhoei extended the period of receptivity of its figs, so that receptive figs that had been waiting for pollinating wasps were almost always available. In summary, dioecious figs in Taiwan showed remarkable variation in their phenology, within species among locations or among species within location. Nevertheless, despite this variation, the phenology of the trees always allowed survival of pollinating wasp populations. Dioecious figs seem to have adopted a differentiated set of strategies which result in high resilience of pollinator populations. This resilience could help explain the atypical prevalence of dioecy in Ficus.

The nursery pollination system of fig trees (Ficus) results in the plants providing resources for pollinator fig wasp larvae as part of their male reproductive investment, with selection determining relative investment into pollinating wasps and the pollen they carry. The small size of Ficus pollen suggests that the quantities of pollen transported by individual wasps often limits male reproductive success. We assessed variation in fig wasp pollen loads and its influence on seed production in actively pollinated (Ficus montana) and passively pollinated (Ficus carica) dioecious fig trees. The ratios of number of male flowers on number of female flowers in a glasshouse-maintained F. montana population were highly variable. When fig wasps were introduced into receptive female figs, the resulting seed numbers were strongly linked to the numbers of pollinators that had been seeking access to pollen, relative to the number of anthers in their natal figs. In F. carica estimates of the amounts of pollen produced per fig and the quantities of pollen carried by emerging fig wasps suggest that less than 10% of the pollen is transported. Pollinators of F. carica that emerged earlier from figs carried more pollen, and also generated more seeds when introduced into receptive female figs. We show here that all pollinators are not equally valuable and producing more pollinators is not necessarily a good option in terms of Ficus male fitness. Previous results on F. montana figs showed that only around half of the flowers where pollinators lay eggs produced adult offspring. The amount of pollen collected by young female fig wasps may be a major determinant of their reproductive success.

Flowering patterns result from the interactions between genetic and environmental factors. While the genetic basis for flowering time variation in commercial plants is often well understood, few studies have been conducted to investigate these patterns in plants without economic importance. Ficus microcarpa is a commonly introduced horticultural fig tree. Asynchrony in syconium development and the initiation, frequency, and size of crops may affect its fitness as well as the success of mutualism with its pollinating wasps. In order to identify genetically determined patterns in the flowering traits in F. microcarpa , a 14-month census was taken on the flowering characteristics of 28 trees growing in close proximity along an urban street in Taipei, Taiwan. Weekly surveys were taken on 7 characteristics: crop number, syconia per branch, crop asynchrony, as well as flowering onset and seed development duration for both the spring and summer crops. Post-census genotyping at microsatellite loci distinguished 16 genetic groups (5 clonal groups and 11 non-clone trees). All crop characteristics presented higher variation across different genotype groups than within groups except for seed development duration. We found no evidence of adjacency effects or spatial auto-correlation of flowering traits. The study offers the first evidence of genetic variations in the flowering patterns in a species of Ficus . These findings lend insight into the adaptive characteristics that potentially facilitate the local establishment of F. microcarpa in new locations.

Understanding the ecology of non-pollinating fig-wasp communities depends on a good knowledge of larval feeding habits of the species involved, which can be gall inducers, kleptoparasites, parasitoids or seed eaters. However, larval feeding habits are poorly known and most community ecology studies on NPFW are based on hypothetical feeding habits or data analyzed independently of feeding habit. Here we take advantage of the particular situation in Ficus guianensis whose community is dominated by large NPFW, i.e. species that are obviously larger than pollinators, to establish the community structure and feeding habits of the most frequent wasps. We provide the first non-ambiguous negative correlation between the number of NPFW and the production of pollinators and seeds. Each developing large NPFW represents a disproportionate cost to the mutualism as it is responsible for the loss of about ten seeds plus pollinators, i.e. about 10% of the production of a fig.

Standard Sanger chloroplast markers provide limited information to resolve species level relationships within plants, in particular within large genera. Figs (Ficus L., Moraceae) compose one of the 50 largest genera of angiosperms with ∼750 species occurring in the tropics and subtropics worldwide. Figs, in addition to being a keystone food resource in rainforests, are well-known for the mutualistic interactions with their pollinating wasps. It is regarded as a model system for understanding co-evolution dating back more than 75 million years. However, despite significant taxon sampling, combinations of low copy nuclear, nuclear ribosomal and chloroplast regions have not been able to confidently resolve relationships among major groups of figs. Using a high throughput sequencing approach we attempted to resolve the major lineages of Ficus based on plastome data. In this study, we show that the use of a de novo assembled plastome from within the genus provides less ambiguity and higher coverage across the 59 Ficus and 6 outgroup plastome assemblies compared to using the nearest available reference plastome outside the genus resulting in improved resolution and higher support of the phylogenetic relationships within Ficus inferred from plastome data. Chloroplast genome data confidently resolved relationships among major groups of figs and largely support current understanding based on nuclear sequence data including passively pollinated Neotropical section Pharmacosycea as sister lineage to all other Ficus. However, conflicts between the new plastome topology and previous nuclear studies are observed for both individual species as well as relationships among some sections at deeper levels. Conflicts could be caused by lack of resolution in the nuclear data or may indicate potential cyto-nuclear discordance as previously observed in an African lineage of Ficus.