Exploring systematic biases, rooting methods and morphological evidence to unravel the evolutionary history of the genus Ficus (Moraceae).

Despite many attempts in the Sanger sequencing era, the phylogeny of fig trees remains unresolved, which limits our ability to analyze the evolution of key traits that may have contributed to their evolutionary and ecological success. We used restriction-site-associated DNA sequencing (c. 420 kb) and 102 morphological characters to elucidate the relationships between 70 species of Ficus. To increase phylogenetic information for higher-level relationships, we targeted conserved regions and assembled paired reads into long loci to enable the retrieval of homologous loci in outgroup genomes. We compared morphological and molecular results to highlight discrepancies and reveal possible inference bias. For the first time, we recovered a monophyletic subgenus Urostigma (stranglers) and a clade with all gynodioecious Ficus. However, we show, with a new approach based on iterative principal component analysis, that it is not (and will probably never be) possible to homogenize evolutionary rates and GC content for all taxa before phylogenetic inference. Four competing positions for the root of the molecular tree are possible. The placement of section Pharmacosycea as sister to other fig trees is not supported by morphological data and considered 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 Ficus into monoecious versus gynodioecious species appears most plausible. It seems most likely that the ancestor of fig trees was a freestanding tree and active pollination is inferred as the ancestral state, contrary to previous hypotheses. However, ambiguity remains on the ancestral breeding system. Despite morphological plasticity, we advocate restoring a central role to morphology in our understanding of the evolution of Ficus, as it can help detect systematic errors that appear more pronounced with larger molecular datasets.

Genomic evidence of prevalent hybridization throughout the evolutionary history of the fig-wasp pollination mutualism.

Ficus (figs) and their agaonid wasp pollinators present an ecologically important mutualism that also provides a rich comparative system for studying functional co-diversification throughout its coevolutionary history (~75 million years). We obtained entire nuclear, mitochondrial, and chloroplast genomes for 15 species representing all major clades of Ficus. Multiple analyses of these genomic data suggest that hybridization events have occurred throughout Ficus evolutionary history. Furthermore, cophylogenetic reconciliation analyses detect significant incongruence among all nuclear, chloroplast, and mitochondrial-based phylogenies, none of which correspond with any published phylogenies of the associated pollinator wasps. These findings are most consistent with frequent host-switching by the pollinators, leading to fig hybridization, even between distantly related clades. Here, we suggest that these pollinator host-switches and fig hybridization events are a dominant feature of fig/wasp coevolutionary history, and by generating novel genomic combinations in the figs have likely contributed to the remarkable diversity exhibited by this mutualism.

A comparative venomic fingerprinting approach reveals that galling and non-galling fig wasp species have different venom profiles.

The galling habit represents a complex type of interaction between insects and plants, ranging from antagonism to mutualism. The obligate pollination mutualism between Ficus and fig wasps relies strongly on the induction of galls in Ficus flowers, where wasps' offspring develop. Even though gall induction plays an important role in many insect-plant interactions, the mechanisms that trigger gall formation are still not completely known. Using a fingerprinting approach, we show here that venom protein profiles from galling fig wasps differ from the venom profiles of non-galling species, suggesting the secretion plays different roles according to the type of interaction it is involved in. Each studied cleptoparasitic species had a distinct venom profile, suggesting that cleptoparasitism in fig wasps covers a vast diversity of molecular interactions. Fig wasp venoms are mainly composed of peptides. No low molecular weight compounds were detected by UPLC-DAD-MS, suggesting that such compounds (e.g., IAA and cytokinines) are not involved in gall induction. The differences in venom composition observed between galling and non-galling fig wasp species bring new perspectives to the study of gall induction processes and the role of insect secretions.

Taxonomic revision and molecular phylogenetics of the Idarnes incertus species-group (Hymenoptera, Agaonidae, Sycophaginae).

Sycophaginae is a group of non-pollinating fig wasps considered closely related to the fig pollinators (Agaoninae, Tetrapusiinae, and Kradibiinae) in the most recent phylogenetic analyses. They occur in all tropical regions and are associated with Ficus subgenera Urostigma and Sycomorus. There are six described genera of Sycophaginae, and two are native and confined to the Neotropics, namely Idarnes Walker, 1843 and Anidarnes Boucek, 1993. Genus Idarnes is divided into three morphologically distinct groups that were proven to be monophyletic by recent molecular phylogenetic analyses. In this paper we reviewed the Idarnes incertus species-group and provide detailed morphological descriptions and illustrations for the species belonging to this group. Three previously described species were redescribed: I. brasiliensis (Mayr, 1906) comb. nov., I. hansoni Boucek, 1993, and I. incertus (Ashmead, 1900). Seventeen new species are described by Farache and Rasplus: I. amacayacuensissp. n., I. amazonicussp. n., I. americanaesp. n., I. badiovertexsp. n., I. brevissp. n., I. brunneussp. n., I. comptonisp. n., I. cremersiaesp. n., I. dimorphicussp. n., I. flavicrussp. n., I. flaviventrissp. n., I. gibberosussp. n., I. gordhisp. n., I. maximussp. n., I. nigriventrissp. n., I. pseudoflavussp. n. and I. ramirezisp. n. We provided keys for the identification of the species as well as for recognising the different species-groups of Idarnes and a closely related genus (Sycophaga Westwood, 1840). Additionally, phylogenetic relationships among 13 species of the I. incertus species-group were inferred using four molecular markers and discussed in the light of Ficus taxonomy and host specificity.

Diversity of fig glands is associated with nursery mutualism in fig trees.

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.

Convergent structure of multitrophic communities over three continents.

Ecological theory predicts that communities using the same resources should have similar structure, but evolutionary constraints on colonisation and niche shifts may hamper such convergence. Multitrophic communities of wasps exploiting fig fruits, which first evolved about 75MYA, do not show long-term 'inheritance' of taxonomic (lineage) composition or species diversity. However, communities on three continents have converged ecologically in the presence and relative abundance of five insect guilds that we define. Some taxa fill the same niches in each community (phylogenetic niche conservatism). However, we show that overall convergence in ecological community structure depends also on a combination of niche shifts by resident lineages and local colonisations of figs by other insect lineages. Our study explores new ground, and develops new heuristic tools, in combining ecology and phylogeny to address patterns in the complex multitrophic communities of insect on plants, which comprise a large part of terrestrial biodiversity.

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

BACKGROUND: Non-pollinating Sycophaginae (Hymenoptera, Chalcidoidea) form small communities within Urostigma and Sycomorus 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. RESULTS: The resulting trees are well resolved and strongly supported. With the exception of Apocrytophagus, which is paraphyletic with respect to Sycophaga, all genera are monophyletic. The Sycophaginae are divided into three clades: (i) Eukoebelea; (ii) Pseudidarnes, Anidarnes and Conidarnes and (iii) Apocryptophagus, Sycophaga and Idarnes. The ancestral states for galling habits and male morphology remain ambiguous and our reconstructions show that the two traits are evolutionary labile. CONCLUSIONS: 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.

New occurrence of non-pollinating fig wasps (Hymenoptera: Chalcidoidea) in Ficus microcarpa in Brazil.

Ficus microcarpa is an Asian fig tree that is ornamentally cultivated. The specific pollinator, Eupristina verticillata Waterston, and the non-pollinators Walkerella microcarpae Boucek and Philotrypesis emeryi Grandi, have been reported associated to F. microcarpa in Brazil. In here we report for the first time the occurrence of Odontofroggatia ishii Wiebes and Philotrypesis taiwanensis Chen et al in F. microcarpa in Brazil. Our results suggest that P. taiwanensis and O. ishii represent a recent influx of these wasps into Brazil. Considering that approximately 20 fig wasp species are associated with F. microcarpa in its native area, novel occurrences can be reported in the future in Brazil.

New occurrence of non-pollinating fig wasps (Hymenoptera: Chalcidoidea) in Ficus microcarpa in Brazil / Nova ocorrência de vespas não-polinizadoras (Hymenoptera: Chalcidoidea) em sicônios de Ficus microcarpa no Brasil

Ficus microcarpa is an Asian fig tree that is ornamentally cultivated. The specific pollinator, Eupristina verticillata Waterston, and the non-pollinators Walkerella microcarpae Bouček and Philotrypesis emeryi Grandi, have been reported associated to F. microcarpa in Brazil. In here we report for the first time the occurrence of Odontofroggatia ishii Wiebes and Philotrypesis taiwanensis Chen et al in F. microcarpa in Brazil. Our results suggest that P. taiwanensis and O. ishii represent a recent influx of these wasps into Brazil. Considering that ~20 fig wasp species are associated with F. microcarpa in its native area, novel occurrences can be reported in the future in Brazil.

Ficus microcarpa é uma figueira asiática cultivada com finalidades ornamentais. A espécie polinizadora específica, Eupristina verticillata Waterston, e as não-polinizadoras Walkerella microcarpae Bouček e Philotrypesis emeryi Grandi, foram relatadas associadas a F. microcarpa no Brasil. No presente estudo, relatamos pela primeira vez a ocorrência de Odontofroggatia ishii Wiebes e Philotrypesis taiwanensis Chen et al em F. microcarpa no Brasil. Nossos resultados sugerem que tais vespas foram introduzidas recentemente no país. Considerando que ~20 espécies de vespas são associadas a F. microcarpa em sua região de origem, novas ocorrências poderão ser registradas no futuro no Brasil.