Paternity analysis of the breeding structure of strangler fig populations: evidence for substantial long-distance wasp dispersal

Abstract. The mutualistic interaction of figs with their species-specific wasp pollinators and the role of figs as 'keystone' plant resources in tropical communities has received substantial attention from both plant and animal ecologists. Despite this focus on the reproductive biology of figs, the minute size of the wasps has effectively precluded our ability to monitor patterns of wasp dispersal and fig mating relationships in natural forest habitats. In this paper we use genetic markers and genealogy reconstruction techniques to examine the breeding structure of populations of four strangler fig species occurring in central Panama. The natural history of figs facilitates the genetic analysis of full-sib progeny arrays from which the genotypes of successful pollen donors can be reconstructed precisely. Paternity reconstruction in the four study species reveals that individual flowering trees may routinely receive pollen from numerous donors despite characteristically low densities of co-flowering individuals. These data indicate not only that breeding populations of these figs are larger than the minimum critical sizes predicted to be necessary to support populations of their species-specific pollinators, but are more extensive in size and area than has been described for any plant species yet examined. Further, the fig wasps are shown to be efficient agents of long-distance dispersal, routinely moving up to 10 km between flowering trees. In accord with the potential for substantial long-distance gene flow and large effective population sizes, ten of eleven species of Panamanian figs assayed were found to maintain exceptionally high levels of genetic variation within their populations. Combined with other reports of occasional long-distance dispersal, the results of this study suggest that fig wasps may be more effective at colonizing isolated fig populations than previously thought.     

Investigation of Microbes in the Rhizosphere of Selected Trees for the Rhizoremediation of Hydrocarbon-Contaminated Soils

Hydrocarbon-degrading microorganisms (HDMs), associated with the rhizosphere of Conocarpus lancifolius and Ficus infectoria trees grown in bioremediated soil, were isolated under controlled laboratory conditions. The selected trees were used to phytoremediate oil-contaminated soil for three successive growing seasons. At the end of the phytoremediation experiment, 85.7% of measurable total petroleum hydrocarbon was degraded in the rhizosphere soil associated with Conocarpus lancifolius compared to 78.6% in the rhizosphere of Ficus infectoria. The detectable concentrations of some polyaromatic hydrocarbons were less than 0.02 ppm. The HDM isolation process was conducted at 35°C under aerobic conditions. The isolated HDMs were identified using 16S rRNA gene sequencing and fatty acid methyl ester analysis. Differences in the genera of the isolated HDMs and their assessed efficiency in degrading a mixture of hydrocarbon compounds between the two trees were noted.     

What makes a fig: insights from a comparative analysis of inflorescence morphogenesis in Moraceae

Background and AimsMoraceae, 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.MethodsInflorescences 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 ResultsThe 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.ConclusionComparison 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.     

闽南常见榕属汤料植物提取物的斑马鱼急性毒性研究

利用斑马鱼模型评价闽南常见桑科榕属草药粗叶榕(Ficus hirta)、天仙果(F. erecta var. beecheyana)、薜荔(F. pumila)、变叶榕(F. variolosa)不同药用部位水提取物及醇提取物的急性毒性。实验给药浓度分别为200 μg·mL^-1、 100 μg·mL^-1，记录给药后48 h、96 h鱼的死亡率，并采用体视显微镜观察斑马鱼胚胎畸形率和胚胎发育情况。结果表明，上述桑科榕属植物根、茎、叶、果等不同药用部位的水提取物在200 μg·mL^-1剂量下是低毒或无毒的，对斑马鱼胚胎无不良影响，反而具有促进胚胎生长的作用，但高剂量醇提取物对斑马鱼胚胎发育有一定的负面影响，粗叶榕叶，天仙果茎、叶及变叶榕叶导致斑马鱼胚胎尾部畸形，薜荔叶、果醇提取物处理出现明显心包水肿现象。上述药材作为传统的汤料材料使用是安全无毒的，但用作药酒原料使用时应注意使用剂量。     

Sexual differences in the attractiveness of figs to pollinators: females stay attractive for longer

1. Figs on male dioecious fig trees (Ficus, Moraceae) are breeding sites for pollinator fig wasps (Hymenoptera, Agaonidae), but figs on female plants are traps that produce only seeds. As the short‐lived fig wasps cannot reproduce in female figs, natural selection should favour individuals that avoid them. Several studies have failed to detect such discrimination, a result attributed to inter‐sexual mimicry and ‘selection to rush’ in the wasps, but their experiments failed to explicitly take into account fig age (how long they had been waiting to be pollinated). 2. We compared the relative attraction of male and female figs of known ages of the South East Asian Ficus montana Burm. f. to its pollina tor Liporrhopalum tentacularis Grandi and examined how the reproductive success of the plant and its pollinator change with the age of the figs. 3. Mean retention time for un‐pollinated figs on female plants was 16 days whereas in male figs it was 12 days. Female figs remained attractive for up to 2 weeks, although the wasps were less willing to enter older figs. After pollinator entry, receptivity continued for several days, lasting longer in figs entered by a single wasp. Consistent with abortion rates, attractiveness persisted longer in female figs. Older figs produced fewer fig wasp offspring, but similar numbers of seeds. 4. The sexual differences in floral longevity in F. montana may represent part of a previously un‐recognised reproductive strategy in some fig trees that allows male plants to ‘export’ pollinators while also maintaining a resident fig wasp population.     

Regeneration of monsoon rain forest in northern Australia: the dormant seed bank

Abstract. As part of a wider study examining regeneration pathways in monsoon rain forest vegetation in northern Australia, the dormant component of the soil seed bank was assessed by storing soil samples for over six dry season months, before watering in shade-house trials. Six soil samples were collected from each of 34 sites broadly representative of the range of regional monsoon rain forest vegetation. Four floristic seed bank groups were derived through TWINSPAN classification. Mean group densities of germinants ranged from 25–144/m². Dormant seed banks were least dense, and most sparsely distributed, in sandy soils. Seed bank samples were dominated by woody pioneer monsoon rain forest species, especially figs; exotic weeds and savanna taxa (e.g. Poaceae) were relatively more common at seasonally dry sites. Dormant seed banks comprised species mostly present in the standing vegetation, although a small number of germinants represented species not growing at half the sites. Regeneration of woody pioneers from dormant seed banks is least likely to be of importance on infertile, seasonally dry sites.     

The pollination of Ficus vogelii in Ghana

Ficus vogelii is a primitive monoecious species, in which staminate and pistillate flowers are distributed throughout the syconium without localization. There is no bimodal structural distinction between seed flowers and gall flowers, and any pistillate flower is capable of seed production. Each syconium follows a development cycle lasting approximately 45 days. The chief pollen vector is the agaonid wasp Allotriozoon heterandromorphum , which is an obligate symbiont. Adult females of this species have mesothoracic "pockets" in which pollen is carried. Adult males do not display the anther-cutting activity reported in other species. The life cycle of the pollinator is described in relation to the developmental cycle of the syconium.     

Strangler fig-host associations in roadside and deciduous forest sites, South India

Abstract. Understanding the regeneration niche of animal-dispersed epiphytes is important in understanding forest community structure, maintenance of species richness in plant communities, animal movements and distributions, and in managing plant and animal communities for conservation. Strangler figs are particularly interesting for studying epiphyte-host relations because they are hemiepiphytes, implying that strangler and host can potentially belong to the same species and either fuse together or strangle each other, and because all stranglers have many-seeded, animal-dispersed fruit, providing many opportunities for seed dispersal to other stranglers. A study was conducted at a roadside and at a forest site in Karnataka State, south India, to determine factors influencing host choice of strangler figs. Stranglers were found more frequently at the roadside site than at the forest site. At the roadside site, stranglers were found much more abundantly on Ficus hosts than on non-Ficus hosts, whereas at the forest site, stranglers were found more abundantly on non- Ficus hosts. Host tree species with animal-dispersed fruit bore significantly more stranglers than those with mechanically dispersed fruit. More stranglers were found on hosts in large d.b.h. size classes (>80 cm d.b.h.) than on those in small d.b.h. classes. Prior studies of strangler-host relations have never found stranglers growing on other stranglers. The results of this study suggest that stranglers are fully capable of regenerating on other stranglers, including conspecifics, but these regeneration events are not observed in forests because of relatively low strangler seed rain, due to lack of clumping of strangler hosts, and low insolation in these habitats.     

New insight into the phylogenetic and biogeographic history of genus Ficus: Vicariance played a relatively minor role compared with ecological opportunity and dispersal

Studies on the evolution of tropical taxa emphasize the role ofvicariance and the break-up of Gondwana in explaining modern distributions.Earlier studies on figs (Ficus spp.) support this view.In the current study,we used an expanded sample (208 spp.) and improved molecular dating techniques to reconstruct the phylogenetic and biogeographic history of Ficus.Consistent with previous studies,our biogeographic analysis indicated that the ancestor of Ficus was present in Gondwana.However,a relaxed clock analysis relying on uncorrelated rates in BEAST suggested that the Neotropical section Pharmacosycea split-off in South America 86.67 Mya,and that other Ficus lineage ancestors originated in India.Most of the basal lineages appeared to have diverged following KT extinction,then rapidly diversified after India collided with continental Asia.The Afrotropical species most likely evolved initially in the Indian subcontinent then dispersed to Africa,either in the late Cretaceous of Madagascar or even later,following the Eocene collision of India with Asia.The Neotropical section Americana,either islandhopped to South America or took a northern route to the Americas through Europe prior to the terminal Eocene global cooling event.Ficus may have arrived in eastern Malesia following the collision of India with Asia,then widely dispersed thereafter.Given the wide ranges in our date estimates,several other scenarios are possible.However,contrary to earlier reports,our analyses suggest that vicariance played a relatively minor role compared with ecological opportunity and dispersal in the diversification of genus Ficus.