A generalized deceptive pollination system of Doritis pulcherrima (Aeridinae: Orchidaceae) with non-reconfigured pollinaria

<p>Abstract</p> <p>Background</p> <p>As one of largest angiosperm families, orchids have long fascinated evolutionary biologists with their staggering diversity in floral design and display to promote outcrossing. Two of the most intriguing aspects of orchid pollination that promote cross-pollination are pollinarium reconfiguration (PR) and deceptive pollination. PR and generalized food deception employ virtually antagonistic methods of promoting cross-pollination: PR occurs through delayed pollination, involving the relatively long visitation periods that are typically observed for the pollinators of one flower or inflorescence; conversely, generalized food deception leads to reductions in the visitation periods of pollinators to one flower or inflorescence. Thus, it is logical to hypothesize that PR is unnecessary or PR happens soon in generalized food-deceptive orchids in the promotion of cross-pollination. Using <it>Doritis pulcherrima</it> as a model, the aim of this study was to understand the following: (1) the pollination and breeding system of <it>D. pulcherrima</it>; (2) the morphological interactions between orchids and their pollinators; and (3) whether PR is necessary in the promotion of cross-pollination in <it>D. pulcherrima</it>.</p> <p>Results</p> <p>Our observations indicated that <it>Doritis pulcherrima</it> is pollinated almost exclusively by <it>Amegilla nigritar</it> (Hymenoptera: Apidae) and possesses pollinia that are deposited on the “occiputs” (cervical membranes) of these insects. All of evidences are indicated that <it>D. pulcherrima</it> is a generalized food-deceptive orchid. Our morphometric measurements of the flowers and pollinators show that the heights of the “occiputs” with un-oriented pollinaria were equal to the distances between stigmas and surfaces of the middle lobes, suggesting that pollinarium reconfiguration is not necessary in <it>Doritis pulcherrima</it>.</p> <p>Conclusions</p> <p>Our observation and analyses supported the hypothesis that pollinarium reconfiguration is unnecessary in generalized food-deceptive orchids, such as <it>Doritis pulcherrima</it>, for the promotion of cross-pollination. This conclusion was indirectly supported by the abundance of deceptive orchids that do not exhibit pollinarium reconfiguration. There are two mechanisms (i.e. clone-growing characteristics and a long flowering season) that promote fruit sets in the epiphytic food-deceptive orchids in tropical regions.</p

Effects of Plant Virus and Its Insect Vector on Encarsia Formosa, a Biocontrol Agent of Whiteflies

In this study, we investigated the tritrophic interactions among a persistently transmitted plant virus, Tomato yellow leaf curl virus (TYLCV), its insect vector, the sweetpotato whitefly Bemisia tabaci, and a parasitoid, Encarsia formosa Gahan, one of the most extensively used biological control agents. As an emerging invasive pest worldwide, the two most damaging whiteflies are B. tabaci B and Q cryptic species. On healthy tomato plants, parasitoid-induced mortality was significantly higher in B. tabaci B than in Q. In contrast, similar mortality levels of B and Q were observed on TYLCV-infected plants. A higher rate of parasitism was consistently observed in B, independent of the TYLCV infection. Similarly, the life history traits of E. formosa were influenced by both TYLCV and the two cryptic species of B. tabaci. Specifically, E. formosa parasitizing B had a greater adult longevity and shorter developmental time on healthy plants, whereas the parasitoids developing from Q has a greater adult longevity on TYLCV-infected plants. The emergence rate of E. formosa was unaffected by either B. tabaci cryptic species or the virus. These results suggest that the vector-borne pathogen can manipulate the host suitability of a parasitoid and hence the parasitoid-host interactions

Bilateral-secure signature by key evolving

In practice, the greatest threat against the security of a digital signature scheme is the exposure of signing key, since the forward security of past signatures and the backward security of future signatures could be compromised. There are some attempts in the literature, addressing forward-secure signature for preventing forgeries of signatures in the past time; however, few studies addressed the backward-security of signatures, which prevents forgeries in the future time. In this paper, we introduce the concept of key-evolving signature with bilateral security, i.e., both forward security and backward security. We first define the bilateral security formally for preventing the adversaries from forging a valid signature of the past and the future time periods in the case of key exposure. We then provide a novel construction based on hub-and-spoke updating structure and the random oracle model, and show that the construction achieves bilateral security and unbounded number of time periods. Finally, we compare our scheme with the existing work by rigorous analysis and experimental evaluation, and demonstrate that our construction is more secure and efficient for practical applications

Integrating palaeontological and molecular data uncovers multiple ancient and recent dispersals in the pantropical Hamamelidaceae

Aim The integration of palaeontological and phylogenetic data can improve our understanding in the spatio-temporal evolutionary processes of living organisms. However, how best to use fossil data in divergence time estimation and ancestral range reconstruction remains challenging. Here, we integrated palaeontological and molecular data to investigate the historical biogeography of Hamamelidaceae, a pantropical angiosperm family with abundant fossils outside its present distribution. Location Global tropical/subtropical areas. Methods Using seven DNA regions (>7,500 bp) from plastid and nuclear genomes, we reconstructed a robust phylogenetic framework for Hamamelidaceae with the first complete genus-level sampling. We used the tip-dating method with the 22 fossils to estimate divergence times for the family, and inferred the ancestral range of lineages under the dispersal-extinction-cladogenesis model by incorporating the fossils. Results Our biogeographic analysis indicates that extant Hamamelidaceae most likely originated in tropical Asia during the mid-Cretaceous, and in the family 20 dispersals occurred during three major time intervals: the Upper Cretaceous (c. 93-69 Ma), Palaeocene-Eocene (c. 63-39 Ma) and late Oligocene (c. 27-23 Ma). Main conclusions Overland migrations through available land bridges and island chains may have been mainly responsible for hamamelidaceous range expansions during these three episodes. This study contributes to our knowledge on the assembly and evolution of angiosperm-dominated tropical and subtropical forests

Hemiboea albiflora, a new species of Gesneriaceae from Guizhou, China

Hemiboea albiflora X.G.Xiang, Z.Y.Guo & Z.W.Wu, sp. nov., a new species of Gesneriaceae from Guizhou, China, is described and illustrated. This species was previously listed informally as a variety of H. gamosepala, but it differs significantly from H. gamosepala by its 5-parted calyx from the base, longer peduncle, white corolla and longer pistil. Based on recent extensive observations, this new species is similar to H. cavaleriei var. paucinervis and H. subcapitata but differs from them by its longer petiole, larger involucre, white corolla and longer staminal filaments. The conservation status of this species is considered to be “Vulnerable” (VU) according to the IUCN Red List Categories and Criteria

Paraboea dolomitica (Gesneriaceae), a new species from Guizhou, China

Here we describe Paraboea dolomitica Z.Y. Li, X.G. Xiang & Z.Y. Guo, a new species of Gesneriaceae from Guizhou, China. Based on recent extensive observations, this new species is morphologically similar to Paraboea filipes (Hance) Burtt, in having obovate leaf blades, 1-4-flowered cymes and purplish corolla, but differs from that species by the combination of denticulate leathery leaves, sparsely brown haired peduncles, two woolly bracts, reniform anthers and two glabrous staminodes. Additionally, molecular data support this new species as a member of a clade that includes P. crassifolia, P. tetrabracteata, P. peltifolia, P. vetutina, P. dushanensis, P. dictyoneura, P xiangguiensis and P. guilinensis, but it is distinct from them in leaf position, inflorescence, penduncle, bract and capsule. The conservation status of this species is considered to be Vulnerable (VU) according to the IUCN Red List Categories and Criteria

Characterization of the complete chloroplast genome of Pterocarya macroptera var. delavayi (Juglandaceae)

In this study, the complete chloroplast genome sequence of Pterocarya macroptera var. delavayi was reported and characterized. The chloroplast genome is 160,168 bp in length, and consists the typical quadripartite structure, a pair of inverted repeats (IRs, 26,007 bp) separated by a large single-copy region (89,701 bp) and a small single-copy region (18,453 bp). A total of 136 unique genes were predicted, including 88 protein-coding genes, 40 tRNA genes, and 8 rRNA genes. The GC content of the chloroplast genome is 36.2%. Phylogenetic analysis confirmed the close relationship between Pterocarya and Juglans