Rare plant species are at a disadvantage when both herbivory and pollination interactions are considered in an alpine meadow.

Rare plant species often suffer less damage than common species because of positive density-dependent herbivory, and it has been suggested that this 'rare species advantage' fosters plant species coexistence. However, it is unknown whether rare species have an advantage when pollination interactions are also considered. We hypothesized that a 'positive density-dependent pollination success' across plant species would result in common plants experiencing higher seed set rates compared to rare species, and that positive density-dependent effects would negate or even override the positive density-dependent damage due to herbivory resulting in higher seed loss rates in common plant species. We tested this hypothesis by concurrently examining a plant-predispersal seed predator system and a plant-pollinator system for 24 Asteraceae species growing in an alpine meadow community (Sichuan Province, China). Having previously reported a positive density-dependent effect on seed loss rates due to seed predators, we here focus on the density-dependent effects on pollination success by investigating pollinator species richness, visitation frequencies and seed set rates for each plant species. We also estimated the seed output rate of each plant species as the product of seed set rate and the rate of surviving seeds (i.e. 1 - the seed loss rate). Consistent with our hypothesis, a positive density-dependent effect was observed for pollinator species richness, visitation frequencies and seed set rates across plant species. Moreover, the positive effect overrode the negative density-dependent effect of herbivores on seed production, such that common species tended to have a higher seed output rate than rare species (i.e. we observed a 'rare species disadvantage'). These results indicate that the low seed output rate of rare species might result from a pollination limitation, and that both mutualistic and antagonistic interactions should be examined simultaneously to fully understand plant species coexistence in local communities.

Mixed mating system and variable mating patterns in tropical woody bamboos.

BACKGROUND: So far, little is known in detail about mating systems of woody bamboos. Paternity analysis of offspring improved our understanding of these systems, and contributed to their germplasm conservation and genetic improvement. RESULTS: In this study, a paternity analysis of offspring from two consecutive mass or sporadically flowering events of Dendrocalamus membranaceus and D. sinicus were conducted to determine their mating system and pollen dispersal using the program COLONY based on simple sequence repeat (SSR) markers. Two sporadically flowering populations of D. sinicus (C1, C2) obtained relatively high paternity assignments rates (69.0-71.4%). Meanwhile, among three populations of D. membranaceus, the sporadically flowering population A also had much higher paternity assignments rates (56.4%) than mass flowering populations B1(28.6%) and B2 (42.5%). Both D. membranaceus and D. sinicus had mixed mating systems while their mating patterns were variable depending on pollination conditions. The maximum pollen dispersal distances were 90 m and 4378 m for D. membranaceus and D. sinicus populations, respectively, and the mating distances of these two species focused on ranges of ca. 0-50 m and 0-1500 m, respectively. CONCLUSIONS: These results revealed for the first time variable mating patterns in woody bamboos. This suggests half-sib seeds from the same bamboo clump may have different male parents and it is crucial to clarify genetic origin in woody bamboos' breeding programs. The results also indicate the importance of pollinators in the mating systems of tropical woody bamboos.

Domestic honeybees affect the performance of pre-dispersal seed predators in an alpine meadow.

Flowering plants interact simultaneously with mutualistic pollinators and antagonistic herbivores such that plant-mediated interactions between pollinators and herbivores must exist. Although the effects of herbivores on pollinator behavior have been investigated extensively, the effect of pollinators on herbivore performance has seldom been explored. We hypothesized that insect pollinators could improve the survival and growth of pre-dispersal seed predators by increasing seed production. We tested this hypothesis along three transects radiating from well-established apiaries in an alpine meadow by supplementing pollination in sites close to and distant from apiaries and subsequently examining seed production of the dominant nectariferous plant species Saussurea nigrescens (Asteraceae) and the performance of three dominant pre-dispersal seed predators (tephritid fly species). Pollen supplementation (1) significantly increased seed set and mass of developed seed per capitulum (i.e., flowerhead) in the distant but not the close sites, (2) did not change the survival and growth rates of the smaller-bodied species (Tephritis femoralis and Campiglossa nigricauda) at either site, but (3) improved the performance of the larger-bodied seed predator (Terellia megalopyge) at distant sites but not close sites. In addition, the larger-bodied tephritid fly showed higher infestation rates and relative abundance in the close sites than in the distant sites, whereas the smaller-bodied species had lower relative abundances in the close sites and similar infestation rates in both site types. These observations demonstrate contrasting effects of plant mutualists on the performance of antagonists with potential consequences for population sizes of insect herbivores.

The evolutionary adaptation of wood-decay macrofungi to host gymnosperms differs from that to host angiosperms.

Wood-decay macrofungi play a vital role in forest ecosystems by promoting nutrient cycling and soil structure, and their evolution is closely related to their host plants. This study investigates the potential evolutionary adaptation of wood-decay macrofungi to their host plants, focusing on whether these relationships differ between gymnosperms and angiosperms. While previous research has suggested non-random associations between specific fungi and plant deadwood, direct evidence of evolutionary adaptation has been lacking. Our study, conducted in a subtropical region, utilized metabarcoding techniques to identify deadwood species and associated fungi. We found significant evidence of evolutionary adaptation when considering all sampled species collectively. However, distinct patterns emerged when comparing angiosperms and gymnosperms: a significant evolutionary adaptation was observed of wood-decay macrofungi to angiosperms, but not to gymnosperms. This variation may be due to the longer evolutionary history and more stable species interactions of gymnosperms, as indicated by a higher modularity coefficient (r = .452), suggesting greater specialization. In contrast, angiosperms, being evolutionarily younger, displayed less stable and more coevolving interactions with fungi, reflected in a lower modularity coefficient (r = .387). Our findings provide the first direct evidence of differential evolutionary adaptation dynamics of these fungi to angiosperms versus gymnosperms, enhancing our understanding of forest ecosystem carbon cycling and resource management.

Aspleniumguodanum (Aspleniaceae), a distinct new fern species from northern Guangdong, China, based on morphological data and molecular phylogeny.

A new spleenwort species, Aspleniumguodanum, was found and described from Danxia landform region in Guangdong, China. The new species has close resemblance to A.subcrenatum Ching ex S.H.Wu in morphology, but can be distinguished by having plants small, stipes and rachises not covered with fibrous scales, relatively fewer pairs of pinnae, pinnae short, pinna margin weakly biserrate, pinna apex acute and lower pinnae obviously reduced. Phylogenetic analyses, based on six plastid markers (atpB, rbcL, rps4 & rps4-trnS and trnL & trnL-F) of the new species and its relatives, support a close relationship between A.guodanum and A.subcrenatum. Only one population with no more than 50 individuals were found and, therefore, it is recommended to be classified as Critically Endangered (CR) following IUCN Red List Criteria.

Decreased expression of WWOX in the development of esophageal squamous cell carcinoma.

The WW domain-containing oxidoreductase (WWOX) gene, located on chromosome 16q23.3-24.1 in the region recognized as the common fragile site FRA16D is considered to be a tumor suppressor gene involved in various carcinomas. The present study was to investigate the alterations of WWOX expression and its correlation with polymorphism, the level of WWOX loss of heterozygosity (LOH), and methylation status in esophageal squamous cell carcinoma (ESCC). Immunohistochemistry and RT-PCR methods were used, respectively, to examine the protein and mRNA expression of WWOX in ESCC tissues. PCR-RFLP, PCR-SSLP, and MSP approach were used, respectively, to detect polymorphisms of rs3764340, rs2548861, and rs1079635 site, the level of LOH, and WWOX methylation status. Family history of upper gastrointestinal cancer (UGIC) significantly increased the risk of developing ESCC. Protein and mRNA expression of WWOX was reduced in ESCC tumor tissues and was associated with LOH and hypermethylation of the gene. The G allele of rs3764340 significantly elevated the risk of developing ESCC and was associated with TNM stage. LOH at the WWOX loci was observed in 41.4% tumors. The hypermethylation of promoter and exon1 of WWOX was found to be occurred in dysplastic tissues and the methylation frequency of WWOX in ESCC tumor tissues was significantly higher than that in corresponding normal tissues and was associated with UGIC family history. In all, these results indicate that the WWOX gene may play an important role in the development of ESCC especially in individuals with UGIC family history.

An Isolated and Deeply Divergent Hynobius Species from Fujian, China.

It is important to describe lineages before they go extinct, as we can only protect what we know. This is especially important in the case of microendemic species likely to be relict populations, such as Hynobius salamanders in southern China. Here, we unexpectedly sampled Hynobius individuals in Fujian province, China, and then worked on determining their taxonomic status. We describe Hynobius bambusicolus sp. nov. based on molecular and morphological data. The lineage is deeply divergent and clusters with the other southern Chinese Hynobius species based on the concatenated mtDNA gene fragments (>1500 bp), being the sister group to H. amjiensis based on the COI gene fragment, despite their geographic distance. In terms of morphology, the species can be identified through discrete characters enabling identification in the field by eye, an unusual convenience in Hynobius species. In addition, we noted some interesting life history traits in the species, such as vocalization and cannibalism. The species is likely to be incredibly rare, over a massively restricted distribution, fitting the definition of Critically Endangered following several lines of criteria and categories of the IUCN Red List of Threatened Species.

Sixteen novel microsatellite markers developed for Dendrocalamus sinicus (Poaceae), the strongest woody bamboo in the world.

PREMISE OF THE STUDY: Microsatellite primers were developed in the strongest and most economically important bamboo species, Dendrocalamus sinicus, to investigate its genetic variability. METHODS AND RESULTS: Using the Fast Isolation by AFLP of Sequences COntaining Repeats (FIASCO) protocol, 16 polymorphic primer sets were identified within 24 individuals from two geographic locations. The number of alleles per locus ranged from two to four, with a mean of 2.6. The observed and expected heterozygosities varied from 0 to 1.000 and from 0.311 to 0.754, respectively. The cross-amplification of the 16 primer pairs was tested in four other Dendrocalamus species, and nine to 13 (56.3-81.3%) primer pairs were successfully amplified. CONCLUSIONS: These markers will be useful for studies on the genetic diversity of D. sinicus, which may facilitate conservation of this species.

Modeling the potential distribution of different types of Dendrocalamus sinicus, the strongest woody bamboo in the world, with MaxEnt model.

Climate change will significantly affect the distribution area of species. Through establishing distribution model, we can simulate the current and future potential distribution range and provide reference for the introduction and cultivation planning of rare or economic plants. Dendrocalamus sinicus, endemic to Yunnan Province of China, is the strongest woody bamboo in the world. In the present study, the MaxEnt model was performed to simulate the distribution of different types of D. sinicus in China and neighboring countries or regions. The results suggested that the suitable distribution range of "straight type", the main type for cultivation and utilization, was 8°-30°N and 73°-122°E under the current climate conditions, while the potential distribution range of "bending type" was 6°-31°N and 79°-109°E. The two most key climate variables associated with distribution of "straight type" were "Temperature Annual Range" with 36.6% contribution rate and "Temperature Seasonality" (32.4%), while "Isothermality" (47.8%) and "Precipitation of Driest Month" (24.8%) for "bending type". Under different climate change scenarios (SSP1-2.6, SSP5-8.5) and periods (2050, 2090), the potential distribution area of the "straight type" were apparently different, indicating that the distribution area of D. sinicus will be affected significantly by climate changes in the future. Our findings would be not only beneficial to understanding limiting factors for natural distribution of D. sinicus, but also helpful for further germplasm conservation, introduction and cultivation planning of this rare woody bamboo.

Asymmetric interactions of seed-predation network contribute to rare-species advantage.

Although the asymmetry of species linkage within ecological networks is now well recognized, its effect on communities has scarcely been empirically investigated. Based on theory, we predicted that an asymmetric architecture of antagonistic plant-herbivore networks would emerge at the community level and that this asymmetry would negatively affect community-common plants more than rare ones. We tested this prediction by analyzing the architectural properties of an alpine plant and pre-dispersal seed-predator network and its effect on seed loss rate of plants in the Tibetan Plateau. This network showed an asymmetric architecture, where the common plant species (with a larger aboveground biomass per area) were infested by a higher number of predator species. Moreover, they asymmetrically interacted with specialized herbivores, presumably because of greater seed resource abundance. In turn, the asymmetric interactions led to a higher proportion of seed loss in the common plants at the species level. Our results suggest that asymmetric antagonistic networks may improve species coexistence by contributing to a mechanism of rare-species advantage.

Relative species abundance successfully predicts nestedness and interaction frequency of monthly pollination networks in an alpine meadow.

Plant-pollinator networks have been repeatedly reported as cumulative ones that are described with >1 years observations. However, such cumulative networks are composed of pairwise interactions recorded at different periods, and thus may not be able to reflect the reality of species interactions in nature (e.g., early-flowering plants typically do not compete for shared pollinators with late-flowering plants, but they are assumed to do so in accumulated networks). Here, we examine the monthly sampling structure of an alpine plant-pollinator bipartite network over a two-year period to determine whether relative species abundance and species traits better explain the network structure of monthly networks than yearly ones. Although community composition and species abundance varied from one month to another, the monthly networks (as well as the yearly networks described with annual pooled data) had a highly nested structure, in which specialists directly interact with generalist partners. Moreover, relative species abundance predicted the nestedness in both the monthly and yearly networks and accounted for a statistically significant percentage of the variation (i.e., 20%-44%) in the pairwise interactions of monthly networks, but not yearly networks. The combination of relative species abundance and species traits (but not species traits only) showed a similar prediction power in terms of both network nestedness and pairwise interaction frequencies. Considering the previously recognized structural pattern and associated mechanisms of plant-pollinator networks, we propose that relative species abundance may be an important factor influencing both nestedness and interaction frequency of pollination networks.

Genetic and epigenetic alterations of WWOX in the development of gastric cardia adenocarcinoma.

WWOX is a tumor suppressor gene that maps to the common fragile site FRA16D and is involved in carcinogenesis and cancer progression in many different carcinomas. Reduced WWOX expression is associated with more aggressive phenotypes and poor patient outcomes in several cancers. The present study was conducted in order to elucidate more precisely the genetic and epigenetic alterations of WWOX that play a role in gastric cardia adenocarcinoma (GCA) carcinogenesis in a population from Northern China. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), PCR-simple sequence length polymorphism (PCR-SSLP), and methylation specific PCR (MSP) methods were used to characterize polymorphisms in the rs3764340, rs2548861, and rs1079635 loci, the level of loss of heterozygosity (LOH), and methylation status of WWOX, respectively. Protein and mRNA expression of WWOX in GCA tissues was quantified by immunohistochemistry and reverse transcription-PCR (RT-PCR). Family history of upper gastrointestinal cancer (UGIC) significantly increased the risk of developing GCA. The CG+GG genotype of rs3764340 and GT or TT genotype of rs2548861 significantly elevated the risk of developing GCA. LOH at the WWOX locus was observed in 45.6% tumors. The promoter and exon 1 methylation frequency of WWOX in GCA tissues was significantly higher than in corresponding normal tissues and was associated with UGIC family history. Protein and mRNA expression of WWOX was reduced in GCA tumor tissues and was associated with LOH and methylation of the gene. These results indicate that WWOX may play an important role in GCA especially in individuals with UGIC family history.