Prediction and quantification of effective gas source rocks in a lacustrine basin:Western Depression in the Liaohe Subbasin,China

Due to limited data on the geochemical properties of natural gas,estimations are needed for the effective gas source rock in evaluating gas potential.However,the pronounced heterogeneity of mudstones in lacustrine successions complicates the prediction of the presence and geochemical characteristics of gas source rocks.In this paper,the Liaohe Subbasin of Northeast China is used as an example to construct a practical methodology for locating effective gas source rocks in typical lacustrine basins.Three types of gas source rocks,microbial,oil-type,and coal-type,were distinguished according to the different genetic types of their natural gas.A practical three-dimensional geological model was developed,refined,and applied to determine the spatial distribution of the mudstones in the Western Depression of the Liaohe Subbasin and to describe the geochemical characteristics(the abundance,type,and maturation levels of the organic matter).Application of the model in the subbasin indicates that the sedimentary facies have led to heterogeneity in the mudstones,particularly with respect to organic matter types.The effective gas source rock model constructed for the Western Depression shows that the upper sequence(SQ2)of the Fourth member(Mbr 4)of the Eocene Shahejie Formation(Fm)and the lower and middle sequences(SQ3 and SQ4)of the Third member(Mbr 3)form the principal gas-generating interval.The total volume of effective gas source rocks is estimated to be 586 km^(3).The effective microbial,oil-type,and coal-type gas source rocks are primarily found in the shallow western slope,the central sags,and the eastern slope of the Western Depression,respectively.This study provides a practical approach for more accurately identifying the occurrence and geochemical characteristics of effective natural gas source rocks,enabling a precise quantitative estimation of natural gas reserves.

Elevational and temporal patterns of pollination success in distylous and homostylous buckwheats(Fagopyrum)in the Hengduan Mountains

Reproductive strategies of sexually dimorphic plants vary in response to the environment.Here,we ask whether the sexual systems of Fagopyrum species(i.e.,selfing homostylous and out-crossing distylous)represent distinct adaptive strategies to increase reproductive success in changing alpine environments.To answer this question,we determined how spatial and temporal factors(e.g.,elevation and peak flowering time)affect reproductive success(i.e.,stigmatic pollen load)in nine wild Fagopyrum species(seven distylous and two homostylous)among 28 populations along an elevation gradient of 1299-3315 m in the Hengduan Mountains,southwestern China.We also observed pollinators and conducted hundreds of hand pollinations to investigate inter/intra-morph compatibility,self-compatibility and pollen limitation in four Fagopyrum species(two distylous and two homostylous).We found that Fagopyrum species at higher elevation generally had bigger flowers and more stigmatic pollen loads;lateflowering individuals had smaller flowers and lower pollen deposition.Stigmatic pollen deposition was more variable in distylous species than in homostylous species.Although seed set was not pollenlimited in all species,we found that fruit set was much lower in distylous species,which rely on frequent pollinator visits,than in homostylous species capable of autonomous self-pollination.Our findings that pollination success increases at high elevations and decreases during the flowering season suggest that distylous and homostylous species have spatially and temporally distinct reproductive strategies related to environment-dependent pollinator activity.

Both small and large plants are likely to produce staminate(male)flowers in a hermaphrodite lily

Resource allocation to female and male function may vary among individual plants in species with variable sex expression.Size-dependent sex allocation has been proposed in hermaphrodites,in which female-biased allocation may increase with plant size.In many hermaphrodites with large floral displays,however,later-produced flowers tend to be functionally male.This paradoxical relationship between female and male function and plant size remains poorly understood.The subalpine lily Lilium lankongense has individuals of three sexual types:males with only staminate flowers,hermaphrodites with only perfect flowers,and andromonoecious plants with both perfect and staminate flowers.Here we tested theoretical predictions of size-dependent sex allocation in L.lankongense by measuring plant height and flower number of individuals of each sex at five field sites in the mountainous region of Shangri-La,southwestern China.To investigate variation in phenotypic gender,we identified sex expression of 457 individuals one year later.Our investigation showed that male plants,which usually produced one flower,were significantly smaller than and ro monoecious and hermaphrodite plants.In addition,the total flower numbers of andromonoecious and hermaphrodite plants increased significantly with plant size.Large individuals were more likely to produce terminal staminate flowers,as there were more flowers in andromonoecious than in hermaphrodite individuals.Non-flowered plants were significantly smaller than flowering ones.Perfect flowers had significantly larger petals and pistils than staminate flowers,but they did not differ in dry weight of stamens.Our findings indicate that when plants are small,the less costly sex is favored,consistent with the‘size-advantage hypothesis’.When plants are large,both female and male investments change isometrically,as later-produced flowers tend to be functionally male.

Degree of style coiling is associated with corolla-tube length in the nectarless flowers of Roscoea schneideriana

The plant-pollinator‘arms race’model posits that a major driver of the evolution of elongated corollas in flowers is reciprocal selection for‘morphological fit’between pollinator-tongue length and access distance to nectar(usually corolla-tube length).Evidence for the pollinator-mediated selection on tube length and evolution of multiple,correlated floral traits remains inconclusive.To gain possible insights into the strength of stabilizing selection by assessing standing phenotypic variation,we measured a series of functionally important floral traits,including corolla tube length and‘effective’tube depth and degree of style coiling.We then calculated coefficients of variation(CV)for these traits in three field populations of R.schneideriana.Unlike in most long-tubed flowers,the bottom part of the corolla tube is completely occupied by the style,with no room for nectar.The length of this portion of the corolla tube was more variable(higher CV)than the upper part of the corolla tube,suggesting that functional tube depth was under stronger stabilizing selection.The degree of style coiling was negatively related to the corolla-tube length in all three populations of R.schneideriana,suggesting that there may be conflicting selection acting on style length and corolla-tube length,which are otherwise usually tightly correlated.Given the lack of nectar in the flowers of this species,the long corolla tubes and long styles may represent morphological holdovers from ancestors that were pollinated by long-tongued pollinators,as is still seen in related species in the western Himalayas.

Lethal effects of tea-oil Camellia on honeybee larvae due to pollen toxicity

Flowers in the tea family (Theaceae) are bowl-shaped,with numerous anthers presenting large amounts of freely accessible pollen simultaneously.Species that flower mainly in winter and early spring are pollinated by bees and/or birds.In the 1950s,beekeepers in China observed larval mortality if honeybees (Apis cerana) had foraged on the flowers of Camellia oleifera (Zhu,1957).

Interspecific pollen transfer between two coflowering species was minimized by bumblebee fidelity and differential pollen placement on the bumblebee body

Aims When sympatric flowering plant species in a natural community share pollinators,study of plant-plant interactions via interspecific pollen transfer(iPT)is essential for understanding species coexistence.However,little is known about the extent of iPT between interactive species and its causes.Methods To explore how sympatric flowering plants sharing pollinators mini-mize deleterious effects of iPT,we investigated the pollination ecol-ogy of two endemic species,Salvia przewalskii and Delphinium yuanum,in an alpine meadow in the Hengduan mountains,southwest China.We quantified conspecific and interspecific visits by shared bumblebee pollinators,amounts of pollen placed on different body sites of the pollinators and stigmatic pollen loads on open-pollinated flowers.To examine whether iPT affects female fitness,we measured pollen germination and seed production in the two species in an artificial pollination experiment.Important Findingsone bumblebee species,Bombus trifasciatus,was found to be the sole effective pollinator for the two coflowering species.Pollination experiments indicated that deposition of heterospecific pollen could significantly decrease seed set in both species.Experiments showed that S.przewalskii pollen could germinate well on stigmas of D.yuanum,inhibiting conspecific pollen germination in D.yuanum.However,seed set was not lower under open pollination than under cross-pollination within species,suggesting that no female fitness loss was caused by iPT.in foraging bouts with pollinator switches,switches from S.przewalskii to D.yuanum were relatively more fre-quent(8.27%)than the converse(1.72%).However,iPT from S.prze-walskii to D.yuanum accounted for only 1.82%of total stigmatic pollen loads while the reverse iPT to S.przewalskii was 8.70%,indi-cating that more switches of bumblebees to D.yuanum did not result in higher iPT.by contrast,selection for reduced iPT to S.przewalskii would limit pollinator switches from D.yuanum.We found that a bumblebee generally carried pollen grains from both species but the two species differed in the position of pollen placement on the bum-blebee’s body;S.przewalskii’s pollen was concentrated on the dorsal thorax while D.yuanum’s pollen was concentrated ventrally on the head.This differential pollen placement along with pollinator fidelity largely reduced iPT between the two species with a shared pollinator.

Mast fruiting in a hawkmoth- pollinated orchid Habenaria glaucifolia: an 8-year survey

Aims The hypothesis of predator satiation has been proposed to explain mast fruiting in various flowering plants.it considers that the simultaneous production of large numbers of seeds by a plant population reduces the risk of seed predation for each individual.orchids produce huge numbers of seeds per fruit and rarely experience seed predation.it remains unclear which factors may affect fluctuating fruit production in orchids,which generally suffer a widespread pol-len limitation.To explore the temporal pattern of fruiting and poten-tial factors related to fluctuation in fruit production,we investigated reproductive success of a long-spurred orchid(Habenaria glaucifo-lia)in an alpine meadow with thousands of individuals over 8 years.Methods To estimate reproductive success,pollinator observation was con-ducted by day and at night,and pollinia removal and receipt were recorded in the field population for 8 years.To examine whether fruit set and seed set are pollen limited,we conducted supple-mentary pollination experiments and compared fruit set,seed set and pollinia movement of open-pollinated flowers from 2011 to 2013.We measured lengths of spurs and pollinator probos-cises,and nectar volume and concentration,to identify potential pollinators.Important Findings Hawkmoths were seen to be effective pollinators for H.glauci-folia in 3 years,whereas in the remaining 5 years no pollinators were observed,and consequently pollinia were rarely transferred.Numerous pollinia movements were observed in 2012,2013 and 2014(pollinia removal:48,59 and 85%;pollinia receipt 51,70 and 80%),and correspondingly fruit set was significantly higher in 2012 and 2013(59 and 46%)than in 2011(25%).it was fruit set,rather than seed set,that was pollen limited in this orchid in the 3 years,in that supplementary pollination increased fruit set but did not increase seed set per fruit compared to natural.Three species of hawkmoths had proboscis lengths that matched the spur length of H.glaucifolia.Fruit set in this long spurred orchid depends on the activity of long-tongued hawkmoths,resulting in significant tempo-ral variation in fruit production.mast fruiting in this alpine orchid could be attributed to a‘sit and wait’strategy,awaiting an abun-dance of effective pollinators.

Shortened anther-stigma distance reduces compatible pollination in two distylous Primula species

Aims Distyly has been regarded as an adaptation to improve compatible pollination between two floral morphs with reciprocal herkogamy.The hypothesis that the different positions of anthers and stigmas within flowers as well as their reciprocal position between morphs,reduce the probability of self pollination raised by Darwin has been rarely tested.in this study,we measured stigmatic pollen loads in response to reduced reciprocal herkogamy in two Primula species.Methods To see whether reciprocal herkogamy can increase compatible and/or reduce incompatible pollen deposition,thus promoting compat-ible pollination,we shortened the distance between anthers and stigmas within the flowers by changing the position of the corolla tube,to which the anthers were fused,i.e.reduced herkogamy in natural populations of Primula secundiflora and P.poissonii and quantified stigmatic pollen loads in the field over 2 years.Important Findingsin both species,stigmatic pollen loads were significantly higher in the long-styled(l-morph)than in the short-styled morph(s-morph)in both control and manipulated flowers,but percentage of compatible pollen in s-morph were higher.Flowers manipulated to halve the anther-stigma distance showed a similar pattern for 2 years:total pollen grain counts on stigmas did not differ significantly but compatible pollen grains in l-and s-morphs were significantly decreased in both species.The percentage of compatible pollen loads was decreased by 68.7%in P.secundiflora and 65.3%in P.poissonii in l-morphs,while it decreased by 30.6%and 2.9%in s-morphs,respectively.our manipulation of the relative position of anthers and stigmas in the two distylous species indicated that a lower degree of herkogamy reduced compatible but incompatible pollen transfer was likely to increase.The higher proportion of compatible pollen in the s-morph than in the l-morph in the two Primula species could be attributed to the accessibility of two-level sexual organs,floral orientations and pollinator behaviors.This is a first attempt to manipulate intraflower herkogamy for understanding adaptation of heterostyly,shedding insights into how the reciprocal herkogamy promotes compatible pollination.

Effects of floral sexual investment and dichogamy on floral longevity

Aims Floral longevity,the duration that a flower remains open and func-tional,varies greatly among species.Variation in floral longevity has been considered to be optimal strategy for resource allocation under different ecological conditions,mainly determined by the rates of pollination and cost of flower maintenance.However,it is unclear whether an intrinsic factor,floral sexual investment,con-strains evolution of floral longevity.The theoretical model also pre-dicts that dichogamy favors long-lived flowers,but empirical studies to test this prediction remain unexplored.Methods To examine the effect of floral sexual investment on floral longevity,we measured flower size together with pollen and ovule production in 37 sympatric flowering plants in a natural community.The duration of the female and male phase in 21 protandrous species and floral longevity of the other 16 adichogamous species were documented in the field.Important Findings Floral longevity varied from 1 day to 15 days,while pollen num-ber per flower varied from 643 to 710880 and ovule number per flower from 1 to 426 in the 37 species.Flower size was corre-lated with pollen production as well as ovule production.Floral longevity was positively related to pollen production but not to ovule production.Consistent with the prediction that dichogamy favors long-lived flowers,we found the floral longevity of pro-tandrous species was significantly longer than that of adichoga-mous species.in the protandrous species,pollen production per flower was observed to be positively related to male duration,while ovule production was not related to female duration.our analyses of variation in floral longevity and sexual investment among different species suggest that the floral sexual investment could be an intrinsic factor contributing to the selected floral longevity,particularly the male phase,and that high pollen pro-duction could potentially increase pollen removal,i.e.male pro-ductive success.

Pollen size strongly correlates with stigma depth among Pedicularis species

Summary Darwin proposed that pollen size should be positively correlated with stigma depth rather than style length among species given that pollen tubes first enter the stigma autotrophically, then grow through the style heterotrophically. However, studies often show a posi-tive relationship between pollen size and style length. Five floral traits were observed to be correlated among 42 bumblebee-pollinated Pedicularis species （Orobancha- ceae） in which stigmas are distinct from styles. The phylogenetic independent contrast analysis revealed that pollen grain volume was more strongly correlated with stigma depth than with style length, consistent with Darwin＇s functional hypothesis between pollen size and stigma depth.

Does persistence of showy calyces in Limonium leptolobum enhance pollinator attraction?

Aims The calyx,the outermost whorl of a flower(usually green),has been considered to function to protect flowers.in some species,how-ever,calyces are colorful and retained during seed development.Limonium species have been exploited as cut flower crops because the calyces persist for several months after the corolla has closed.To explore the adaptive significance of the persistent calyx in a desert plant Limonium leptolobum,we ask whether persistence of caly-ces can enhance pollinator attraction by enlarging floral displays,increasing reproductive success in this self-incompatible species.Methods The yellow flower of L.leptolobum lasted 1-2 days but its white,membranous calyx extended fully after the corolla closed,and per-sisted for over 2 months in the field,making hundreds of‘showy flowers’on one individual.To examine the ecological function of calyces,we test the pollinator attraction hypothesis.in an experi-mental population,we compared the difference in visit frequency and visitor behavior between intact inflorescences and inflores-cences with their calyces removed on the same individual plants.Important findingsin four experimental plots four types of floral visitors were observed including bees,butterflies,syrphid flies and day-flying moths.No significant preference was observed between calyx-free and intact inflorescences for both first arrivals and total visit frequency of all types of floral visitors,indicating that the persistence of calyces did not make plants more attractive to potential pollinators.The pollina-tor attraction hypothesis for the showy calyces was not supported by the current data.Whether the calyx in this desert plant helps seed development or has other functions needs further study.

Discovery of androecium color polymorphism in Epimedium pubescens with habitat preference of anther/pollen color in the genus

Aims Interspecific and intraspecific variation in flower color in natural populations provides an opportunity for us to understand the evolu-tion and maintenance of diversity of floral traits.Compared to cor-olla color,little is known about the color polymorphism of sexual organs in flowering plants.to explore evolutionary transitions of androecium color and polymorphism within species,interspecific and intraspecific variation in androecium(anther and pollen)color in the genus Epimedium(Berberidaceae)was investigated.Methods to explore the geographical patterns of anther/pollen color variation in Epimedium species,data of 45 species were collected and their phyl-ogeny was constructed based on available DNA sequences.to investi-gate whether intraspecific variation in androecium color relates to habitat preference,three environmental factors were measured in the field popu-lation of Epimedium pubescens in northeastern Sichuan,China,which plants had green or yellow androecia.Vegetative and reproductive traits of this species were compared between the two color morphs.Important Findings Androecium(anther and pollen)color polymorphism in field populations of Epimedium pubescens is reported here where nine populations are monomorphic with a green androecium but three populations are dimorphic with individuals having either a green or a yellow androecium.Inflorescence stalk height,stalk diameter,leaf number,flower number and spur length(as well as spur and nectar volume)were not significantly different between two morphs.Compared to the yellow morph,the green morph had relatively larger leaves and anthers,but smaller sepals.the green morph produced more pollen and larger seeds,but the same number of ovules.Seed set was not significantly different between green and yellow morph.Investigations of environmental factors in the color dimorphic popu-lations of E.pubescens indicated that the green morph was more likely to occur in habitats with relatively lower light intensity.the distribution survey of 45 Epimedium species showed that species with a green androecium tended to appear at lower elevations.Comparative phylogenetic analysis showed that transitions from yellow to a green androecium or to androecial color dimorphism occurred at least seven times.this genus,characterized by anther color diversity and containing some species with anther color polymorphism,provides a model system in which to study the evolution and maintenance of colorful sexual organs in flowering plants.

Are long corolla tubes in Pedicularis driven by pollinator selection?

The evolution of long corolla tubes has been hypothesized to be driven by long-tongued pollinators.Corolla tubes in Pedicularis species can be longer than 10 cm which may function as flower stalks to increase visual attractiveness to pollinators because these species provide no nectar and are pollinated by bumblebees. The corolla tube length was manipulated（shorter or longer） in two Pedicularis species in field to examine whether longer tubes are more attractive to pollinators and produce more seeds than short tubes. Our results did not support the pollinator attraction hypothesis, leaving the evolution of long tubes in Pedicularis remains mysterious.