FLORAL PARAMETERS,BREEDING SYSTEM AND POLLINATOR TYPE IN TRICHOSTEMA (LABIATAE)

Diversity in flower size and degree of exsertion of anthers and stigma from the corolla in the California species of Trichostema appear to be correlated with breeding system and pollinator type (bee vs. bird). Autogamous (self-pollinating) species unlike xenogamous (cross-pollinating) species lack spatially separate anthers and stigma and nototribic pollination. The outcrossing species have significantly larger flowers, significantly larger nectar volumes and significantly higher pollen-ovule ratios than do selfing species. Because autogamous species are less reliant on flower visitors to facilitate pollination, there may be relaxed selection for large nectar producing flowers. Pollen-ovule ratios are correlated with breeding system and reflect the efficiency of pollen transport. Data on floral parameters suggest xenogamous species expend more energy per floral unit and are less efficient seed producers than closely related autogamous species.     

歪叶榕繁殖生态学

该文主要从物候学、行为学和生态学3个方面首次研究报道了我国西双版纳热带雨林下的一种榕树——歪叶榕(Ficus cyrtophylla)的繁殖机制。研究结果表明,歪叶榕榕小蜂(Blastophaga sp.)是歪叶榕唯一的传粉昆虫,传粉行为方式为被动传粉,而且这种榕小蜂也只能在该种榕树中成功繁衍后代。物候学观察结果表明,歪叶榕常绿且叶量常年变化较小,10~11月和3~4月是歪叶榕雄株落叶的高峰期,这时正值西双版纳的雾凉季和干热季,而雌株的落叶高峰期是3~4月;12月和5月是歪叶榕雄株新叶萌发的高峰期,而4~5月是其雌株新叶萌发的高峰期,这时正值西双版纳干热季向雨季过渡的时期,新叶萌发后同时伴随着一次该种榕树的挂果高峰期;歪叶榕在种群水平上常年持续结果,在每年的11月和4~5月有两次结果高峰期,单株每年大量结果2~3次;单棵雄株内结果异步性较高,而雌株内结果高度同步。单果进蜂数(Foundress number)为0~5只,大多数雄果(78.45%)和雌果(84.25%)只有1只传粉榕小蜂,大约16.02%的雄果和13.33%的雌果内含有2只传粉榕小蜂,其它情况均很少。在自然情况下,雄果中的总瘿花量为147.32±62.61(SD)枚,传粉榕小蜂出蜂量为110.94±62.82(SD)只,其中雌蜂多而雄蜂少,传粉榕小蜂性比为0.143 9±0.131 6(SD),瘿花形成率为64.13%±19.89%(SD),雌果中的种子数为231.44±74.25(SD)粒,种子形成率为85.72%±14.19%(SD)。歪叶榕和其传粉榕小蜂在物候学、传粉行为与花药/胚珠比(A/O ratio)和雄花成熟与其羽化出蜂的时期等方面表现出高度的相互适应。     

无花果多糖对鲫鱼非特异性免疫功能的影响

实验研究了无花果多糖对鲫鱼非特异性免疫功能的影响。将鲫鱼分成A0、A1、A2、A3和A4五个组,其中A0组投喂基础饵料,设为对照组,而A1、A2、A3和A4分别投喂添加0.1%、0.2%、0.4%、0.8%无花果多糖的基础饵料,并在试验的第0、第7、第14、第21、第28、第35天检测鲫鱼血清补体C3含量、总蛋白含量、溶菌酶活力、SOD活性和血液白细胞吞噬活性。结果表明,A2组的补体C3含量、总蛋白含量、溶菌酶活力、SOD活性和血液白细胞吞噬活性显著高于A0组(P3组补体C3含量、SOD活性和血液白细胞吞噬活性极显著的高于A0组(P1组、A4组(P3组补体C3含量、总蛋白含量、溶菌酶活力、SOD活性和血液中白细胞吞噬活性与A2组相比差异不显著。A0组、A1组和A4组之间的补体C3含量、总蛋白含量、溶菌酶活力、SOD活性和血液白细胞吞噬活性无显著差异(P>0.05)。       

濒危植物长柄双花木的花部综合特征与繁育系统

 通过野外观察,运用杂交指数、花粉-胚珠比、人工授粉和套袋实验及等位酶电泳等方法,对长柄双花木(Disanthus cercidifolius Maxim. var. longipes H. T. Chang)自然种群和人工种群的开花状态、繁育系统进行了研究。结果如下：该种单花花期一般6～7 d,开花过程中柱头始终高于花药的位置,花药散粉具有先后顺序,一般2花药先散粉,其余3花药滞后1～2 d。单花花期依其形态和散粉时间可分为5个时期：即散粉前期、散粉初期、散粉盛期、凋谢期。种群开花一般历时49～55 d,但不同地点、年份之间有所差异,推测开花持续时间不同主要是环境条件所致。由于其杂交指数大于4,花粉-胚珠比等于1 250,结合人工套袋和授粉实验以及等位酶电泳结果可以确定该种的繁育系统属于异交为主,部分自交亲和,传粉过程需要传粉者。花粉竞争可能是导致该种濒危的主要的生殖生物学原因。     

上海地区常见蝇类的滋生习性

上海地区与人接近的蝇类经滋生场所的调查发现有50余种,但常见的与人接近频繁的计15种,从卫生方面看与人关系密切的计有:大头金蝇(Chrysomyia megacephala(Fab.))、舍蝇(Musca domestica vicina Macq.)、丝光绿蝇(Lucilia sericata(Mg.))、铜绿蝇(Luciliacuprina(Wd.))、麻蝇(Sarcophaga spp.)、山蝇(Musca sorbens Wd.)及厩腐蝇(Muscinastabulans(Flln.))等7种。 滋生场所分为5型,即人粪、畜粪、腐败动物质、腐败植物质及垃圾。这5个类型的滋生场所,所产的蝇类各有不同。同一滋生场所的各种蝇类,有明显的季节性优势变迁。 人粪中主要滋生大头金蝇及麻蝇,畜粪中尤其猪粪及牛粪主要滋生舍蝇,腐败动物质尤其兽骨与禽兽毛羽中主要滋生丝光绿蝇,植物性腐败物中滋生的蝇类最少,主要包括几种麻蝇,而垃圾型中滋生的蝇类最多,如舍蝇、绿蝇、麻蝇等。 由调查结果所示卫生上重要的种类的滋生场所包括人粪、畜粪、兽骨、毛羽与垃圾,其中人粪及垃圾尤为重要。 本文根据各种蝇类的滋生习性对这些蝇类滋生场所与滋生物质的处理提出了一些建议。     

CAUSES AND CONSEQUENCES OF WITHIN-TREE PHENOLOGICAL PATTERNS IN THE FLORIDA STRANGLING FIG,FICUS AUREA (MORACEAE)

The obligate pollinators of figs (Ficus, Moraceae), species-specific agaonid wasps, benefit figs only by transporting pollen between trees; larvae are seed predators. But given the high risk of mortality in flight between trees, adult wasps should prefer to pollinate and oviposit within inflorescences (syconia) at the same tree at which they developed. Flowering within individuals is tightly synchronous in most species, while different trees flower out of phase with each other, suggesting that fig phenology has evolved to assure outcrossing. However, some fig species show distinct within-tree flowering asynchrony. It has been suggested that such asynchrony is an adaptation by which figs in seasonal environments can reduce pollinator mortality, by permitting wasps to persist on individual trees at times when flight would be impossible. We have evaluated and rejected the validity of this Seasonality Hypothesis for the Florida strangling fig, Ficus aurea, near its northern range limit. Crops of individual trees were most, not least, synchronous during the coldest, driest months of 2 years. Maximum asynchrony occurred in seasons that were probably most favorable for wasp transit between trees. However, temporal overlap of the phenological stages that permit wasps to remain on their natal trees was always very rare, implying that consecutive cohorts of developing syconia may be spaced in time to limit this occurrence. We suggest alternative costs and benefits for these phenological traits, as well as the proximate mechanisms that might produce them.     

THE FLORAL AND EXTRA-FLORAL NECTARIES OF PASSIFLORA. I. THE FLORAL NECTARY

Floral nectary development and nectar secretion in three species of Passiflora were investigated with light and electron microscopy. The nectary ring results from the activity of an intercalary meristem. Increased starch deposition in the amyloplasts of the secretory cells parallels maturation of the nectary phloem. Large membrane-bound protein bodies are observed consistently in phloem parenchyma cells, but their function is presently unknown. The stored starch serves as the main source of nectar sugars at anthesis. Plastid envelope integrity is maintained during starch degradation, and there is no evidence of participation of endoplasmic reticulum or Golgi in the secretion of pre-nectar. It is concluded that in these starchy nectaries granulocrine secretion, commonly reported for floral nectaries, does not occur.     

稀有植物小丛红景天花部综合特征与繁育系统

对稀有物种生物学特征及繁育系统的研究将有利于我们对稀有物种的保育。该文通过野外定位观测稀有植物小丛红景天(Rhodiola dumulosa)的花部综合特征,并运用杂交指数、花粉-胚珠比的方法首次对其繁育系统进行初步测定。结果表明:该物种单花花期一般为5~6 d,开花过程中花柱逐渐伸长并向外弯曲,子房开裂并逐渐伸长,花药散粉具有先后顺序,一般外轮对萼花药先散粉,其后1 d左右对瓣花药开始散粉。单花花期依照其形态和散粉时间可分为6个阶段:花蕾期、内轮散粉期、内轮散粉末期、外轮散粉期、外轮散粉末期和凋谢期。而种群花期一般可持续30 d以上,不同海拔观测地点有所不同,海拔2 202 m处的观测地点B开花物候最为滞后。由于其杂交指数不小于4,花粉-胚珠比在700~1 000之间, 根据Dafni(1992)和Cruden(1977)的标准,初步判定该物种的繁育系统属于异交为主,部分自交亲和,传粉过程需要传粉者。     

INFLUENCE OF POLLINATION SPECIALIZATION AND BREEDING SYSTEM ON FLORAL INTEGRATION AND PHENOTYPIC VARIATION IN IPOMOEA

Natural selection should reduce phenotypic variation and increase integration of floral traits involved in placement of pollen grains on stigmas. In this study, we examine the role of pollinators and breeding system on the evolution of floral traits by comparing the patterns of floral phenotypic variances and covariances in 20 Ipomoea species that differ in their level of pollination specialization and pollinator dependence incorporating phylogenetic relatedness. Plants with specialized pollination (i.e., those pollinated by one functional group or by few morphospecies) displayed less phenotypic variation and greater floral integration than generalist plants. Self‐compatible species also displayed greater floral integration than self‐incompatible species. Floral traits involved in pollen placement and pick up showed less variation and greater integration than floral traits involved in pollinator attraction. Analytical models indicate that both breeding system and the number of morphospecies had significant effects on floral integration patterns although only differences in the former were significant after accounting for phylogeny. These results suggest that specialist/self‐compatible plants experience more consistent selection on floral traits than generalist/self‐incompatible plants. Furthermore, pollinators and breeding system promote integration of floral traits involved in pollen placement and pick up rather than integration of the whole flower.     

FLORAL ANATOMY IN THE SAXIFRAGACEAE SENSU LATO. I. INTRODUCTION,PARNASSIOIDEAE AND BREXIOIDEAE

The floral morphology and anatomy of one representative of the Parnassioideae and two of the Brexioideae are described, and some of the recent literature dealing with the Saxifragaceae sensu lato is reviewed. Comparison of the floral structure in Parnassia to that typical of the Saxifragoideae, the subfamily constituting the Saxifragaceae sensu stricto and which, therefore, may be considered to show the basic saxifragaceous characteristics, reveals little similarity. Parnassia differs in pattern of both sepal and androecial vascularization, vascularization and degree of connation of the carpels, height in the gynoecium to which ventral bundles remain compound, possession of nectariferous staminodia, and the absence of epidermal appendages. Brexia and Ixerba (both of the Brexioideae) are strikingly dissimilar in floral structure and probably should be dissociated. While the position of Ixerba is problematical, it shares more floral characters with the Escallonioideae than with either Brexia or the Saxifragoideae and is better associated with that taxon. In both Parnassia and Brexia the vascular pattern suggests derivation of the androecium from a fascicled condition: the vascular supply of each filament consists of a cylinder of closely associated collateral bundles, and each staminodial set receives a single vascular complex which subsequently divides into as many vascular strands as there are staminodia in the set.     

ADAPTATIONS FOR A TWO-PHASE SEED DISPERSAL SYSTEM INVOLVING VERTEBRATES AND ANTS IN A HEMIEPIPHYTIC FIG (FICUS MICROCARPA: MORACEAE)

Figs (Ficus spp., Moraceae) are considered a classic example of plants with fleshy fruits adapted for seed dispersal by vertebrates, usually mammals or birds. Partially covering the endocarp of each individual drupelet of F. microcarpa is a fleshy, discrete lipid-containing exocarp that suggests adaptation for seed dispersal by ants. This structure is highly attractive to ants. F. microcarpa drupelets from which the fleshy exocarp was experimentally removed were much less likely to be transported by ants than those with this structure intact. The exocarps retained their attractiveness to ants and were not visibly altered following passage of the entire fruit through the gut of a frugivorous bird, the Indian Hill Mynah (Gracula religiosa). Germination percentage was not significantly affected by gut passage or exocarp removal. These results suggest that F. microcarpa has a two-stage seed dispersal system, in which primary dispersal by vertebrates is followed by secondary dispersal by ants. Dispersal aided by ants may be of significance in the biology of this exotic hemiepiphyte in southern Florida, where it is naturalized and appears to be spreading.     

片断化生境中濒危植物黄梅秤锤树的开花生物学、繁育系统与生殖成功的因素

 研究处于片断化生境中濒危植物的繁育系统、传粉过程及生殖成功状况, 可为评估物种的受胁迫程度及制订相应的保护和管理策略提 供重要依据。通过野外观察和人工授粉实验等方法,对片断化生境中濒危植物黄梅秤锤树(Sinojackia huangmeiensis)的开花生物学和繁育系统 进行了初步研究, 并探讨了影响其生殖成功的因素。黄梅秤锤树的总状花序上通常有两性花2～6朵, 单花花期约5～7 d, 单花花药不同步开裂 使整朵花花粉活力持续时间延长。虽然花开放过程中柱头始终高于花药, 在单花水平上可在一定程度上避免同花自交的发生, 但由于花粉活力 和柱头可授期之间有一定的重叠期, 在自然情况下, 由于外界媒介动物和风媒的作用, 不可避免地会产生同株同花和同株异花传粉。实验结果 表明, 该种不存在无融合生殖现象, 繁育类型以异交为主, 部分自交亲和且需要传粉者。主要的传粉昆虫为黑带食蚜蝇(Epistrophe balteata) 、中华蜜蜂 (Apis cerana) 和中华回条蜂(Habropoda sinensis)。黄梅秤锤树自然状态下的结实率较低(10.33%), 平均每果种子数较少(0.387 个), 这主要与传粉昆虫少、花粉传递效率低, 以及柱头上自花及同株异花花粉的落置和自交亲和性低有关。但是单株较大的开花量保证了一定 的果实和种子产量, 使居群能自然更新。部分自交亲和性可能为该物种适应生境片断化提供了一定的生殖保障及进化潜力。对该残存居群的保 护, 应着眼于加强对传粉昆虫赖以生存的自然生态系统的恢复。