冬季水淹对秋华柳的开花物候及繁殖分配的影响

开花物候及繁殖分配是植物适应环境的重要因素,为了解长期冬季水淹对三峡库区耐淹物种秋华柳(Salix variegata Franch.)繁殖的影响,研究了长期冬季水淹条件下秋华柳的开花物候和繁殖分配情况。实验在2006年11月份设置了如下处理:对照,完全水淹(植株置于水中,顶部距水面2m)30,60,90,120d和150d。结果表明:(1)对照及各水淹处理的秋华柳花期都较长,在7-11月份持续开花,个体开花进程(开花振幅曲线)呈单峰曲线。(2)冬季水淹对秋华柳群体及个体的开花物候有显著影响。水淹时间越长,始花期越晚,花期持续时间越短(P0.05)。(3)长期冬季水淹下,秋华柳显著降低了繁殖分配比例和全株生物量及单株花序数(P0.05)。(4)开花物候指数与繁殖分配的相关分析表明:始花时间越晚的个体,花期持续时间越短。花期持续时间越短的个体花序数越少,致使繁殖分配越小。总的来说,冬季水淹下,秋华柳通过推迟开花日期、缩短花期持续时间使繁殖分配比例降低,将更多的资源分配到生存力上,是秋华柳对长期冬季水淹的一种适应。同时,在长期冬季水淹后,秋华柳仍保持一定的开花繁殖能力,是其在应用于三峡水库消落区植被构建后产生后代延续种群的前提条件。     

大花百子莲的开花物候与生殖特性

连续2年对引种植物大花百子莲在中国上海市人工种群的开花物候、结实情况进行观测记录,从不同水平分析了大花百子莲的开花物候对其生殖的影响。结果显示:（1）大花百子莲在引种地的开花时间为6月初至7月末;种群花期历时40 d左右,单株花期在14～31 d波动,单花寿命主要为2～3 d;2年的开花振幅平均在6朵·株^-1·d^-1左右,花朵开放百分率值在3.69%~4.87%左右,平均开花式样为11~17朵。（2）大花百子莲种群内2007年比2008年的各项开花物候指标均提前6～9 d;种群开花进程为渐进式的双峰曲线;种群花期重叠时间较长,2年的平均开花同步指数分别为0.663、0.695;植株个体相对开花强度主要分布频度为50%～70%。（3）开花物候指数与座果率的相关分析表明,始花时间与开花数目、座果数、花期长度呈显著负相关关系,开花数目与座果数、花期长度以及花期长度与座果数均呈显著正相关关系,同一花序内单花所发育成果实的数量与单花开放时间呈极显著负相关关系。研究表明,大花百子莲始花时间早的植株比始花时间晚的植株花期更长,开花数目多的植株比开花数目少的植株花期更长,花期长的植株比花期短的植株座果率更高;而且在同一花序上,越早开放的单花其结实的可能性越大。作为引种植物,大花百子莲开花物候年度间具有相似性,说明其在引种地可以适应环境压力,形成稳定的开花时间与开花模式;较长的花期重叠和大量的开花数目可以吸引较多的传粉者访问,为其生殖成功奠定了良好基础。     

中国北亚热带油橄榄(城固32)开花生物学特性研究

为研究北亚热带内陆地区油橄榄（Olea europaea L.）开花物候、开花样式及花器官特征,探讨其有性繁殖系统的特点。试验对西秦岭南坡地区油橄榄（城固32）的开花生物学进行研究,统计开花进程,雄花和两性花在花序上的着生位置和数量,测定雄花和两性花形态指标并切片观察,电镜扫描分析雄花与两性花花粉粒。结果表明：（1）在北亚热带北缘内陆气候条件下油橄榄花期集中在5月,单株花期15~20 d,盛花期持续4~6 d;（2）油橄榄具有雄全同株的性系统且花器官较小,雄花及两性花都具有正常发育的雄蕊。通过制作石蜡切片观察,发现两性花的雌蕊正常发育,而雄花只有较小的子房和败育的柱头;（3）雌蕊是两种花型花器官生物量差异的主要部位,两性花雌蕊的生物量明显比雄花大（P<0.01）,树体分化出雄花投入的资源更少;（4）雄花与两性花在花粉量、花粉粒大小上差异不显著,在着生位置上,花序轴顶花全部为两性花,雄花出现在花序轴的中部和基部的几率分别是21.13%和30.77%。油橄榄品种城固32具有典型的雄全同株现象,雄花更倾向于在花序上出现的位置在行使它雄性功能方面并无优势可言,而且雄花花粉粒在数量、活力方面也没有优势,但是雄花的出现增加了花粉数量和P/O值,提高了植株的雄性适合度,雄花的出现也降低了两性花落花导致的树体资源浪费,保障其在资源有限的环境中能够繁殖最大化。     

川南城市园林中紫薇开花物候变化特征及其影响因素

为了明确城市园林中紫薇(Lagerstroemia indica)开花物候的变化特征,探讨花期影响因素和指导开花植物配置,对川南城市园林栽培的紫薇植株进行定期观测,记录了紫薇的2011—2014年开花物候,分析个体、群体水平上物候事件的差异以及植株大小和气候因子的影响。结果表明:紫薇个体在6月初至9月中旬进入花期,末花期多在10月,花期持续8~137 d,具有60~90 d花期的植株比例最高;不同年份开花植株比例和物候特征存在一定差异,种群水平花期持续时间最短为2014年的106 d,最长为2012年的130 d;但开花植株数量的时间格局总体相似,始花期与花期持续时间之间相关性显著;基径显著影响紫薇的开花物候特征,较大的植株往往开花较早,并且具有更长的花期;紫薇的盛花期多集中在7—9月;开花植株数量与前一个月的平均气温呈显著正相关,与同期温度、降雨量相关性不显著;紫薇开花物候在气候因子影响下年际间存在明显差异,也表现出一定规律性格局;园林中多样化的个体物候有利于维持群体水平上花期的观赏性,选择大植株可获得较稳定的观赏效果。     

浙江低山地区多用途植物无患子的开花物候特征

无患子(Sapindus mukorossi Gaertn.)是我国长江以南地区传统的重要绿化树种,其果皮富含皂苷,种仁富含油脂,是国家林业局审定的新型木本油料树种之一。为研究多用途树种无患子在浙江低山地区的开花特征,2012年和2013年连续两年对位于浙江省天台县9年生无患子人工林在群体、个体、花序和单花水平进行开花物候观测和比较,并运用开花日期、相对开花强度和同步性等指数研究了无患子开花物候特征。观察结果显示:无患子花呈浅黄白色,花的类型有雄花和两性花,没有发现雌花。雄花较两性花大(花径分别为5.09 mm和3.72 mm),雄蕊多为8枚,个别7或9、10枚;雌蕊退化仅留下浅绿色凸起。两性花花萼稍抱拢,花药藏于花被片下,雄蕊大多8枚,极少数7枚或9枚,柱头高于花药并伸出花苞,子房一般具3室,极少数4室或仅2室。无患子2012年的开花进程略早于2013年,其花期集中在在5月中旬至6月上旬,单花从花蕾膨大到花朵凋谢一般为8—9 d。在2012年和2013年,无患子在群体、个体和花序水平的花期约为30 d、20 d、11 d和28 d、19 d、13 d。个体水平的开花振幅均呈单峰曲线,年际间相似性较高;开花同步性在个体水平同步性较高(同步指数为0.868),表现出一种大量、集中的开花式样;相对开花强度在单株间分布范围相对宽泛,但主要分布在30%—40%,在年际间和年际内均呈现极显著差异。花期同步指数在两年的变异范围分别是0.81—0.97和0.70—0.98,不同单株开花同步性在年际内差异极显著,但在年际间差异性则不显著。由此可见,无患子的生殖资源分配存在明显的时空差异,较长的花期可以减少非法花粉的干扰、保持其种群基因多样性,遗传因子是决定无患子开花物候的主要因素,生态环境对无患子开花物候的影响还需进一步研究,本研究以期为探索无患子开花的主要限制因子奠定基础。     

新疆郁金香营养生长、个体大小和开花次序对繁殖分配的影响

植物有性繁殖与资源分配的关系研究对于揭示植物生活史特征及繁育系统进化具有重要意义。新疆郁金香(Tulipa sinkiangensis)是新疆天山北坡荒漠带特有的一种多年生早春短命植物。在自然生境中,该物种仅以有性繁殖产生后代,每株能产生1-8朵花,且不同植株上的花数及果实数以及花序不同位置上的花与果实大小明显不同。本文通过对新疆郁金香有性繁殖与营养生长及植株大小的关系以及花序中不同位置花及果实间的资源分配研究,旨在揭示营养生长、个体大小及开花次序对其繁殖分配的影响。结果表明:在开花和果实成熟阶段,新疆郁金香植株分配给营养器官(鳞茎和地上营养器官)与繁殖器官的资源间均存在极显著的负相关关系(P<0.01),说明其植株的营养生长与生殖生长间存在权衡关系。多花是新疆郁金香的一个稳定性状,其植株上花数目、花生物量、果实生物量和种子数量与植株生物量间均呈极显著的正相关关系(P<0.01),说明新疆郁金香植株的繁殖分配存在大小依赖性。在具2-5朵花的新疆郁金香植株中,花序内各花的生物量、花粉数和胚珠数、结实率、果实生物量、结籽数、结籽率及种子百粒重按其开花顺序依次递减,说明花序内各花和果实的资源分配符合资源竞争假说。植株通过减少晚发育的花或果实获得的资源来保障早发育的花或果实获得较多的资源,从而达到繁殖成功。     

川西风毛菊花期资源分配随海拔的变化

以分布于青藏高原东缘的川西风毛菊(Saussurea dzeure)为试验材料, 研究了其位于不同海拔高度的16个种群的花期资源分配。结果显示: 1)花期植物个体大小、头状花序数量、繁殖器官及营养器官生物量、花瓣质量、雌蕊及雄蕊群质量均与海拔呈负相关关系, 每个头状花序质量与海拔呈正相关关系; 2)繁殖分配和雄性分配与海拔呈正相关关系, 营养分配和雌性分配与海拔呈负相关关系; 3)花期头状花序的数量和大小、繁殖分配和营养分配以及雄性分配和雌性分配之间均存在资源分配上的权衡。由此推论: 1)海拔作为外界因子对川西风毛菊花期各生物量及资源分配有显著的影响; 2)在资源有限的情况下, 川西风毛菊权衡对各结构的资源投入, 通过增加繁殖分配和雄性分配来适应胁迫环境, 提高繁殖的成功率。     

巫山淫羊藿开花物候与生殖特征

研究巫山淫羊藿(Epimedium wushanense)3个种群的开花物候进程和生殖特征,分析了不同种群中的花部特征、开花物候指数和结实率差异,以及开花物候指数对巫山淫羊藿生殖成功的影响。结果表明:巫山淫羊藿花期为3月初到4月中下旬,种群开花一般历时22～27d;单株花期(花序)约12～17d;单花花期一般为3～4d。3个种群的个体水平的开花振幅曲线呈单峰型曲线,均具有较高的开花同步指数,表现出一种集中开花式样。相关分析表明:坐果数与开花高峰期、终花期、花期持续时间和花蕾数均呈极显著正相关,但坐果数与始花期无相关关系。开花物候变异系数分析表明:3个种群中花期持续时间、单花持续时间、终花期、开花高峰期和坐果数差异极显著;总花数、开花振幅和结实率差异显著;开花同步指数和始花期无显著差异性。3个种群中除同步性指数外,其余指数的变异系数均有差异,此外,巫山淫羊藿中结实率受到距的长短的影响。表明巫山淫羊藿的开花物候和生殖特征受到微环境的影响,同时生殖特征还受到花部特征距的影响。     

唐古特雪莲花部特征及生殖分配的海拔差异

为探究高山植物生殖分配策略以及分析唐古特雪莲花部特征对海拔梯度的响应机制,该研究利用采样调查法和烘干称重法,对分布在青藏高原东缘不同海拔14个居群的唐古特雪莲花部特征和生殖分配进行了研究。结果表明:(1)繁殖分配随个体大小(地上生物量和株高)的增大呈线性递减趋势。(2)花期植株地上生物量、株高、管状小花数目、繁殖器官及营养器官生物量均随海拔升高呈线性递减趋势,管状小花生物量随海拔升高呈线性递增趋势。(3)花期管状小花数量及大小、繁殖器官生物量与营养器官生物量、雄蕊重量和雌蕊重量以及花粉数目与花丝长度之间均存在权衡现象。由此推论:(1)海拔作为外界因子对唐古特雪莲花部特征具有显著的影响,个体大小对其繁殖分配也存在潜在调控作用。(2)在不同海拔梯度上,唐古特雪莲有效地整合了有限的资源,其适应性特征之一就是通过减小个体大小来削弱营养生长以达到促进生殖生长的目的。     

青藏高原东缘禾叶风毛菊的繁殖分配与海拔的相关性

通过采样调查法和烘干称重法,对分布在青藏高原东缘不同海拔高度的禾叶风毛菊的繁殖分配的特征进行研究。结果表明：（1）随着海拔的升高,禾叶风毛菊的个体大小、营养器官生物量、繁殖器官生物量、个体管状小花数目、雄蕊质量均与海拔呈负相关关系（P<0.01）;繁殖分配、管状小花生物量、雌蕊质量均与海拔呈正相关关系（P<0.01）;（2）繁殖分配是依赖个体大小的,个体越大,繁殖分配越小（P<0.01）;（3）禾叶风毛菊个体管状小花的数目及重量（P<0.05）、雌雄蕊重量（P<0.05）之间存在权衡关系。由此推论：（1）海拔作为外界因子对禾叶风毛菊花期各生物量及繁殖分配有显著的影响,但海拔并不是影响禾叶风毛菊繁殖分配唯一生态因子,植株个体大小也与其繁殖分配策略密切相关;（2）禾叶风毛菊的垂直分布的特征很有可能就是海拔通过影响植株个体大小变化来完成的。     

Reproductive ecology of distylous Palicourea Padifolia (Rubiaceae) in a tropical montane cloud forest. I. Hummingbirds' effectiveness as pollen vectors

The adaptiveness of distyly has been typically investigated in terms of its female function, specifically pollen receipt. However, pollen loads on stigmas can only provide moderate support for Darwin's hypothesis of the promotion of legitimate crosses. To determine the effectiveness of hummingbirds as pollen vectors between floral morphs and the consequences in terms of male (pollen transfer) and female function (pollen receipt) in Palicourea padifolia (Rubiaceae), floral visitors, their foraging modes, and temporal patterns of floral visitation were observed and documented. Differences in pollen and stigma morphology, pollen flow, rates of pollen deposition, and/or stigmatic pollen loads were then evaluated for their contribution toward differences in reproductive output between floral morphs. A pollination experiment with stuffed hummingbirds that varied in bill size was done to evaluate the contribution of bill variation toward differences between floral morphs in pollen receipt and pollen transfer and female reproductive output. Anthers of long-styled flowers contained significantly more and smaller pollen grains than those of short-styled flowers, independently of corolla and anther lengths. The shape and orientation of the stigma lobes differed between morphs and were significantly longer among short-styled flowers. Hummingbird visitation rates did not differ significantly between floral morphs, and foraging movements from focal plants towards neighboring plants were independent of floral morph. Stigmatic pollen loads under field conditions and those after controlled hummingbird visitation, along with rates of pollen accumulation through the day indicated that stigmas of short-styled flowers receive proportionately more legitimate (intermorph) pollen grains than did those of long-styled flowers. However, the species of hummingbird was marginally significant in explaining variation in pollen deposition on stigmas. Lastly, intermorph pollinations of P. padifolia resulted in significant differences in fruit production between floral morphs, independent of pollination treatment and pollinator species; short-styled flowers proportionately developed almost twice the number of fruits developed by long-styled flowers.     

S-LOCUS EARLY FLOWERING 3 is exclusively present in the genomes of short-styled buckwheat plants that exhibit heteromorphic self-incompatibility

The different forms of flowers in a species have attracted the attention of many evolutionary biologists, including Charles Darwin. In Fagopyrum esculentum (common buckwheat), the occurrence of dimorphic flowers, namely short-styled and long-styled flowers, is associated with a type of self-incompatibility (SI) called heteromorphic SI. The floral morphology and intra-morph incompatibility are both determined by a single genetic locus named the S-locus. Plants with short-styled flowers are heterozygous (S/s) and plants with long-styled flowers are homozygous recessive (s/s) at the S-locus. Despite recent progress in our understanding of the molecular basis of flower development and plant SI systems, the molecular mechanisms underlying heteromorphic SI remain unresolved. By examining differentially expressed genes from the styles of the two floral morphs, we identified a gene that is expressed only in short-styled plants. The novel gene identified was completely linked to the S-locus in a linkage analysis of 1,373 plants and had homology to EARLY FLOWERING 3. We named this gene S-LOCUS EARLY FLOWERING 3 (S-ELF3). In an ion-beam-induced mutant that harbored a deletion in the genomic region spanning S-ELF3, a phenotype shift from short-styled flowers to long-styled flowers was observed. Furthermore, S-ELF3 was present in the genome of short-styled plants and absent from that of long-styled plants both in world-wide landraces of buckwheat and in two distantly related Fagopyrum species that exhibit heteromorphic SI. Moreover, independent disruptions of S-ELF3 were detected in a recently emerged self-compatible Fagopyrum species and a self-compatible line of buckwheat. The nonessential role of S-ELF3 in the survival of individuals and the prolonged evolutionary presence only in the genomes of short-styled plants exhibiting heteromorphic SI suggests that S-ELF3 is a suitable candidate gene for the control of the short-styled phenotype of buckwheat plants.     

Reproductive ecology of distylous Palicourea padifolia (Rubiaceae) in a tropical montane cloud forest. II. Attracting and rewarding mutualistic and antagonistic visitors

By definition, the floral morphs of distylous plants differ in floral architecture. Yet, because cross-pollination is necessary for reproductive success in both morphs, they should not differ in attributes that contribute to attracting and rewarding floral visitors. Floral and vegetative attributes that function in distylous polymorphism in hummingbird-pollinated Palicourea padifolia (Rubiaceae) and the responses of pollinators and insect herbivores to the resources offered by both morphs were investigated. The performance of each morph along multiple stages of the reproductive cycle, from inflorescence and nectar production to fruit production, was surveyed, and pollinator behavior and nectar standing crops were then observed. Costs associated with such attractiveness were also evaluated in terms of herbivore attack and of plant reproductive fitness (female function) as a function of leaf herbivory. The number of inflorescences, floral buds, open flowers, and ripe fruits offered by either floral morph were similar, but short-styled plants almost doubled the number of developing fruits of long-styled plants. Long-styled flowers produced higher nectar volumes and accumulated more nectar over time than short-styled flowers. Measures of nectar standing crop and data on pollinator behavior suggest that hummingbirds respond to this morph-specific scheduling of nectar production. Lastly, long-styled plants suffered a higher herbivore attack and lost more leaf area over time than those with short-styled flowers. Herbivory was negatively correlated with fruit number and fruit mass, and long-styled plants set significantly less fruit mass than short-styled plants. The results suggest that pollinators and herbivores may exert selective pressures on floral and vegetative traits that could also influence gender function.     

Dimorphisms and self-incompatibility in the distylous species <Emphasis Type="Italic">Palicourea demissa</Emphasis> (Rubiaceae): possible implications for its reproductive output

Distyly has been interpreted as a mechanism that favors cross-fertilization. In this research we describe floral attributes and ancillary floral polymorphisms typically associated to heterostylous plants in Palicourea demissa (Rubiaceae), a distylous shrub of the Venezuelan Andes cloud forests. A hand-pollination experiment was done to evaluate self- and intramorph incompatibility and female reproductive output in both floral morphs. The studied population was morphologically distylous but morph differences in most ancillary floral polymorphisms and reciprocity of the sexual organ heights were found. The floral morphs were self-incompatible and did not differ in fruit set under controlled cross-pollination conditions, but at the population level they exhibited imperfect reciprocal herkogamy. Fruits and seeds of short-styled plants were larger than those of long-styled plants and fruit set was higher in short-styled plants under natural conditions, suggesting a higher reproductive potential among short-styled plants. Given the 1:1 morph ratio within the studied population, further evidence is needed to determine the influence of floral visitors and seed dispersers in the expression of heterostyly in P. demissa under natural conditions.     

绣球茜的二型花柱及其传粉生物学初步研究

首次对绣球茜(Dunnia sinensis Tutch)的花药和柱头高度、花粉和柱头形态,以及人工辅助授粉的结实情况等进行了研究.结果表明:绣球茜在同一居群中同时具有长花柱(Pin 型)和短花柱(Thrum)两种花型,长花柱植株的柱头和雄蕊高分别为9.61±0.36 mm和6.79±0.38 mm,短花柱则为6.11±0.56 mm和8.96±0.59 mm,表现出互补式雌雄异位的花部特征.通过人工辅助授粉,两种花型植株的自交和同型植株间异交都不结实,仅在型间异交方能正常结实,说明绣球茜中存在极强的自交不亲和和型内不亲和现象.在花粉与柱头形态方面:长柱型花的单花花粉量(38555.6±6258.4)显著地小于短柱型花(52145.45±8924.5)(t=4.009,P＜0.01),长柱花和短柱型花的胚珠数分别为38.73±1.85和39.1±2.25(t=-4.13,P＞0.01);长柱型花花粉粒的大小(极径21.27±0.70 μm)显著地小于短柱花(21.92±0.79μm)类型(t=3.890,P＜0.01),而柱头乳突大小长柱类型要大于短柱类型,表现出明显的二型性.研究结果表明绣球茜是一种典型的二型花柱植物.此外,对其传粉昆虫及昆虫访花行为的观察表明,蝶类(青风蝶属Graphium)和蜂类(熊蜂Bombus sp.和木蜂Xylocopa magnifica Smith)为绣球茜的主要访花昆虫和传粉昆虫,它们能够在两种不同花型植株之间有效地传粉.     

Morph-specific patterns of variation in stigma height in natural populations of distylous Jasminum fruticans

The purpose of this study was to describe morph-specific patterns of stigma–anther separation and style curling in the distylous Jasminum fruticans . We also examined whether variation in floral traits is correlated with variation in seed production. Stigma–anther separation is more variable in short-styled plants than in long-styled plants. In all populations studied, some plants bear flowers that lack any stigma–anther separation. These plants have the pollen characteristics (size and number) and compatibility relations of short-styled plants. Comparison with other distylous species illustrates that the variability of stigma–anther separation in short-styled plants is a novel finding for a distylous species. Long-styled plants have greater stigma–anther separation than short-styled plants, styles are often curled and protrude from the corolla, and anthers are placed well within the corolla tube. The frequency of long-styled plants with curled styles and the mean degree of style curling were significantly correlated with style length. Short-styled plants have larger corollas than long-styled plants and never have curled styles. Morph ratios are always 50:50 in natural populations. Mean values of each floral trait in the two morphs were significantly correlated among populations. There were no consistent differences in fecundity of the two morphs nor any correlation between floral traits and seed set for each morph in natural populations. We discuss the potential causes and significance of the two morph-specific patterns we describe; reduced stigma–anther separation in short-styled plants and the presence of curled styles in long-styled plants.     

Pollen and ovule production, floral nectary structure, and nectar secretion dynamics in tristylous Lythrum salicaria L.

Lythrum salicaria L. (Lythraceae) is tristylous, each plant forming one of three floral morphs that differ in reciprocal placement of the stigma and two sets of anthers. Several reproductive traits were compared quantitatively among these morphs. Although mean pollen viability (??93%) and total pollen per mature, indehiscent anther within a staminal level (mean CV?=?11%) were constant, the patterns of mean pollen production per anther were complex, being significantly lowest in long stamens (1,490 grains) of the short-styled morph, but highest in intermediate stamens (3,590) of the long-styled morph. Overall, pollen production was greatest (38,200) in long-styled flowers and least (22,000) in short-styled ones. On the contrary, ovule quantities per ovary (mean 107) were similar among floral morphs; thus, pollen-to-ovule ratios spanned 192 (short-styled morph) to 364 (long-styled morph), relatively low values for a strictly xenogamous species. Each morph had a recessed annular nectary of similar dimensions encircling the ovary base, with equal numbers of modified stomata distributed uniformly on the nectary surface. Most stomata were solitary (94%), whereas 5% occurred in pairs and 1% of stomatal units had just one guard cell. During nectar secretion, about 16% of pores were closed plus 28% of pores were fully occluded. Similarly, nectar volumes and solute concentrations, peak rates of nectar secretion (mean 72?C79???g sugar?h^?1) at early afternoon, and the nectar??s sucrose prevalence [S/(G?+?F) ??4.3] were not significantly different among morphs. Based on these similarities in nectary structure and nectar-secretion dynamics, traits rarely studied in tristylous species, the preferential visitation of any particular floral morph of L. salicaria during nectar foraging by insects is unlikely. Indeed, lack of discrimination among morphs by potential pollinators may be a key tenet of successful sexual reproduction in tristylous species.     

二型花柱植物海仙花报春花部性状随地理梯度的变异

植物的花部性状在异质环境中表现出不均一的适应性进化, 其自然变异可能在时空格局上呈现一定的规律性。选择同一物种的不同地理居群进行花部表型变异分析, 能揭示花部性状随地理梯度的变异模式。海仙花报春(Primula poissonii)属于典型的二型花柱植物, 依赖昆虫传粉实现严格的型间异交。该物种广布于横断山地区亚高山-高山草甸, 其分布海拔跨度大且花部性状在种内具有较高变异, 但这些变异在不同地理梯度(海拔梯度和经纬度梯度)的特定选择因子作用下的变化规律尚不清楚。本研究选择海仙花报春16个居群, 对8个花部关键性状和二型花柱繁殖器官的互补度与海拔和经纬度的关系进行研究, 探究花部性状随地理梯度变异的模式及其潜在的选择因素。研究表明, 海仙花报春两种花型的花冠管开口大小、花药高度以及短柱花柱头高度与海拔均呈正相关, 但两种花型的花冠大小, 长柱花的花瓣长度、柱头到花冠管开口的距离, 以及短柱花的花冠管长度与海拔高度间均呈负相关, 其余性状与海拔无显著相关性。除短柱花中柱头高度以外的性状均随着纬度升高而逐渐减小。长柱花中除花药和柱头间的距离以及柱头到开口的距离外, 其余性状均随着经度的增加而减小; 短柱花的花瓣长度、花药高度以及花药和柱头间的距离随着经度的增加而变大, 其余性状均随着经度的增加而减小。繁殖器官间的互补度并不随地理环境的变化而变化。花部性状的地理变异可能受访花昆虫组成的地理变化驱动。繁殖器官间互补程度的高度保守表明非选型交配在居群二态性的维持和稳定过程中起关键作用。本研究为进一步深入开展报春花属(Primula)花部性状及其选择压力的地理变异研究奠定了基础。     

Elevation-related variation in the population characteristics of distylous Primula nivalis affects female fitness and inbreeding depression

The population characteristics of distylous species are highly sensitive to stochastic natural selection pressure.Therefore,populations growing under different environmental conditions may vary in floral morph ratios,potentially affecting female fitness and leading to inbreeding depression.However,the variation in offspring quality among populations as a result of inbreeding depression is poorly understood in distylous species.This study investigates variations in plant density,seed mass,seed viabilityfemale fitness,and post-dispersal inbreeding depression in both sexual morphs(long-styled and shortstyled plants)of the distylous Primula nivalis that were subjected to different pollination treatments along an elevational gradient from 1657 to 2704 m a.s.l.Population characteristics(morph plant density and ratio)and fruit set were significantly affected by sexual morph and elevation.Plant density and fruitset frequencies were lower for short-styled than for long-styled plants at 2704 m a.s.l.The seeds from the cross-pollinated flowers of both morphs were higher in quality than those of self-pollinated flowers.The female fitness of seeds from cross-pollinated flowers of both morphs was higher than that of seeds from open-pollinated and self-pollinated flowers.The female fitness of seeds from long-styled flowers was higher than that of seeds from short-styled flowers at all elevations.Inbreeding depression increased with elevation among plants with short-styled flowers but not among those with long-styled flowers.Variation in the elevation-dependent mating system might influence female fitness and affect inbreeding depression in both floral morphs.In conclusion,the low quality of seeds from short-styled flowers at high elevations might decrease short-styled flower frequency,affecting population characteristics.     

Between-year changes in functional gender expression of Palicourea padifolia (Rubiaceae), a distylous, hummingbird-pollinated shrub

BACKGROUND AND AIMS: Because distylous species have two hermaphroditic style-length floral morphs, they face two sex allocation problems: the equilibrium morph ratio and the optimal allocation to pollen and seed production in each floral morph. Gender specialization is expected among distylous species when floral morphs differ in reproductive output. However, spatio-temporal variability in female reproductive output between morphs needs to be investigated to fully understand patterns of sexual expression and gender specialization in distylous plants. Between-year variation in flower and fruit production of hummingbird-pollinated Palicourea padifolia (Rubiaceae) was examined, focusing on functional gender expression of long- and short-styled morphs and comparing their reproductive performance in five consecutive years (1998-2002). METHODS: Between-year variation in inflorescence, floral bud and fruit production was monitored and quantified. These traits were then used as parameters to determine functional gender differences between floral morphs through time. KEY RESULTS: Inflorescence production varied among years but no significant differences were found between floral morphs. Long-styled plants initiated more floral buds per inflorescence every year than short-styled plants, suggesting higher allocation to pollinator attraction and, potentially, an increase in male fitness through pollen donation. Although fruit production was similar between morphs, their functional gender shifted across years. CONCLUSIONS: The gender expression inconsistency across years is surprising because a number of floral characters and attributes that contribute to differently attracting and rewarding effective pollinators in P. padifolia suggest gender specialization. The evidence that morphs of distylous species might specialize in functional gender mostly comes from differences among populations in seed production and non-equilibrium morph ratios based on 1-year field population surveys. The results suggest that more sampling through time is needed to detect gender specialization among distylous species with a perennial habit.