Reproductive ecology in the endemic Primula apennina Widmer (Primulaceae)

Abstract

Disassortative mating in distylous self-incompatible species should result in the equilibrium of morph types in natural populations. Deviation from isoplethy may affect pollen transfer, and in isolated populations it could lead to Allee effect and genetic drift. Pollen limitation has been found to occur in several distylous species, for which mating opportunities are actually reduced to half population. In this study, we investigated the reproductive features and pollination ecology of the narrow endemic Primula apennina. We recorded equilibrium of morph frequencies in the studied population, reflecting the comparable fecundity found in the two morphs. Long-styled flowers produce more pollen grains of smaller size than short-styled ones: we hypothesize that in thrum flowers, pollen is more easily removed by the insect pollinator Macroglossum stellatarum, resulting in equal pollen amounts carried to both short styles and long styles. This lower pollen transfer efficiency from long-styled to short-styled flowers is also reflected in legitimate pollen–ovule ratio values. Despite results show no evidence of imminent threats to population persistence at study site, the strict dependence on one or very few pollinator species, and ecological traits, may increase extinction risks in the long-term period.     

Breeding system of the threatened endemic Primula cusickiana var. maguirei (Primulaceae)

Maguire primrose (Primula cusickiana var. maguirei) is a threatened, narrow endemic found only along a 20‐km section within a single canyon in northern Utah, USA. Here we describe the breeding strategy of this perennial, distylous, primarily cliff‐dwelling species to test for reproductive constraints on the plants. Intermorph outcrossing treatments (i.e. between pin and thrum flowers) were the most successful hand pollinations performed, but those were usually inferior to natural pollination. Intramorph out‐crossing also was somewhat successful, but was consistently inferior to intermorph outcrossing. Seed‐set resulting from autogamy and geitonogamy treatments was least successful. Morph‐specific differences in seed set were observed for our hand pollinations, but not in natural pollination conditions. Our results suggest that pollinators play a crucial role by providing the pollen transfer necessary for maximal seed set in this rare and narrowly distributed distylous plant.     

Chromosomal variability in the genus Primula (Primulaceae)

Chromosome numbers and measurements were recorded in 47 individuals of ten taxa of Primula , representing eight species and two subspecies from ten populations. The basic numbers of chromosomes were x  = 8, 9 or 11, and they were mostly metacentric, medium-long to medium-small, ranging in length from c . 3.6 µm to 1.6 µm. Diploid chromosome numbers of 2 n  = 2 x  = 24 and 22 were scored for the first time in P. loeseneri Kitag. and P. prenantha Balf. & Sm., respectively. A new ploidy level of 2 n  = 4 x  = 44 was found in P. burmanica Balf. & King. The recorded diploid numbers of the remaining species confirmed earlier reports. Interspecific variability in chromosome numbers was correlated with heterogeneity in their mean length. Comparison of the data with those in the literature revealed that the observed variability of chromosomal characters was compatible with the other taxonomic criteria and supports the current taxonomic delimitation. Chromosomal variation at the diploid level is the predominant feature in Primula evolution, and allopatric speciation has played a major role in its specific diversity. Subgen. Aleuritia could represent the main clade from which the other subgenera have evolved. The origin of the chromosome numbers, geographical distribution and evolution of the species were assessed, and the parallel polyphyletic mode of evolution in the genus was confirmed.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 211–219.     

High genetic diversity detected in the endemic Primula apennina Widmer (Primulaceae) using ISSR fingerprinting

Primula apennina Widmer is endemic to the North Apennines (Italy). ISSR were used to detect the genetic diversity within and among six populations representative of the species distribution range. High levels of genetic diversity were revealed both at population percentage of polymorphic band (PPB = 75.92%, H _S = 0.204, H _pop = 0.319) and at species level (PPB = 96.95%, H _T = 0.242, H _sp = 0.381). Nei gene diversity statistics (15.7%), Shannon diversity index (16.3%) and AMOVA (14%) detected a moderate level of interpopulation diversity. Principal coordinate and Bayesian analyses clustered the populations in three major groups along a geographic gradient. The correlation between genetic and geographic distances was positive (Mantel test, r = 0.232). All together, these analyses revealed a weak but significant spatial genetic structure in P. apennina, with gene flow acting as a homogenizing force that prevents a stronger differentiation of populations. Conservation measures are suggested based on the observed pattern of genetic variability.     

鄂报春(Primula obconica Hance)亲缘地理学的初步研究

为了获得鄂报春（Primula obconica Hance）的种内亲缘地理学信息,对叶绿体基因组上非编码区trnL-trnF的序列变异进行了分析.获得的20个单倍型具有一定的地理分布结构.对这些单倍型进行系统发育分析,得到了三个主要分支：东部分支广泛分布于中国东南部、湖南、湖北、四川和云南;四川分支分布于四川西部;云南分支分布于云南西北部.东部分支分布面积较后两个分支大,并且在东部分支中可以发现一定的演化关系.结合古气候学和地质学信息,推测东部分支中现存的单倍型由冰期时气候变冷导致鄂报春快速迁移而形成,云南、四川分支中的单倍型可能是在各自的避难所中得以保存.同时本文也简要地探讨了鄂报春几个亚种之间的分类学关系.     

Primula cusickiana (Primulaceae) and its varieties

Primula domensis Kass & S. L. Welsh,P. maguirei L. O. Williams, andP. nevadensis N. H. Holmgren are reduced to varietal status underP. cusickiana (A. Gray) A. Gray.     

木里报春一新异名

将新近发表的Primula hongshanensis D. W. H. Rankin, Z. D. Fang &; H. Sun处理为木里报春P. boreiocalliantha的异名, 对近缘的几个种列出了检索表。     

Pollination ecology and breeding system of the very narrow coastal endemic Seseli farrenyi (Apiaceae). Effects of population fragmentation

The reproductive biology of Seseli farrenyi (Apiaceae), a very narrow endemic to Cape Creus (Catalonia, Spain), including flowering timing patterns, quantity and quality of pollination services (type and frequency of pollinators, pollen carryover, pollen deposition on stigmas and reproductive success measured as fruit set), and breeding system was studied. Given the decline of population size detected in the last twenty years, we also analyzed the effects of fragmentation on pollination mechanisms. Protandry along with strong synchrony of floral development within umbels and sequential inflorescence emission within individual stalks, produces sexual phase alternation that promotes a strong outcrossing despite its non-specific pollination system and its (at least partial) self-compatibility. This pronounced xenogamy is supported by results of the insect exclusion test, hand-pollination experiments, and high P/O ratio. S. farrenyi flowers received visits from at least 28 species of insects, including wasps, small bees, ants, flies, syrphid flies, beetles and stink bugs, with different pollen carry-overs. Heterospecific pollen on stigmas decreased notably during the season (50% to 2.5%), averaging 12%. In the small population the stigmatic pollen loads and seed set decreased, but there was no effect of pollinator visitation rates. It was more affected by the composition of pollinators and their efficiency. The wind had a considerable effect on the plant. Some conservation measures are proposed.     

九种报春花属植物的核形态学研究

对报春花属（Prinula)4个组9种植物进行了核形态学研究。这9个种的间期核构形均为复杂染色中心型,前期染色体属于中间型,体细胞有丝分裂中期染色体的数目及核型如下：中甸海水仙报表P.monticola(Hand.-Mazz.)Chen et C.M.Hu,K(2n)=16=12m 4sm;高穗花报春P.vialii Delavay ex Franch.,K(2n)=20=16m 2sm 2st;偏花报春P.secundiflora Franch.,K(2n)=22=18m 4sm;海仙花报春P.poissonii Fanch.,K(2n)=22=16m 6sm;霞红灯台报春P.beesiana Forr.,K(2n)=22=18m 4sm;桔红灯台报春P.bulleyana Forr., K(2n)=22=18m 4sm;橙红灯台报春P.aurantiaca W.W.Smith et Forr.,K(2n)=22=16m(sat) 6sm;粉被灯台报春P.pulverulenta Duthie,K(2n)=22=19m 2sm 1st;钟花报春P.sikkimensis Hook.,K(2n)=20=14m(1sat) 4sm 2T。其中,中甸海水仙报春和高穗花报春两种的染色体数目及核型为首次报道。同时,本文还将偏花报春与灯台组报春以及钟花组报春进行了细胞学的比较分析。     

Primula alcalina (Primulaceae): A new species from Idaho

Brittonia - Primula alcalina, endemic to east-central Idaho, is described and illustrated. Closely related toP. incana, it differs in having smaller flowers that are white instead of lilac, and a...     

Flavonoid diversification in different leaf compartments of Primula auricula (Primulaceae)

Populations of Primula auricula L. subsp. auricula from Austrian Alps were studied for flavonoid composition of both farinose exudates and tissue of leaves. The leaf exudate yielded Primula-type flavones, such as unsubstituted flavone and its derivatives, while tissue flavonoids largely consisted of flavonol 3-O-glycosides, based upon kaempferol (3, 4) and isorhamnetin (5–7). Kaempferol 3-O-(2″-O-β-xylopyranosyl-[6″-O-β-xylopyranosyl]-β-glucopyranoside) (3) and isorhamnetin 3-O-(2″-O-β-xylopyranosyl-[6″-O-β-xylopyranosyl]-β-glucopyranoside) (6) are newly reported as natural compounds. Remarkably, two Primula type flavones were also detected in tissues, namely 3′-hydroxyflavone 3′-O-β-glucoside (1) and 3′,4′-dihydroxyflavone 4′-O-β-glucoside (2), of which (1) is reported here for the first time as natural product. All structures were unambiguously identified by NMR and MS data. Earlier reports on the occurrence of 7,2′-dihydroxyflavone 7-O-glucoside (macrophylloside) in this species could not be confirmed. This structure was now shown to correspond to 3′,4′-dihydroxyflavone 4′-O-glucoside (2) by comparison of NMR data. Observed exudate variations might be specific for geographically separated populations. The structural diversification between tissue and exudate flavonoids is assumed to be indicative for different ecological roles in planta.     

Pollination ecology and pollination system of Impatiens reptans (Balsaminaceae) endemic to China

BACKGROUND AND AIMS: China is one of the centres of geographical distribution of Impatiens L. Studies of the pollination ecology of this genus in China have, until now, been unreported. Impatiens reptans, a species endemic to China, was studied. The aims were to examine the pollination ecology and pollination system of this species, to compare its pollination ecology with other Impatiens species growing in Sumatra and Japan, and to discuss possible reasons for its limited distribution. METHODS: The pollination ecology of I. reptans was studied by carrying out continuous observations within three naturally growing populations. Its pollination system was studied using different pollination methods, marking and counting pollen grains, assessing pollen viability and observing pollinator behaviour. KEY RESULTS: The flowering phase of the protandrous I. reptans lasted for 89 d. The life span of an individual flower was 3.6 d. Primary pollinators were honey-bees and bumble-bees. Secondary pollinators were diurnal hawk moths and butterflies. Bombus briviceps and Bombus sp. were nectar gatherers. The mean nectar sugar concentration was 29.5 %, and the mean value of sucrose/glucose + fructose was 0.82. The proportion of seed set ranged from 0.857 to 0.873. Distances that seeds were ejected ranged from 0.58 to 1.17 m. Percentage seed germination under controlled conditions was 23.1. Pollen viability was highest on the day of anthesis and thereafter decreased. Ratios of pollen : ovules ranged from 958.8 to 970.6. CONCLUSIONS: Impatiens reptans reproduces by means of cross-pollination. Its dependence on a specialized habitat, a narrow environmental niche, a low percentage of seed germination, and habitat loss could be reasons for its limited distribution and endemism.     

横断山地区海仙报春的谱系地理学研究

由于横断山地区特殊的地理效应,第四纪冰期气候的反复变化对该地区植物的地理分布和居群遗传结构产生重要影响。为了揭示该地区分布的物种的谱系地理结构,检测了该地区特有的、生于湿地环境的植物海仙报春（Primula poissonii）的叶绿体trnL—F和trnT—L两个序列变异。共对13个居群167个个体的两个叶绿体片段进行测序,共发现11个单倍型。三种单倍型被共享,其他单倍型都只存在于单个居群内。分子变异分析（AMOVA）结果表明分布区内海仙报春的遗传变异主要存在于居群间（99．08％）,且居群间的遗传分化很高（GST=0．916,FST=0．99077,NST=0．973）,有着极显著的谱系地理学结构（NST〉GST,P〈0．01）和较低的居群间平均基因流（Nm=0．08）。结合嵌套分支分析（NCA）,本文的研究结果推测该物种在冰期可能存在多个避难所,并没有表现出大多数温带植物在第四纪冰期所经历过的种群集体扩张和迁移的现象,异域片段化被认为是该物种现有单倍型分布格局形成的主要原因。海仙报春的谱系地理结构是气候的反复波动和横断山特殊的地理环境互相作用的结果。     

Pollination ecology of the pre-Pyrenean endemic Petrocoptis montsicciana (Caryophyllaceae): effects of population size

Petrocoptis montsicciana (Caryophyllaceae) is a threatened pre‐Pyrenean endemic that grows exclusively on caves and walls of limestone. We studied its pollination ecology by monitoring phenology and by evaluating pollen and nectar production, pollinator activity (frequency and behaviour of visitors), quantity and quality of pollination services, pollen/ovule ratio, and seed set in response to insect exclusion and self‐compatibility tests. We also analysed the effect of population size on reproductive mechanisms by comparing a large and a small population. Flowers of P. montsicciana produced nectar and were visited by Hymenoptera (79.7%), Diptera (11.5%), and Lepidoptera (8.8%). The most frequent pollinators (60.6% of total visits) were long‐tongued bees of the genus Anthophora. Both populations had a similar range of pollinators. We found a correlation between the number of visited flowers and the number of open flowers per census; 88.7% of pollen grains deposited on the stigmas were conspecific and the main competitor was another chasmophyte plant, Antirrhinum molle. Bagged flowers set seeds but significantly less so than hand‐self‐pollinated and control flowers. Thus, although self‐compatible and self‐pollinated, entomophilous pollination of P. montsicciana is required in order to explain c. 10–40% of total seed set, in accordance with P/O ratio estimations. Bagged flowers from the small population set significantly more seeds than the large one. Visitation rates were lower in the small population, but, unexpectedly, showed higher stigmatic pollen loads and similar or higher seed set. These results suggest an increase of spontaneous selfing rates in the small population, probably favoured by a smaller flower size, which can not only assure reproductive success when pollinators are scarce, but also provide additional potential to adapt to climatic changes. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 76 , 79–90.     

喜马拉雅-横断山区钟花报春居群遗传多样性及遗传分化

应用简单序列重复区间(ISSR,Inter-simple sequence repeat)分子标记,对喜马拉雅．横断山区钟花报春(Primula sikkimensis)进行居群遗传分析。用10个ISSR引物对13个居群的254个个体进行扩增,共检出91条扩增片段,全部为多态带,总的多态位点百分率为100％。Shannon多样性指数(Ho)从0．2293到0．4016,居群水平上平均值(HPCP)为0．3211,物种水平上(Hsp)为0．5576。利用分子方差(AMOVA)软件分析,其结果为：在总的遗传变异中,有50．28％的遗传变异属于居群之间;用POPGENE计算出的遗传分化系数GST=0．4127,即居群间的分化变异占居群总遗传变异的41．27％,比AMOVA分析所得的结果偏低。居群间遗传距离变化范围从0．0780到0．4748,遗传一致度(I)的变化范围从0．6220到0．9250。居群间的基因流Nm=0．7114,相对低的基因流可能是维持钟花报春居群遗传分化的原因。这表明,喜马拉雅．横断山区钟花报春的13个居群具有很高的遗传多样性,并且居群间的分化也很大。     

Distribution range and ecological niche of Primula marginata Curtis (Primulaceae)

The distribution range of Primula marginata Curtis (Primulaceae) has never been fully characterized. In the present study, authors did a revision of the distribution range using herbaria material, database records and in situ populations' check-up. P. marginata was confirmed extending from Cottian to Maritime and Ligurian Alps, with few outlier occurrences in the northern Apennines. The localities previously reported from northern Piedmont (Val d'Ossola) were not confirmed. Maximum entropy model (Maxent) was used to simulate the potential distribution of P. marginata under current climate conditions. According to the distribution modelling performed, the species prefers rocky calcareous habitats mainly at high elevations, with abundant precipitation, but low moisture retention at soil level and marked temperature range between winter and summer seasons. The potential distribution area drawn by Maxent seemed to describe P. marginata at its maximum extension, and any future climate changes might cause limitations for the survival of the species.     

Characterization of microsatellite loci in Primula modesta Bisset et Moore (Primulaceae)

Eleven microsatellite loci were isolated from alpine plant Primula modesta. Enriched repeat libraries were constructed and screened by colony hybridization. Forty‐eight polymerase chain reaction (PCR) primer pairs were designed, of which 11 pairs producted successful amplification. A total of 31–35 adult individuals were genotyped for allelic diversity. The polymorphism ranged from three to 14 alleles, and the heterozygosity ranged from 0.161 to 0.828. No linkage disequilibrium was found between these 11 loci.     

Effect of plant traits and population structure on the female reproductive success of the endemic Primula elatior subsp. bergidensis (Primulaceae)

This study explores the possible causes of variation in female reproductive success of the subspecific taxon Primula elatior subsp. bergidensis, a distylic endemic to the north-western Iberian Peninsula, by analysing both vegetative and reproductive traits. In three populations, we marked vegetative and reproductive individuals either by mapping the spatial position of every individual (in one population), or by establishing permanent quadrats (in the remainder two populations). We recorded floral morph (pin or thrum), width and length of the largest leaf, scape length, and number of flowers produced; all individuals were monitored to estimate the number of fruits and seeds produced. The results show that the morph ratio did not differ significantly from 1:1 in any of the populations. The number of flowers per plant varied between populations, and longer scape length was associated with higher fruit set in all populations. Plant size, scape length, and population spatial structure all had major effects on reproductive success, but the strength—and in some cases the direction—of the effects varied among populations.     

Isolation and characterization of fifteen polymorphic microsatellite loci from Primula merrilliana (Primulaceae), an endemic from China

Primula merrilliana (Primulaceae) is an endangered plant endemic to south Anhui Province in China. In this study, we isolated fifteen polymorphic microsatellite loci from a population of 22 individuals using a modified biotin-capture method. Our isolated loci provided microsatellite markers with polymorphism of 3–11 alleles per locus. The expected and observed heterozygosities ranged from 0.392 to 0.855 and from 0.136 to 1.000, respectively. These markers would be the useful tools for analyzing questions concerning population genetic structure and mating system of Primula merrilliana.