A molecular phylogeny for the large African orchid genus Disa

Phylogenetic relationships were inferred for the African subtribe Disinae (Orchidoideae, Orchidaceae), which include the large genus Disa and the small genus Schizodium. One nuclear (ITS) gene region and two plastid (trnLF and matK) gene regions were sequenced for 136 ingroup, representing 70% of all known Disinae species, as well as for 7 outgroup taxa. The combined data matrix contained 4094 characters and was analysed using parsimony and Bayesian inference. Our results show that the generic status of Schizodium can no longer be supported, as it is deeply embedded within the genus Disa. Furthermore, the currently recognised subgenera do not reflect the phylogenetic relationships and should be rejected. Several of the currently recognised sections are monophyletic, others contain misplaced elements, while some are polyphyletic. Morphological divergence, rather than convergence, has hampered previous attempts at a phylogenetic classification of the Disinae. On the basis of our molecular phylogenetic hypothesis, we propose a monotypic subtribe Disinae and a subdivision of the genus Disa into 18 sections.     

Comparative vegetative anatomy and classification of Diseae (Orchidaceae)

The leaf, stem, root, tuber and dropper anatomy of the orchid tribe Diseae (including the subtribes Satyriinae, Disinae, Brownlecinac, Huttonaeinae and Coryciinae) is reviewed. The study is largely based on investigations of 123 species, and data from several previous publications have also been incorporated. Two characters were identified as being taxonomically valuable: (1) the presence of sclerenchyma caps associated with leaf vascular bundles, and (2) the degree of dissection of the siphonostele of the tuber ('polystelic' or 'monostelic'). The phylogenetic analysis shows that anatomical characters do not change the basic structure of a cladogram that is based on morphological characters. The taxa of Diseae are discussed on the basis of anatomical data. Subtribes Satyriinae (excluding the anatomically unusual genus Pachites), Brownleeinae, Huttonaeinae, and Coryciinae are uniform in. critical anatomical characters. However, subtribe Disinae is rather diverse in vegetative anatomy. Disa sect. Micranthae differs from the rest of the genus in its leaf anatomy. The occurrence of foliar sclerenchyma bundle caps and 'polystelic' tubers supports the incorporation of Herschelianthe in Disa sect. Stenocarpa.     

Comparative vegetative anatomy and classification of Diseae (Orchidaceae)

The leaf, stem, root, tuber and dropper anatomy of the orchid tribe Diseae (including the subtribes Satyriinae, Disinae, Brownlecinac, Huttonaeinae and Coryciinae) is reviewed. The study is largely based on investigations of 123 species, and data from several previous publications have also been incorporated. Two characters were identified as being taxonomically valuable: (1) the presence of sclerenchyma caps associated with leaf vascular bundles, and (2) the degree of dissection of the siphonostele of the tuber (‘polystelic’ or ‘monostelic’). The phylogenetic analysis shows that anatomical characters do not change the basic structure of a cladogram that is based on morphological characters. The taxa of Diseae are discussed on the basis of anatomical data. Subtribes Satyriinae (excluding the anatomically unusual genus Pachites), Brownleeinae, Huttonaeinae, and Coryciinae are uniform in. critical anatomical characters. However, subtribe Disinae is rather diverse in vegetative anatomy. Disa sect. Micranthae differs from the rest of the genus in its leaf anatomy. The occurrence of foliar sclerenchyma bundle caps and ‘polystelic’ tubers supports the incorporation of Herschelianthe in Disa sect. Stenocarpa.     

Floral morphology,micromorphology and palinology of selected Sedum s.l. species (Crassulaceae)

Sedum L. (Crassulaceae) is a large and taxonomically difficult genus whose delimitation and classification are under debate. Due to the controversial results of previous cytological, morphological, and molecular studies, further investigations are needed in order to gain a shared taxonomy of the current recognized species clades. In the present paper, morphological and micromorphological features of 23 selected Mediterranean species of Sedum s.l. – collected from exsiccata or fresh specimens throughout Italy – were investigated, in order to provide additional data toward their classification above species level. In particular, the study focused on flower structure and morphology, floral epidermal surfaces and pollen morphology. The distribution pattern of the examined microcharacters across the species revealed a wide range of variation and different combinations of the single characters. NMDS analysis allowed individuating discrete groups that showed a general consistency with the current systematic delimitation of species groups. Our study also evidenced for the first time the wide morphological variability of nectaries and of the glandular indumentum, not previously investigated in detail. In addition, we proposed the combined use of floral diagrams and floral formulae as valuable tools in studying the variability of flower structure at genus level.     

Are there pollination syndromes in the Australian epacrids (Ericaceae: Styphelioideae)? A novel statistical method to identify key floral traits per syndrome

Background and Aims

Convergent floral traits hypothesized as attracting particular pollinators are known as pollination syndromes. Floral diversity suggests that the Australian epacrid flora may be adapted to pollinator type. Currently there are empirical data on the pollination systems for 87 species (approx. 15 % of Australian epacrids). This provides an opportunity to test for pollination syndromes and their important morphological traits in an iconic element of the Australian flora.

Methods

Data on epacrid–pollinator relationships were obtained from published literature and field observation. A multivariate approach was used to test whether epacrid floral attributes related to pollinator profiles. Statistical classification was then used to rank floral attributes according to their predictive value. Data sets excluding mixed pollination systems were used to test the predictive power of statistical classification to identify pollination models.

Key Results

Floral attributes are correlated with bird, fly and bee pollination. Using floral attributes identified as correlating with pollinator type, bird pollination is classified with 86 % accuracy, red flowers being the most important predictor. Fly and bee pollination are classified with 78 and 69 % accuracy, but have a lack of individually important floral predictors. Excluding mixed pollination systems improved the accuracy of the prediction of both bee and fly pollination systems.

Conclusions

Although most epacrids have generalized pollination systems, a correlation between bird pollination and red, long-tubed epacrids is found. Statistical classification highlights the relative importance of each floral attribute in relation to pollinator type and proves useful in classifying epacrids to bird, fly and bee pollination systems.     

Profile of a flower: How rates of morphological evolution drive floral diversification in Ericales and angiosperms

Premise

Recent studies of floral disparity in the asterid order Ericales have shown that flowers vary strongly among families and that disparity is unequally distributed between the three flower modules (perianth, androecium, gynoecium). However, it remains unknown whether these patterns are driven by heterogeneous rates of morphological evolution or other factors.

Methods

Here, we compiled a data set of 33 floral characters scored for 414 species of Ericales sampled from 346 genera and all 22 families. We conducted ancestral state reconstructions using an equal-rates Markov model for each character. We estimated rates of morphological evolution for Ericales and for a separate angiosperm-wide data set of 19 characters and 792 species, creating “rate profiles” for Ericales, angiosperms, and major angiosperm subclades. We compared morphological rates among flower modules within each data set separately and between data sets, and we compared rates among angiosperm subclades using the angiosperm data set.

Results

The androecium exhibits the highest evolutionary rates across most characters, whereas most perianth and gynoecium characters evolve more slowly in both Ericales and angiosperms. Both high and low rates of morphological evolution can result in high floral disparity in Ericales. Analyses of an angiosperm-wide floral data set reveal that this pattern appears to be conserved across most major angiosperm clades.

Conclusions

Elevated rates of morphological evolution in the androecium of Ericales may explain the higher disparity reported for this floral module. Comparing rates of morphological evolution through rate profiles proves to be a powerful tool in understanding floral evolution.     

Floral morphology and ontogeny in Orchidaceae subtribe Disinae

Floral morphology and ontogeny in Orchidaceae subtribe Disinae. The flower structure and development of 24 species of the orchid subtribe Disinae are described and illustrated by drawings and scanning electron micrographs with special attention being paid to the gynostemium. The morphogenesis of this subtribe is fundamentally similar to that of the closely related tribe Orchideae. This includes the initiation of the auricles on the anther base in a dorsolateral position, and hence their interpretation as being mere appendages of the filament. The keel connecting the petals and the gynostemium plus its protrusion is considered homologous to the inner lateral staminodeS. Presumed vestiges of the adaxial staminodes were detected in one specieS. A peculiarity of the Disinae is that the entire apex of the median carpel develops into the rostellum, whereas its stigmatic portion emerges from the median carpel below the rostellum in later stages. The main diagnostic feature of the group is the reflexed position of the mature anther. However, it is shown here that this anther movement occurs in the later stages and that the initial anther is erect.     

Breeding system and floral morphometry of distylous Psychotria L. species in the Atlantic rain forest, SE Brazil

General patterns of floral morphology and incompatibility mechanisms have been described for many distylous plants. The absence of these patterns in typically distylous groups, as observed especially in tropical environments, is interpreted as atypical distyly, or as a new reproductive strategy derived from it. Data are presented here on the morphological and compatibility relations between floral morphs of four Psychotria dimorphic species in the Atlantic rain forest in SE Brazil: Psychotria jasminoides, P. birotula, P. mapourioides, and P. pubigera. When significant differences were found, floral parts were larger in thrum flowers. Results of controlled crosses showed that most incompatible pollen tubes were arrested in the stigma, and only in a low proportion in the upper parts of the style. We conclude that, at the study site, the majority and most important morphological and mating features of typical distyly seem to be conserved in P. jasminoides and P. mapourioides, which presented reciprocal herkogamy, self and intramorph incompatibility, and a balanced morph ratio in the population. Typical distyly in P. birotula is supported by floral morphology, pollen tube data and morph ratio and, in P. pubigera, only by floral morphology and pollen tube data.     

Molecular phylogenetics of Diseae (Orchidaceae): a contribution from nuclear ribosomal ITS sequences

We present here the first molecular phylogeny of tribe Diseae (Orchidoideae: Orchidaceae). Nuclear ribosomal ITS1, 5.8S rDNA, and ITS2 sequences were compared for 30 Diseae, 20 Orchideae, and four Cranichideae and Diurideae outgroups. ITS - rDNA sequences exhibited a transition:transversion ratio of 1.3 and extensive ITS length polymorphism. Phylogenetic analyses using maximum parsimony identified seven major core orchidoid groups. The branching order of the five Diseae and two Orchideae clades was weakly supported but indicated paraphyly of Diseae, with Disperis sister to the rest, followed by successive divergence of Brownleea, Disinae, Coryciinae sensu stricto (s.s.), Satyriinae, and terminated by Orchidinae plus Habenariinae. Within the monophyletic Disinae, Herschelia and Monadenia were nested within a paraphyletic Disa and clustered with D. sect. Micranthae. Within monophyletic Satyriinae, Satyridium rostratum plus Satyrium bicallosum was sister to the rest of Satyrium, and then Satyrium nepalense plus S. odorum was distinct from a cluster of six species. Coryciinae are paraphyletic because Disperis is sister to all other core orchidoids. Coryciinae s.s. are sister to Satyriinae plus Orchideae, with Pterygodium nested within Corycium. Maximum likelihood analysis supported possible affinities among Disinae, Brownleeinae, and Coryciinae but did not support monophyly of Diseae or an affinity between Disinae and Satyriinae. Morphological characters are fully congruent with the well-supported groups identified in the ITS phylogeny.     

Asymmetric gene introgression in two closely related Orchis species: evidence from morphometric and genetic analyses

ABSTRACT: BACKGROUND: In food-deceptive orchids of the genera Anacamptis, Neotinea and Orchis floral isolation has been shown to be weak, whereas late-acting reproductive barriers are mostly strong, often restricting hybridization to the F1 generation. Only in a few species hybridization extends beyond the F1 generation, giving rise to hybrid swarms. However, little is known about the abundance of later-generation hybrids and what factors drive their occurrence in hybrid populations. In this study, molecular analyses were combined with detailed morphological measurements in a hybrid population of two closely related Orchis species (Orchis militaris and O. purpurea) to investigate the hypothesis that the abundance of later-generation hybrids is driven by changes in floral characters after hybridization that exert selective pressures that in turn affect hybridization. RESULTS: Both the molecular and morphological data point to extensive genetic and morphological homogenization and asymmetric introgression. Estimating genomic clines from the multi-locus genotype data and testing for deviation from neutrality revealed that 30 out of 113 (27%) AFLP markers significantly deviated from neutral expectations. Plants with large floral displays or plant with flowers that resembled more O. purpurea had higher female fitness than plants with small floral displays or plants with flowers resembling more O. militaris, suggesting that directional selection may have contributed to the observed patterns of introgression. CONCLUSIONS: These results indicate that in closely related orchid species hybridization and gene introgression may be partly driven by selection for floral traits of one of the parental types. However, because some pure individuals were still present in the studied population, the parental species appeared to be sufficiently isolated to survive the challenge of sympatry.     

石山苣苔属(苦苣苔科)花形态演化及分类学意义

石山苣苔属(苦苣苔科)约30种,主要分布于我国南部的石灰岩地区.目前该属已知物种数虽少但花形态极其多样,是该科中分类最为困难的类群之一.基于分子证据,其它8个属中花形态迥异的一些物种被并入石山苣苔属.然而,该属花形态的演化趋势缺乏系统性的研究,传统分类对属的界定与分子系统学研究结果相矛盾的原因,以及是否有形态特征支持新界定的石山苣苔属还不清楚.该研究中,总共编码了19种石山苣苔属植物和9种报春苣苔属植物的35个形态特征,其中包括26个花部形态特征,在分子系统树上追踪了它们的演化路径.结果表明:无论属内还是属间,多数花部形态特征,尤其以往属的分类界定特征,在演化过程中变化频繁且发生了高度同塑性演化,这是导致传统形态分类不自然的关键因素.此外,在观察研究的所有特征中,花丝和柱头的差异可能在石山苣苔属植物共同祖先中经历了演变,或可用于区分石山苣苔属与其姐妹报春苣苔属的大多数种类.因此,在苦苣苔科植物的分类学研究中应当慎用这些花部性状作为分类依据,而且应对形态特征进行广泛地观察研究,在密集的取样和分辨率更高、更可靠的系统树上追踪它们的演化规律.更为重要的是,需要进一步研究导致复杂形态性状演化的内在分子调控机理和外在的自然选择动力,最终更加深入地理解石山苣苔属等典型喀斯特植物的演化过程和机理.     

Floral development and anatomy of Salvadoraceae

Background and Aims

This study is an investigation into the floral development and anatomy of two genera of the small family Salvadoraceae, which belongs to the Brassicales in a clade with Batis and Koeberlinia. Salvadoraceae remains little known, despite its wide distribution in arid areas of the globe. Floral morphological data are scarce, and information on floral anatomy is limited to a single study, although morphological and anatomical characters are now used increasingly as a counterpart of molecular data. There remain a number of controversial morphological questions, such as the fusion of the petals, the number of carpels and the nature of the nectaries.

Methods

Floral anatomy and ontogeny were studied in two species of Salvadora and one species of Dobera. Only for S. persica could a full floral developmental sequence be done.

Key Results

The floral development demonstrates that the ovary of Salvadoraceae is basically bicarpellate and pseudomonomerous with a single locule and parietal placenta. The ovary of Dobera resembles Azima tetracantha in the presence of a false apical septum. Evidence for a staminodial nature of the nectaries is not decisive. In Salvadora petals and stamens are lifted by a short hypanthium.

Conclusions

Salvadoraceae share several morphological and developmental synapomorphies with Batis (Bataceae) and possibly Koeberlinia (Koeberliniaceae), supporting their close relationship as indicated by molecular phylogeny.Key words: Batis, Brassicales, Dobera, Emblingia, floral development, floral anatomy, Koeberlinia, phylogeny, Salvadora, Salvadoraceae, SEM     

Pollinator behavior and deceptive pollination: learning process and floral evolution

Some species of flowering plants engage in nonmodel deceptive pollination, attracting pollinators by large nonmimetic floral displays and providing no reward. Pollinators can learn to avoid deceptive plants and to favor nectariferous species. The reproductive success of these species is expected to be density dependent for two opposite reasons: the commoner cheating flowers are, the easier they are to avoid and the lower the quality of the patch, making it more difficult to recognize that unrewarding flowers are not profitable. When a deceptive species is made up of multiple floral variants, pollinators' learning could decrease the reproductive success of any particularly common floral variant. Within a population of deceptive plants, mean reproductive success could, therefore, vary with the number of floral variants. We investigate these three hypotheses by modeling the behavior of pollinators foraging in communities of deceptive and rewarding flowers. Simulations revealed that the reproductive success of deceptive flowers varies in a density-dependent manner and that floral variants can be submitted to negative frequency-dependent selection. We compare density dependence in nonmodel deceptive species to what is expected in Batesian mimics and discuss possible selection of morphological variants. Finally, we survey how pollinators' learning capacities can make mean reproductive success depend on morphological variability within a population.     

The relative lability of floral vs. non-floral characters and a morphological phylogenetic analysis of Cobaea (Polemoniaceae)

The relative levels of lability in floral vs. vegetative characters have been suggested to give insight into the mechanisms of adaptation and speciation. Cobaea (Polemoniaceae) exhibits a remarkable diversity in floral form. A morphology-based phylogeny was constructed and is congruent in most regards with a previously published molecular phylogeny, but significant incongruence was found in the placement of two taxa. A combined analysis was performed, excluding C. aquatoriensis and C. lutea, and was nearly identical to the molecular analysis. The phylogenies are compatible with a recently published classification. Incongruencies between the phylogenies within section Rosenbergia may have profound implications for floral evolution. A simple method for testing the levels of homoplasy, as an indicator of lability between two classes of data, is developed and used to test for differences between floral and non-floral classes of characters. The method is based on repeated randomization of the data into partitions and recalculation of a test statistic defined as the difference between consistency index (CI) values of the data in each partition over a given tree. The null hypothesis that the floral characters are no more homoplasious than the non-floral characters cannot be rejected (P=0.09).     

Competence to respond to floral inductive signals requires the homeobox genes PENNYWISE and POUND-FOOLISH

The transition from vegetative to reproductive development establishes new growth patterns required for flowering. This switch is controlled by environmental and/or intrinsic developmental cues that converge at the shoot apical meristem (SAM). During this developmental transition, floral inductive signals cause the vegetative meristem to undergo morphological changes that are essential for flowering. Arabidopsis plants containing null mutations in two paralogous BEL1-like (BELL) homeobox genes, PENNYWISE (PNY) and POUND-FOOLISH (PNF), disrupt the transition from vegetative to reproductive development. These double mutants are completely unable to flower even though the SAM displays morphological and molecular changes that are consistent with having received floral inductive signals. These studies establish a link between the competence to receive floral inductive signals and restructuring of the SAM during floral evocation.     

中国头细蛾属昆虫(鳞翅目,细蛾科)与大戟科植物互利共生关系研究进展

细蛾科头细蛾属昆虫与大戟科算盘子属、叶下珠属和黑面神属植物互利共生关系的发现为研究昆虫与植物协同演化过程提供了一个全新的模式。目前,国内对头细蛾与大戟科植物的互利共生关系了解和研究都很少。本文介绍了头细蛾的分类、生物学和形态适应;大戟科相关5属植物(算盘子属、叶下珠属、黑面神属、白饭树属和守宫木属)的生物地理学,开花生物学,花的结构与传粉系统的关系;寄主植物与传粉者的对应关系;互利共生关系的维持机制等。研究表明中国有丰富的头细蛾与大戟科植物资源,开展其互利共生关系的研究有重要科学意义。很多新的、复杂的头细蛾与大戟科植物的生态关系和大量的头细蛾种类有待我们去发现和研究。     

Pollinarium morphology and floral rewards in Brazilian Maxillariinae (Orchidaceae)

BACKGROUND AND AIMS: There is strong support for the monophyly of the orchid subtribe Maxillariinae s.l., yet generic boundaries within it are unsatisfactory and need re-evaluation. In an effort to assemble sets of morphological characters to distinguish major clades within this subtribe, the pollinarium morphology and floral rewards of representative Brazilian species of this subtribe were studied. METHODS: The study was based on fresh material from 60 species and seven genera obtained from cultivated specimens. Variation of pollinarium structure and floral rewards was assessed using a stereomicroscope and by SEM analysis. KEY RESULTS: Four morphological types of pollinaria are described. Type 1 appears to be the most widespread and is characterized by a well-developed tegula. Type 2 lacks a stipe and the pollinia are attached directly to the viscidium. Type 3 also lacks a stipe, and the viscidium is rigid and dark. In Type 4, the stipe consists of the whole median rostelar portion and, so far, is known only from Maxillaria uncata. Nectar, trichomes, wax-like and resin-like secretions are described as flower rewards for different groups of species within the genus Maxillaria. Data on the biomechanics and pollination biology are also discussed and illustrated. In Maxillariinae flowers with arcuate viscidia, the pollinaria are deposited on the scuttellum of their Hymenopteran pollinators. In contrast, some flowers with rounded to rectangular, pad-like viscidia fix their pollinaria on the face of their pollinators. CONCLUSIONS: Pollinarium morphology and floral features related to pollination in Brazilian Maxillariinae are more diverse than previously suggested. It is hoped that the data presented herein, together with other data sources such as vegetative traits and molecular tools, will be helpful in redefining and diagnosing clades within the subtribe Maxillariinae.     

Morphological evolution in the variable resin-producing Detarieae (Fabaceae): do morphological characters retain a phylogenetic signal?

Background and Aims

Previous molecular phylogenetic studies disagree with the informal generic-level taxonomic groups based on morphology. In this study morphological characters in the caesalpinioid clade Detarieae are evaluated within a phylogenetic framework as a means of better understanding phylogenetic relationships and morphological evolution.

Methods

Morphological characters were observed and scored for representative species of Detarieae focusing on the resin-producing genera. Phylogenetic analyses were carried out with morphological characters alone and then combined with DNA sequences.

Key Results

Despite a high level of homoplasy, morphological data support several clades corresponding to those recovered in molecular phylogenetic analyses. The more strongly supported clades are each defined by at least one morphological synapomorphy. Several characters (e.g. apetaly) previously used to define informal generic groups evolved several times independently, leading to the differences observed with the molecular phylogenetic analyses. Although floral evolution is complex in Detarieae some patterns are recovered.

Conclusions

New informal taxonomic groupings are proposed based on the present findings. Floral evolution in the diverse Detarieae clade is characterized by a repeated tendency toward zygomorphy through the reduction of lateral petals and toward complete loss of petals.Key words: Caesalpinioideae, Detarieae, floral evolution, Leguminosae, morphology, phylogeny, resins, taxonomy