Floral and reproductive biology of Drosophyllum lusitanicum (L.) Link (Droseraceae)

We studied the floral and reproductive biology of Drosophyllym lusitanicum (Droseraceae), a species endemic to the western Iberian Peninsula and northwest Morocco. Flowering lasted from March to August, peaking in April. The species is clearly homogamous, with pollen germination and stigma receptivity occurring even in preanthesis. This was reflected in the high rates of fruit set and seed set in bagged inflorescences. Fructification did not differ significantly between different pollination treatments, although we did find differences between some treatments in the numbers of viable seeds per flower and fruit. However, seed weight did not differ significantly. The importance of self-pollination over cross-pollination was also supported by the low percentages of fructification (24.67%) after emasculation and open pollination. Metameric deviations were seen in flowers, although this abnormality was not translated as any reproductive benefit or disadvantage (fructification, number or weight of seeds) in comparison with normal flowers.     

Regional differences in land use affect population performance of the threatened insectivorous plant Drosophyllum lusitanicum (Droseraceae)

Abstract. We analyse populations of the insectivorous plant Drosophyllum lusitanicum (L.) Link (Droseraceae) and their habitats throughout the species' distribution range (Portugal, Spain and Morocco), and examine their relations. We have surveyed 32 populations and we analyse their demographic structures, accompanying plant communities (by twinspan analyses), and relationships between population features and several edaphic and nonedaphic environmental variables (by multiple regression analyses). Plant communities, their floristic richness and degree of endemism change across the geographical range of Drosophyllum . Populations vary strongly in size, density and age structure. Their recruitment seems largely determined by competition with the surrounding vegetation, while only weak relationships were detected between population performance and other environmental factors. The demographic structure of populations exhibits a marked geographical differentiation, with populations becoming older and sparser towards the north-western part of the range. The largest and presumably most stable populations are mostly found in southern Spanish heathlands, which are nowadays scarcely affected by man. Moroccan populations suffer from browsing by cattle and experience an accelerated generation turnover, while most Portuguese populations occur in afforested areas and experience strongly reduced recruitment. The historical distribution range of Drosophyllum within its peculiar habitat has probably been relatively stable, but recent regional differences in human land use have resulted in present-day differences in population performance, as well as in types and degrees of threat across the three countries involved. Conservation strategies should take into account this range-wide variation and combine approaches on different spatial scales.     

Plumbagin recovery from field specimens of Drosophyllum lusitanicum (L.) link

The naphthoquinone plumbagin has a broad spectrum of biological activities. The aim of this study was to investigate the efficiency of two extraction methods (Soxhlet and ultrasound-assisted extraction) and three solvents (methanol, chloroform and hexane) to recover plumbagin from fresh and dried tissues of field specimens of Drosophyllum lusitanicum (L.) Link. The highest extraction yields were obtained with methanol as solvent and using fresh plant material. The obtained extracts were analysed by gas chromatography with mass spectrometric detection and plumbagin was the major compound present. Plumbagin was quantified in the extracts using the external standard methodology. The results obtained showed that the best recoveries of plumbagin were attained using fresh plant material and there were no significant differences between Soxhlet and ultrasound-assisted extraction. Moreover, hexane proved to be the more appropriate solvent for the extraction of plumbagin, providing high recoveries and the most concentrated extracts, yielding 2.42 mg of plumbagin per gram of plant material with the highest degree of purity. This method is a simple and efficient one to extract large amounts of plumbagin from D. lusitanicum field specimens.     

Cryptic dioecy in Mammea (Clusiaceae)

The flowers of Mammea (Clusiaceae) have been reported to be androdioecious, a rare condition in the angiosperms. Pollen from eight taxa from most of the geographic range of the genus was examined to clarify the type of flowers, and thus the breeding system, of the genus. In six of these taxa pollen from both morphologically perfect and male flowers was examined, while in the other two, only pollen from the perfect flowers was used. In all cases pollen from perfect flowers was inaperturate, while that from the staminate flowers was aperturate. Since the inaperturate pollen probably cannot germinate, it is concluded that the perfect flowers are functionally female. Therefore, Mammea has a cryptic dioecious breeding system.The author would like to thank Peter Endress, Michael Hesse, Toby Kellogg, P. Mick Richardson, and Peter F. Stevens for editorial comments and advice. Andrew Doust, Sara Fuentes and Ken Hiser helped on the SEM. Much thanks goes to Peter F. Stevens for his helpful support throughout this project.     

Ruellia subsessilis (Nees) Lindau (Acanthaceae): A species with a sexual reproductive system that responds to different water availability levels

In Ruellia subsessilis the typical cleistogamy (cleistogamous and chasmogamous morphs), which is common in species of this genus, was not observed. Flowering and fruiting of this species are continuous and the selfing flowers are polymorphic. Objective of present study was to analyze the mechanisms of self-pollination in R. subsessilis. In addition, we studied its reproductive phenology, floral biology, breeding system, seed germination and how its sexual reproductive system responds to different water availability levels. The study was conducted with plants of a natural population and others in a greenhouse, under different water availability levels, in southeastern Brazil. The distribution of the reproductive phenophases was seasonal and concentrated in the rainy season. Production of distinct floral morphs could be observed. These different morphs are named ‘reduced chasmogamous morphs’ (RC), in the dry season, and ‘normal chasmogamous morphs’ (NC), which latter develop in the rainy season. The morph production of the cultivated plants was likewise influenced by water availability: RC developed under drought stress and NC in moist soil. Significant differences between morphs were observed in size parameters of the corolla, androecium and gynoecium, and concerning the number of ovules and pollen grains. In both morphs, selfing occurred late (delayed self-pollination), and pre-anthesis cleistogamy (early self-pollination) occurred sporadically in RC. The seeds resulting from self-pollination were more vigorous and germinated faster than those from cross-pollination.     

Naphthalene glucoside and other phenolics from the shoot and callus cultures of Drosophyllum lusitanicum

The callus and, for the first time established, shoot cultures of Drosophyllum lusitanicum Link. (Droseraceae) yielded new naphthalene glucoside-5-hydroxy-4-methoxy-2-naphthalenecarboxylic acid 5-O-beta-glucoside (drosophylloside) and 5-hydroxy-4-methoxy-2-naphthalenecarboxylic acid methyl ester besides other phenolics like naphthalenes-5-hydroxy-4-methoxy-2-naphthalenecarboxylic acid (ancistronaphthoic acid B), hydroplumbagin 4-O-glucoside, naphthoquinones-plumbagin and 3-chloroplumbagin, C-glycosylflavones- vitexin, isovitexin, orientin and isoorientin. The pattern of phenolics found supports affinity of Drosophyllum to the families-Droseraceae, Ancistrocladaceae and Dioncophyllaceae.     

Cryptic species in Diacyclops bicuspidatus (Copepoda:Cyclopoida): evidence from crossbreeding studies

The problem of cryptic species in Diacyclops bicuspidatus was examined using interpopulation crosses of four populations collected from a: (1) permanent flood lake in Kiev, Ukraine, (2) temporary pool in Kiev, (3) permanent pond in St. Petersburg, Russia (1200 km to north from Kiev) and (4) lake in Crimea (1100 km south of Kiev). The only interpopulation crosses to exhibit fertility were those between the St. Petersburg population and each of the two Kiev populations. The crosses between the Kiev and Crimea populations, between the St. Petersburg and Crimea populations, and between the two Kiev populations were sterile, as evidenced by either nonviable eggs, empty egg membranes or incomplete copulations. The F₁ hybrids resulting from the St. Petersburg permanent pond X Kiev flood lake cross were fertile and produced mature F₂ offspring. Some data on development times of parental and hybrid lines are presented. The St. Petersburg parental line showed development times almost twice as long as those of the Kiev flood lake population when reared at 10 °C and 20 °C in the laboratory. The F₁ offspring of the cross between St. Petersburg females and Kiev floodlake males showed similar development times to females of the St. Petersburg parental lines at both temperatures. The F₂ hybrids also showed development times that approximated those of the St. Petersburg parental line. These crossbreeding studies suggest the presence of cryptic species in the D. bicuspidatus inhabiting ecologically different populations in many parts of its large holarctic range.     

Elicitation of plumbagin by chitin and its release into the medium in Drosophyllum lusitanicum Link. suspension cultures

Polysaccharides (chitin/pectin) that are involved in the interactions between plants and microorganisms were applied to the cultured cells of Drosophyllum lusitanicum. In the case of chitin addition, elicitation and crystallization of plumbagin in the medium were observed. N-Acetylchitooligosaccharides smaller than heptamers [(GlcNAc)n (n<7)] elicited the biosynthesis of plumbagin but did not increase the hypersensitive response (HR). On the other hand, carboxymethylchitin (DP200) led to the accumulation of plumbagin in cells and to HR death as well as to the lysis of the cells and release of plumbagin into the medium. The response of cultured cells to the N-Acetylchitosaccharides varied depending on the chemo/physiological conditions of the cells. Addition of pectin (1g/l) resulted in enhanced HR and decreased biosynthesis of plumbagin. © Rapid Science Ltd. 1998     

Cryptic seed heteromorphism in Packera tomentosa (Asteraceae): differences in mass and germination

Seed mass variation and heteromorphism may afford plant species differential germination behavior and ultimately seedling success, particularly in disturbed habitats. We asked whether such variation occurs in Packera tomentosa (Michx.) C. Jeffrey (Asteraceae), a clonal species of the southeastern USA. Seed mass was compared within and among genetic individuals differentiated using amplified fragment length polymorphisms. We compared central and peripheral seeds produced by disc and ray florets, respectively, for their morphology, mass, and germination behavior, including response to water availability, aging, and cold stratification. Seed mass was highly variable both within and among individuals and influenced germination behavior. We found cryptic seed heteromorphism in P. tomentosa. Central and peripheral seeds had similar morphologies but dissimilar mass and biomass allocation. We used failure time analysis to detect different germination behavior. Central seeds were heavier, contained larger embryos, and germinated faster and at a higher proportion in most germination studies. Highly variable mass and heteromorphism of seeds may allow persistence of P. tomentosa in its disturbed habitats. Based on our results, some future studies of Asteraceae species with disc and ray florets may need to account for possible differences between seed types, even when morphological differences are not apparent. Evaluation of individual seed mass and maternal differences in germination studies may assist in the detection of cryptic seed heteromorphism, a phenomenon thought to be common, yet rarely documented.     

Cryptic species and morphological plasticity in long-lived bivalves (Unionoida: Hyriidae) from inland Australia

Molecular (mitochondrial DNA, isozyme) and morphological diversity of freshwater mussels (Family Hyriidae) was examined at 21 sites encompassing four large river systems, across southwest Queensland, Australia. Evidence was found for two major morphological groups. One group, which occurred in every river system, closely matched a recognized species (Velesunio ambiguus) both morphologically and in a well-supported lineage within a mitochondrial phylogeny generated from partial cytochrome c oxidase subunit I (COI) sequences. The second group most closely matched Velesunio wilsonii in shell morphology but formed three deeply divergent mitochondrial DNA lineages. All four lineages occurred sympatrically in some areas and displayed corresponding fixed differences at nuclear allozyme loci, which suggests an absence of recent hybridization and the presence of separate species.     

Directed Positioning of Micronuclei in Paramecium tetraurelia with Laser Tweezers: Absence of Detectible Damage After Manipulation

Possible covert damage from the use of the laser optical force trap (laser tweezers) to reposition micronuclei in Paramecium tetraurelia was assessed by measuring proliferation rates and postautogamous survival and mutation rates of cells after laser manipulations. No differences in subsequent daily proliferation rates among laser manipulated and various control classes of cells were seen. Similarly, the rates of postautogamous lethality and of “slow growth mutations” after repositioning of both micronuclei were not different from such rates in unmanipulated controls. In spite of extensive manipulations of micronuclei by the laser tweezers, there is no evidence of any damage induced by these manipulations. The laser tweezers therefore appears to be a tool of benign effect upon living cells, with tremendous potential use in many cell and developmental biological investigations.     

Glandular hairs in the genusDrosera (Droseraceae)

On the leaves and sepals of 52 species, representing all sections of the genusDrosera except one, 14 different types of glandular hairs were found: two-celled papillae, peltate scales, several types with unbranched, bi- or multiseriate stalk with a two- or multicellular gland, and one type with a multiseriate stalk and a two-armed gland. The combination of these hairs and the presence of non-glandular hairs confirm the actual classification of the genus. In combination with simple morphological characters (e.g., the type of insertion of the petiole) glandular hairs facilitate the identification of species even in the pharmaceutically important cut crude drug.     

Mechanisms and evolution of deceptive pollination in orchids

The orchid family is renowned for its enormous diversity of pollination mechanisms and unusually high occurrence of non-rewarding flowers compared to other plant families. The mechanisms of deception in orchids include generalized food deception, food-deceptive floral mimicry, brood-site imitation, shelter imitation, pseudoantagonism, rendezvous attraction and sexual deception. Generalized food deception is the most common mechanism (reported in 38 genera) followed by sexual deception (18 genera). Floral deception in orchids has been intensively studied since Darwin, but the evolution of non-rewarding flowers still presents a major puzzle for evolutionary biology. The two principal hypotheses as to how deception could increase fitness in plants are (i) reallocation of resources associated with reward production to flowering and seed production, and (ii) higher levels of cross-pollination due to pollinators visiting fewer flowers on non-rewarding plants, resulting in more outcrossed progeny and more efficient pollen export. Biologists have also tried to explain why deception is overrepresented in the orchid family. These explanations include: (i) efficient removal and deposition of pollinaria from orchid flowers in a single pollinator visit, thus obviating the need for rewards to entice multiple visits from pollinators; (ii) efficient transport of orchid pollen, thus requiring less reward-induced pollinator constancy; (iii) low-density populations in many orchids, thus limiting the learning of associations of floral phenotypes and rewards by pollinators; (iv) packaging of pollen in pollinaria with limited carry-over from flower to flower, thus increasing the risks of geitonogamous self-pollination when pollinators visit many flowers on rewarding plants. All of these general and orchid-specific hypotheses are difficult to reconcile with the well-established pattern for rewardlessness to result in low pollinator visitation rates and consequently low levels of fruit production. Arguments that deception evolves because rewards are costly are particularly problematic in that small amounts of nectar are unlikely to have a significant effect on the energy budget of orchids, and because reproduction in orchids is often severely pollen-, rather than resource-limited. Several recent experimental studies have shown that deception promotes cross-pollination, but it remains unknown whether actual outcrossing rates are generally higher in deceptive orchids. Our review of the literature shows that there is currently no evidence that deceptive orchids carry higher levels of genetic load (an indirect measure of outcrossing rate) than their rewarding counterparts. Cross-pollination does, however, result in dramatic increases in seed quality in almost all orchids and has the potential to increase pollen export (by reducing pollen discounting). We suggest that floral deception is particularly beneficial, because of its promotion of outcrossing, when pollinators are abundant, but that when pollinators are consistently rare, selection may favour a nectar reward or a shift to autopollination. Given that nectar-rewardlessness is likely to have been the ancestral condition in orchids and yet is evolutionarily labile, more attention will need to be given to explanations as to why deception constitutes an 'evolutionarily stable strategy'.     

Cryptic female exaggeration: the asymmetric female internal genitalia of Kaliana yuruani (Araneae: Pholcidae)

Males of the Venezuelan pholcid spider Kaliana yuruani have unique genitalia, with the procursi about six times as long as usual in the family. The present article describes the previously unknown female, searching for a morphological correlate in the female genitalia to the male's exaggeration. Reconstruction of histological serial sections reveals an internal female complexity that is unequalled in pholcid spiders. An intricate system of ducts and folds is arranged in an asymmetric way, making this the third known case of genital asymmetry in spiders. The term "cryptic female exaggeration" is used in analogy to cryptic female choice, pointing to the fact that from the outside, the female genitalia do not appear unusual. I propose that cryptic female exaggeration may be relatively common in copulatory structures if male exaggerations need to be evaluated according to the female choice by mechanical fit model. Finally, the evolution of genital asymmetry in spiders is contrasted with that in insects.     

Cryptic lineage diversity,body size divergence,and sympatry in a species complex of Australian lizards (Gehyra)

Understanding the joint evolutionary and ecological underpinnings of sympatry among close relatives remains a key challenge in biology. This problem can be addressed through joint phylogenomic and phenotypic analysis of complexes of closely related lineages within, and across, species and hence representing the speciation continuum. For a complex of tropical geckos from northern Australia—Gehyra nana and close relatives—we combine mtDNA phylogeography, exon‐capture sequencing, and morphological data to resolve independently evolving lineages and infer their divergence history and patterns of morphological evolution. Gehyra nana is found to include nine divergent lineages and is paraphyletic with four other species from the Kimberley region of north‐west Australia. Across these 13 taxa, 12 of which are restricted to rocky habitats, several lineages overlap geographically, including on the diverse Kimberley islands. Morphological evolution is dominated by body size shifts, and both body size and shape have evolved gradually across the group. However, larger body size shifts are observed among overlapping taxa than among closely related parapatric lineages of G. nana, and sympatric lineages are more divergent than expected at random. Whether elevated body size differences among sympatric lineages are due to ecological sorting or character displacement remains to be determined.     

Chemical evidence for hybridity in Drosera (Droseraceae)

Naphthoquinone patterns found in Drosera hybrids between quinone-heterogenous parent species are reported here for the first time. Quinone patterns are constant in and characteristic for all taxa investigated. Each investigated parent species contains only one quinone isomer (either plumbagin or 7-methyljuglone), whereas all investigated hybrids between quinone-heterogenous parent species contain both isomers at almost equal concentrations, which indicates co-dominant heredity resulting from expression of both parental loci affecting regioselectivity in the biosynthesis of these acetogenic metabolites. This allows predictions on hybridity (and possibly on parentage) in some taxa of the genus.