Heterophylly in Ranunculus flabellaris: The Effect of Abscisic Acid on Leaf Ultrastructure

Ranunculus flabellaris Rafin., an aquatic buttercup, exhibitsheterophylly at the level of cellular ultrastructure. Comparedto terrestrial leaves, underwater leaves have thinner epidermalcell walls and more numerous paramural bodies per epidermaland mesophyll cell cross-section. The number of chloroplastsand mitochondria in cell cross-sections also contrasts betweenthe two leaf types. Despite within-and between-leaf variations,different patterns of organelle distribution for the two leafforms were found using principal coordinates analysis. In addition,underwater leaf chloroplasts are smaller, have fewer grana,a greater number of thylakoids/granum, and less starch comparedto chloroplasts from terrestrial leaves. At the ultrastructurallevel, submergence in ABA solution does not produce a leaf withas many characteristics of the terrestrial environment, as shownin previous studies of leaf morphology and anatomy. While numberand distribution of organelles in ABA-treated leaves are similarto terrestrial leaves, some features of chloroplast internalstructure and paramural body number and distribution resembleunderwater leaves. It is postulated that ABA acts as a morphogeninvolved in guiding the irreversible processes of leaf development,but certain subcellular characteristics may be determined directlyby the physical environment. Difficulties encountered in quantitativeanalyses of cellular ultrastructure are discussed. Ranunculus flabellaris, ABA, heterophylly, leaf ultrastructure, principal coordinates analysis     

Ultrastructural Characterisation and Molecular Taxonomic Identification of Nosema granulosis n. sp., a Transovarially Transmitted Feminising (TTF) Microsporidium

A novel microsporidian parasite is described, which infects the crustacean host Gammarus duebeni. The parasite was transovarially transmitted and feminised host offspring. The life cycle was monomorphic with three stages. Meronts were found in host embryos, juveniles, and in the gonadal tissue of adults. Sporoblasts and spores were restricted to the gonad. Sporogony was disporoblastic giving rise to paired sporoblasts, which then differentiated to form spores. Spores were not found in regular groupings and there was no interfacial envelope. Spores were approximately 3.78 x 1.22 microns and had a thin exospore wall, a short polar filament, and an unusual granular polaroplast. All life cycle stages were diplokaryotic. A region from the parasite small subunit ribosomal RNA gene was amplified and sequenced. Phylogenetic analysis based on these data places the parasite within the genus Nosema. We have named the species Nosema granulosis based on the structure of the polaroplast.     

The Carotenoids of Various Berries

Eleven different berries from six families were investigatedfor their carotenoid composition. Phytofluene and ß-carotenewere the only two polyenes identified in all of them, lutein(universally present in photo-synthetic tissue) was found insmall quantities in only six species, while lycopene (a characteristicfruit pigment) was not always present. (1) The results emphasizethe view that the distribution of carotenoids in berries appearsto have no taxonomic significance, although rubixanthin wasonly obtained from rose hips. (2) There was no correlation betweentotal carotenoids and colour of berries. The colour dependson which major carotenoids are present and also on the presenceof other non-carotenoid pigments, e.g. flavonoids and chlorophyll.(3) Three berries (holly, cuckoo pint and black bryony) studiedat various stages of maturation showed that as they aged, thecontrol of carotenoid synthesis was removed. Oxidative processestook place with the result that very few of the a-carotene serieswere found and there was an increase in total carotenoids, mostlydue to epoxy-carotenoids and to their derivatives. (4) ß-Carotenewas probably the precursor of cryptoxanthin in the cuckoo pint,while it was that of the 5,6 mono- and 5,6:5', 6'-diepoxy-ß-carotenesand of their derivatives in the holly.     

Phylogenetic relationships of North American Gomphidae and their close relatives

Intrafamilial relationships among clubtail dragonflies (Gomphidae) have been the subject of many morphological studies, but have not yet been systematically evaluated using molecular data. Here we present the first molecular phylogeny of Gomphidae. We include six of the eight subfamilies previously suggested to be valid, and evaluate generic relationships within them. We have included examples of all genera reported from the Nearctic except Phyllocycla. This sample includes all North American species of Ophiogomphus, which has allowed us to explore intrageneric relationships in that genus. Our particular focus is on the closest relatives of the genus Gomphus, especially those North American species groups that have been commonly treated as subgenera of Gomphus. The Gomphus complex is split into additional genera, supported by molecular and morphological evidence: Phanogomphus, Stenogomphurus, Gomphurus and Hylogomphus are here considered to be valid genera. The genus Gomphus, in our restricted sense, does not occur in the western hemisphere; in addition, G. flavipes is transferred to Stylurus.     

The environmental impacts of biomass crops: use by birds of miscanthus in summer and winter in southwestern England

We compared birds in a group of established and well‐managed miscanthus (Miscanthus x giganteus) fields in Somerset and East Devon, southwestern England, with plots of short rotation coppice (SRC) willow, arable crops and grassland in two winters and one summer. Following early spring cutting, 19 miscanthus fields grew taller, initially produced greater cover and were less weedy than SRC. As stubble in May, the miscanthus contained broadly similar species at similar densities to arable and grassland comparison plots. By July, at 2‐m‐tall, miscanthus held higher densities of birds but of fewer species, most of them characteristic of woodland and scrub. SRC, previously identified as being a beneficial crop for many birds, always contained more species and individuals than miscanthus. Throughout each of two winters, 15 miscanthus plots remained unharvested and contained more wood/scrub species such as Blackbirds Turdus merula, tits, Reed Buntings Emberiza schoeniclus and Woodcock Scolopax rusticola than the comparison plots, which held more corvids and Skylarks Alauda arvensis amongst others. Similar overall mean densities of birds in the miscanthus and the comparison plots masked relatively low density variance in miscanthus and very high variance in the comparison plots. Unharvested miscanthus crops grown in place of habitat types supporting flocks of wintering birds would displace these flocks. Miscanthus plantations with open patches attracted more finches and waders in winter. The two previous studies of birds in miscanthus in the UK found more species and more individuals than we did in summer and winter. Both these studies documented high levels of weediness and patchy crop growth. In the context of this previous work our data suggest that bird use of miscanthus in summer and winter is likely to be variable, affected by region, weediness, crop structure and patchiness. While large‐scale cropping of SRC in England is likely to have a positive overall impact on a suite of common farmland and woodland birds, our data suggest that miscanthus in the southwest of England may have an approximately neutral effect. However, some open farmland specialist species may be lost when planting either crop.     

The winter diet and parasitic fauna of a population of Rednecked Wallabies Macropus rufogriseus recently introduced to Scotland

Although the Red-necked Wallaby is native to south-east Australia and Tasmania, at least four colonies have become established in the UK and two of these still survive. Here we provide the first account of a colony that became established following the deliberate release of four individuals to an island in Loch Lomond, Scotland in 1975. Data presented here show that this population is well established, having grown to at least 26 individuals by 1992. Wallaby diet in winter (a critical period for survival in the other remaining UK population) is composed of Blaeberry Vaccinium myrtillus and Heather Calluna vulgaris, each making up 35% of the plant fragments by occurrence in faecal pellets, with grasses making up a further 13%. Two species of parasitic coccidian protozoa and four species of strongyle nematode were found in faecal samples from this colony but the infection rate was low compared with what limited published data exist for this species. The possible reasons for the success of this most northerly of the UK wallaby populations are its isolation, the maritime climate and vegetation structure of the inhabited area.     

The potential implications of rainforest history, hybridization, and climate change on the phylogenetics of a rare genus of herbs Romnalda (Dasypogonaceae) from New Guinea and Australia

There are many genera shared between Australian and Papua New Guinean rainforests. Species in the rare rainforest herbaceous genus Romnalda have a relictual and disjunct distribution within the major rainforest blocs of southern Queensland, north Queensland, and New Guinea. There are only four species in this genus: R. strobilacea , R. grallata , and R. sp. 'Cooper Ck' from Australia, and R. papuana from New Guinea. The Australian species have restricted distributions and high conservation status. Allozymes were used to study the genetic variation and distinctiveness of all four species. Genetic diversity varied significantly amongst the four species. The species in the centre of the genus distribution contained the highest genetic diversity, regardless of rarity. The undescribed R. sp. 'Cooper Ck' was identified as a clearly distinct species with morphological affinities to R. papuana , but genetic affinities to R. grallata. The study showed that, where the distributions of R. grallata and R. sp. 'Cooper Ck' overlapped, there was evidence of hybridization. Reproductive participation within populations was typically low with limited flowering synchrony. Populations of all four species were inbred, but higher levels of inbreeding were not correlated with lower genetic diversity. The timing of flowering appeared to be determined by climate. Altitudinal variation in phenological timing in R. sp. 'Cooper Ck' has led to genetic isolation within the species, but has also limited its genetic introgression with the co-occurring R. grallata . © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 455–474.