The performance of morphological characters in broad-scale phylogenetic analyses

In view of their propositional content (i.e. they can be right or wrong), character statements (i.e. statements that predicate characters of organisms) are treated as low-level hypotheses. The thesis of the present study is that such character statements, as do more complex scientific theories, come with variable scope. The scope of a hypothesis, or theory, is the domain of discourse over which the hypothesis, or theory, ranges. A character statement is initially introduced within the context of a certain domain of discourse that is defined by the scale of the initial phylogenetic analysis. The doctrine of 'total evidence' requires the inclusion of previously introduced characters in subsequent studies. As a consequence, the initial scope of character statements is widened to the extent that the scale of subsequent analyses is broadened. Scope expansion for character statements may result in incomplete characters, in the subdivision of characters, or in ambiguity of reference (indeterminacy of the extension of anatomical terms). Character statements with a wide scope are desirable because they refer to characters with the potential to resolve deep nodes in phylogenetic analyses. Care must be taken to preserve referential unambiguity of anatomical terms if the originally restricted scope of a character statement is expanded to match a broad-scale phylogenetic analysis.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 297–308.     

Dynamics of indole-3-acetic acid and indole-3-ethanol during development and germination of Pinus sylvestris seeds

Indole-3-acetic acid (IAA) and indole-3-ethanol (IEt) were identified in immature seeds of Pinus sylvestris L. by combined gas chromatography-mass spectrometry. Indole-3-methanol was tentatively identified using multiple ion monitoring. Anatomical investigations of seeds, as well as measurements of free and alkali-hydrolysable IAA and IEt, were made during seed development and germination. Levels of free IAA and IEt decreased during seed development. In the later stages of seed maturation most IAA and IEt were present in alkali-hydrolysable forms. Bound IAA and bound IEt rapidly decreased during germination, while levels of free IAA and IEt increased dramatically for a short period.     

The population dynamics of Cheilosia fasciata (Diptera,Syrphidae): significance of environmental factors and behavioural adaptations in a phytophagous insect

Summary A population of Cheilosia fasciata Schin. & Egg., 1853 was studied in a beech forest (Melico-Fagetum allietosum) near Göttingen (FRG). This syrphid species is closely associated with ramson (Allium ursinum L.), as the larvae mine the plant's leaves. Adult abundance was determined using emergence traps (1981–1986); egg and larval abundance was determined by examining ramson leaves: puparia were extracted from soil samples (1984 and 1986). Cheilosia fasciata is a univoltine species; the imagines emerge in late April/early May. Larval development took five (1986) to six (1984) weeks. In late June/early July the larvae enter the soil for pupariation. A linear relationship was found between the area of the mines and larval biomass (dry wt.). It was concluded that one larva had to mine 51.90 cm² of leaf area in order to gain the mean maximum dry weight (11.15 mg). Furthermore, it was shown that ovipositing females, laying just one egg per leaf, tended to select large leaves providing this minimum amount of food. It is hypothesized that females probably follow straight-lined routes on their oviposition flights, rather than ovipositing on leaves chosen at random. By applying such a strategy, females can almost completely avoid competition for food among their own offspring. Furthermore, competition among the progeny of the whole population is also reduced, particularly in years when adult abundance is very low. The significance of certain factors influencing the population dynamics of Cheilosia fasciata was evaluated by applying a rank correlation analysis. It was shown that high precipitation rates in April reduced the time available for mating and oviposition resulting in low emergence abundance in the next spring. Larval survivorship was enhanced by high precipitation rates in May and June, indicating that drought may be unfavourable to larvae and reduce food availability. Predation by a parasitoid Phygadeuon ursini Horstmann, 1986 (Hymenoptera, Ichneumonidae), appears to be just an imperfect (Milne 1984) density-dependent control mechanism; in fact, it was shown that food limitation is the only significant mechanism of density-dependent population control.     

Leaf water relations and anatomy of a tropical rainforest tree species vary with crown position

Summary Leaf water potentials, osmotic properties and structural characteristics were examined in the Australian tropical rainforest tree species, Castanospermum australe. These features were compared for individuals growing in the understorey and canopy of the undisturbed forest and in an open pasture from which the forest had been cleared. Leaf water potentials during the day declined to significantly lower values in the open-grown and canopy trees than in the understorey trees. During most of the day the opengrown tree experienced the lowest water potentials. These differences were paralleled by significant differences in tissue osmotic properties. The tissue osmotic potential at full hydration was lowest in the open-grown tree (-1.80 MPa), intermediate in the canopy trees (-1.38 MPa), and highest in the understorey trees (-0.80 MPa). As a result, the degree to which high and positive turgor pressures were maintained as water potentials declined was highest in the open-grown tree, intermediate in the canopy trees, and lowest in the understorey trees. The differences in tissue osmotic properties between individuals in the three crown positions were paralleled, in turn, by differences in leaf structual characteristics. Relative to leaves of the canopy and open-grown trees, leaves of the understorey trees had significantly larger epidermal cells with thinner cell walls, larger specific leaf areas and turgid weight: dry weight ratios, and a higher proportion of intercellular air space.Abbreviations ₁ Leaf tissue water potential - _min Lowest value of ₁ during the day ( noon) - _{P=0 1} zero turgor - R Relative water content - P Tissue turgor pressure - Tissue osmotic potential - ₀ at full hydration     

Diagnosis of iron deficiency in groundnut,Arachis hypogaea L.

Summary Investigations into iron deficiency have been hindered by the lack of a satisfactory diagnostic tissue test, which in turn results from the total iron content of plant tissue commonly being an unreliable index of the iron status. Our measurements of chlorotic and normal leaves of field grown groundnut (Arachis hypogaea L.) showed that total iron was unsatisfactory as the measure of iron status of plant tissue. It was found that iron status was better assessed from an estimate of the ferrous iron content of fresh leaf materials obtained by extraction with o-phenanthroline. Extractable iron content increased with leaf age. Chlorotic buds or the first fully opened leaf always contained less than 6μg extractable-Fe/g fresh tissue. Approved for publication as ICRISAT Journal Article No. 307.     

The fate of15N labeled nitrogen applied to mature citrus trees

Summary The efficiency and balance of nitrogen from one year's application was studied in a long-term fertigation experiment. Enriched nitrogen fertilizer, K¹⁵NO₃, was applied to a 22-year-old Shamouti orange tree with a history of high N applications (N₃) and to an N-starved tree (N₁). The distribution of N in the different parts of the trees and in the soil was determined after the experimental trees were excavated. Similar total recovery of the labeled fertilizer N was found in the trees and soil in both treatments (N₁−61.7% N₃−56%). However, the distribution between tree and soil was different. The amount of recovered residual fertilizer in the soil was much larger in the N₃ treatment than in N₁. The highest percentage of fertilizer N was found in the new organs,i.e. fruits, twigs and leaves. The roots and branches took up only 6–14% from the labeled fertilizer. Only 20.9% of the leaf N and 23.4% of the fruit N in the N₃ tree originated in the labeled fertilizer, indicating translocation of N from older parts of the tree to new growth. Evidence was found of storage of N in the wooded branches, while the roots contained a surprisingly small part of labeled fertilizer. Contribution 1599E.     

Phosphorus nutrition of jarrah (Eucalyptus marginata) seedlings

Summary Effects of calcium phosphate supply on plant dry matter and phosphorus concentrations of parts of jarrah (Eucalyptus marginata) seedlings grown in a lateritic topsoil from the jarrah forest were examined in two glasshouse trials. Phosphorus deficiency depressed root and shoot dry weights and severely deficient leaves were smal and purple with prominent red major veins. Phosphorus deficiency severely reduced stem phosphorus levels (0.5% to 0.02%, experiment 1). Phosphorus concentrations were higher in bark than wood and the amount of phosphorus in the bark was sensitive to stem age and phosphate supply. Phosphorus adequate plants had bark phosphorus concentrations in the range 0.2–0.9% compared to <0.1% in deficient plants (experiment 2). Jarrah leaves accumulated dry matter up to 80 days after expansion and some leaves exported phosphorus during this period. Bark analysis may therefore be preferable to leaf analysis for detecting phosphorus deficiency in this species.     

Taxonomic studies ofAsarum sensu lato

The floral vascular anatomy of 12 species representing each ofAsarum s. str.,Asiasarum, Geotaenium, Heterotropa andHexastylis are compared to clarify intergeneric relationships. The five genera have basically similar structures in floral morphology and vasculature, and consistently have a six-carpelled compound ovary and the associated similar placental vasculature. They show, however, a significant difference in the position and the constituent of the “ventral” carpellary bundles in the placental axis betweenAsiasarum-Heterotropa-Hexastylis andAsarum-Geotaenium. InAsiasarum, Heterotropa andHexastylis the ventral bundles of each carpel are basically free and antilocular as expected in the least specialized compound ovary of angiosperms; in contrast, inAsarum andGeotaenium the ventral carpellary bundles are antiseptal and heterogenous (i.e., formed by the lateral fusion of ventral bundles of adjacent carpels). Shared probable apomorphic floral vasculature, as well as shared single style-column, suggests the closest mutual relationships betweenAsarum andGeotaenium. In terms of floral morphology and anatomy,Asiasarum, Heterotropa andHexastylis retain plesiomorphies. Possible chromosomal evolution in the related genera is also discussed.     

The midline metathoracic ear of the praying mantis,Mantis religiosa

Summary The praying mantis, Mantis religiosa, is unique in possessing a single, tympanal auditory organ located in the ventral midline of its body between the metathoracic coxae. The ear is in a deep groove and consists of two tympana facing each other and backed by large air sacs. Neural transduction takes place in a structure at the anterior end of the groove. This tympanal organ contains 32 chordotonal sensilla organized into three groups, two of which are 180° out of line with the one attaching directly to the tympanum. Innervation is provided by Nerve root 7 from the metathoracic ganglion. Cobalt backfills show that the auditory neuropile is a series of finger-like projections terminating ipsilaterally near the midline, primarily near DC III and SMC. The auditory neuropile thus differs from the pattern common to all other insects previously studied.