bluuebunny/crossref_metadata_2025_split huggingface dataset:
The use of inositol hexaphosphate as a phosphorus source by mycorrhizal and non‐mycorrhizal Scots Pine (Pinus sylvestris)
Authors: COLPAERT J. V. , VAN LAERE A. , VAN TICHELEN K. K. , VAN ASSCHE J. A. 
Published: November 2003

1. The external mycelia of the ectomycorrhizal fungi Thelephora terrestris and Suillus luteus, associated with Pinus sylvestris roots, exhibited a substantial extracellular acid phosphatase activity. The activity was positively correlated with the ergosterol concentration in the growth substratum and decreased with an increasing P nutrition. 2. The pioneer species T. terrestris grew best at a high Pi nutrition level whereas S. luteus, a ‘late‐stage’ mycobiont, produced more active biomass at a low Pi nutrition level. 3. The phytase activity of the external mycelia could not be detected; at the root surface a phytase activity was observed. Mycorrhizas had significantly higher activities than uninfected roots. 4. The addition of a relatively high concentration of a soluble phytate to the growth substratum resulted in an increased relative growth rate (RGR) in both mycorrhizal and non‐mycorrhizal plants. The influence of the mycorrhizal fungi on the use of the phytate‐P was small, despite the phytase activity of the mycorrhizal feeder roots. 5. The addition of phytate fixed on a HPLC resin did not result in an increase of the RGR and P uptake neither in the non‐mycorrhizal nor in the mycorrhizal Pines. The experiment did not support the hypothesis that phytate, which has a low solubility in soils, is a useful P source for ectomycorrhizal plants.
Phytochrome signalling in plant canopies: testing its population‐level implications with photoreceptor mutants of Arabidopsis
Authors: BALLARÉ C. L. , SCOPEL A. L. 
Published: November 2003

1. A number of signalling mechanisms are responsible for triggering plastic morphological and physiological responses of plants to the proximity of neighbours. Among these mechanisms, the phytochrome‐mediated control of branching and elongation in response to alterations in red:far‐red ratio (R:FR) has been investigated in considerable detail. 2. While the role of phytochrome B in R:FR perception has been well established, and the consequences of neighbour photo‐detection on competitive ability are receiving attention, several important issues remain to be addressed regarding the ecology of plant–plant signalling in canopies. In particular, the role of other photoreceptors in neighbour detection and the impact of neighbour detection on population‐level attributes, such as size structure and productivity:density relationships are poorly characterized. 3. In the experiments reported here we addressed these questions using wild‐type (WT) plants and photomorphogenic mutants of Arabidopsis thaliana that are specifically deficient in phytochrome A, phytochrome B, all phytochromes or the blue‐light photoreceptor cryptochrome. Plants were grown in monocultures of different densities (between ~300 and 2400 plants m–2) from planting to seed set. Full competition among neighbouring plants was allowed both above‐and below‐ground. 4. WT plants responded to crowding with the predictable increase in elongation growth and by producing more steeply orientated leaves. Similar responses were observed in mutants deficient in phytochrome A or cryptochrome. Mutant plants lacking phytochrome B had an ‘elongated’ phenotype even when grown at low density and, in comparison with the other genotypes, showed markedly reduced morphological responses to crowding. 5. All genotypes having functional phytochrome B had similar biomass production and fruit production, and fruit production per unit area was constant over the range of densities used. Stands of phytochrome‐B‐deficient plants were as productive as WT canopies at intermediate densities, but had significantly reduced fruit production at low and, more strikingly, also at high densities. Size inequality among neighbours, measured as the coefficient of variation of reproductive output per plant, increased with density in all genotypes, but significantly more in phytochrome‐B‐deficient stands than in WT crops. 6. Our results suggest that: (1) phytochrome B plays a unique role in neighbour photo‐detection, while other photoreceptors appear to be less important in this respect; (2) in WT stands, phytochrome‐B‐mediated neighbour detection leads to inverse rank‐dependent morphological adjustments (i.e. greater fractional response in the small plants), which tend to buffer the plant population against size structuring; (3) the strong size‐structuring in populations of R:FR ‘blind’ phytochrome‐B mutants results in reduced stand fecundity at high densities.
Male larval nutrition influences the reproductive success of both sexes of the Spruce Budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae)
Authors: DELISLE J. , HARDY M. 
Published: November 2003

1. It has recently been demonstrated that the species of host plant used by males during larval development may significantly affect the reproductive success of both sexes in a polygophagous tortricid, Choristoneura rosaceana (Delisle & Bouchard 1995). In the present study, using the Spruce Budworm, C. fumiferana, the hypothesis was tested that in oligophagous species, similar effects would result from within‐species variability in foliage quality. 2. It was demonstrated that male larval diet (young and old Balsam Fir foliage (YF vs OF) or artificial diet (AD)) significantly influences the reproductive success of both sexes of C. fumiferana. 3. Male body size and spermatophore size were positively correlated, with AD > YF > OF; however, males fed on YF had better mating success than those on OF and AD, indicating that size may not always be a good estimate of male quality. 4. The propensity of females to resume calling (CA+) and remate (RM+) was significantly lower, and the length of the refractory period longer, following first mating with high (YF) rather than low (OF and AD) male quality. 5. Females that resumed calling (CA+) had a lower reproductive output than those that did not (CA–), with the effect being more pronounced following mating with males fed on low (OF and AD) rather than high (YF) quality diet. A similar trend was observed in the proportion of females that were unsuccessfully mated, as shown by their low incidence of fertility (<25%). In contrast to their reproductive output, females that resumed calling lived as long as those that did not, regardless of male larval diet. However, the resumption of calling was also observed in a large number of highly fertile (48%) females, indicating that infertility was not the only reason for the resumption of sexual receptivity. 6. Females that remated (RM+) following an initial mating with low quality males (OF and AD) had fecundities and longevities similar to those that did not (RM–). However, their incidence of fertility was significantly higher. In contrast, females that remated following an initial mating with high quality males (YF) were more fecund and lived slightly longer than those that did not (RM–). A similar pattern was observed with females initially mated with OF and AD males, if only individuals with high fertility following first mating were considered in the analyses. 7. Male larval diet had no effect on fecundity, percentage fertility and longevity in females that remained refractory following their first mating. 8. The first mating occurred earlier in the night and lasted longer than the second, with both variables being independent of the diet of the first mate. This may explain why overall the proportion of females that remated was lower than that for females that resumed calling following mating.
Associations between shell morphology and land crab predation in the land snail Cerion
Authors: QUENSEN III J. F. , S WOODRUFF D. 
Published: November 2003

1. The land crab Gecarcinus lateralis is a significant predator of the abundant Bahamian land snails of the genus Cerion. The crabs typically ‘scissor’ the cylindrical shells in half or break the lip and peel back the shell to reach the animal which withdraws two or three whorls into the shell. Scars on shells of live adults at 73 sites in the Bahamas and Florida Keys show that about 8% (range: 0–44%) of the snails have survived attacks of this type. 2. An artificial crab claw was used to investigate the compressive force required to break Cerion shells of different morphotypes. Defining shell strength as the ability to withstand compressive forces, 10 morphotypes were found that exhibited mean relative strengths of between 30 and 300 newtons. Feeding trials with one adult crab showed that snails whose shells could withstand compressive forces of > 95 N were safe from this individual predator. 3. Multiple linear regression analyses showed that both shell size (length and width) and shell wall thickness were the ultimate determinants of shell strength. Ribs strengthen the shell by contributing to wall thickness and also by increasing overall shell width. The thickened adult shell lip and collabral ribs provide effective protection from attack by peeling.
Evidence for a genetic component of female fecundity in British Roe Deer from studies of cranial morphometrics
Authors: HEWISON A. J. M. 
Published: November 2003

1. The fecundity of adult female Roe Deer varies by a factor of 2·35 among populations across Britain. Although much of this variation may be related to environmental differences, there could also be a genetic influence on this component of fitness. In this paper, the relationship between morphological variation of the skull and female fecundity in Roe Deer from 13 populations across the deer’s entire range in Britain is investigated. 2. First, principal components analysis of cranial data was used to infer genetic relationships among populations. Three distinct morphological types were identified, all significantly differentiated from the others in terms of both size and shape. The results are compared with earlier analyses of biochemical variation among the same sites; a possible native morph is identified. 3. Subsequently, canonical ordination techniques (redundancy analysis) were used to control for the effects of ‘environmental’ variation (female body mass, density, climate) and, with the residual variation, the correlation between skull morphology and female fecundity was investigated. This correlation is significant for both the extracted axes (R>0·7), indicating that there are heritable differences between populations affecting female fecundity. 4. The analysis suggests that Roe Deer native to Britain are of a genetically less fecund type relative to populations established by introductions from the continent.
Haematocrit correlates with tail ornament size in three populations of the Barn Swallow (Hirundo rustica)
Authors: SAINO N. , CUERVO J. J. , NINNI P. , DE LOPE F. , MØLLER A. P. 
Published: November 2003

1. Handicap models of sexual selection propose that male ornaments are indicators of male quality and that honesty is enforced by the costs imposed by the exaggerated ornamental traits. In long‐distance migratory birds that feed on the wing, the aerodynamic cost of exaggerated ornamental characters should be particularly high because the size of the ornaments deviates from the natural selection optimum. During migration, birds are expected to raise their oxygen consumption in relation to the energetic demands imposed by their morphology. An increase of haematocrit is an adaptive response to enhance oxygen uptake and efficiency of transfer to the muscular tissues during spells of intense muscular activity. 2. The change of haematocrit of Barn Swallows (Hirundo rustica) after their arrival to the breeding sites, and the relationships between haematocrit values recorded after migration and the size of ordinary and sexually selected morphological characters in three Barn Swallow populations were analysed. 3. Males had higher haematocrit values than females. Individual haematocrit values declined after arrival to the breeding sites. Haematocrit values of males were significantly and positively correlated with the size of their ornamental tail but not correlated with other characters, thus suggesting that well‐ornamented males, in order to arrive early, have to raise their haematocrit above the level of short‐tailed males. 4. Males and females of similar tail length did not differ in their haematocrit, thus suggesting that sexual dimorphism in haematocrit might be functionally related to dimorphism in tail length. 5. Our results are consistent with the handicap principle because long‐tailed males experience lower mortality and larger seasonal reproductive success compared with short‐tailed males.
Fruit size in wild olives: implications for avian seed dispersal
Authors: REY P. J. , GUTIÉRREZ J. E. , ALCÁNTARA J. , VALERA F. 
Published: November 2003

1. The response of frugivorous birds to an enlargement of fruit size, and the consequences for both birds and plants, are analysed for the interaction between avian seed dispersers and olives (Olea europaea). 2. The enlargement of fruit size promotes a shift in frugivorous birds’ feeding behaviour, from swallowing fruits whole to pecking pieces of pulp. The relative frequency of olive consumption using each feeding behaviour was assessed by combining field data on frequency of appearance of olive pulp and seeds with data from laboratory trials. 3. Sardinian Warblers (Sylvia melanocephala) and European Robins (Erithacus rubecula) were mainly peckers both on cultivated and wild olives. Blackcaps (Sylvia atricapilla) consumed wild olives mainly by swallowing but consumed cultivated olives (larger than the wild ones) primarily by pecking. Song Thrushes (Turdus philomelos) were primarily swallowers of both types of fruits. 4. Laboratory trials with Song Thrushes, Blackcaps and European Robins showed that: (a) all were able to peck fruits; (b) fruit size determined a shift from swallowing to pecking, as pecking frequency increased with the enlargement of the fruit size; (c) all the species had an increased fruit handling failure rate when trying to swallow increasingly large fruits; and (d) from the birds’ perspective, small shifts in fruit size may have important consequences on fruit profitability. 5. Pecking on olives turns the mutualistic fruit–frugivore interaction into a fruit‐pulp predator interaction, thus arising a conflict between the plant and frugivorous birds. 6. This study shows that heavy dependence on fruit is not always simply related to seed dispersal. The same frugivorous bird species can act as a seed disperser or a pulp predator for the same plant species. The threshold between these roles is highly influenced by the ratio gape size/fruit size.
Response of Deer Mice (Peromyscus maniculatus) to shrubs in shortgrass prairie: linking small‐scale movements and the spatial distribution of individuals
Authors: STAPP P. , VAN HORNE B. 
Published: November 2003

1. Organisms respond to the abundance and spatial distribution of resources at both individual and population scales but there have been relatively few attempts to link insights from studies of these different phenomena, especially for wide‐ranging vertebrates. 2. Deer Mice (Peromyscus maniculatus) were live‐trapped and tracked across a gradient of shrub cover in shortgrass prairie to determine patterns of abundance, microhabitat use and movements. 3. In areas with few shrubs, mice preferred shrub microhabitats and their movement trails were relatively straight. Both trail tortuosity and population density increased with increasing shrub cover, so that mice tended to accumulate in areas where their trails were most convoluted. However, movements were also linear where shrubs were dense, presumably because mice could achieve the benefits of association with shrubs without travelling directly beneath them. Areas with dense shrubs also had high but variable population densities, suggesting that other factors such as intraspecific interactions may have affected movements on a larger, home‐range scale. 4. Apparent thresholds in the selective vs random use of shrubs, movement patterns and abundance occurred over a narrow range of shrub cover where shrubs were most aggregated, underscoring the importance of both shrub density and dispersion. Non‐linear relationships in the response to resources at both behavioural and population scales thus may complicate our ability to predict abundance from individual movements across a broad range of resource distributions.
Thermoregulation in four species of British grasshoppers (Orthoptera: Acrididae)
Authors: WILLOTT S. J. 
Published: November 2003

1. This study examines the extent to which thermal balance and thermoregulatory ability may contribute to habitat partitioning in insect herbivores. 2. The distribution of four species of grasshopper on a Breckland grass heath is described. Myrmeleotettix maculatus is restricted to short swards, Omocestus viridulus is restricted to long swards, and Chorthippus brunneus and Stenobothrus lineatus are found on swards of intermediate length. 3. Short swards are warmer on average than long swards, but lack cooler refuges on hot days. 4.
Chorthippus brunneus and O. viridulus are better able to raise their body temperatures at low ambient temperatures than M. maculatus and S. lineatus. Omocestus viridulus is less able to reduce body temperature at high ambient temperature. 5.
Myrmeleotettix maculatus may be precluded from inhabiting cooler long swards because of its inability to raise body temperatures at low ambient temperatures. Omocestus viridulus may avoid short swards because of the danger of overheating. 6. Thermoregulatory ability is a good predictor of the distribution of the grasshoppers in swards of differing length and microclimate.
Nitrogen‐use efficiency in six perennial grasses from contrasting habitats
Authors: VÁZQUEZ DE ALDANA B. R. , BERENDSE F. 
Published: November 2003

1. We studied the nitrogen‐use efficiency (NUE) in six perennial grasses adapted to a wide range of nutrient availability. The glasshouse experiment was carried out in pots containing nutrient solution, with two fertility treatments. Nitrogen‐use efficiency was considered as the product of nitrogen productivity and mean residence time of the nitrogen in the plant (calculated using 15N pulse labelling). 2. The species investigated are characteristic of habitats ranging from very nutrient rich to extremely nutrient poor, in the following order: Lolium perenne, Arrhenatherum elatius, Festuca rubra, Anthoxanthum odoratum, Festuca ovina and Molinia caerulea. 3.
Lolium perenne (adapted to nutrient‐rich habitats) had higher nitrogen productivity (A) than M. caerulea (species adapted to nutrient‐poor habitats) but lower than that of F. rubra (from habitats with an intermediate availability of nutrients). 4. In the low fertility treatment, species with the lowest nitrogen‐use efficiency had the lowest N productivity and the highest mean nitrogen residence time (MRT); however, although species with the highest nitrogen use efficiency had the highest N productivity they did not have the lowest MRT. In all species the nitrogen‐use efficiency decreased with increasing N supply. The two components of the NUE (A and MRT) are inversely correlated along gradients of nutrient availability, but not at very high levels of nutrient availability. 5. The nitrogen‐use efficiency of species at constant levels of nutrient supply tends to increase with increasing nutrient availability in their preferred habitat, according to the Clausman nutrient index, up to a certain nutrient availability and then decreases. The results support the contention that species from nutrient‐poor sites are not necessarily adapted by a high nitrogen‐use efficiency, but by low nutrient loss rates (high mean residence time of N in the plant).
Relationships between branch spacing, growth rate and light in tropical forest saplings
Authors: KING D. A. , LEIGH E. G. , CONDIT R. , FOSTER R. B. , HUBBELL S. P. 
Published: November 2003

1. The spacing of branches along central stems was related to growth rate and light level in forest saplings and trees in tropical moist forest on Barro Colorado Island (BCI), Panama. The study included 14 species with tiers of plagiotropic branches (having planar leaf arrangements) and four species with continuous distributions of plagiotropic branches. 2. All species showed increases in branch spacing with increasing light and growth rate of diameter, similar to the patterns in leaf spacing noted previously in species which initially bear large leaves on unbranched stems. 3. Non‐tiered species had shorter internodes than tiered species but because the latter bear more branches per node, both groups had similar numbers of branches per unit stem length, when compared at similar growth rates. 4. Differences in the relationship between internode length and growth rate among tiered species were related to demographic characteristics, suggesting that tree architecture may influence forest composition. 5. The strong correlation observed between branch spacing and growth rate suggests that branch spacing may be used to estimate past growth histories of forest tree species with plagiotropic branches.
Genetic variation in photosynthetic capacity, carbon isotope discrimination and mesophyll conductance in provenances of Castanea sativa adapted to different environments
Authors: LAUTERI M. , SCARTAZZA A. , GUIDO M. C. , BRUGNOLI E. 
Published: November 2003

1. Provenances of Castanea sativa from populations adapted to different climatic areas of Turkey were grown in a field trial in Italy. Carbon isotope discrimination (Δ) in leaf dry matter and in leaf soluble sugar, were measured, along with photosynthesis, stomatal conductance and mesophyll conductance, to study the variability of primary productivity and its ecological significance in European Chestnut. 2. Genetic variations were found in RuBP carboxylase, chlorophyll, leaf soluble protein and leaf thickness. 3. Carbon isotope discrimination (Δ) in leaf dry matter was greater in drought‐adapted than in wet‐adapted provenances. A similar variation of Δ was observed in leaf soluble carbohydrates either under watered or drought conditions. Possible environmental effects of variables such as vapour pressure difference, on the relationship between transpiration efficiency and carbon isotope discrimination are discussed, on the basis of short‐term and long‐term results. 4. Generally low values of Δ encountered among provenances were explained not only by low values of intercellular CO2 partial pressure but also by consistently low values of mesophyll conductance leading to reduced chloroplastic CO2 partial pressure. A decrease in mesophyll conductance was induced by water shortage. Co‐ordination was found between stomatal and mesophyll conductance, with the drought‐adapted provenances showing much higher mesophyll conductance than the wet‐adapted provenances. Variations in mesophyll conductance were related to differences in leaf protein content. 5. Possible ecophysiological adaptive mechanisms are discussed taking into account stomatal sensitivity, modulation of photosynthetic capacity and water‐use efficiency under drought conditions.