bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seed size, shape and vertical distribution in the soil: indicators of seed longevity
Authors: Bekker R. M. , Bakker J. P. , Grandin U. , Kalamees R. , Milberg P. , Poschlod P. , Thompson K. , Willems J. H. 
Published: March 2003

1. We investigated the vertical distribution of seeds in the soil, using data from nine studies in five European countries. We discovered significant correlations between seed shape and distribution in the soil. 2. The classification of the longevity of seeds of plant species has been improved by the introduction of a ‘longevity index’, expressing on a continuous scale the most recent information on seed longevity represented as the proportion of non‐transient seed bank records in the database of Thompson et al. (1997). Remarkably, no difference in seed longevity was found if the index was based on direct observations only when compared with the index based on the complete data set where indirect, ‘depth‐derived’ observations were included. 3. Seed longevity was best estimated using a multiple regression model with an integrated measure of seed size and shape and depth distribution of seeds. 4. The shape of seeds, known to be a consistent character of species, was shown to be constant within species, whereas depth distribution of seeds was highly variable among sites. This is consistent with the variability of seed longevity found in published seed bank data.
Energetically costly behaviour and the evolution of resting metabolic rate in insects
Authors: REINHOLD K. 
Published: March 2003

1. A general hypothesis is presented to explain interspecific differences in size‐independent resting metabolic rate. This hypothesis is based on a presumed trade‐off between a low resting metabolism and adaptations of metabolism during activity. 2. With such a trade‐off, selection to reduce resting metabolism is less intense in active species than in species where resting metabolism constitutes a large proportion of the daily metabolic costs. Those animals that spend more energy on activity should therefore have a higher resting metabolic rate than animals that spend less energy on activity. 3. A literature review reveals that flying insects have higher resting metabolic rates than species that use energetically less demanding types of locomotion. 4. Insects producing acoustic advertisement signals can be shown to have higher mass‐independent resting metabolic rates than closely related species without this energetically demanding behaviour. 5. Literature data on vertebrate resting metabolic rates are also consistent with the presented hypothesis: the more energy animals spend on activity, the higher the mass‐independent resting metabolic rate.
Relationships between body composition, body size and alternative reproductive tactics in a lekking sandpiper, the Ruff (Philomachus pugnax)
Authors: Bachman G. , Widemo F. 
Published: March 2003

1. The Ruff is a lekking sandpiper in which males have two genetically determined alternative mating strategies: ‘satellite’ or ‘independent’. Satellite males are non‐territorial, following groups of females on and off leks. Independent males attempt to establish territories on leks and can be either ‘resident’ territory holders, or non‐territorial ‘marginals’. The time budgets of the three behavioural tactics (resident, marginal and satellite) differ notably in time allocated to foraging, aggression and display activity. These differences have led to the suggestion that the benefits of size and energy stores may vary with mating tactic. 2. In this paper in vivo estimates of body composition (fat, fat‐free mass) for breeding male Ruffs using total body electrical conductivity (TOBEC) are presented. 3. Satellite males have significantly shorter tarsi and wings than independent males. 4. After correcting for size, independent males are significantly heavier and fatter than satellites, and marginals in particular are heavier and fatter than both residents and satellites. 5. Estimates of energy expenditure during flight suggest that satellites may maintain reduced energy reserves to minimize flight costs, while the larger fat stores of independent males are consistent with the benefits of endurance as a territory holder.
The role of mycorrhizal fungi in growth enhancement of dune plants following burial in sand
Authors: Perumal J. V. , Maun M. A. 
Published: March 2003

1. Burial in sand of Agropyron psammophilum and Panicum virgatum plants had a stimulating effect on carbon dioxide exchange rate, leaf area and biomass, irrespective of whether sand used for burial did or did not contain mycorrhizal fungi. 2. Plants of both A. psammophilum and P. virgatum species grown in mycorrhiza‐containing sand and then buried with mycorrhiza‐containing sand had the highest CO2 exchange rate, leaf area and biomass. 3. The growth stimulation following a burial episode is probably a composite response of several factors. The major contribution of mycorrhizal fungi will possibly be the exploitation of resources in the burial deposit.
Biomarkers and fluctuating asymmetry as indicators of pollution‐induced stress in two hole‐nesting passerines
Authors: Eeva T. , Tanhuanpää S. , Råbergh C. , Airaksinen S. , Nikinmaa M. , Lehikoinen E. 
Published: March 2003

Abstract1. The stress caused by air pollutants was studied at biochemical, morphological and ecological levels in the Pied Flycatcher, Ficedula hypoleuca, and Great Tit, Parus major, nestlings in 10 study sites along the pollution gradient of a copper smelter.2. First, stress was measured using four biomarkers from blood and liver: ethoxyresorufin O‐deethylase (EROD) enzyme, haemoglobin, stress protein Hsp70 and delta‐aminolevulinic acid dehydratase (ALA‐d) enzyme. Second, the amount of fluctuating asymmetry (FA) in the length of the 3rd primary and the outermost rectrix (in P. major) and the length and thickness of the tarsus were measured. These stress indicators were further examined in relation to the breeding performance of birds, i.e. the ecological response.3. EROD activity was increased in F. hypoleuca nestlings near the pollution source. In P. major, it was not related to the pollution gradient but correlated well with the proportion of starved nestlings, i.e. the nutritional stress during the nestling period. The variations in haemoglobin, Hsp70 and ALA‐d enzyme activity were not significantly related to pollution gradient.4. The tarsus length of F. hypoleuca nestlings and primary length of P. major nestlings showed increased asymmetry in the vicinity of the pollution source. Breeding success decreased towards the pollution source in both species.5. In F. hypoleuca, the pollution‐related stress was verified at all three target levels. In P. major, pollution‐related effects were found at morphological and ecological levels but not at the biochemical level, which suggests that direct toxic effect of heavy metals was not the main mechanism in this species.
Growth and physiological acclimation to temperature and inorganic carbon availability by two submerged aquatic macrophyte species, Callitriche cophocarpa and Elodea canadensis
Authors: Olesen B. , Madsen T. V. 
Published: March 2003

Abstract1. Interactive effects of temperature and inorganic carbon availability on photosynthetic acclimation and growth of two submerged macrophyte species, Elodea canadensis and Callitriche cophocarpa, were examined to test the hypotheses that: (1) effects of temperature on growth rate and photosynthetic acclimation are suppressed under low inorganic carbon availability; (2) the plants compensate for the reduction in activity of individual enzymes at lower temperatures by increasing the activity per unit plant mass, here exemplified by Rubisco. The experiments were performed in the laboratory where plants were grown in a factorial combination of three temperatures (7–25 °C) and three inorganic carbon regimes.2. The relative growth rate of both species was strongly affected by growth conditions and increased by up to 4·5 times with increased temperature and inorganic carbon availability. The sensitivity to inorganic carbon was greatest at high temperature and the sensitivity to temperature greatest at high carbon concentrations.3. Photosynthetic acclimation occurred in response to growth conditions for both species. The affinity for inorganic carbon and the photosynthetic capacity, both measured at 15 °C, increased with reduced inorganic carbon availability during growth and were greater at warmer than at cooler growth temperature. The acclimative change in photosynthesis was related to the extent of temperature and inorganic carbon stress. Using data for Elodea, a negative relationship between degree of temperature stress and photosynthetic performance was found. In relation to inorganic carbon, a linear increase in CO2 affinity and photosynthetic capacity was found with increased inorganic carbon stress during growth.4. The total Rubisco activity declined with increased inorganic carbon availability during growth and with enhanced growth temperature. In addition, the activation state of Rubisco was higher at cooler than at warmer temperatures for Callitriche. This suggests that low‐temperature grown plants compensate for the temperature‐dependent reduction in activity of the individual Rubisco molecules by enhancing resource allocations towards Rubisco.
Spatial and temporal variations in hectare‐scale net CO2 flux, respiration and gross primary production of Arctic tundra ecosystems
Authors: Vourlitis G. L. , Harazono Y. , Oechel W. C. , Yoshimoto M. , Mano M. 
Published: March 2003

Abstract1. Eddy covariance was used to measure the net CO2 flux of Alaskan moist‐tussock and wet‐sedge tundra ecosystems between 1 June and 31 August 1995. The sites were located within 2·5 km of each other and, depending on wind speed and thermal stability, the eddy‐covariance measurements integrated surface fluxes over 0·8–26·5 ha (mean 3·8 ha) at the moist‐tussock site and 0·1–4·2 ha (mean 0·6) at the wet‐sedge site.2. Both sites were net sinks for atmospheric CO2 during the 92‐day measurement period but wet‐sedge tundra accumulated 1·5 times more CO2 than moist‐tussock tundra. Wet‐sedge tundra was a net CO2 sink of −6·4 mol m−2 and moist‐tussock tundra was a net sink of −4·6 mol m−2 over the June–August measurement period.3. Estimates of whole‐ecosystem respiration (R) were made using multiple non‐linear regression by quantifying the response of measured nocturnal CO2 efflux (Fn) to fluctuations in air temperature and water‐table depth (r2 = 0·68). Partial regression analysis revealed that water‐table depth explained relatively more of the variance in Fn (45%) than temperature (11%). R was estimated to be 14·9 mol m−2 for moist‐tussock tundra and 5·4 mol m−2 for wet‐sedge tundra over the 92‐day measurement period. The large difference in R was apparently owing to a substantially higher water table in wet‐sedge tundra.4. Estimated rates of gross primary production (GPP), calculated from measured net CO2 flux and estimated R, were 40% lower for wet‐sedge tundra over the 92‐day measurement period. Rates of GPP integrated over diel (24 h) periods were substantially larger for moist‐tussock tundra ecosystems throughout June and July but during the month of August, total diel rates of GPP for moist‐tussock and wet‐sedge tundra were comparable.5. Our results demonstrate that R and GPP of moist‐tussock and wet‐sedge tundra ecosystems can be reliably estimated from eddy‐covariance measurements using functional relationships developed from plot‐scale studies. Given the large spatial differences in hydrology, the larger sink observed for wet‐sedge tundra was probably the result of relatively lower rates of R.
Geographical variation in the size of body organs in seabirds
Authors: Hilton G. M. , Lilliendahl K. , Solmundsson J. , Houston D. C. , Furness R. W. 
Published: March 2003

Abstract1. The size of body organs shows adaptive temporal variation in many animal species. The variation in the size of body organs was examined to see if it is also a component of local adaptation to geographical variation in ecological conditions.2. Major body organs were measured in five species of Icelandic seabirds, sampled from two areas where birds experience slightly different ecological conditions. Between‐area differences in ecological conditions were consistent among the study species, allowing tests of the generality of ecological effects on organ size.3. All major body organs showed geographical size variation. Livers and kidneys were larger in locations where daily energy expenditure was expected to be higher; small intestines were heavier where food was of lower energy density; stomachs were heavier where food was less digestible; heart and flight muscle were larger where flight costs were greater.4. It is concluded that adaptive variation in organ size may be an important means by which animals optimize exploitation of their local environment, and may be a proximate factor in intraspecific life‐history and metabolic variations between geographically separate populations.
Patterns and consequences of stigma height variation in a natural population of a distylous plant, Primula sieboldii
Authors: Nishihiro J. , Washitani I. , Thomson J. D. , Thomson B. A. 
Published: March 2003

Abstract1. In order to reveal the direction and magnitude of phenotypic selection on the stigma height of heterostylous morphs in a natural population of Primula sieboldii E. Morren (Primulaceae), morphological traits including stigma and anther heights, flowering phenology, local density of potential mating partners, size of ramet, number of pollen grains deposited from the opposite morph and seed set were measured in two flowering seasons.2. Both components of female reproductive success, pollen receipt and seed set, were significantly larger in the long‐styled than in the short‐styled morph in both years.3. Selection analyses based on bivariate correlation and path‐analysis models revealed positive relationships between stigma height and pollination or seed set in the short‐styled morph only, although the effect was statistically significant only in one year. In contrast, seed set in the long‐styled morph was correlated with ramet size.4. Morph difference in reproductive success and the natural selection revealed for higher stigmas in the short‐styled morph should be ascribed to the narrow corolla tube of the species that strictly restrict the path of the proboscis of the pollinators.
Metabolic cold adaptation in insects: a large‐scale perspective
Authors: Addo‐Bediako A. , Chown S. L. , Gaston K. J. 
Published: March 2003

Summary1. Despite its significance from both life‐history and physiological perspectives, metabolic cold adaptation (MCA) in insects remains controversial. Although several small‐scale studies have provided support for such adaptation, many others have not.2. Using a global‐scale analysis of the standard metabolic rates of 346 species, it is shown that after removing the effects of trial temperature and body mass, environmental temperature significantly influences interspecific variation in metabolic rate, such that insects from colder environments tend to have higher, whole‐organism, metabolic rates. Although this effect is weak, it does provide evidence in favour of MCA in this important terrestrial group.3. Although data from the Southern Hemisphere are limited, we show that this adaptation also takes the form of an increase in the slope of the metabolic rate–temperature relationship in Northern, but not in Southern, Hemisphere species.4. Metabolic cold adaptation and its variation among the hemispheres should be counted among the causes of interspecific variation in metabolic rate.
Leaf size and foraging for light in a sclerophyll woodland
Authors: Bragg J. G. , Westoby M. 
Published: March 2003

Summary

It has been suggested that leaf size may represent a foraging scale, with smaller‐leaved species exploiting and requiring higher resource concentrations that are available in smaller patches.
Among 26 shrub species from a sclerophyll woodland community in New South Wales, Australia, species with smaller leaves tended to occur in better light environments, after controlling for height. The dark respiration rates of small‐leaved species tended to exceed those of larger‐leaved species.
However, the higher‐light environments where smaller‐leaved species tended to occur had a patch scale larger than whole plants. There would not have been any foraging‐scale impediment to large‐leaved species occupying these higher‐light patches. An alternative explanation for small‐leaved species being more successful in higher‐light patches, in this vegetation with moderate shading, might be that they were less prone to leaf overheating.
Such relationships of leaf size to light across species at a given height may be important contributors to the wide spread of leaf sizes among species within a vegetation type, along with patterns down the light profile of the canopy, and effects associated with architecture and ramification strategy.
Trade‐offs between net assimilation rate and specific leaf area in determining relative growth rate: relationship with daily irradiance
Authors: Shipley B. 
Published: March 2003

Summary

Three separate experiments were conducted, involving 27 herbaceous species and 14 woody species aged 15–30 days, in order to determine the relative importance of net assimilation rate (NAR), specific leaf area (SLA) and leaf weight ratio (LWR) in explaining interspecific variations in relative growth rate.
Daily quantum inputs were 31·12 mol m−2 day−1 in the first experiment and 33·17 mol m−2 day−1 in the second and third experiments. This is about twice the typical irradiance of most other experiments in this area, but only about 85% of the daily photon flux in nature. Plants were cultivated in hydroponic sand culture in a solution containing 5·8 mm nitrogen.
RGR was strongly and positively correlated with NAR in all three experiments. RGR was weakly and negatively correlated with SLA, while the correlation between RGR and LWR was weak and variable.
These results are compared to those already published in the literature: the commonly reported result that interspecific variation in RGR is determined primarily by SLA is partly due to the low irradiance used in most experiments, and the relative importance of SLA and NAR changes depending on irradiance.
A hypothesis is proposed in which direct and indirect effects of SLA on each of NAR and RGR are decomposed, and which leads to a trade‐off between SLA and NAR as a function of daily irradiance.
Leaf dry matter content as an integrative expression of plant palatability: the case of freshwater macrophytes
Authors: Elger A. , Willby N. J. 
Published: March 2003

Summary

We examined the possibility of using the dry matter content (DMC) of macrophytes (the ratio of dry mass to wet mass) as an integrative variable to predict their palatability to generalist invertebrate grazers.
We assessed the palatability of 20 macrophyte species, using the snail Lymnaea stagnalis (L.) in non‐choice feeding experiments. Three of the species were studied at two different dates in the year, at two or four sites.
The average dry mass consumed by L. stagnalis ranged widely between species, and was negatively correlated to plant DMC. At the intraspecific level, the dry mass consumed varied over time but was not related to site location. Again, the dry mass consumed was negatively correlated to plant DMC.
The DMC of the macrophytes studied explained about 30% of interspecific variability, and >80% of seasonal variability, in snail consumption rate. Therefore this trait could be used as a shortcut to predict variations in macrophyte palatability, especially at the intraspecific level. At the interspecific level, the relationship between DMC and palatability might be weakened by the presence in some plants of low molecular weight chemical deterrents.
Scaling foliar respiration in two contrasting forest canopies
Authors: Turnbull M. H. , Whitehead D. , Tissue D. T. , Schuster W. S. F. , Brown K. J. , Griffin K. L. 
Published: March 2003

Summary

The responses of night‐time dark respiration (Rd) to temperature and leaf characteristics were measured through the canopies of tree species from two distinct forests – an oak‐dominated deciduous forest in north‐eastern USA, and a conifer‐dominated temperate rainforest in New Zealand. These were chosen to examine the extent to which canopy level changes in dark respiration can be applied across forest biomes, and the appropriateness of scaling rules to calculations of whole‐canopy carbon efflux.
The response of respiration to temperature differed significantly between species and with height in the canopy. This involved changes in both Rd at a reference temperature, and the extent to which Rd increased with temperature (described by the energy of activation, Eo, or the change in Rd over a 10 °C range, Q10). Eo ranged from 25 (lower‐canopy leaves) to 53·8 kJ mol−1 K−1 (upper‐canopy leaves) in the deciduous forest, and from 24–37 kJ mol−1 K−1 in the temperate rainforest site.
Relationships between respiratory and leaf characteristics indicated that the instantaneous rate of respiration covaries with soluble sugar concentration and leaf nitrogen, but the temperature response of respiration (Eo or Q10) appears to be driven by leaf N.
Scaling leaf respiratory carbon loss to the whole‐canopy level indicated that simplifying assumptions regarding the variation in respiration and its temperature response with canopy height tend to underestimate carbon loss if the assumptions are based on lower‐canopy leaf physiology, but overestimate carbon loss if the assumptions are based on upper‐canopy physiology. Thus, canopy‐level differences in leaf respiratory characteristics should be considered in modelling efforts attempting to estimate whole‐canopy respiration.
Defect in cytokinesis of fission yeast induced by mutation in the WD40 repeat motif of a TFIID subunit
Authors: Yamamoto Tohru , Horikoshi Masami 
Published: March 2003

Background:TBP‐associated factors contain a variety of structural motifs and their related in vivo significance has remained unclear. We have attempted to identify specific biological phenomena linked to a particular domain of a TAF by analysing domain‐exchanged chimeric mutants between Schizosaccharomyces pombe (Sp) and Saccharomyces cerevisiae (Sc) counterparts.Results:Contrary to the case of TBP, Sp TAF containing the WD40 repeat cannot be exchanged for its Sc counterpart, despite their highly conserved primary structures. This ‘species‐specific’ function locates in the N‐terminal region. The C‐terminal region, largely consisting of the WD40 repeat, is exchangeable for the corresponding region of its Sc counterpart. Growth of the strain harbouring this C‐terminal chimeric mutant is temperature‐sensitive. The chimeric gene product did not disappear at a restrictive temperature, a finding which strongly suggests that the growth defect is caused by an aberration in the interactions through the WD40 repeat structural motif. With temperature elevation, the chimeric mutants underwent drastic morphological changes due to a defect in cytokinesis.Conclusions:The WD40 repeat of TAF is primarily involved in reactions which might regulate cytokinesis in Sp.