Capacity Of Different Species Research Articles

Do species’ traits predict recent shifts at expanding range edges?

Although some organisms have moved to higher elevations and latitudes in response to recent climate change, there is little consensus regarding the capacity of different species to track rapid climate change via range shifts. Understanding species' abilities to shift ranges has important implications for assessing extinction risk and predicting future community structure. At an expanding front, colonization rates are determined jointly by rates of reproduction and dispersal. In addition, establishment of viable populations requires that individuals find suitable resources in novel habitats. Thus, species with greater dispersal ability, reproductive rate and ecological generalization should be more likely to expand into new regions under climate change. Here, we assess current evidence for the relationship between leading-edge range shifts and species' traits. We found expected relationships for several datasets, including diet breadth in North American Passeriformes and egg-laying habitat in British Odonata. However, models generally had low explanatory power. Thus, even statistically and biologically meaningful relationships are unlikely to be of predictive utility for conservation and management. Trait-based range shift forecasts face several challenges, including quantifying relevant natural history variation across large numbers of species and coupling these data with extrinsic factors such as habitat fragmentation and availability.

Estimating the capability of different phytoplankton groups to adapt to contamination: herbicides will affect phytoplankton species differently

• Investigating the differential capacity of the response of phytoplankton to human-induced environmental forcing has become a key issue to understanding further the future repercussions on the functioning of aquatic ecosystems. • The initial tolerance to the widely dispersed herbicide simazine was measured in diverse phytoplankton species. An experimental ratchet system maintaining large populations of dividing cells (which ensures the occurrence of rare spontaneous mutations that confer adaptation) and a strong selection pressure (which ensures the preservation of such mutations within the population) was later applied to estimate the capability of different groups of phytoplankton to adapt to simazine. • Initially, simazine doses between 0.05 and 0.15 ppm were able to inhibit 100% growth in all the species tested. However, a significant increase in simazine resistance was achieved in all derived populations during the ratchet experiment. The differential capacity for simazine adaptation was observed among the different species. • The capacity of different species to adapt to simazine can be explained in relation to taxonomic group, ploidy, growth rate and habitat preference. Haploid populations of continental Chlorophyta showed the greatest capacity to adapt to simazine. By contrast, populations of Haptophyta of open ocean regions were the group least capable of adapting to the herbicide.

MRI of the Microarchitecture of Myocardial Infarction

Myocardial infarction (MI) is a leading cause of death and disability. In addition to the immediate incidence of death in acute infarction caused by pump failure or arrhythmias related to the immediate loss of functioning cardiac tissue and the possibility of later progression to intractable pump failure in the subacute or chronic phases of infarction, a significant number of patients with prior MI have sudden death,1 presumably largely caused by arrhythmias related to the infarction. There are various theories about the mechanisms of infarction-related arrhythmias, many centering around the idea that the altered transmission through the region of the infarction can alter the propagation of waves of electric activation in such a way that they can set up self-perpetuating foci of electric activity. However, there is still much uncertainty about the area. Article see p 206 In MI, there is ischemia of a portion of the heart wall that is sufficiently severe and prolonged that cells in the heart wall start to die. Whereas the myocytes, with their relatively high metabolic demands, are likely to be irreversibly damaged by such a significant period of ischemia and thus lost from the wall, the fibroblasts in the heart wall are more resistant to the effects of ischemia and thus are more likely to survive. In the healing phases of MI, these fibroblasts can become activated and effectively “patch” the wall with a meshwork of collagen. The resistance of the heart wall to the effects of ischemia is species-dependent, in part reflecting the different capacities of different species for supplying collateral blood to myocardium at risk. A correlate of this is seen in the degree of definition of the infarcted myocardium from the adjacent spared myocardium. Species such …

Minding the gap: Why there is still no theory in comparative psychology

AbstractThe prevailing view that there is significant cognitive continuity between humans and other animals is a result of misinterpretations of the role of evolution, combined with anthropomorphism. This combination has often resulted in an over-interpretation of data from animal experiments. Comparative psychology should do what the name indicates: study the cognitive capacities of different species empirically, without naive evolutionary presuppositions.

Swimming performance of the migratory Neotropical fish Leporinus reinhardti (Characiformes: Anostomidae)

The fishways built in Latin America were mainly based on those used in the northern hemisphere for passing salmonids upstream. However, the swimming capacity in terms of speed and endurance is a major factor concerning the design of a fishway, and this information is not available for migratory neotropical fish species. Therefore, studies on swimming performance of neotropical species is fundamental. The aim of this study was to estimate the critical, sustained and prolonged speeds for the piau-três-pintas Leporinus reinhardti, and to evaluate the influence of water temperature on the swimming performance of the species. Variable (increasing) and fixed velocity tests were performed in a respirometer. When compared to other species whose critical speed data are available, the piau showed higher speeds, for a given total length. Fatigue times per prolonged speed class were estimated as well as prolonged speed per fatigue time class. The changing point from sustained to prolonged swimming was estimated to occur approximately at a speed of seven body-lengths per second (1.12 m/s for an individual with 16 cm total length: the first maturation length). In spite of the great swimming performance of piau, the adoption of efficient directives in fishway projects to allow the passage of neotropical ichthyofauna, will depend on a more detailed analysis of the swimming capacity of different species.

A study on nitrate reductase activity (NRA) of geophytes from Mediterranean environment

Nitrate reductase activity (NRA) in different compartments of 14 Mediterranean geophytes (bulbous, tuberous and rhizomatous) and actual mineral nitrogen (NO 3 − and NH 4 +) in their soils were investigated. The nitrate reduction capacities of each species were determined as NRA per total plant material. Differences among compartments for NRA were significant in all species. The highest NRA was found in leaves of tuberous species ( Anemone coronaria, Cyclamen coum) and of most bulbous species ( Allium flavum, Allium guttatum, Bellevelia sarmatica, Galanthus plicatus, Leucojum aestivum, Ornithogalum nutans, Tulipa sylvestris). Therefore, in this group of species the contribution of the leaves to total plant NRA was the highest. The other bulbous species ( Allium scorodoprasum, Crocus chrysanthus, Fritillaria bithynica, Muscari neglectum) and one rhizomatous taxon ( Iris suaveolens) have a different NRA distribution within the plants. In these species the highest values of NRA were found in different organs. For example, in Allium scorodoprasum the highest NRA was in tunics, and in flowers in M. neglectum. Although leaves are the main compartments reducing nitrate in most of the studied geophytes, other compartments also contribute to total plant nitrate reduction. Our results show that the nitrate reduction capacity is different among geophyte species. Even if it roughly reflects the nitrogen supply in a habitat, differences in nitrate reduction capacities of different species collected from same sites indicate that the nitrate reducing capacity is species-specific.

Nutrient uptake in eastern deciduous tree seedlings

Tree seedlings that colonize large treefall gaps are generally shade-intolerant species with high potential relative growth rates. Nutrient availability may be significantly elevated in disturbance-induced gaps, however, little is known about the role of differences in nutrient uptake capacities of different species in structuring the community response to gap openings in eastern North American deciduous forests. Seven tree species were grown from seed under both a high and a low nutrient regime, and uptake kinetics of phosphate, ammonium, and nitrate were studied. Yellow birch, a species with intermediate shade tolerance and relative growth rate, had the highest maximum rates of uptake of all ions, while tulip tree, a gap-colonizing species with high relative growth rate, had the lowest rate of phosphate uptake and intermediate rates of ammonium and nitrate uptake. Beech and hickory, which have low relative growth rates and are not gap-colonizing species, had intermediate levels of nutrient uptake. There was no evidence that species with the highest maximum uptake rates measured at high supply concentrations had relatively low uptake at low nutrient supply concentrations. Although birch increased phosphate absorption capacity when grown under a low nutrient regime, this pattern did not hold for nitrate or ammonium uptake, and other species showed no change in nutrient uptake capacity according to nutrient growth regime. Clearly, factors other than nutrient absorption capacity, such as nutrient use efficiency or allocation to root vs. shoot biomass, underlie differences in species' capacities to colonize and maintain a high relative growth rate in canopy gaps.

NITROGEN METABOLISM IN HALOPHYTES V. THE OCCURRENCE OF MULTIPLE FORMS OF GLUTAMINE SYNTHETASE IN LEAF TISSUE

SummaryIon‐exchange chromatography was used to examine the occurrence of glutamine synthetase (GS) isoforms in leaf tissue of 18 species of coastal plants. Two groups of species were recognizable on the basis of their complement of GS isoforms. One group comprised those species which exhibited two forms of GS, the properties of which were consistent with their being cytoplasmic and chloroplastic isoforms. In the second group were species which had only a single isoform, and exhibited properties similar to those of the chloroplastic isoform. Immunoprecipitation studies with antibody raised to the cytoplasmic isoenzyme of barley were carried out to identify the isoform present in species having only one peak of activity on ion‐exchange chromatography. No relationship was evident between either total GS activity or the occurrence of the cytoplasmic isoform and the photo respiratory capacity of different species.

The β-adrenergic receptor in mammalian placenta: Species differences and ontogeny

Summary β-Adrenergic receptors were demonstrated in placental membrane fractions of five mammalian species (rat, rabbit, guinea pig, sheep and human) with the radiolabelled antagonist (−)-[3H]-dihydroalprenolol ((−)-[3H]DHA). Identical membrane preparations showed a variable maximum binding capacity in different species, ranging from 70±6.7 in the term rat to 315 ±28.2 in the term rabbit. Binding affinity did not change with species and (−)-[3H]DHA binding was associated with a catecholamine-sensitive adenylate cyclase in each. In the rabbit placenta, β-adrenergic receptor subtypes were partially characterized and the ontogeny of the placental β-receptor demonstrated. Agonist competition for the (−)-[3H]DHA binding site showed the order of potency (−)-isoproterenol≫ (−)-epinephrine≫ (−)-norepinephrine characteristics of a β2 subtype. Guanine nucleotides (Gpp(NH)p) significantly reduced agonist affinity for the binding site and increased the Hill coefficient from 0.6 to approximately 1.0, as expected in a ‘coupled’ β-adrenergic receptor. Competition between (−)-[3]DHA and β-adrenergic receptor subtype selective agents was performed to define the β-receptor subtype populations. In contrast to the linear Hofstee plots obtained with classical agonists, curvilinear Hofstee plots were obtained with both metoprolol (β1 selective) and zinterol (β2 selective), indicating the presence of two distinct receptor subtype populations. A predominance of the β2 subtype was demonstrated with both agents in the term rabbit placenta (35 per cent β1, 65 per cent β2). β-Adrenergic receptor density in rabbit placentae from 16 to 30 days' gestation was determined. Protein and DNA content were also determined in these placentae. A period of growth by cellular hyperplasia from day 16 to day 25, during which DNA increased threefold and protein per DNA remained constant, was followed by a period of growth by cellular hypertrophy from day 25 to day 30, during which DNA remained constant and protein per DNA increased twofold. The β-adrenergic receptor density increased markedly with gestation (181±29 to 330±37 fmol/mg). There was no change in binding affinity with gestation. β-Receptor density per DNA remained constant during the period of cellular hyperplasia, increased twofold during early cellular hypertrophy (day 25 to day 27) and then remained constant to term (day 30). An adenylate cyclase coupled β-adrenergic receptor is present in the placentae of several mammalian species and changes in density in parallel with maturational events in one species, suggesting a role for catecholamines in placental function.

Studies in the Physiological Action of 2,2-Dichloropropionic Acid

The factors determining the pattern of uptake by Lemna minor of 2,2-dichloropropionic acid (DCPA), containing chlorine-36, have been examined. Entry takes place via both the roots and frond and is largely in the ionic form. Initially, the net rates are high and are replaced by slower but steady rates. It is concluded that over the first 30 minutes, net uptake is dependent on the physico-chemical processes since (i) the rate is directly proportional to the external concentration, (ii) on transference to buffer containing non-radioactive DCPA up to 90 per cent of the radioactivity is exchangeable, (iii) the temperature coefficients for the rates of net influx and efflux range from 1.2 to 1.4. During the second phase, the net rates of uptake are curvilinearly related to concentration, the temperature quotients are higher and the rates of efflux markedly lower than in the first phase. Phenylmercuric nitrate and cupric sulphate at 5×10−6 M halve the net rate of uptake but higher concentrations are demanded for dinitrophenol, arsenite, aside, and iodoacetate. The depression induced by phenylmercuric nitrate can to some degree be reversed by the addition of either glutathione or cysteine. For pyruvic acid to halve the rate of uptake of DCPA, it requires more than a three hundredfold greater concentration. It is postulated that in the second phase, uptake is mediated by metabolic processes involving thiol groups. The ability of calcium pantothenate and β-alanine to reverse the inhibitory effects of DCPA on the growth of L. minor were investigated in multifactorial experiments. Over a narrow range of concentrations, calcium pantothenate partially offset the inhibitions of growth but the interactions for β-alanine were not significant. These results do not support the view that the primary action of DCPA is to interfere with the biosynthesis of Co-enzyme A. In a comparison of the maximal capacity of different species to accumulate DCPA in their roots, up to a six-fold difference was recorded in the eight species examined. On the basis of these findings, the mechanisms determining selective action and the inhibition of meristematic activity are discussed.

Production of experimental scurvy in a bird species.

IT has been generally supposed that all species of animals except the primates and the guinea pig are able to synthesize ascorbic acid according to their requirements. In a previous communication1, using our technique of incubating liver and kidney tissues of different species of animals with D-glucuronolactone as substrate in presence of cyanide, it was shown that in some species the kidney could effect the synthesis and in some the liver. In the evolutionary ascent the mechanism for the synthesis of ascorbic acid appeared to pass from the kidney to the liver and then to disappear altogether. It was also unexpectedly observed that neither the liver nor the kidney tissue of the red-vented bulbul (Pycnonotus cafer, Linn.) and of the Indian fruit-bat (Pteropus medius) could effect the synthesis. Thus at least one avian species, the red-vented bulbul, and one mammalian species, the Indian fruit-bat, were apparently incapable of synthesizing ascorbic acid. It was suggested, therefore, that the cyanide technique might offer a simple means for determining the capacity of different species for the synthesis of ascorbic acid. This supposition has now been proved to be correct by actually placing some red-vented bulbuls on a scorbutic diet and producing in them ascorbic acid deficiency symptoms, which could be cured by ascorbic acid.

Resistance to Hunger in Birds

importance to birds, especially in the winter when air temperature may also be low. Hunger becomes more quickly critical at low air temperatures because general metabolism is higher and more energy is required to maintain constant body temperatures. Small wild birds do not feed during the hours of darkness, and in winter the nights may be too long and too cold for some species to survive. Thus, the capacity of different species to survive for periods without food is important in controlling their migration, distribution, and abundance (Kendeigh, 1934). There have been few studies to date on the survival time of wild birds with-