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Scaling Relationships (scaling + relationships)
Selected AbstractsOntogenetic scaling of scansorial surface area and setal dimensions of Chondrodactylus bibronii (Gekkota: Gekkonidae): testing predictions derived from cross-species comparisons of gekkotansACTA ZOOLOGICA, Issue 1 2009Nicole B. Webster Abstract Little is known of how the adhesive apparatus of gekkotans scales with growth. Cross-species comparisons of certain characteristics, using size as a comparator to investigate scaling relationships, suggest certain relationships between subdigital pad area and body size. The manner in which the adhesive apparatus grows and scales within any one species, however, remains unknown, and it is unclear whether interspecific and intraspecific patterns are similar. To address this, we examined a post-hatching ontogenetic series of the southern African gecko Chondrodactylus bibronii and demonstrate that setal density, setal basal diameter and setal spacing remain relatively constant in relation to size, indicating conserved subdigital pad assembly rules that are independent of size. Conversely, however, average and maximal setal lengths increase slightly and isometrically with size, an outcome that is probably explained by setal row recruitment, and the surface area of the subdigital pads scales close to, but below, isometry with respect to body mass and snout,vent length, it therefore does not increase sufficiently with size to compensate for the increase in mass. As a result, relative adhesive capacity decreases with growth with a regression slope of ,0.45. [source] Close range digital photogrammetric analysis of experimental drainage basin evolutionEARTH SURFACE PROCESSES AND LANDFORMS, Issue 3 2003J. Brasington Abstract Despite the difficulties of establishing formal hydraulic and geometric similarity, small-scale models of drainage basins have often been used to investigate the evolution and dynamics of larger-scale landforms. Historically, this analysis has been restricted to planform basin characteristics and only in the last decade has the topographic similarity of experimental landscapes been explored through explicitly three-dimensional parameters such as the distributions of cumulative drainage area, area,slope and catchment elevation. The current emphasis on three-dimensional morphometry reflects a growing awareness of the descriptive paucity of planform data and the need for more robust analysis of spatial scaling relationships. This paradigm shift has been significantly facilitated by technological developments in topographic survey and digital elevation modelling (DEM) which now present the opportunity to acquire and analyse high-resolution, distributed elevation data. Few studies have, however, attempted to use topographic modelling to provide information on the changing pattern and rate of sediment transport though an evolving landscape directly by using multitemporal DEM differencing techniques. This paper reports a laboratory study in which digital photogrammetry was employed to derive high-resolution DEMs of a simulated landscape in declining equilibrium at 15 minute frequency through a 240 minute simulation. Detailed evaluation of the DEMs revealed a vertical precision of 1·2 mm and threshold level of change detection between surfaces of ±3 mm at the 95 per cent confidence level. This quality assurance set the limits for determining the volumetric change between surfaces, which was used to recover the sediment budget through the experiment and to examine local - and basin-scale rates of sediment transport. A comparison of directly observed and morphometric estimates of sediment yield at the basin outlet was used to quantify the closure of the sediment budget over the simulation, and revealed an encouragingly small 6·2 per cent error. The application of this dynamic morphological approach has the potential to offer new insights into the controls on landform development, as demonstrated here by an analysis of the changing pattern of the basin sediment delivery ratio during network growth. Copyright © 2003 John Wiley & Sons, Ltd. [source] Selection on defensive traits in a sterile caste , caste evolution: a mechanism to overcome life-history trade-offs?EVOLUTION AND DEVELOPMENT, Issue 1 2009Estelle A. Roux SUMMARY During development and evolution individuals generally face a trade-off between the development of weapons and gonads. In termites, characterized by reproductive division of labor, a caste evolved,the soldiers,which is completely sterile and which might be released from developmental trade-offs between weapons and testes. These soldiers are exclusively dedicated to defense. First, we investigated whether defensive traits are under selection in sterile termite soldiers using allometric analyses. In soldiers of the genus Cryptotermes phragmotic traits such as a sculptured and foreshortened head evolve rapidly but were also lost twice. Second, we compared the scaling relationships of these weapons with those in solitary insects facing a trade-off between weapons and gonads. Defensive traits consistently had lower slopes than nondefensive traits which supports the existence of stabilizing selection on soldier phragmotic traits in order to plug galleries. Moreover, soldier head widths were colony specific and correlated with the minimum gallery diameter of a colony. This can proximately be explained by soldiers developing from different instars. The scaling relationships of these termite soldiers contrast strikingly with those of weapons of solitary insects, which are generally exaggerated (i.e., overscaling) male traits. These differences may provide important insights into trait evolution. Trade-offs constraining the development of individuals may have been uncoupled in termites by evolving different castes, each specialized for one function. When individuals in social insect are "released" from developmental constraints through the evolution of castes, this certainly contributed to the ecological and evolutionary success of social insects. [source] Allometric relationships between lamina area, lamina mass and petiole mass of 93 temperate woody species vary with leaf habit, leaf form and altitudeFUNCTIONAL ECOLOGY, Issue 4 2008Guoyong Li Summary 1The allometric scaling relationship between lamina and lamina support has rarely been examined, such that its significance to plant life-history strategies has not been fully explored and understood so far. We investigated the sizes of leaf lamina and petiole for 93 temperate broad-leaved woody species at two altitudes of a southwestern mountain, and analysed the scaling relationship in relation to leaf habit (evergreen vs. deciduous), leaf form (simple- vs. compound-leaved species), and habitat type (low vs. high altitude). 2Significant allometric scaling relationships were found between petiole mass and lamina mass, and between petiole mass and lamina area, with common slopes of 0·872 and 0·742, respectively, both significantly departed from the value of 1·0. The results of phylogenetic comparative analyses were in accordance with the observed positive scaling relationships. 3The evergreen species were found to have a greater petiole mass than the deciduous at a given lamina area; whilst a contrasting pattern was observed between lamina mass and petiole mass, in which the evergreens had a greater biomass allocation to lamina for the same petiole mass relative to the deciduous. 4The compound-leaved species were observed to be significantly greater in both lamina area and lamina support (including petioles, rachis and petiolules) than the simple-leaved species, whereas the former had a smaller lamina area or lamina mass at a given petiole mass than the latter. 5The plants from the high altitude had less lamina area at a given petiole investment compared to those from the lower altitude, likely due to the large mechanic and transporting requirements of petioles in the species at high altitude. 6Our results indicate that petioles serve as an adverse forcing on the maximization of lamina area and lamina biomass and that the allometric relationship between lamina and lamina support varies with leaf habit, leaf form and habitat. [source] From molecules to ecosystems through dynamic energy budget modelsJOURNAL OF ANIMAL ECOLOGY, Issue 6 2000R. M. Nisbet Summary 1. Dynamic energy budget (DEB) models describe how individuals acquire and utilize energy, and can serve as a link between different levels of biological organization. 2. We describe the formulation and testing of DEB models, and show how the dynamics of individual organisms link to molecular processes, to population dynamics, and (more tenuously) to ecosystem dynamics. 3. DEB models offer mechanistic explanations of body-size scaling relationships. 4. DEB models constitute powerful tools for applications in toxicology and biotechnology. 5. Challenging questions arise when linking DEB models with evolutionary theory. [source] Prey availability directly affects physiology, growth, nutrient allocation and scaling relationships among leaf traits in 10 carnivorous plant speciesJOURNAL OF ECOLOGY, Issue 1 2008Elizabeth J. Farnsworth Summary 1Scaling relationships among photosynthetic rates, leaf mass per unit area (LMA), and foliar nitrogen (N) and phosphorus (P) content hold across a diverse spectrum of plant species. Carnivorous plants depart from this spectrum because they dedicate substantial leaf area to capturing prey, from which they derive N and P. We conducted a manipulative feeding experiment to test whether scaling relationships of carnivorous plant leaf traits become more similar to those of non-carnivorous taxa when nutrients are not limiting. 2We examined the effects of prey availability on mass-based maximum photosynthetic rate (Amass), chlorophyll fluorescence, foliar nutrient and chlorophyll content, and relative growth rate of 10 Sarracenia species. We hypothesized that increased prey intake would stimulate Amass, reduce stress-related chlorophyll fluorescence, increase photosynthetic nutrient-use efficiencies (PNUEN, PNUEP), and increase relative biomass allocation to photosynthetically efficient, non-carnivorous phyllodes. 3Two plants per species were assigned in a regression design to one of six weekly feedings of finely ground wasps: 0,0.25 g for small plant species; 0,0.5 g for intermediate-sized species; and 0,1.0 g for large species. The first two leaves emerging on each plant were fed. 4Increased prey availability increased photosystem efficiency (Fv/Fm ratio) in the first two leaves, and chlorophyll content and Amass in younger leaves as older leaves rapidly translocated nutrients to growing tissues. Higher prey inputs also led to lower N : P ratios and a shift from P- to N-limitation in younger leaves. PNUEP was significantly enhanced whilst PNUEN was not. Better-fed plants grew faster and produced a significantly higher proportion of phyllodes than controls. 5Feeding shifted scaling relationships of P relative to Amass, N and LMA from outside the third bivariate quartile to within the 50th bivariate percentile of the universal spectrum of leaf traits; other scaling relationships were unaffected. Carnivorous plants can rapidly reallocate P when nutrients are plentiful, but appear to be less flexible in terms of N allocation. 6Synthesis. Our results support the general hypothesis put forward by Shipley et al. (2006) that observed scaling relationships amongst leaf traits derive from trade-offs in allocation to structural tissues vs. liquid-phase (e.g. photosynthetic) processes. These trade-offs appear to be especially constraining for plants growing in extremely nutrient-poor habitats such as bogs and other wetlands. [source] A unifying explanation for diverse metabolic scaling in animals and plantsBIOLOGICAL REVIEWS, Issue 1 2010Douglas S. Glazier The scaling of metabolic rate with body mass has long been a controversial topic. Some workers have claimed that the slope of log-log metabolic scaling relationships typically obeys a universal 3/4-power law resulting from the geometry of resource-transport networks. Others have attempted to explain the broad diversity of metabolic scaling relationships. Although several potentially useful models have been proposed, at present none successfully predicts the entire range of scaling relationships seen among both physiological states and taxonomic groups of animals and plants. Here I argue that our understanding may be aided by three shifts in focus: from explaining average tendencies to explaining variation between extreme boundary limits, from explaining the slope and elevation (metabolic level) of scaling relationships separately to showing how and why they are interrelated, and from focusing primarily on internal factors (e.g. body design) to a more balanced consideration of both internal and external (ecological) factors. By incorporating all of these shifts in focus, the recently proposed metabolic-level boundaries hypothesis appears to provide a useful way of explaining both taxonomic and physiological variation in metabolic scaling relationships. This hypothesis correctly predicts that the scaling slope should vary mostly between 2/3 and 1 and that it should be related to metabolic (activity) level according to an approximately U-shaped function. It also implies that the scaling of other energy-dependent biological processes should be related to the metabolic level of the organisms being examined. Some data are presented that support this implication, but further research is needed. [source] | ||||||||||