environmental variation Research Papers - Academia.edu (original) (raw)

The paper presents a new generation of torque-controlled lightweight robots (LWR) developed at the Institute of Robotics and Mechatronics of the German Aerospace Center. In order to act in unstructured environments and interact with humans, the robots have design features and control/software functionalities which distinguish them from classical robots, such as: load-to-weight ratio of 1:1, torque sensing in the joints, active vibration damping, sensitive collision detection, as well as compliant control on joint and Cartesian level. Due to the partially unknown properties of the environment, robustness of planning and control with respect to environmental variations is crucial. After briefly describing the main hardware features, the paper focuses on showing how joint torque sensing (as a main feature of the robot) is consequently used for achieving the above mentioned performance, safety, and robustness properties.

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- Mechanical Engineering, Mechatronics, Aerospace, Medical Robotics
- by Renaat Van Rompaey
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- Soil moisture, Forest Management, Regional scale, Agricultural land use change

Scale is a concept that transcends disciplinary boundaries. In ecology and geography, scale is usually defined in terms of spatial and temporal dimensions. Sociological scale also incorporates space and time, but adds ideas about representation and organization. Although spatial and temporal location determine the context for social and ecological dynamics, social-ecological interactions can create dynamic feedback loops in which humans both influence and are influenced by ecosystem processes. We hypothesize that many of the problems encountered by societies in managing natural resources arise because of a mismatch between the scale of management and the scale(s) of the ecological processes being managed. We use examples from southern Africa and the southern United States to address four main questions: (1) What is a "scale mismatch?" (2) How are scale mismatches generated? (3) What are the consequences of scale mismatches? (4) How can scale mismatches be resolved? Scale mismatches occur when the scale of environmental variation and the scale of social organization in which the responsibility for management resides are aligned in such a way that one or more functions of the social-ecological system are disrupted, inefficiencies occur, and/or important components of the system are lost. They are generated by a wide range of social, ecological, and linked social-ecological processes. Mismatches between the scales of ecological processes and the institutions that are responsible for managing them can contribute to a decrease in social-ecological resilience, including the mismanagement of natural resources and a decrease in human well-being. Solutions to scale mismatches usually require institutional changes at more than one hierarchical level. Long-term solutions to scale mismatch problems will depend on social learning and the development of flexible institutions that can adjust and reorganize in response to changes in ecosystems. Further research is needed to improve our ability to diagnose, understand, and resolve scale mismatches in linked socialecological systems.

- by Charles Redman
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- Institutional Change, Southern Africa, Social learning, Multidisciplinary

Interannual variation in biogenic emissions is not well quantified, especially on regional scales. We use a land surface model augmented with a short-term dynamic phenology scheme to estimate the interannual variation in the emission of biogenic volatile organic compounds (BVOCs) between 1982 and 2004. We use North American Regional Reanalysis data to drive two versions of the National Center for Atmospheric Research Community Land Model (CLM) on a 0.1°grid over eastern Texas. The first version is the standard CLM with prescribed leaf area index (LAI) (i.e., LAI varies seasonally but not interannually); the second version is the standard CLM augmented with a dynamic phenology scheme (CLM-DP) that allows LAI to respond to environmental variation. We calibrate CLM-DP using satellite-derived LAI as our visual constraint. When phenology is prescribed, the domain-mean (domain-maximum) average absolute departure from the monthly mean BVOC flux is 11.7% (70.6%); when phenology is allowed to vary with environmental conditions, it is 22.4% (137.7%). The domain-mean (domain-maximum) average absolute departure from the monthly mean flux is lower during summer: using CLM-DP, it is 15.7% (35.3%); using the standard CLM, it is 7.0% (23.0%). The domain-average, mean-normalized standard deviation of the June-July-August mean BVOC flux is 0.0619 when LAI is prescribed and 0.183 when LAI varies with environmental conditions. Our results imply that interannual variation of leaf biomass density, which is primarily driven by interannual variability of precipitation, is a significant contributor to year-to-year differences in BVOC flux on a regional scale, of at least equal importance to interannual variation of temperature and shortwave radiation. Phenology-driven biogenic emission variability is most pronounced in regions with relatively low emissions: as a grid cell's mean BVOC flux decreases, the mean-normalized standard deviation of BVOC flux tends to increase. BVOC flux is most variable between years in subhumid, sparsely wooded regions where interannual variability of precipitation is relatively large.

- by Zong-Liang Yang
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- Environmental Science, Climate Change, Multidisciplinary, Global change

The use of molecular markers in the mapping of traits of agronomic importance holds great promise for speeding the development of improved plant varieties and increasing our understanding of the physiological or molecular mechanisms behind biological phenomena. The technique is now being applied to drought resistance in rice (Oryza sativa L.). Drought is important because a considerable proportion of the world rice area is not irrigated and can be prone to water deficit. A large number of people, particular some of the poorest rice farmers, stand to gain if new varieties which combine high yield and drought resistance can be developed. Rice should be particularly useful for the molecular genetic analysis of drought resistance because of its growing role as a model monocot species and the diversity of drought resistance mechanisms which are found in the germplasm. We briefly review the traits which might be considered important in improving drought resistance in rice, before explaining the molecular mapping approach. We review progress at locating quantitative trait loci (QTLs) for individual mechanisms of drought resistance in controlled environment conditions. This includes a detailed comparison of reported QTLs related to root morphological characters. The search for QTLs associated with field performance under drought stress is analysed and the problems associated with understanding the genetic control of a complex physical and physiological phenomenon under conditions of substantial environmental variation are highlighted. We emphasise that the use of near isogenic lines in overcoming some of the problems offers considerable promise for the future.

- by Techale Birhan
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- Genetics, Plant Biology, Molecular Genetics, Drought Stress

The Peru Chile Current ecosystem is characterized by high biological productivity and important fisheries. Although this system is likely to be severely affected by climate change, its response to current global warming is still uncertain. In this paper, we analyze 10-166 year-old sediments in two cores collected from Mejillones Bay, an anoxic sedimentary setting favorable for the preservation of proxies. Based on a 166-year chronology, we used proxies of bottom-water oxygenation (Mo, V, S, and the (lycopane+n-C 35)/n-C 31 ratio) and surface water productivity (biogenic opal, counts of diatom valves, biogenic Ba, organic carbon, and chlorins) to reconstruct environmental variations in Mejillones Bay. During the last two centuries, a shift took place in the coastal marine ecosystem of Bahia Mejillones at decadal scales. This shift was characterized by intense ENSO-like activity, largescale fluctuations in biological export productivity and bottom water oxygenation, and increased eolian activity (inferred from Ti/Al and Zr/Al). This short-term variability was accompanied by a gradual increase of sulfidic conditions that has intensified since the early 1960s.

- by Javier Diaz O.
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- Earth Sciences, Environmental Science, Oceanography, Climate Change

Concepts from the literature on the relationship between environmental variation and strategic change are used to analyze the effects of deregulation on strategic management in the railroad industry. Specific hypotheses are presented about the impact of regulation and change in regulation on strategy, strategic change and performance. A survey of experts identified the strategies of 27 railroads prior to and after deregulation. Five different railroad strategies and five different kinds of strategic changes are identifed and described. Results suggest that most firms changed their strategies in response to environmental variation, and that those that did change their strategies out-performed those that did not. Among the strategic changes, those involving innovation and contingency strategies were found to be the most profitable. Other empirical results are presented and discussed.

- by Ken Smith
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- Marketing, Strategic Management, Firm Performance, Business and Management

The annual catch of glass eels of the Japanese eel Anguilla japonica highly fluctuates in East Asia, which is a great risk to the eel aquaculture industry and makes resource management difficult. An analysis of data of the catch of glass eels from 1972 to 2008 in Taiwan indicated that the glass eel catch mainly fluctuates in a cycle of 5 and 6 yr, which matches the dominant reproductive cycle of this species. The peak catch percentage of silver eels in the estuary of the Kaoping River in southwestern Taiwan occurred 1 yr before a glass eel peak catch, implying a possible spawner-recruit relationship. Burst catches of glass eels every 11 yr match periods of maximum solar activity. The annual glass eel catch was not statistically correlated with the El Nino-Southem Oscillation (ENSO) index, although strong El Nino events seemed to correspond to years of poor catches. Thus, fluctuations in the annual glass eel catch are likely shaped by both the reproductive cycle of the eel and enviro...

- by Wann Nian Tzeng
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- East Asia, Time series analysis, Solar Activity, Key words

The magnitude and nature of genotype-by-environment (G Â E) interactions for grain yield, days-to-¯ower and plant height of rainfed lowland rice in Northeast Thailand were examined using random F 7 lines from seven crosses developed by the Thai breeding program. A total of 1116 lines and checks were evaluated in a multi-environment trial conducted across three years (1995±1997) and eight sites. The G Â E interaction was partitioned into components attributed to genotype-by-site (G Â S), genotype-by-year (G Â Y) and genotype-by-site-by-year (G Â S Â Y) interactions. The G Â S Â Y interaction was the largest G Â E interaction component of variance for all three traits. There was little G Â S interaction for grain yield and days-toower. The G Â S interaction was signi®cant for plant height, but was the smallest component of variance for that trait. The G Â Y interaction component of variance was signi®cant for all three traits, but was small relative to the genotypic component for days-to-¯ower and plant height. For grain yield the G Â Y interaction component was comparable in size to the genotypic component. Partitioning the genotypic and G Â E interaction components of variance into among-cross and within-cross components indicated that there was signi®cant variation both among and within the crosses for each trait. The relationships between the three traits differed among the crosses and the environments. A major factor contributing to the large G Â S Â Y interactions for grain yield was the genotypic variation for days-to-¯ower in combination with environmental variation for the timing and intensity of drought. Some of the interactions associated with timing of drought were repeatable across the environments sampled in the multi-environment trial, and to some extent the environments were characterised on the basis of whether there was pre-¯owering, intermittent, or terminal drought. There was genotypic variation for grain yield after taking into consideration the in¯uences of timing of drought in relation to plant development. Three of the seven crosses involved the Thai cultivars KDML105 and RD6 as parents. These crosses produced an array of progeny with lower yield than the Thai cultivars, suggesting it would be dif®cult to improve on the yield of these cultivars. In contrast three of the remaining four crosses, which did not have a Thai cultivar as a parent, produced progeny that had higher yield than KDML105 and RD6 indicating that yield of rainfed lowland rice could be improved above that of the these popular cultivars.

- by Pannarut Romyen
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- Genetics, Biology, Computer Simulation, Field Crops

Cephalopods are highly sensitive to environmental conditions and changes at a range of spatial and temporal scales. Relationships documented between cephalopod stock dynamics and environmental conditions are of two main types: those concerning the geographic distribution of abundance, for which the mechanism is often unknown, and those relating to biological processes such as egg survival, growth,

- by ANGEL GONZALEZ
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- Earth Sciences, Water quality, Life history, Biological Sciences

In order to assess the potential of various marine ecosystems for shellfish aquaculture and to evaluate their carrying capacities, there is a need to clarify the response of exploited species to environmental variations using robust ecophysiological models and available environmental data. For a large range of applications and comparison purposes, a non-specific approach based on 'generic' individual growth models offers many advantages. In this context, we simulated the response of blue mussel (Mytilus edulis L.) to the spatio-temporal fluctuations of the environment in Mont Saint-Michel Bay (North Brittany) by forcing a generic growth model based on Dynamic Energy Budgets with satellitederived environmental data (i.e. temperature and food). After a calibration step based on data from mussel growth surveys, the model was applied over nine years on a large area covering the entire bay. These simulations provide an evaluation of the spatio-temporal variability in mussel growth and also show the ability of the DEB model to integrate satellite-derived data and to predict spatial and temporal growth variability of mussels. Observed seasonal, inter-annual and spatial growth variations are well simulated. The large-scale application highlights the strong link between food and mussel growth. The methodology described in this study may be considered as a suitable approach to account for environmental effects (food and temperature variations) on physiological responses (growth, reproduction) of filter feeders in varying environments. Such physiological responses may then be useful for evaluating the suitability of coastal ecosystems for shellfish aquaculture. Research highlights ► We used satellite data (temperature, Chl-a) with a dynamic energy budget model. ► The model correctly describes the observed spatio-temporal variability in mussel growth. ► A large-scale application highlights the strong link between food and mussel growth. ► The methodology developed may be useful for evaluating the suitability of coastal ecosystems for shellfish aquaculture.

- by stephane POUVREAU
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- Oceanography, Aquaculture, Seasonality, Environmental Effect

We studied the demography of Viola elatior, V. pumila, and V. stagnina, three rare and endangered Central European floodplain species, to (i) analyse variation in life-cycles among congeners and between regions (Dyje-Morava floodplains, Czech Republic; Upper Rhine, Germany), (ii) to define sensitive stages in the life-cycles, and (iii) to identify possible threats for population viability and species conservation.Matrix models were based on the fate of marked individuals from a total of 27 populations over two years. We analysed population growth rate (λ), stage distribution, net reproductive rate (R 0), generation time, age at first reproduction, and elasticity and calculated a life table response experiment (LTRE).Most populations were declining and λ did not differ between species or regions during the observed interval. Despite higher probabilities for survival and flowering in the Dyje populations, R 0 was higher in the Rhine populations. Also other demographic traits showed co...

- by Jiří Danihelka
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- Demography, Stochastic Process, Conservation, Czech Republic
- by Marina Borro
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- Free Radicals, Proteomics, Membrane Proteins, Oxidative Stress

The long-lived (about 20 yr) bryozoan Adeonellopsis sp. from Doubtful Sound, New Zealand, precipitates aragonite in isotopic equilibrium with seawater, exerting no metabolic or kinetic effects. Oxygen isotope ratios (δ18O) in 61 subsamples (along three branches of a single unaltered colony) range from −0.09 to +0.68‰ PDB (mean = +0.36‰ PDB). Carbon isotope ratios (δ13C) range from +0.84 to +2.18‰ PDB (mean = +1.69‰ PDB). Typical of cool-water carbonates, δ18O-derived water temperatures range from 14.2 to 17.5 °C. Adeonellopsis has a minimum temperature growth threshold of 14 °C, recording only a partial record of environmental variation. By correlating seawater temperatures derived from δ18O with the Southern Oscillation Index, however, we were able to detect major events such as the 1983 El Niño. Interannual climatic variation can be recorded in skeletal carbonate isotopes. The range of within-colony isotopic variability found in this study (0.77‰ in δ18O and 1.34 in δ13C) means that among-colony variation must be treated cautiously. Temperate bryozoan isotopes have been tested in less than 2% of described extant species — this highly variable phylum is not yet fully understood.

- by Marcus Key
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- Archaeology, Geology, Climate Change, Kinetics

Ecologists have long speculated that species with wider environmental ranges would have broader ranges in phenotype; however, most tests of this hypothesis have involved small numbers of species and/or closely related taxa. We related phenotypic variation in twelve salt marsh plant species from six families to variation in four environmental variables using multiple regression. Within species, plant phenotype was predictably related to environmental variation. Salinity was the most common predictor of plant traits, followed by organic content, water content and elevation. Across species, regressions of single plant trait CVs on range ͑2 ϫ SD͒ of single environmental variables were not significant and did not support the hypothesis that species occupying broad environmental ranges would have broad ranges in phenotypes. However, regression of a composite phenotypic PCA1 on a composite environmental PCA1 showed a marginally significant ͑P ϭ 0.054͒ linear relationship for 10 species. Considering the different patterns of response across species, the lack of a relationship between variation in single phenotypic traits and single environmental variables is likely because the distantly-related taxa employed fundamentally different morphological and physiological strategies to respond to environmental stress gradients. The significant relationship between composite environmental and phenotypic variables reflects the complex nature of species phenotypic response to multivariate environmental gradients. Specifically, in this system, species increase variation in the number of leaves, but decrease variation in leaf size in response to an increase in range of salinity and decrease in range of water and organic content.

- by Christina Richards
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- Plant Ecology, Plant Biology, Ecology, Evolutionary Ecology

MacDonald, K. B. (1996). What do children want? An evolutionary perspective on children's motivation in the peer group. International Journal of Behavioral Development, 19(1), 53-73. This is part of a special issue on "Evolutionary... more

- by Kevin MacDonald
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- Genetics, Psychology, Cognitive Science, Personality

We describe methods to fit structured latent growth curves to data from MZ and DZ twins. The well-known Gompertz, logistic and exponential curves may be written as a function of three components-asymptote, initial value, and rate of change. These components are allowed to vary and covary within individuals in a structured latent growth model. Such models are highly economical, requiring a small number of parameters to describe covariation across many occasions of measurement. We extend these methods to analyse longitudinal data from MZ and DZ twins and focus on the estimation of genetic and environmental variation and covariation in each of the asymptote, initial and rate of growth factors. For illustration, the models are fitted to longitudinal Bayley Infant Mental Development Scale data published by McArdle (1986). In these data, all three components of growth appear strongly familial with the majority of variance associated with the shared environment; differences between the models were not great. Occasionspecific residual factors not associated with the curve components account for approximately 40% of variance of which a significant proportion is additive genetic. Though the growth curve model fit less well than some others, they make restrictive, falsifiable predictions about the mean, variance and twin covariance of other (not yet measured) occasions of measurement. Twin Research (2000) 3, 165-177.

- by Michael Neale
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- Genetics, Cognitive Science, Algorithms, Cognition
- by Catherine Girard
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- Evolutionary Biology, Geology, Biology, Ecology

The relative importance of environmental filtering, biotic interactions and neutral processes in community assembly remains an openly debated question and one that is increasingly addressed using phylogenetic approaches. Closely related species may occur together more frequently than expected (phylogenetic clustering) if environmental filtering operates on traits with significant phylogenetic signal. Recent studies show that phylogenetic clustering tends to increase with spatial scale, presumably because greater environmental variation is encompassed at larger spatial scales, providing opportunities for species to sort across environmental gradients. However, if environmental filtering is the cause of species sorting along environmental gradients, then environmental variation rather than spatial scale per se should drive the processes governing community assembly. Using species abundance and light availability data from a long-term experiment in Minnesota oak savanna understory comm...

- by C. Lehman
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- Evolutionary Biology, Plant Ecology, Community Ecology, Biology

Landcover change has substantially reduced the amount of tropical rain forest since the 1950s. Little is known about the extent of remaining forest types. A multivariate analysis of 144 forest plots across Costa Rica's San Juan-La Selva Biological Corridor resulted in eight floristically defined old-growth forest categories. Spectral separability was tested between categories using Landsat TM bands and vegetation indices for old-growth types, palm swamps, tree plantations and regrowth. Image filtering and NDVI increased spectral separability among categories by 30%. Separability tests resulted in seven welldiscriminated forest categories. Factors driving forest beta-diversity are not well quantified for wet tropical environments. We examined the relationship between rain forest composition and environmental variation for a 3000 km 2 area in northeastern Costa Rica. Mid-to uppercanopy tree species abundance and soil characteristics were measured from 127, 0.25-ha plots across Caribbean lowlands and foothills. Partial Mantel tests produced significant correlations between floristic distance and soil, terrain, and climate variables controlling the effects of geographical distance. Niche-factors showed a significant trend with forest composition more than dispersal limitation or disturbance related factors. The Organization of American States provided me with a scholarship to continue research at CATIE in Costa Rica. vi DEDICATION To Stacy and Ashley, for their unwavering patience vii TABLE OF CONTENTS Authorization to submit dissertation.

- by Steven Sesnie
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- Geography, Climate variability, Habitat Mapping, Beta diversity
- by Glenn Marion
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- Genetics, Biology, Ecology, Population Dynamics

/ Fishes in midwestern streams of the United States experience strong upstream-downstream gradients in natural environmental variability. Upstream fishes experience greater temporal variability in physical-chemical conditions than downstream fishes, particularly in intermittent streams. Associated with these changes in environmental variability, basic changes occur in life history attributes and temporal variation in community structure of stream fishes. As a whole, upstream species have a shorter lifespan , smaller body size, and earlier sexual maturity than downstream species. Descriptive studies also suggest upstream species exhibit more rapid recolonization after severe physical disturbance than downstream species, and fish community structure is temporally more variable in upstream than downstream areas. These longitudinal differences in life history characteristics suggest that upstream fish communities will exhibit more rapid recovery from severe anthropogenic disturbances than downstream fish communities. The greater temporal variability of fish community structure in upstream areas also suggests it will be more difficult in upstream than downstream areas to use fish-based indices to distinguish whether subtle changes in environmental quality are due to natural or anthropogenic disturbances. Long-term monitoring of fishes throughout drainage basins is critically needed to establish more precisely the natural range of variation in community structure. Such monitoring will allow regulatory agencies to distinguish, with greater confidence, the influence of anthropogenic disturbances on stream fishes from the influence of natural environmental variation.

- by Isaac Schlosser
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- Environmental Management, Life history, Multidisciplinary, United States

A preference is not located anywhere in the agent's cognitive architecture, but it is rather a constraining of behavior which is in turn shaped by behavior. Based on this idea, a minimal model of behavioral preference is proposed. A simulated mobile agent is modeled with a plastic neurocontroller, which holds two separate high dimensional homeostatic boxes in the space of neural dynamics. An evolutionary algorithm is used for creating a link between the boxes and the performance of two different phototactic behaviors. After evolution, the agent's performance exhibits some important aspects of behavioral preferences such as durability and transitions. This article demonstrates (1) the logical consistency of the multi-causal view by producing a case study of its viability and providing insights into its dynamical basis and (2) how durability and transitions arise through the mutual constraining of internal and external dynamics in the flow of alternating high and low susceptibility to environmental variations. Implications for modeling autonomy are discussed.

- by Ezequiel Di Paolo
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- Psychology, Cognitive Science, Dynamical Systems, Evolutionary Robotics

Desert locust population dynamics were modelled using the logistic equation with switches in r and K to mimic phase changes. An earlier model with stepwise switches of reproductive rates was modified to include switches of carrying capacity, dependent on population density and random environmental variation. This model reproduced the bi-stable pattern of plagues and recessions found in observed records. The mean duration and variance of plague lengths was dependent on parameter values, with lower values of both when the rates of reproduction were high enough to induce chaotic dynamics. A second family of models was explored in which the phase changes are treated as a catastrophic process governed by a cusp catastrophe function. Although it was necessary to constrain the models to prevent negative population values, these models also successfully reproduced the general pattern observed in nature, provided the parameters were held within limits and there was adequate environmental variation.

- by R.A. Cheke
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- Population Dynamics, Multidisciplinary, Ecological Modelling, Chaotic Dynamics

Seasonal variations of phytoplankton and chlorophyll-a along with its environmental variations including nutrients were studied from June-2004 to March-2007. Samples were collected in three different seasons pre-monsoon (May-June), post-monsoon (October-November) and summer (February-March) from the Mahanadi estuary. Seventy seven species of phytoplankton were encountered during the study period of which, diatoms (Bacillariophyceae) was the dominant group followed by dinoflagellates (Dinophyceae)

- by Bhaskar Acharya
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- Water quality, Seasonality, Seasonal variation, Dissolved Oxygen

Reintroduction is defined as an attempt to establish a species in an area that was once part of its historical range, but from which it has been extirpated or become extinct. Historically, one of the most successful programs was the reintroduction of 254 American black bears (Ursus americanus) from Minnesota to the Interior Highlands of Arkansas in the 1960s; that population has grown to >2,500 today. More recent efforts have involved fewer but better monitored animals and have sometimes employed techniques to improve site fidelity and survival. In Pennsylvania, for example, pregnant female American black bears were successfully translocated from winter dens, the premise being that the adult females would be less likely to return because of the presence of young cubs. That winter-release technique was compared to summer trapping and release in Tennessee; winter releases resulted in greater survival and reduced post-release movements. Homing has not been a problem for small number...

- by Chris Servheen
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- Genetics, Public Perception, Brown bear, Site fidelity

Apex ?1 predators are often threatened with extinction, and reintroduction is one method conservation managers are using to secure their persistence. Yet the ability to predict what these predators will eat upon reintroduction is lacking. Here we test predictions of the diet of the lion (Panthera leo), derived from dietary electivity index and optimality theory, using independent data collected from

- by Matt Hayward
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- Optimality Theory, Wildlife Management, Data Collection, Conservation Management
- by Robert Anholt
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- Genetics, Biology, Drosophila melanogaster, Quantitative Genetics

Due to extensive land clearing in northeastern Mexico, there is an increasing need for restoration for which knowledge on plant establishment biology becomes a priority, for restoration practices. In here we tested the influence of current environmental variation on the establishment biology of common woody species from Tamaulipan thornscrub. Seedling establishment was monitored; four native species (Acacia berlandieri Benth., Ebenopsis ebano (Benth.) Coult, Havardia pallens (Benth.) Brintton and Rose, Prosopis laevigata (Humb & Bonpl. ex. Wild.) M.C. Johston), and one exotic species (Leucaena leucocephala (Lam.) de Wit). Seedling emergence, seedling survivorship, length of stems and number of leaves were evaluated over 1 year in environments with different light regimes: (i) dense thornscrub; (ii) thornscrub edge; (iii) cleared thornscrub (direct sunlight). Ten plots of 4 m 2 (2 m Â 2 m) were sampled in each environment. Seedling emergence occurred on spring and late summer and was greater on dense thornscrub for all species. Native species had higher survivorship and growth and had more leaves in dense thornscrub than in other environments. Exotic L. leucocephala had similar survivorship, shoot length and number of leaves across environments. All seedlings from all species died by late spring, possibly due to environmental stress. Seedling survival was longer for all native plants, as there were surviving seedlings in early spring for all species but not of exotic L. leucocephala. Perhaps mainly as a result of high temperature and low humidity. Additional watering, shading and moisture retaining gels should thus be considered when rehabilitation programs are made with seeds and seedlings in the region.

- by Eduardo Estrada
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- Exotic Species, Biology, Biological Sciences, Growth

The relationship between physiological systems and modern electromechanical technologies is fast becoming intimate with high degrees of complex interaction. It can be argued that muscular function, limb movements, and touch perception serve supervisory functions for movement control in motion and touch-based (e.g. manipulable) devices/interfaces and humanmachine interfaces in general. To get at this hypothesis requires the use of novel techniques and analyses which demonstrate the multifaceted and regulatory role of adaptive physiological processes in these interactions. Neuromechanics is an approach that unifies the role of physiological function, motor performance, and environmental effects in determining human performance. A neuromechanical perspective will be used to explain the effect of environmental fluctuations on supervisory mechanisms, which leads to adaptive physiological responses. Three experiments are presented using two different types of virtual environment that allowed for selective switching between two sets of environmental forces. This switching was done in various ways to maximize the variety of results. Electromyography (EMG) and kinematic information contributed to the development of human performance-related measures. Both descriptive and specialized analyses were conducted: peak amplitude analysis, loop trace analysis, and the analysis of unmatched muscle power. Results presented here provide a window into performance under a range of conditions. These analyses also demonstrated myriad consequences for force-related fluctuations on dynamic physiological regulation. The findings presented here could be applied to the dynamic control of touch-based and movement-sensitive human-machine systems. In particular, the design of systems such as human-robotic systems, touch screen devices, and rehabilitative technologies could benefit from this research.

Climate is one of the most important factors determining variation in forest structure, but whether soils have independent effects is less clear. We evaluate how climate and soil independently affect forest structure, using 89 200 stems ≥ 10 cm dbh from 220 1-ha permanent plots distributed along environmental gradients in lowland Bolivia. Fifteen forest structural variables, related to vertical structure (forest height and layering), horizontal structure (basal area, median and the 99th percentile of the stem diameter and size-class distribution) and density of life forms (tree, palm and liana), were evaluated. Environmental variables were summarized in four multivariate axes, related to rainfall, temperature, soil fertility and soil texture. Multiple regression indicates that all structural variables were affected by one or more of the environmental axes, but the explained variation was generally low (median R 2 = 0.15). Rainfall and soil texture affected most forest structural variables (respectively 87% and 80%) and had qualitatively similar effects. This suggests that plant water availability, as determined by rainfall and soil water retention capacity, is the strongest driver of forest structure, whereas soil fertility was a weaker driver of forest structure, affecting 53% of the variables. Maximum forest height, palm density, total basal area and liana infestation showed the strongest responses to environmental variation (with R 2 ranging from 0.31-0.82). Forest height, palm density and total basal area increased with plant water availability, while liana infestation decreased with plant water availability. Therefore, multiple rather than single environmental factors must be used to explain the structure of tropical forests.

- by Frans Bongers
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- Tropical Ecology, Water Availability, Ecology, Tropical forest

1. The environmental conditions that migratory birds experience during their stay at different locations throughout the year can have significant impact on the variation of annual survival rates. Because migrants often crowd during non-breeding, environmental conditions can affect survival rates of individuals originating from different breeding populations, thus also provoking spatial synchronisation of annual survival rates. The identification of critical environmental factors affecting survival is therefore crucial for understanding large-scale population dynamics of migrants. 2. We studied temporal and spatial variation of survival rates of migratory white stork Ciconia ciconia from eastern Germany and Poland and examine factors associated with this variation. We used resighting and dead-recovery data from more than 30 000 individuals sampled over 19 years to estimate survival. 3. Survival rates of juvenile and adult white storks originating from the two countries varied in parallel over time. Thus, variation in survival was caused by environmental variation to which individuals of both age classes from both countries were similarly sensitive. Variation in the primary production (as reflected by the normalized difference vegetation index) at one staging area in the eastern Sahel that is visited from October to November contributed up to 88% to the temporal variation in survival. Annual survival was reduced when primary production in the Sahel was low. 4. As the population growth rate of white storks is very sensitive to changes in survival, variation in primary production in the Sahelian staging area contributed significantly to population changes and is likely to be an important reason for population synchrony. 5. This study demonstrates that dynamics of migratory bird populations inhabiting large breeding areas can result from environmental variation encountered at a staging area that is visited for only a short period of time.

- by Ulrich Köppen
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- Migration, Decomposition, Animal Ecology, Biological Sciences

Recent developments in both the policy arena and the climate impacts research community point to a growing interest in human adaptation to climatic variability and change. The importance of adaptation in the climate change question is affirmed in the Intergovernmental Panel on Climate Change (IPCC) Technical Guidelines for Assessing Impacts and Adaptations and the IPCC's more recent Second Assessment Report. Yet, the nature and processes of human adaptation to climate are poorly understood and rarely investigated directly. Most often, human responses of one form or another are simply assumed in impacts research. Analyses that do address adaptation use a variety of interpretations and perspectives resulting in an incomplete, and at times inconsistent, understanding of human adaptation to environmental variations. This paper reviews and synthesizes perspectives from an eclectic body of scholarship to develop a framework for characterizing and understanding human adaptation to climatic variabllily and change. The framework recognizes the characteristics of climatic events, the ecological properties of systems which mediate effects, and the dlstinctions which are possible among different types of adaptation. A classification scheme is proposed for differentiating adaptation strategies.

- by john smithers
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- Climate Change, Climate variability, Global Environmental Change, Multidisciplinary

- by Angel Revolledo Guerra
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- Earth Sciences, Water quality, Life history, Biological Sciences

Efect of the altitudinal gradient on the vegetation of Lihue Calel sierras (La Pampa, Argentina). The Lihue Calel Sierras are a low elevation small mountain range located in the SW region of the Monte region. Our objective was to evaluate the spatial and temporal variations in microhabitat conditions induced by topography and their influence on plant species assemblages. Transects were established on north and south slope aspects. Measurements of temperature, wind, radiation, soil properties and vegetation were taken along the altitudinal gradient on each transect. Higher incoming radiation, soil temperature, and rockiness lead to more xeric conditions on north-facing slope in comparison with the southern aspect. Variations in soil temperature, moisture, pH and rock cover accounted for 64% of the environmental variation of the slopes. Plant community composition followed a pattern of drought tolerance and light availability. CAM and C 4 species dominated the warmer north-facing slopes, and C 3 species dominated the more shaded and cooler southern exposures. Our observations highlight the role of topography induced changes on the environmental factors and their effect on plant species distribution in low elevation mountainous ecosystems.

This paper describes some new approaches for enhancing infrared thermometry (IRT) as a technique for detecting stomatal closure as a measure of plant water stress in humid environments. Although infrared thermometry has been widely used in arid climates for detecting plant stress (as indicated by stomatal closure) and for irrigation scheduling it has been found to be less reliable in more cooler humid climates. The use of wet and dry reference surfaces to reduce the method's sensitivity to environmental variation is described and indexes based on IRT measurements of the temperatures of individual leaves and of reference surfaces in the same environment are evaluated. Both an index that corresponds to Idso's original crop water stress index, but based on`wet' and`dry' reference leaves, and an index that is linearly related to leaf conductance were derived and shown to be closely related to measured leaf conductance in runner bean crops under a range of conditions. Various types of reference surface were evaluated and the use of non-transpiring and wet real leaves was found to be particularly convenient.

- by Hamlyn Jones
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- Earth Sciences, Irrigation Management, Biological Sciences, Crop Water Stress Index

A clinal female ßight polymorphism exists in the gypsy moth, Lymantria dispar L., where female ßight diminishes from east to west across Eurasia. A Russian population where females are capable of sustained ascending ßight and a North American population with females incapable of ßight were crossed: parentals, reciprocal F 1 hybrids, double reciprocal F 2 hybrids, and all possible backcrosses to both the parental lines were compared. Heritabilities were estimated using a threshold model, female offspring on female parent regressions, and joint-scaling analyses. Heritability of female ßight capability measured using a free ßight test was at least 0.60, and variation in wing size, muscle strength, and ßight behaviors contributed to the ßight polymorphism. Relative wing size varied continuously and had a heritability of 0.70. Environmental variation accounted for Ͼ90% of the variation in female preßight weight and relative ßight muscle strength, as estimated by an inverted femaleÕs ability to right herself. Preßight walking behavior and early deposition of eggs were each inherited through a single gene with two co-dominant alleles. There was no evidence for sex-linkage or maternal effects in female ßight capability or associated traits. Continued vigilance to exclude and eradicate introductions of strains capable of female ßight in North America is warranted even in areas where no females ßy, because some of the alleles needed for full ßight capability may not be present in the North American populations, and some ßight capability is maintained in the hybrids that could increase the rate of spread of L. dispar. KEY WORDS female ßight propensity, hybrids, Lymantria dispar, dispersal, inheritance Reduction or loss of wings has occurred in most pterygote orders of insects, and many species are polymophic for ßight ability or behavior (Harrison 1980, Zera and Denno 1997). The complete range of wing reduction occurs in females of the genus Lymantria L. Males are all fully winged and capable of strong directed ßight, which is critical in mate Þnding. In the Indian species Lymantria ampla Walker, females have only lobes for wings, and in the Indian gypsy moth, Lymantria obfuscata Walker, the femalesÕ wings are about one half of what would be expected for its size (Schaefer 1989). In female gypsy moths, Lymantria dispar L., two morphs have been identiÞed, both with apparently fully developed wings that differ in ßight capability and associated traits (e.g., size of wings,

- by Melody Keena
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- Zoology, Polymorphism, Muscle strength, North America

Both environmental and genetic factors interact to produce the orientation maps found in the primary visual cortex of adult mammals. However, it is not clear how this interaction occurs during development, or whether both factors are crucial. Previous computational models have focused on either environmentally driven or genetically driven development alone. In contrast, we show that a two-stage model of development can account for a wider range of experimental data. The model explains how environmental and genetic information can be incorporated into the same neural hardware, using a common set of learning mechanisms. Our results suggest that while either environmental or genetically driven development is sufficient for maps and selectivity to form, prenatal activity speeds up early development and makes it more robust against environmental variation.

- by James A. Bednar
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- Engineering, Genetics, Computer Model, Early development

Coral bleaching due to thermal and environmental stress threatens coral reefs and possibly people who rely on their resources. Here we explore patterns of coral bleaching and mortality in East Africa in 1998 and 2005 in a region where the equatorial current and the island effect of Madagascar interact to create different thermal and physicochemical environments. A variety of temperature statistics were calculated, and their relationships with the degree-heating months (DHM), a good predictor of coral bleaching, determined. Changes in coral cover were analyzed from 29 sites that span .1000 km of coastline from Kenya to the Comoros Islands. Temperature patterns are influenced by the island effect, and there are three main temperature environments based on the rise in temperature over 52 years, measures of temperature variation, and DHM. Offshore sites north of Madagascar that included the Comoros had low temperature rises, low DHM, high standard deviations (SD), and the lowest relative coral mortality. Coastal sites in Kenya had moderate temperature rises, the lowest temperature SD, high DHM, and the highest relative coral mortality. Coastal sites in the south had the highest temperature rises, moderate SD and DHM, and low relative coral mortality. Consequently, the rate of temperature rise was less important than background variation, as reflected by SD and kurtosis measures of sea surface water temperature (SST), in predicting coral survival across 1998. Coral bleaching responses to a warm-water anomaly in 2005 were also negatively related to temperature variation, but positively correlated with the speed of water flow. Separating these effects is difficult; however, both factors will be associated with current environments on the opposite sides of reefs and islands. Reefs in current shadows may represent refugia where corals acclimate and adapt to environmental variation, which better prepares them for rising temperature and anomalies, even though these sites are likely to experience the fastest rates of temperature rise. We suggest that these sites are a conservation priority and should be targeted for management and further ecological research in order to understand acclimation, adaptation, and resilience to climate change.

- by joseph maina
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- Environmental Science, Climate Change, Adaptation, East Africa

We tested the importance of micro-environmental topographic parameters as predictors of emmer wheat genetic variation using three classes of single-locus (or maximum several-loci) genetic markers (allozymes, glutenins and qualitative traits) and two classes of markers of polygenic inheritance (phenological and morphological traits). Canonical correspondence analysis (CCA) and redundancy analysis (RDA) detected a significant effect of spatially structured environmental variation on genetic differences between plants for allozymes, glutenins and quantitative morphological and phenological traits. However, after removing a spatial component of variation in partial CCA and partial RDA the relationship of the remaining environmental variation with these genetic markers could be explained by chance alone, allowing us to rule out microniche topographic specialization in emmer wheat. Topographic autocorrelation exhibited a certain degree of similarity with genetic marker autocorrelation, in...

- by Linda Whittaker
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- Evolutionary Biology, Genetics, Geography, Demography

The Chumbe Island Coral Park is a privately established and managed island nature reserve formally recognized by the Zanzibar Government since 1994 and UNEP-WCMC since 1995. The park is located on and around a small formerly uninhabited coral island west of the larger island of Zanzibar off the coast of Tanzania. The park includes a 30-hectare marine reef sanctuary and a 22-hectare coral-rag forest reserve covering most of the island. Founded in 1992 to establish and manage the reserve, Chumbe Island Coral Park Ltd. (CHICOP) won management contracts and a lease from the Government of Zanzibar (GoZ) to create and manage the park, which has become both a successful ecotourism destination and an internationally recognized conservation success. Training by volunteers and employment of local fishermen as park rangers proved cost effective and facilitated direct partnership with local fishing communities. Chumbe is recognised and classified as a Class II protected area under IUCN's WDPA listings. Project Overview Agreement Mechanisms Negotiations on the investment proposal that included the gazettement of the Marine Protected Area (MPA) started 1991 and in 1992 the reef to the west of Chumbe was declared closed by the Department of Fisheries. In 1993, the GoZ Commission for Lands and Environment (COLE) leased 2.44 ha of land on the island to CHICOP for a period of 33 years.

- by Abdirahman Nur
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- Climate Change, Adaptation, East Africa, Ecology

Continuous phenotypic variation in life span results from segregating genetic variation at multiple loci, the environmental sensitivity of expression of these loci, and the history of environmental variation experienced by the organism throughout its life. We have mapped quantitative trait loci (QTL) that produce variation in the life span of mated Drosophila melanogaster using a panel of recombinant inbred lines (RIL) that were backcrossed to the parental strains from which they were derived. Five QTL were identified that influence mated life span, three were male-specific, one was female-specific, and one affected life span in both sexes. The additive allelic effects and dominance of QTL were highly sex-specific. One pair of QTL also exhibited significant epistatic effects on life span. We summarize all of the QTL mapping data for Drosophila life span, and outline future prospects for disentangling the genetic and environmental influences on this trait. Life span and the age-related physiological decline that culminates in death are extremely complex traits. As typical quantitative traits, variation in life span and the rate of aging result from segregating genetic variation at multiple loci, the effects of which are sensitive to environmental variation.

- by Jeff Leips
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- Genetics, Psychology, Drosophila melanogaster, Longevity

- by stephane POUVREAU
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- Oceanography, Aquaculture, Seasonality, Environmental Effect

Behavioral and/or developmental plasticity is crucial for resisting the impacts of environmental stressors. We investigated the plasticity of adult foraging behavior and chick development in an offshore foraging seabird, the black noddy (Anous minutus), during two breeding seasons. The first season had anomalously high sea-surface temperatures and 'low' prey availability, while the second was a season of below average sea-surface temperatures and 'normal' food availability. During the second season, supplementary feeding of chicks was used to manipulate offspring nutritional status in order to mimic conditions of high prey availability. When sea-surface temperatures were hotter than average, provisioning rates were significantly and negatively impacted at the day-today scale. Adults fed chicks during this low-food season smaller meals but at the same rate as chicks in the unfed treatment the following season. Supplementary feeding of chicks during the second season also resulted in delivery of smaller meals by adults, but did not influence feeding rate. Chick begging and parental responses to cessation of food supplementation suggested smaller meals fed to artificially supplemented chicks resulted from a decrease in chick demands associated with satiation, rather than adult behavioral responses to chick condition. During periods of low prey abundance, chicks maintained structural growth while sacrificing body condition and were unable to take advantage of periods of high prey abundance by increasing growth rates. These results suggest that this species expresses limited plasticity in provisioning behavior and offspring development. Consequently, responses to future changes in sea-surface temperature and other environmental variation may be limited.

A sigmoid curve with three fitting parameters is proposed as a descriptive model for the spatial velocity field in one-dimensional growth of plant organs. Analytic expressions are derived for the relative elemental growth (REG) rate, the position and value of the REG rate maximum, the length of the growth zone, the inverse of the growth trajectory and cell length in the "elongation only" zone. The expressions are fit to published data to characterize the effects of environmental variation on growth of monocotyledonous roots. The simple expressions for growth may prove useful in mechanistic models. The fitted curves summarize more than a decade of observations and thus provide a challenge to theorists.

- by Wendy Silk
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- Biological Sciences, Mathematical Sciences, Velocity Field, environmental variation

- by Praxedes Munoz Parra
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- Earth Sciences, Climate Change, Peru, Global Warming

Energy balance depends on the efficiency with which organisms make use of their trophic resources, and has direct impact on their fitness. There are environmental variations that affect the availability as well as the quality of such resources; energy extraction also depends on the design of the digestive tract. It is expected that features associated with food utilization will be subjected to selective pressures and show some adjustment to the variability of the environment. Since energetic constraints challenge animals to display digestive compensatory mechanisms, the objective of this study is to determine the physiological and behavioral responses to spatial and seasonal heterogeneity in food quality. We investigated digestive strategies (digestive efficiency and coprophagy) in cavies inhabiting two different populations, and hence naturally experiencing different levels of diet quality. Cavies under experimentally different quality diets showed changes in dry matter digestibility and intake, digesta retention time and coprophagy. Our results partially support the expectations from theory and also reveal interpopulation differences in the ability to cope with changes in food quality, and may explain the capability of Microcavia australis to colonize extreme habitats.

- by Paola Sassi
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- Physiology, Food, Diet, Argentina
- by fernando hiraldo
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- Life history, Biological Sciences, Population Aging, Environmental Sciences