Competitive Exclusion
Historical development of the niche theory is very closely related to one of the most important topics of ecology, that is, the problem of species competition and coexistence. Since the beginning of the ecological niche concept, it has been assumed that no two species sharing a single niche could locally coexist. Originally, the later Volterra-Gause principle states that ''under constant conditions, no two species utilizing, and limited by, a single resource can coexist in a limited system''...
CWs with Duckweed
Duckweeds are tiny free-floating vascular plants with worldwide distribution. Their communities occur, as a rule, in small water bodies, namely in fishponds, ditches, or lagoons. The family Lemnaceae consists of about 35 species in four genera, Lemna, Spirodela, Wolfiella, and Wolffia. Duckweeds are among the fastest growing plants in the world, frequently doubling their biomass under optimal conditions in 2 or 3 days with night growth equaling or exceeding day growth for some species....
What Is Ecological Engineering
The most used definition of ecological engineering employs the following formulation ecological engineering is defined as the design of sustainable natural and artificial ecosystems that integrate human society with its natural environment for the benefit of both. It requires, on the one hand, that we understand nature and ensure a sustainable development of natural resources and ecosystems and, on the other hand, that we make use but not abuse of natural resources to the benefit of the human...
Acclimation
B Demmig-Adams, M R Dumlao, M K Herzenach, and WW Adams III, University of Colorado, Boulder, CO, USA 2008 Elsevier B.V. All rights reserved. Do Plants Have a Particularly High Potential for Acclimation Acclimation Patterns Depend on Species and the Severity of the Environment Principal Types of Adjustments Plant Form, Function, and Lifecycle Acclimation Responses to Specific Environmental Factors Oxidative Stress and Redox Signaling as Common Denominators in Stress Perception and Response...
Tools for Characterization and Measurements of Bioavailability
Because bioavailability processes are embedded in ecosystem health risk frameworks, the development of tools that quantitate bioavailability is important. Environmental assessment tools capable of spatially and temporally resolving contaminant variation are important for assessment of exposure frequencies and levels, episodic spills, and natural and anthropogenic remediation. Conventional methods for ecological exposure assessment involve measuring contaminant concentrations in the ambient...
Indicator Organisms
Different classes of indicator organisms are used for 'biological monitoring', where each class may offer a very different response to pollution. Certain organisms have capacity to accumulate pollutants, whereas others are sensitive to the presence of pollutants and react either negatively or positively. Following are some different classes of indicator organisms used in environmental monitoring 1. Sensitive organisms introduced into the environment to test for early warning of pollution, for...
Allomones
Allomones are allelochemicals that evoke in the receiver ofthe signal a behavioral releaser effect or physiological response primer effect that is adaptively favorable to the sender but not the receiver. This definition includes repellent or toxic compounds, which provide defense against attack or infection e.g., secondary plant metabolites , suppressants, which inhibit competitors e.g., antibiotics, allelopathics , and venoms, which poison prey organisms venoms of predatory animals . Another...
Pink Hibiscus Mealybug
Pink hibiscus mealybug Maconellicoccus hirsutus Green Figure 1 invaded the Caribbean nation of Grenada in c. 1993, where it infested young shoots, flowers, and fruits of a wide range of plants, particularly those in the family Malvaceae. Among the important plants affected were ornamental hibiscus Hibiscus rosa-sinensis L. , soursop Annona muricata L. , cotton Gossypium hirsutum L. , cocoa Theobroma cacao L. , and citrus Citrus spp. . The mealybug reached high densities and began to spread...
Restricted Boltzmann Machine
Boltzmann learning underlies an artificial neural network ANN model - the Boltzmann machine - based largely on the Hopfield network model see Hopfield Network with numerous improvements. An understanding of the principles of neural networks in general see Multilayer Perceptron , and Hopfield networks in particular, is highly recommended to better understand this article. Boltzmann learning uses stochastic binary units rather than the deterministic binary threshold units in a Hopfield model. It...
Conclusion 1
Natural selection works through responses of individuals within populations to different environments. Therefore, population dynamics is intimately linked to natural selection, and speciation may have its foundations in within-species polymorphisms for resources. Adaptations may serve to either enhance population stability or lead to increased variation in demographic parameters, and are key to species performance across a wide range of environments, such as across latitudes. A new suite of...
Types of Adaptations Relevant to Population Dynamics
Adaptations of feeding, antipredator, and reproductive morphology can directly affect population demography, and if they vary in space or time, can consequently drive variation in population demography. Alternative feeding morphologies in response to increased competition may increase population size but with reduced growth. Considerable variation in morphology associated with resource use is a classic example of local adaptation to the environment, and can therefore lead to variable population...
Introduction What Is an Adaptive Agent
An 'agent' is an entity in a model that is motivated or goal driven, can adapt its behavior as a function of environmental stimuli, and makes decisions based on local information. An agent may also have memory, allowing it to adapt and make decisions based on past experience. Agents typically represent animals or humans. Due to their decision-making ability and due to the fact that they operate independently, without any top-down, centralized control, agents are often said to be 'autonomous'....