Ecology Ecological valance M. Saadatian

Ecological valance Ecological balance is an balance within a community where the organisms remain stable and the changes are slow and gradual. A ecological balance must be retained in order for species to thrive comfortably in their habitat. Removal of things like plants, animals, trees and other natural items can shift the balance. This shifting can lead to a loss of something. The loss may be something like lost vegetation or animals or an increase in pollution. Stenoece: a species do not ability to stable with environmental (weak dispersion) Euryece: a species ability to stable with environmental (wide dispersion)

Liebig rule Liebig's law of the minimum, often simply called Liebig's law or the law of the minimum, is a principle developed in agricultural science by Carl Sprengel (1828) and later popularized by Justus von Liebig. It states that growth is controlled not by the total amount of resources available, but by the scarcest resource (limiting factor). This concept was originally applied to plant or crop growth, where it was found that increasing the amount of plentiful nutrients did not increase plant growth. Only by increasing the amount of the limiting nutrient (the one most scarce in relation to "need") was the growth of a plant or crop improved.

Blackman rule According to this law, when a process depends on a number of factors, its rate is limited by the pace of the slowest factor. Blackman's law of limiting factors determines the rate of photosynthesis.

Shelford rule It states that an organism's success is based on a complex set of conditions and that each individual or population has a certain minimum, maximum, and optimum environmental factor or combination of factors that determine success. Increasing in ecological agent can be effects on life of organism.

Environmental selection Ecomorphological selection: environmental effects on morphological style in plants and stable to tolerance environmental conditions Genetic selection: changes in environmental factors due to change in gene expression (ecotype). Variety: in a communication a species plant have a minor different from each other.

Evolution Evolution is the change in the inherited characteristics of biological populations over successive generations. Evolutionary processes give rise to diversity at every level of biological organization, including species, individual organisms and molecules such as DNA and proteins. Evolution agents: 1: mutation 2: natural selection 3: genetic drift 4: migration

1. Mutation In genetics, a mutation is a change of the nucleotide sequence of the genome of an organism, virus, or extrachromosomal genetic element. Mutations result from unrepaired damage to DNA or to RNA genomes (typically caused by radiation or chemical mutagens), errors in the process of replication, or from the insertion or deletion of segments of DNA by mobile genetic elements. Mutations may or may not produce discernible changes in the observable characteristics (phenotype) of an organism.

2. Natural selection Natural selection is the gradual process by which biological traits become either more or less common in a population as a function of the effect of inherited traits on the differential reproductive success of organisms interacting with their environment.

3. Genetic drift Genetic drift or allelic drift is the change in the frequency of a gene variant (allele) in a population due to random sampling. The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces.

4. Migration Migration, as it is now known among modern birds and mammals, probably appeared gradually by stages. Some animals changed their habitat only slightly, never leaving the same general region. The movements of other animals were more erratic, their dispersal being oriented toward the most favorable places. Such movements are the first stages of true migration—a phenomenon characterized by elaborate mechanisms—which gradually acquired stability through natural selection.

Adoption Change in an organism so that it is better able to survive or reproduce, thereby contributing to its fitness. Adaptedness is the state of being adapted: the degree to which an organism is able to live and reproduce in a given set of habitats.

Extinction In biology and ecology, extinction is the end of an organism or of a group of organisms (taxon), normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point.