Trophic level is a step or division of food chain which is characterized by the method of obtaining its food. The number of trophic levels are equal to the number of steps in the food chain. The two fundamental trophic levels are producers and consumers.
A group of species belonging to a trophic level which exploits a common resource base in a similar fashion is known as ecological guild. Examples: Nectar feeding birds, grazing animals.
An ecad of a plant species is a population of individuals which although belong to the same genetic stock (genetically similar) but differ in vegetative characters such as size, shape, number of leaves, stem etc.
In parasitic food chain, the pyramid of number always inverted, because a single plant may support the growth of many herbivore and each herbivore provide nutrition to several parasites, which support many hyperparasite. Thus, the number of organisms gradually shows an increase, making the pyramid inverted.
Food Chain: 1. It is straight, single pathway through which food energy travels in an ecosystem. 2. Presence of separate food chains adds to instability of ecosystem. Food Web: 1. It consists of number of interconnected food chains through which food energy passes through ecosystem. 2. Presence of food web increases stability of ecosystem.
