The following points highlight the two main factors which stimulate, affect and control the dispersal of animals. The factors are: 1. Physical Factors 2. Biotic Factors. 1. Physical Factors: Environmental factors include land and water distribution, sediments, physical barriers, physical events, distance etc. Lands and waters are barriers for the dispersal and migration of aquatic and terrestrial or land animals [...]
In this article we will discuss about historical evolution of the plants that can be traced through the geological periods. (1) Evolution of organisms on the earth's surface begins from the pre-cambrian period when probably the first life in the form of single celled or unicellular microscopic organisms resembling the present-day cocoid or spheroid bacteria, was evolved in aquatic environment. [...]
There is a wide range of variations in the distribution of vegetation on the globe. There is a zonal pattern of vegetation from equator towards the poles and from seal level to vegetation level on the high mountains. The distribution of plants is affected and controlled by a variety of factors e.g.: (i) Climatic factors (sunlight, temperature, moisture and humidity, [...]