what are the postulates of lamarkism
give any five...
Answers
THE ANSWER IS:
POSTULATES OF DARWINISM :
The postulates of Darwin’s theory of evolution is known as Darwinism. Darwinism is based on three important postulates. They are :
Multiplication of individuals of species in a geometric proportion.
Occurrence of variation.
Operation of Natural Selection.
MULTIPLICATION OF INDIVIDUALS OF SPECIES IN A GEOMETRIC PROPORTION :
As we all that a Salmon produces around 28,000,000 eggs in a season and an Oyster produces around 114,000,000 eggs at a single spawning. Imagine that if all these have to survive and reproduce in each generation the population of these species will increase in a geometric proportion.
Hence, as result there will be shortage of food and shelter. This will further lead to Struggle of Existence.
VARIATIONS :
Variation is a natural phenomenon and is defined as that no two individuals of the same species are exactly similar and they will differ in some other qualities. Hence a group of individuals or even a population of a species may have a difinite pattern of variation which differentiates them from other population of the same species. These are known as Sub species. Also there are two types of variation and they are termed as Continuous and Discontinuous variations.
Struggle for Existence :
Due to enormous multiplication of individuals, the food and space becomes limited. The struggle may occur between the individuals of the same species or any other different species or due to some environmental factors.
There are three kinds of struggles and they are Intraspecific struggle, Interspecific struggle and Extra specific struggle.
Survival of the fittest :
In this struggle only those individuals which are able to withstand themselves to the new environmental conditions will survive and those which are unable to fit themselves to the environmental conditions will perish. Those individuals which adapt themselves to the environment shows various modifications to suit themselves in the changed conditions of life. Survival of the fittest results in the Theory of Natural Selection.
THEORY OF NATURAL SELECTION :
Evolution is a long term process and during that long period the organisms which proves to the fittest survives in this environment and later they adapt themselves according to the nature.
Since Nature is the super power and it selects only the organisms which become different species with the accumulation of variations.
LAMARCKISM :
The postulates of Lamarck is known as Lamarckism. The three main postulates are :
BODY SIZE INCREASES DURING EVOLUTION :
According to Lamarck during the time of evolution there is a tendency to increase in the size of body parts. It is true in certain organisms there is increase in size of body parts during evolution. But in many cases, during evolution there is only reduction of the size of body parts.
ENVIRONMENT AND NEW NEEDS :
Lamarck strongly believed that the environment plays a vital role in the evolution and all the organisms co-ordinates with the environment for their survival. Whenever there is a change in the environment the organisms adapt themselves to the environment and also develops new structures and characters.
USE AND DISUSE THEORY :
According to this law the organism will develop an organ due to use and will degenerate the organ due to disuse. This postulate is genuine as far as growth of an organ within the lifespan of an organism.