An Introduction to Comparative Biology with Special Reference to Medicago SPP

The environment is a complex whole of so many interacting factors. These factors influence every plant and animal species. It is the that genotype determines the range of phenotypic expression. The phenotypic expression of a specific genotype may have some variabilities with regard to different sets of environmental complexes. These phenotypes are objects of immediate concern to taxonomists because of taxa are shaped along the lines of discontinuity of phenotypic characters. Therefore, it becomes worthwhile to examine the nature of adaptation in the light of the physiological effect of the environmental factors. In recent years’ attention has been paid to visualize the interrelationships of plant and environment in order to understand their comparative performance which is of great survival value of a species. In such comparative studies, adaptations which enable the species to cope with the environmental fluctuations are looked into.

Though such adaptations are genetically determined, their ontogenetic manifestations are influenced by the factors of environment, the magnitude of which determines the ecological amplitude of a species. The fitness of a genotype is directly related to the contribution of its phenotype made to the gene pool of its future generation while interacting with environmental factors. Once it is realized that the success of gene transmission depends upon the interactions between phenotype and its environment then it becomes important to know that why certain phenotypes are better than others in a given environmental condition. This way comparative biologists consider the fitness of a species and is referred to as an adaptational approach. The technique of comparative culture was first introduced by De Candolle and his contemporaries in the nineteenth century.