Speciation is the method of formation of new species. A species can be defined as one or more populations of interbreeding organisms that are reproductively isolated in nature from all other organisms. As natural selection adapts populations occupying different environments, they will diverge into races, subspecies, and finally separate species. When populations no longer interbreed, they are thought to be [...]
Jean Baptiste Lamarck put forth the theory of inheritance of acquired characters, which is also known as Lamarckism. It was published in 'Philosophie Zoologique' in the year 1809. The four propositions of Lamarckism are as follows: a. Living organisms and their parts tend to increase in size continuously due to internal forces of life. b. New organs are formed in [...]
A reproductive isolating mechanism is a structural, functional, or behavioural characteristic that prevents successful reproduction from occurring between different species. This helps in accumulating genetic variations in species. If reproductive isolation does not exist, variant forms freely interbreed with the normal forms and this would lead to intermixing of their genotypes. These mechanisms are of two types: 1. Pre-Mating Mechanisms: [...]