Module 2 : Origin of Life and Evoloution

Lecture 8 : Theories of Evolution (Part-II)

 

2. Mimicry and Protective colouration: The mimicry and protective colouration is very common in several organisms as the product of natural selection.Most of these organism acquire the pattern of coloration by gradually changing color at each stage.


3. Correlation of nectarines and proboscis: The position of nectarines and proboscis in insect correlates well and match well to facilitate pollination. This relation does not develop in single days but evolve gradually envisaged via the process of natural selection.

 

Evidences Againist the theory of natural selection:


1. Perpetuation of Vestigial Organs: Vestigial organs are selected despite the fact that they are not useful for animals but even then they are preserved generation over generation.


2. No explanation for variation: Darwin could not be able to explain the source and mechanism of generation of variation in organisms.


3. Distinction between continuous and discontinuous variations: According to theory, Darwin assumed that any variation essential for animal survival will be carried forward to next generation. We know that it is not true as per present knowledge of genetics.


4. Disapproval of Pangenesis theory of Darwin:  Darwin put forward the theory of Pangenesis to explain the process of inheritance. It was disapproved by the experiments performed by August Weismann in 1892.