Question

what do you think distinguishes our present understanding of epigenetics from Larmarck's, now debunked, theory referred to as the Inheritance of Acquired Characteristics Theory? How, in contrast, might our understandings of the epigenome actually give support to some elements of Lamarckism? What role does epigenetics play in the operation of Natural Selection?

Answer 1

Theory of inheritance of Acquired charecteristics was coined by Jean Baptist Lamark. It states that physicall changes in organisms during their life time such as greater development of an organ or a part through increased use could be transmitted to their offsprings.He proposed that if an organ is used a lot ,then it will develop and strengthen and also if it is not used it will degenerate. This is the law of use and disuse. Organism tend to increase in size and complexity with time, formation of new organs, extension of the development of organs etc.

Epigenetics is the study of heritable changes in the gene expression (active versus inactive genes) that does not involve changes to the underlying DNA sequence that is a change in phenotype without a change in genotype. The theory of epigentics and studies have highlighted the possible inheritance of traits acquird by the previous generation so some part of Lamarkism it is agreed. Epigenetics showed that reversible and heritable changes can occur without a change in DNA sequence (genotype) and this changes cam happen spotaneously because of the response in environment.

Epigenetics also have impact on natural selection becuase the creation of pheotype that leads to differential natural selection of genotypes. Such a process is evolutionary in nature and aslo leads to permenant shifts in the genetic makeup of the population. An example is the 'Baldwin effect' it is the ability of an animal to study new behaviours and this can be epigenetically inherited. So this behaviour will help the animal for reproduction and natural selection of this animal will take place. It is fit to the enviroment and can reproduce.