Question

Describe the “Modern Synthesis” of the theory of evolution. Include all aspects of Darwin’s original theory and the ways in which it has been improved/added to with new discoveries since his time.

Answer 1

The modern synthetic theory of evolution is combined form of Darwinian and genetic theory. The theory identifies four processes for evolution that are mutations in genes, chromosomal anomalies, Recombination, Natural selection.

Gene Mutations: These are sudden changes in the gene that may alter the phenotype of the individual leading to variations. They are usually of low frequency and occur spontaneously.

Chromosomal Anomalies: These are changes in number of chromosomes that may occur due to non disjunction during cell division. They can be of two types : Aneuploidy and Euploidy. Aneuploidy refers addition or deletion of chromosome from the diploid genome. Euploidy refers to change in chromosome set.

Recombinations are result of certain processes like crossing over, gene flow, random mating, migrations. These add new genes to the gene pool of the population.Darwin did mention variation in his theory but wasn’t able to explain source of variations. Neo Darwinism provided those answers.

Natural Selection: This concept was given by Darwin , where the individual with the best fitted traits  get an advantage and is selected by nature through differential reproduction. Environmental factors influence phenotypic expression of a trait. A phenotype may be influenced by the environment but the genotype doesn’t. Inheritance of the variations take place that accumulate over a long time period leading to evolution and speciation.