Question

Modern theory called the synthetic theory of evolution is based on
A. Genetic and chromosomal mutations
B. Genetic recombination and natural selection
C. Reproductive isolation
D. All of the above

Answer 1

Hint: The neo-Darwinism theory was replaced by new concepts which consisted of many other mechanisms in addition to natural selection. This new hypothesis of evolution is referred to as modern synthesis which is described by Futuyma as that the major tenets of synthesis of evolution were that the population contains genetic variation that arises by random recombination and mutation.

Complete answer: Evolution is a process in which the population of organisms will change over generations. Genetic variations are the main cause of evolution. It may be due to gene mutations or recombination. These variations change the gene activity or the protein functions which leads to the formation of new traits in organisms. Recombination is the process that occurs through crossing over of chromosomes during the meiosis, in which the DNA gets exchanged between a pair of chromosomes, thus the two genes which were previously not linked will be linked because of recombination. Like mutation, recombination is also an important source for creating new variation for natural selection.
A species is defined as a group of similar organisms which can interbreed to produce viable, fertile offspring. Biological species are those species which are isolated reproductively from one another.
Hence, the correct answer is option D.

Note: The modern synthetic theory of evolution was put forth by many numbers of scientists namely J.B.S. Haldane, R.A. Fisher, Ernst Mayr, etc. The book includes many several factors like variation, mutation, heredity, natural selection, isolation. In addition to these five factors, there are three more factors that affect them: Migration of individuals from one population to another and hybridization between races or closely related species both increases the genetic variability in a population.