# Modern Synthetic Theory of Evolution- “The Neo-Darwinism”.
Principle: All or a few evolutionary drivers such as Natural selection, Mutationism, Genetic Drift, Gene Flow etc., cumulatively force the organisms to adapt newly, according to the environmental changes, and finally achieve successful organisms.
Introduction:
Modern Synthetic theory also called Neo-Darwinism, is a collective pressure, that insists organisms adapt into new species over time. It emphasizes that only one force of the environment itself doesn’t promote evolution. This modern evolutionary theory is formulated from the empirical discoveries in genetics, palaeontology, ecology, Taxonomy, embryology and more, which combines Charles Darwin’s original ideas of natural selection with the principles of genetics, which were not known to Darwin in the 19th century. This synthesis was developed in the early to mid-20th century and represents a significant advancement in understanding how evolution works in Nature.
Core Discussion:
“Mutations” (Hugo de Vries) occur in the genetic makeup of parental organisms during the meiotic division and form the “New Genetic Recombinations” which are the raw material for the changes in the organisms. But, which cells are the sites for these mutations? ” Germplasm Theory” (August Weismann) emphasized that changes in the “Sex cells or Germ cells” could be inherited by the next generation. Then, what are the causes of mutations? Natural Selection (Charles Darwin) explored that “Nature” with its dynamic components forces organisms to mutate, modify and develop new variations that are selected as adaptations. The newly selected variations are actually “Acquired Characters” (Lamarck) and could be inherited ( principles of Inheritance – Gregor Mendel’s) over the generations. The accumulated small adaptations in the population aggregated gradually (gradualism) and stand as the “New Species” on this planet. Genetic variations arise in “Small Populations” via the “Genetic Drift (Sewel Right) with variable allelic or gene frequencies also contributing to Evolution. “Gene flow” of emigrated and immigrated populations provokes the changes in the “Gene Pool” and supports the origin of new species in nature. Thus, it is concluded that all the evolutionary drivers work in nature simultaneously or one by one and force changes in the organisms. This amalgamation of factors framed the “Modern Synthetic Theory of Evolution” by “Neo-Darwinists”.
Causes from the force for evolution, in detail:
- Natural Selection: Neo-Darwinism retains the central concept of natural selection proposed by Charles Darwin. It suggests that within a population of organisms, those individuals with traits that provide a survival and reproductive advantage in a given environment are more likely to pass those traits on to the next generation. Over time, this process leads to the gradual adaptation (gradualism) of populations to their environments.
- Genetics: One of the major additions to Darwin’s theory in neo-Darwinism is the incorporation of genetics. This theory integrates Gregor Mendel’s principles of inheritance, which describe how traits are inherited through the transmission of genes from parents to offspring. It also includes an understanding of the mechanisms of “genetic mutation, recombination, and DNA replication”.
- Genetic Variation: Neo-Darwinism emphasizes that genetic variation is the raw material for evolution. Genetic variation arises through several mechanisms, including mutations (random changes in an organism’s DNA sequence) and genetic recombination (the shuffling and exchange of genetic material during the meiosis of sexual reproduction). This genetic diversity provides the basis for natural selection to act upon.
- Allele Frequencies: Neo-Darwinism focuses on changes in the frequencies of alleles (alternative forms of genes) within populations over time. Natural selection favours the propagation of alleles that enhance an organism’s fitness in its environment, leading to an increase in the frequency of those advantageous alleles.
- Speciation: Neo-Darwinism explains how new species arise through the process of speciation. When populations become isolated from one another and accumulate genetic differences over time, they may eventually become reproductively isolated. This reproductive isolation can lead to the formation of distinct species.
- Adaptation: Adaptation is a central concept in neo-Darwinism. It describes how organisms evolve traits that are well-suited to their environments. Over time, adaptations accumulate in a population through the process of natural selection, enabling organisms to better survive and reproduce in their specific ecological niches.
- Gene Flow and Genetic Drift: Neo-Darwinism also considers the effects of gene flow (the exchange of genetic material between populations) and genetic drift (random changes in allele frequencies due to chance events) in shaping the genetic makeup of populations over time.
Q; Is there any proof to explain the process of evolution in populations?
Final proof for Evolution: “Hardy Weinberg law of Equilibrium”:
Hardy Weinberg Equilibrium states that there would be no change in the characters of organisms in a population until there is no change in the “allelic frequency” or “Gene frequency” of that population “Gene Pool”. Contrastingly, evolutionary drivers in nature, such as Natural selection, Mutations, Genetic Drift, Gene Flow etc., promote the changes in “Genetics and their frequencies” with their forces. This is proven by a mathematical principle (a+b)²=a²+2ab+b², where ‘a’ and ‘b’ are alleles and a², ab and b² are genotypes. If no evolutionary driver force on the population, then there would be no changes in the frequency of a and b alleles, the populations transfer their characters over the generations without any changes, and as a result of this there would be “no evolution”. But, could the organisms be forever in nature without any adaptations? Impossible! This proof emphasises that “Hardy Weinberg equilibrium does not work in Nature”! while the evolutionary drivers are always working.