An Introduction: Genetics and Evolution

As basic concept of genetics, phenotype is all morphological, physiological and even behavioural characteristics of organisms. According to Weatherall (2009), phenotype is all the observable characteristics. Examples of phenotype are flower color, eye color, blood type and the amino acid sequence of a protein. The genotype is the genetic constitution of the individual, the genes it inherited from its parents. The genotype with an environmental interaction establishes the phenotype.
          One significant question over genetics is, due to complex interactions of thousands of genes between themselves and the environment, how to relate gene organization and function to a phenotype. This is an issue which many researchers are focused on. For the moment, evolutionary biologists know that mutations can alter the structure of genes products, giving a rise to diversity of phenotypes. Each genetic makeup can provide a phenotype with adaptive capabilities to certain individuals and for a given environment at a given time. This means natural selection does not act on genes or genetic characteristics singly, but on individuals with all their genetic load.

Therefore, genetics is a determinant factor in the evolutionary processes. Indeed, heritable fitness variation within a population is a key factor to evolution by natural selection (Zhang, 2010). Although Darwin understanding that a factor of heritage and a source of variability are required in his theory, he did not know those mechanisms.   

Biologists strove to join Darwinian evolution with Mendelian genetics creating the synthetic theory of evolution, or Neo-Darwinism. They concluded that evolution is a gradual process including mutation, selection and drift which is explained by population genetic (Zhang, 2010). In this way, it was discovered that the primary source of variability are mutations and genetic recombination. Mutations introduce genetic newness to genotypes, while genetic recombination by sexual reproduction creates variability due to the arising of multiple different gene combinations.

The greater the diversity, the greater the probability of a population to adapt to changes occurring in this environment. Homogeneous population could be eliminated from their habitat if change occurs. Over time, certain genes and consequently certain characteristics are eventually eliminated from populations to the detriment of others that are implanted, thereby causing evolution.

From these basic concepts and knowledge, I will post here related matters objects of scientific study.

REFERENCE LIST

Zhang, J. (2010) Evolutionary genetics: progress and challenges. In: Evolution Since Darwin: The First 150 Years. M. A. Bell, D. J. Futuyma, W.F. Eanes, J. S. Levinton, eds., Sinauer, Sunderland, Mass. Pp. 87-118

Weatherall, David J(Mar 2009) Genotype–Phenotype Relationships. In: eLS. John Wiley & Sons Ltd, 
Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0003403.pub2]