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Molecular Evolution, a topic that is currently being researched and studied. It is a process of change occurring within organisms or the sum total of such changes within one lineage over time. There are many different types of molecular evolution, some documented and others theoretical. Molecular Evolution is also sometimes called Genetic Evolution as it pertains to DNA changes in an organism’s genome.
What is Evolution?
Evolutionary science explains the diversity of life on earth by using observable evidence to hypothesise how species diversity might have appeared in a given evolutionary time period. Evolutionary science proposes that life has evolved from primitive living organisms into modern day species as a result of natural selection acting on random mutations that are beneficial.
What is Molecular Evolution?
Molecular evolution is the process by which DNA changes that occur in one lineage of an organism (such as a species) and is passed on to subsequent generations. These changes are not visible without further analysis, but they are still important, because they affect the fitness of an organism.
Driving Forces in Molecular Evolution:
Natural selection, genetic drift, hybridization, non-random mating and gene flow are the major driving forces behind molecular evolution.
Natural Selection: It is a process of change that occurs as a result of the reproductive success of certain biological entities over others. When biological entities compete to survive they succeed based on their ability to physically adapt to their surroundings and reproduce. This process of “survival of the fittest” comes in many forms, but all are subject to the same laws of biology and genetics. When one organism or gene changes, those with similar genomic characteristics will likely survive better than those who do not. This selection leads to the accumulation of useful mutations in a population. Over time entire new species can emerge from a single organism.
Natural selection is responsible for the evolution of all life on Earth, from bacteria to humans. Every adaptation (the acquisition of which is not necessarily beneficial) and every extinction event has been driven by natural selection over evolutionary time. As such, it is considered to be the most powerful evidence for evolution.
Genetic Drift: A phenomenon by which alleles become more or less common in a population due to random sampling and genetic drift is another driving force behind molecular evolution. Genetic drift is the process by which the frequency of an allele changes from generation to generation as a result of random sampling . Random sampling is caused by the fact that organisms are not equally likely to reproduce in a population. For example, in a population of 100 foxes, there might be 10 red foxes and 90 grey foxes. The selection process favours those who can survive and reproduce better. However, if a red fox and grey fox had an offspring that happened to be red, it would have a reproductive advantage over its mother (the red fox) as well as its father (the grey). As such, over time the red gene would become more common until eventually all of the new generation of foxes would be red.
Genetic drift works similarly but with larger numbers of alleles and longer periods of time. In the example above, if there was a red fox, the odds of its offspring being red would increase each generation. The frequency of the red allele would continue to rise until eventually all foxes were red. On the other hand, if a grey fox mated with a grey fox or an orange fox mated with an orange fox, their offspring would be less likely to be red as they were not matched up with a carrier of the same gene. This results in either even greater reduction in the frequency of that particular allele or switching back to an alternate allele found in either parent.
Hybridization: Hybridization is another driving force behind molecular evolution. When two closely related species which are capable of hybridising (interbreeding) produce fertile offspring, then eventually one of the parental species becomes extinct. This process can also lead to increased genetic diversity within a population, which is important in developing a new species through evolution. Hybridization is also responsible for the creation of new genomes from combining genomes from two closely related organisms.
Molecular Evolutionary Genetics Analysis:
Molecular evolutionary genetics analysis (or simply, molecular evolution) is a growing subcategory of the science of genetics. It studies evolution at the level of DNA and genetics in order to gain insights about organisms that we cannot see. It has been used to study the evolution of multicellular organisms as well as viruses and bacteria, determining how these organisms came to be. While it does not make assumptions about how an organism came to be, it can provide information that allows scientists to draw conclusions from DNA sequencing and its patterns.
Molecular Evolution is a relatively new concept in genetics and research is still being done on possible driving forces behind this change. It is important to note that genetic drift (the idea that alleles become more or less common in a population from generation to generation because of chance) is a natural occurrence in all populations, including humans. It is also important to remember that the major driving force behind all evolution from the origin of life was natural selection. While natural selection occurs every day, it can take thousands, or even millions of years for enough mutations and changes to occur for it to result in speciation, where a species diverges into two separate species.
Molecular Biology and Evolution:
Molecular biology and evolution is a subcategory of molecular evolutionary genetics analysis that studies the relationship between direct observation of a biological process and the corresponding DNA and amino acid sequences. It has been used to study the evolution of multicellular organisms as well as viruses, bacteria and fossils. It has advanced through three main scientific concepts in its history:
Evolutionary Model: The evolutionary model states that DNA encodes information about how an organism is structured (phenotype) as well as how it reproduces (genotype). These genetic changes can be passed down to offspring. These changes can be the result of random sampling, natural selection and hybridization.
Molecular Evolution: The actual process through which the phenotypes (appearance) and genotypes (DNA) of organisms change over time. This can occur through a variety of means including but not limited to; mutation, recombination, horizontal gene transfer and gene duplication.
Conclusion:
Molecular Evolution is a growing field of research within the science of genetics, biochemistry and biology. It studies how much information is encoded in DNA and has been used to study the evolution of multicellular organisms as well as viruses and bacteria. The process can be broken down into three main categories: evolutionary model, gene duplication and molecular evolution. This discipline has allowed scientists to draw many conclusions about how organisms change over time, including whether or not certain adaptations are inspired by other species. Molecular Biology and Evolution is becoming more important to the field of genetics because it allows scientists to utilise current methods for DNA sequencing in order to answer questions about origins that have eluded us for years.
