What is the difference between microevolution and macroevolution?
What is the main difference between microevolution and macroevolution? The macroevolution and microevolution are two concepts related to processes of biological evolution. The macroevolution refers to observable evolutionary changes over long periods of time and can lead to the emergence of new species. For its part, the concept of microevolution refers to small and progressive changes.
Currently, the most accepted concept is that macroevolution is a cluster of micro-evolutionary changes and that there is no real difference between the two.
The Main Difference between Microevolution and Macroevolution:
What is Microevolution?
The evolutionary changes that occur at a level equal to or less than the species are classified as microevolutionary changes. From the perspective of population genetics, microevolution is the change in allelic frequency of a perceptible population in a few generations.
Most of these changes are produced by:
Mutations: changes in the genotype of one or more individuals that are transmitted to the offspring
Natural selection: defined as the differential reproduction of genotypes of a biological population. Basically, it consists of the better reproduction of some individuals with respect to others thanks to a certain genotype that makes them better adapted to the environmental conditions in which they live.
Genetic flow or migration: genes are transferred between different populations of the same species.
Genetic drift: effect of chance on reproduction and genetic transmission.
Microevolution changes can also be produced by selection and artificial manipulation by humans. For example, the crossing and selection of seeds for the crop alter the allelic frequency and produces microevolution changes.
It is very important to highlight the most important difference: microevolution changes, unlike macroevolution changes, would not lead to new species.
What is Macroevolution?
The macroevolution refers to large — scale evolutionary changes that break the species barrier and can lead to new species and even affect higher taxonomic groups (genera, families, etc).
However, Dobzhansky ended up stating that the processes that give rise to macroevolution are the same as those that give rise to microevolution: mutation, natural selection, migration and genetic drift, the only difference being the time and scale at which they occur and observe.
Difference and controversy
Within the theory of biological evolution more accepted today, modern evolutionary synthesis or neo-Darwinism, there are two concepts of thought:
Naturalism: accept macroevolution.
Ultradarwinism: only accepts the existence of microevolution processes.
As mentioned earlier, Dobzhansky himself, who coined the term of macroevolution for the first time, ended up doing both equivalent concepts, although currently there is still debate about whether macroevolution phenomena exist that may be outside the genetics of classical populations.
This hole has been appropriated by creationists, supporters of a supernatural or divine creation of species. Creationists accept microevolution, which is clearly observable even in the time range of human life, but they do not accept macroevolution as the origin of species. They are based on the impossibility of observing the macroevolution and the “act of faith” which implies acceptance.
Is there a real difference?
Currently, the existence of macroevolution is widely accepted by most of the scientific community. It is also widely accepted that there is no real difference between macroevolution and microevolution beyond the scale at which they occur.
In most current theories of evolution, macroevolution is simply a cluster of microevolutionary changes over time until they give rise to the appearance of new species.
Many scientists, however, try to avoid the use of these terms by arguing that they have been co-opted by creationists for their own benefit, that they do not represent an evolutionary theory as such and that they are the same after all and should not be distinguished.
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Originally published at https://everydayscience.blog on February 26, 2020.