How do genetic drift and microevolution differ?
1 Answer
On the observational or empirical evidence genetic drift and microevolution do not differ, in the theoretical level they differ.
Explanation:
Microevolution is the idea that adaptational changes take place within a species due to environmental conditions. There is good observational evidence that natural selection operates to favor one genetic variation ( existing alleles) within a population over another genetic variation.
A Classic example is the peppered moth of England that adapted to the Industrial Revolution by moving toward the melanic or black variety. When the pollution of the Industrial Revolution was corrected the the movement toward the melanic black variety was also reversed and the movement was back to the white variety
Genetic drift is the idea that adaptational changes take place within a species due to environmental conditions acting on random changes in the genome. There is good observational evidence that natural selection operates to favor one genetic variation ( existing alleles) with over other genetic variation that cause a separation in the species, creating new species. Some of the random changes in the genome are due to mutations that result in the loss of genetic information.
A Classical example is the Darwin Finches of the Galapagos Islands.
A small pioneer population of finches have divergent into 13 theoretical species. Each species tends to occupy a different niche within the environment. The different types of finch tend not to interbreed with the other varieties of finch.
Microevolution in theory says that the changes are the result of natural selections on existing genetic variation and do not create new information or new novel forms of organisms. While genetic drift in theory says that the changes result in creation of new forms of life forms, even to the extent of resulting in the transitions of one form of life like amphibians into new forms of life like reptiles.
There is no empirical evidence that genetic drift does result in novel forms. The Galapagos finches have been observed to form hybrids that merge the different species. In the sense that the different forms of finches can interbreed they are not actually different species by definition.
Genetic drift and microevolution are the same observationally. The theoretical basis is different.
