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Speciation 6


MICROEVOLUTION mi·cro·ev·o·lu·tionˌmīkrō-evəˈlo͞oSHən,-ˌēvə-/nounBiologynoun: microevolution; noun: micro-evolution#evolutionary change within a species or small group of organisms, esp. over a short period.


Scientists have actually observed many cases of natural selection in the wild:

Such as with sparrows, pests and bacteria


The change of alleles in a population may be selected for if it helps with resistance of a pesticide

Pests such as insects that destroy crops can exhibit microevolution.  A pesticide is designed to kill most of the insects, however there may be an allele that selects for a certain insect because it provides a resistance to the pesticide.  Within that generation and the future generations there will be insects with mostly that allele as it provides resistance which leads to survival of the insect.  

Microevolution and Humans[]

When talking about microevolution and humans we often talk about race because we can see rapid changes in a race, evolution on a sub-species level (Hamilton, 2010).

The main pathways for microevolution include mutation, migration, gene flow, genetic drift, and natural selection and even artifical selection which humans have been doing for thousands of years - think of dog breeders who maniupulate breeds (or races), and create new ones and at a very rapid pace.

The same is true for people, races of people are rarely stagnant, they change and exchange genetic material and hybridize.

Geneticist Theodosius Dobzhansky wrote:

So long as populations can exchange genes, the genetic differences between them are subject to swamping and dissolution by hybridization. The races of man furnish some of the clearest illustrations of this—history records many examples of race fusion and of emergence of new hybrid races. It is possible at least to imagine a fusion of all human races into a single, greatly variable population.(Dobzhansky, 1962).

Dobzhansky expressed the view that “human races are relics of the precultural stage of evolution” because civilization causes race convergence (through gene exchange) to outrun race divergence (1962, p. 185).

Mankind Evolving: The Evolution of the Human Species (New Haven: Yale University Press, 1962), 185.