Difference Between Gradualism and Punctuated Equilibrium

The main difference between gradualism and punctuated equilibrium is that the gradualism is the selection and variation that occur in small increments whereas punctuated equilibrium is a radical change that occurs in a short period of time. Furthermore, gradualism helps to select better variations to the environment while punctuated equilibrium emphasizes consistent and cumulative changes to the species.

Gradualism and punctuated equilibrium are two phenomena that bring variations to a particular species during evolution.

Key Areas Covered

1. What is Gradualism
     – Definition, Facts, Importance
2. What is Punctuated Equilibrium
     – Definition, Facts, Importance
3. What are the Similarities Between Gradualism and Punctuated Equilibrium
     – Outline of Common Features
4. What is the Difference Between Gradualism and Punctuated Equilibrium
     – Comparison of Key Differences

Key Terms

Genetic Changes, Gradualism, Neo Darwinism, Punctuated Equilibrium, Variation

What is Gradualism

Gradualism is the slow, steady changes of a particular species. Here, the selection and variation occur more gradually. Hence, gradualism takes a long period of time and the changes are hard to notice within a short period of time. In brief, the population changes over a long period of time while the changes are slow, constant, and consistent.

Figure 1: Gradualism and Punctuated Equilibrium

Gradualism is the basis of the classic Neo Darwinism and it is also called uniformitarianism. It assumes that the tree of life starts with a one-celled organism, which increases its complexity to form modern life forms gradually. But, fossil records do not support this concept of emerging from small, gradual changes. Besides, new life forms spurt in fossils rather than transitioning between types of species.

What is Punctuated Equilibrium

Punctuated equilibrium describes the punctuation of the slow evolution by short events, leading to rapid evolution. It was the theory proposed to explain the deviations of the fossil records from gradualism. According to punctuated equilibrium, the oppression caused by the environmental stress on a small, isolated population forces the population to produce variations fairly rapidly. Therefore, the genetic changes occur more rapidly. However, Neo Darwinism describes that genetic changes within a population are slow.  

Figure 2: Punctuated Equilibrium

In punctuated equilibrium, it is considered that conditions of the environment are constant. However, the environment can also change due to climate changes or the introduction of new predators. This also can emphasize changes in a particular population that lives within that environment in a short period of time. In conclusion, punctuated equilibrium is the better model in describing the appearing of variations within a population.

Similarities Between Gradualism and Punctuated Equilibrium

• Gradualism and punctuated equilibrium are two phenomena that help to establish variations in species.
• Natural selection help to choose the best fitting type of organisms to the environment.

Difference Between Gradualism and Punctuated Equilibrium

Definition

Gradualism refers to the hypothesis that evolution proceeds by imperceptibly small, cumulative steps over long periods of time rather than by abrupt, major changes while punctuated equilibrium refers to the hypothesis that evolutionary development is marked by isolated episodes of rapid speciation between long periods of little or no change.

Type of Variation

Gradualism brings small variation to a particular species while punctuated equilibrium emphasizes consistent and cumulative changes to a species.

Duration

Furthermore, gradualism occurs over a long period of time while punctuated equilibrium occurs within a short period of time.

Evolution

Also, gradualism describes evolution as a slow process while punctuated equilibrium brings short events, which speed up the slow evolution.

As a Model

Fossil records do not prove gradualism while punctuated equilibrium is the better model to describe evolution.

Conclusion

Gradualism is the introduction of variations to a particular population over a long period of time while punctuated equilibrium is the quick variation in a particular population due to sudden changes in the environment called environmental stress within a short period of time. The main difference between gradualism and punctuated equilibrium is the appearance of variations in a particular population.

Reference:

1. Saylo, Monalie C, et al. “Punctuated Equilibrium vs. Phyletic Gradualism.” International Journal of Bio-Science and Bio-Technology, vol. 3, ser. 4, Dec. 2011, pp. 27–42. 4, Available Here

Image Courtesy:

1. “PunctuatedEquilibrium” By Miguel Chavez – Own work (CC BY-SA 4.0) via Commons Wikimedia   
2. “Punctuated Equilibrium” By Ian Alexander – Own work (CC BY-SA 4.0) via Commons Wikimedia