Difference Between Adaptive Radiation and Divergent Evolution

Main Difference – Adaptive Radiation vs Divergent Evolution

Adaptive radiation and divergent evolution are two mechanisms of evolution of species from a common ancestor. Artificial selections, as well as natural selection, are involved in the evolution of a population. The evolutionary path may depend upon the environmental and biological factors of the habitat the population lives in. Adaptive radiation is a type of microevolution mechanism, but divergent evolution is a type of macroevolution. The main difference between adaptive radiation and divergent evolution is that adaptive radiation is the diversification of a species into various forms that are adaptively specialized to a specific environmental niche whereas divergent evolution is the development of a new species from a pre-existing species.

Key Areas Covered

1. What is Adaptive Radiation
      – Definition, Features, Examples
2. What is Divergent Evolution
      – Definition, Features, Examples
3. What are the Similarities Between Adaptive Radiation and Divergent Evolution
      – Outline of Common Features
4. What is the Difference Between Adaptive Radiation and Divergent Evolution
      – Comparison of Key Differences

Key Terms: Adaptive Radiation, Biological Factors, Common Ancestor, Divergent Evolution, Environmental Factors, Macroevolution, Microevolution, Natural Selection

What is Adaptive Radiation

Adaptive radiation is the diversification of a group of individuals according to different ecological niches. Many species emerge due to adaptive radiation from a common ancestor. When an individual of a particular organism enters a new area, different traits of the individual change in order to adapt to the new mode of life. Adaptive radiation is a relatively rapid process of evolution. Closely related species are evolved from adaptive radiation. One of the most precise examples of adaptive radiation is the development of mammals after the extinction of dinosaurs. The forelimbs of mammals adapted to run, swim, fly, climb, and leap through divergent evolution.

Figure 1: Different Beak Shapes in Darwin’s Finches

Darwin’s finches, Australian marsupials, and cichlid fish are some other examples of adaptive radiation. Though Darwin’s finches have a similar appearance, their beak shapes are different as an adaptation to various food sources. Since these finches with different beak shapes can no longer interbreed, they become less similar over time, changing into different species.

What is Divergent Evolution

Divergent evolution is the development of two or more species from a common ancestor. Environmental factors such as natural disasters, changes in the climate, and biological factors such as spreading of diseases cause the divergent evolution over time. In order to survive these environmental and biological factors, individuals in a population should have favorable characters. The most beneficial traits will be selected through natural selection. The emerging characters of individuals within a population cause sexual incompatibility with each other. This allows the emergence of new species.

Figure 2: Evolution of Different Forelimb Structures in Mammals

Divergent evolution is a process of macroevolution, creating more diversity of species in the biosphere over long periods of time. Physical barriers, as well as biological or reproductive differences within a population, will keep the population away from reproducing with each other. This process is called allopatric speciation, which increases the rate of the divergent evolution. The evolution of forelimbs in mammals is one of the most common examples of divergent evolution. 

Similarities Between Adaptive Radiation and Divergent Evolution

• Both adaptive radiation and divergent evolution are mechanisms which bring changes to a particular population.
• Both adaptive radiation and divergent evolution are involved in the emergence of a new species from pre-existing species depending on the selective environmental pressure.
• Adaptive radiation causes divergent evolution over time.

Difference Between Adaptive Radiation and Divergent Evolution

Definition

Adaptive Radiation: Adaptive radiation is the diversification of a group of individuals into forms filling different ecological niches.

Divergent Evolution: Divergent evolution is a process of developing two or more species from a common ancestor over time.

Type of Evolution

Adaptive Radiation: Adaptive radiation is a type of microevolution.

Divergent Evolution: Divergent evolution is a type of macroevolution.

Emerging Characters

Adaptive Radiation: Adaptive radiation brings morphological and ecological changes to a particular population.

Divergent Evolution: Divergent evolution generates a new species that is unable to interbreed with the original species. 

Speed

Adaptive Radiation: Adaptive radiation is a rapid process of evolution.

Divergent Evolution: Divergent evolution is a slow process of evolution.

Examples

Adaptive Radiation: Darwin’s finches, Australian marsupials, and cichlid fish are some examples of adaptive radiation.

Divergent Evolution: The forelimb structures of mammals is an example of divergent evolution.

Conclusion

Adaptive radiation and divergent evolution are two evolution processes which are involved in the emergence of a new species due to the selective pressure of the environment. Adaptive radiation is a type of microevolution process, which causes changes in morphological and ecological diversity. Divergent evolution is a type of macroevolution process, which causes the emergence of new species through sexual incompatibility between individuals. The main difference between adaptive radiation and divergent evolution is in the levels of changes which are brought by each mechanism to a particular population.

Reference:

1. “Adaptive radiation.” Encyclopædia Britannica. Encyclopædia Britannica, inc., n.d. Web. Available here. 22 July 2017.  
2. Scoville, Heather. “More Diversity: What is Divergent Evolution?” ThoughtCo. N.p., n.d. Web. Available here. 22 July 2017. 

Image Courtesy:

1. Darwin’s finches” By John Gould (14.Sep.1804 – 3.Feb.1881) – From “Voyage of the Beagle” as found on [1] and [2], (Javna last) via Commons Wikimedia
2, “Evolution pl” By Mcy jerry at the English language Wikipedia (CC BY-SA 3.0) via Commons Wikimedia