Adaptive Radiation Evolution

May 02, 2023, 16:45 IST

Darwin’s theory of evolution states that living organisms change their anatomical and physical structures over some time to adapt to the changing environment.

The point of initiation for evolution occurred when organisms wanted to exploit a niche and were unable to do so with their existing structural components. This led the organisms to split and adapt to various versions suited for survival.

What is Adaptive Radiation Evolution?

Adaptive radiation evolution is the process where animals from a certain species change or develop from their ancestral species into a new kind of species. In other words, it is an evolutionary process where a species that originated from one species, radiates to a different species.

Such an evolution tends to take place when a change occurs in the environment. This results in biological alternations and marks new environmental opportunities.

Adaptive radiation evolution was first observed by Darwin when he traveled to Galapagos Island. He observed finches with different beaks and concluded that all the finches that radiated from a single ancestral finch developed their beaks based on the kind of food that was available to them. The change in the environment was a factor that led them to evolve from seed-eating finches to both vegetarian and insectivorous ones. The finches later came to be known as Darwin’s finches.

What Causes Adaptive Radiation?

Adaptive radiation is common during environmental changes and when physical disturbances occur. Let us take a look at the major factors that cause adaptive radiation.

1. Ecological Opportunities

When organisms enter a new area with several ecological opportunities they diversify to exploit those resources.

In other words, when organisms or groups of organisms enter a new adaptive zone they tend to adapt to the zone which results in adaptive divergence.

An adaptive zone is an unexplored or unexploited area where ecological opportunities are plenty. For instance, nocturnal flying to catch insects, and swimming at the surface of the ocean to catch plankton are examples of ecological opportunities.

2. Mass Extinction

When environmental changes or any physical disturbances lead to mass extinction then adaptive radiation evolution is also possible.

Mass extinction leads to empty adaptive zones that provide new opportunities to species. For instance, after the mass extinction of dinosaurs, mammals diversified quickly and exploited adaptive zones.

3. Evolutionary Traits

A slight change in the genes, otherwise called gene mutation, can result in structural changes in an organism.

For instance, some adult salamander species retain their external gills and tail fin, which is ideally found only in the larval stages. These characteristics or features were caused due to a gene mutation that blocks the hormones responsible for metamorphosis.

What are Some Examples of Adaptive Radiation?

Let us take a look at a couple of examples of adaptive radiation.

1. Darwin finches

In the Galapagos islands, Darwin observed an amazing diversity of finches. He found that all of the finches, which stemmed from the same ancestral species, evolved from original seed-eating finches to insectivorous and vegetarian finches on the island.

The finches radiated to different geographical areas and changed physically - this was most noticeable in the beaks. The alternation in the beaks led to changes in their eating habits i.e. from seed-eating birds to insectivorous and vegetarian birds.

2. Australian Marsupials

Several marsupials or pouched mammals evolved differently from an ancestral stock within the Australian continent.

Conclusion

Adaptive radiation evolution plays an important part in macroevolution and gives rise to diversification via ecological specialization which is important to understand how ecological forces drive diversification.

Frequently Asked Questions (FAQs)

Q1. What type of evolution is adaptive radiation?

Ans. Adaptive radiation is an example of divergent evolution. It is a type of evolution wherein closely related organisms become more and more different from each other, over some time.

Q2. Is adaptive radiation the same as evolution?

Ans. Adaptive radiation is to a degree a rapid process of evolution. In adaptive radiation, closely related species evolve. The best example of this would be the development of mammals after the extinction of dinosaurs.

Q3. Can we call human evolution as adaptive radiation?

Ans. No, we cannot call human evolution adaptive radiation because adaptive radiation is an evolution that creates or produces a new species from a single and rapidly diverse lineage.

Q4. What is convergent evolution?

Ans. In simple terms, convergent evolution is a term used to describe evolution where distantly related organisms independently evolve and evolve or develop traits to adapt to similar necessities. For example, a shark and a dolphin look somewhat similar but are unrelated.

Q5. What is speciation?

Ans. Speciation is a term that refers to the development of a new species. This can be a new animal species, microbe, or even a plant. This happens when a group within a species departs from the rest of the species and develops its own distinct features.