What Is Rapid Evolution? - Definition

Although we have made incredible discoveries about the process of evolution and how it affects organisms over time, there is much we do not know. While some fundamental processes remain the same, our knowledge of how they work over time also evolves. For this reason, we know that the evolutionary process of adaptation occurs in different ways.

One such form of evolution is known as rapid evolution. This is when significant changes in generations of elated living beings occur in a period of less than 100,000 years. While this may not seem very rapid at all, it is relatively fast in terms of evolutionary adaptation.

We can see evidence of this rapid evolution in the different strata of geological deposits. In these strata can be found drastic variations between ancestors and their descendants with less gradual variations. These are known as rapid jumps in the fossil record or bursts of evolution.

Within rapid evolution, speciation events occur. This is where new species are formed through the differentiation of characters and the impossibility of reproducing between them. After a moment of rapid evolution occurs, a period of non-modification and non-speciation follows. This period is known as stasis. This burst-and-pause dynamic is called punctuated equilibrium theory.

In opposition to rapid evolution we have the so-called slow or gradual evolution. This is where clear transitions can be observed between one specimen and another within the fossil record.

Sometimes the jumps typical of rapid evolution may not be due to an accelerated modification in the genetic code. The reason may lie in the fact there has been no record of the transitions between ancestors and descendants. It could also be due to a conservation irregularity of fossils. It is important to remember that for the fossil record to be maintained, very specific soil and environmental conditions are necessary.

Why is rapid evolution important?

The science of rapid evolution is something which is still being explored. There are various reasons why a better understanding of evolution and its types is important. Not only can it helps us to understand the past, but it can help us support our ecosystems in the present and prevent them from harm in the future^[1].

This is summed up in the journal Frontiers in Ecology and Evolution which states:

evolutionary change can affect the interactions between species within a few generations and that ecological interactions may influence the outcome of evolution in return. This tight link between ecology and evolution is of fundamental importance as it can determine the stability of populations and communities, as well as the generation and maintenance of diversity within and among populations.

Although the exact links are not well understood, by having a greater understanding of rapid evolution, we have have a better impact on current ecosystems. Learn more on how we know about evolution with our article on types of fossil preservation.

Rapid evolution can occur due to various evolutionary circumstances, including the following:

• Isolation: biological communities can become isolated for various reasons such as rising water levels, continental separation or a rising mountain range through orogenesis. In these cases, there will be intense selection exerted by selective pressures from the changed environment which will be responded to with new traits. These organisms will reproduce with each other and form new species. In contrast, large populations have no observable rapid evolution.
  
  
• Environmental changes: changes in the environment can favor certain characters. By the process of natural selection, some organisms will die, while others will survive.
  
  
• Decrease of competitors: when some natural phenomenon makes certain species disappear, others that were previously subjugated can prosper and diversify into new species.
  
  
• Migration: when certain organisms permanently migrate to other latitudes, they can adapt to the conditions of the place, diversifying themselves more quickly in the process.
  
  
• Human intervention: finally, we have the great impact that human civilizations have generated on the planet. It has been observed that when humans exert certain pressures on a given ecosystem, species species within these ecosystems may have to evolve quickly.

There are several rapidly evolving events happening right now. Some of these observable examples of rapid evolution include the following examples:

Human populations in Tibet

Our first example is related to evolutionary changes in human beings. The high mountains are not a common habitat for man given the low availability of oxygen, but human populations that live in these regions adapted to them by increasing their blood oxygen level. This is the fastest recorded evolutionary change in humans, occurring in Tibet just 3,000 years ago. Other similar cases are observed in Ethiopia and in the Andes.

Learn more about high-altitude ecosystems with our article on Andean plants and animals.

Small fish

An example of rapid evolution caused by anthropogenic intervention is the effect that fishing has on the size of fish. When an area has been overfished, the fish adapt by reproducing at younger age and birthing smaller fish, influencing the amount of fishing carried out in the area.

Evolution of the Brazilian gecko

To the east of Brazil an artificial dam was created that formed as a consequence 300 islands. In these islands, many reptile species disappeared, but Gymnodactylus amarali survived thanks to a quick adaptation. Their head was found to have grown by 4% so that they could feed on large termites that were now available in the absence of competition from other geckos. This change occurred in just 15 years, an exceptional case of rapid evolution.

Carolina green anoles

The habitat of the green anoles was invaded by brown lizards which gradually displaced them due to competition for habitat and food. But the green anoles adapted by shifting their habitat to higher parts of the trees around them. In order to live there, they had to develop larger legs with more gripping capacity to avoid falling. This adaptation was developed in a span of only 15 years.

Antibiotic resistance

Even microorganisms can have faster adaptation processes. The indiscriminate administration of antibiotics has caused a selection of the strongest bacterial strains. This has lead to increasing cases of antibiotic resistance. This represents a serious problem, because new antibiotics must be created each time since the previous ones are no longer functional to control bacterial strains.

Find out more about hoe ecosystems function with our guide to the difference between biomes and ecosystems.

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