What is evolution?

Evolution is the process by which living organisms gradually change over time, adapting to changing environmental needs, the emergence of new predators, changes in the food chain, and other factors. The driving force is natural selection, in which individuals with more beneficial traits survive, reproduce, and pass on their characteristics to the next generation.

In Darwin’s famous example of finches from the Galapagos Islands, different species evolved different beak shapes and sizes over just a few decades to specialize in feeding on different types of nuts and insects. This process is called adaptive evolution.

There’s another component: speciation. This is when a species splits into two different species over time. This happens much more slowly than adaptive evolution.

In the early and mid-20th century, scientists realized that: Evolution may be happening much faster than Darwin thought. By using the theory of natural selection to make crops tastier in just seven years and domesticating dogs in just a few generations, humans have effectively made evolution possible before our eyes.

We have seen changes occurring on a multi-generational scale.
Timothée Bonnet, an evolutionary biologist at the French National Center for Scientific Research and the University of La Rochelle, says:

The speed of evolution

Human-dominated artificial selection has accelerated evolution, but how much faster could this process happen naturally?

• To find out, Bonnet and an international team of researchers analyzed decades of genetic data from 19 species of birds and mammals. They found that the rate of adaptive evolution was two to four times higher than previously thought. Specifically, each generation increased survival and reproduction by an average of 18.5% under absolutely stable conditions. This means that if survival and reproduction were reduced by a third, Adaptive evolution will help the population adapt to new conditions and recover its numbers within three to seven generations..
• Over the course of 20 years, or three generations, the horns of Canadian mountain sheep (Ovis canadensis) became 0.7 inches (2 centimeters) shorter than before as hunters took down the larger antlers.
• Snow voles (Chionomys nivalis) declined by 0.1 ounces (3 grams) in 10 years, or eight generations, likely due to changes in snowfall.

However, conditions in nature are never constant.

We have populations that are adapting, but we don’t know what they are adapting to. Evolution exists to compensate for, or at least moderate, changes in the environment.
Changes in the environment, competition, disease and humans can trigger rapid evolution, Bonnet added.

Climate change is another major driver of adaptive evolution, but scientists aren’t sure whether populations will be able to keep up. As temperatures and weather patterns change and sea levels rise, some species have responded by moving to cooler areas or adapting to saltier conditions. But the environment can deteriorate too quickly for evolution to keep up.

“Evolution happens all the time,” said James Stroud, an evolutionary biologist at the Georgia Institute of Technology. But if natural selection is so powerful, “why doesn’t everything just evolve quickly all the time?” Stroud asked himself that question, and it led him to publish research on the subject. He and his colleagues found that natural selection in tropical lizards is very dynamic over short timescales (generations or years), but static over longer timescales (millions of years), leading to almost no change.

How do scientists measure the rate of evolution?

University of Michigan paleontologist Philip Gingerich developed a method for determining the rate of evolution using a unit of measurement he called Darwin. He discovered that evolution occurs slowly on long time scales and rapidly on short time scales.

Because of the constant changes in the environment, the pace of evolution can be incredibly fast. The shorter the time interval, the faster the pace.
Michael Benton, a vertebrate palaeontologist at the University of Bristol, said:

Stroud and his colleagues at the University of Miami are now using non-native green iguanas as an example of rapid evolution. The heat-adapted lizards are known to freeze and fall from trees during Miami’s rare cold spells. “We saw some die, but some survive. The survivors can actually tolerate lower temperatures than we’ve measured before, which shows that evolution can happen,” Stroud said.

Fossils also provide some clues. During the Triassic period (251.9 to 201.3 million years ago), after the Permian extinction, large marine reptiles called ichthyosaurs evolved to giant sizes and in less than 3 million years became the oceans’ top predators, faster than whales.

Factors such as adapting to new conditions, filling new niches, avoiding predators and competing with other animals often increase the rate of an animal’s evolution, according to Benton.

The answer to the main question seems to be that under today’s conditions, everything can evolve extremely quickly if necessary.