Evolution is usually associated with processes that last thousands or millions of years. However, in some cases, it can happen much faster, in just a few generations. For example, the beak shape of the famous Darwin's finches on the Galapagos Islands quickly adapted to changing food resources, and green anoles (Anolis carolinensis) developed larger pads on their toes, allowing them to escape predators by climbing higher. But despite these examples and other vertebrates, the question of which animals evolve the fastest remains a subject of debate in the scientific community. Michael Benton, a paleontologist at the University of Bristol (UK), believes that it is extremely difficult to identify specific organisms that always evolve quickly. We explain why.
In the future, we will see more species that evolve faster. Image: hakaimagazine.com
Contents
- 1 Speed of evolutionary change
- 2 Evolutionary record holders
- 3 Climate change and evolution
- 4 Conclusions and implications for science
Speed of evolutionary change
The answer to the question of which vertebrates evolve the fastest is difficult to find. For example, researchers are not sure that there are specific organisms that always change, adapting to environmental conditions, faster than others. Paleontologist Michael Benton identifies two leading reasons for the “rapid” evolution of vertebrates.
The first is internal factors. Some scientists believe that certain organisms have fundamental features that make them predisposed to rapid evolution.
The second is external factors. Many researchers believe that, in fact, all organisms on our planet can evolve rapidly, but the rate of change depends on external factors such as changes in the environment.
The vertebrate tuatara (Sphenodon punctatus) is the fastest-changing vertebrate on the planet. Image: reptiles.org.nz
And yet, there are organisms on Earth that biologists have called the “fastest evolving”. This title belongs to the vertebrate tuatara (Sphenodon punctatus), a reptile found only in New Zealand.
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Although these “living fossils” have changed little in appearance over millions of years, a 2008 study published in the journal Trends in Genetics found that they have the fastest rate of molecular evolution of any known vertebrate. This means that their DNA changes rapidly, even if their physical appearance remains the same.
Adelie penguins have remained virtually unchanged in appearance. Image: penguinworld.com
Moreover, a similar situation is observed in Antarctic Adelie penguins (Pygoscelis adeliae), whose genome is evolving two to seven times faster than previously thought, despite their “stable” appearance.
Evolutionary record holders
However, not all scientists agree that the title of “fastest evolving” vertebrate should go to tattoos. Thus, evolutionary biologist Michael Lee from Flinders University believes that the palm should be given to cichlids living in Lake Victoria, the largest and youngest lake in Africa.
Cichlids (Cichlidae) are a family of ray-finned fish from the order Cichliformes.
Lake Victoria is located on the territory of Uganda, Tanzania and Kenya. According to researchers, over the past 15,000 years, more than 500 species of cichlids have evolved in it. This is a relatively short period of time for the a process called adaptive radiation, which occurs when one species rapidly splits into many others.
Species not only split into new ones, but also change their appearance to fit different niches in the environment, Lee told LiveScience.
Cichlids of Africa come primarily from Lakes Malawi, Tanganyika and Victoria and from several rivers. Image: scientificamerican.com
Among the reasons for such rapid evolution of cichlids, scientists highlight the second set of jaws located deeper in the throat. They probably allow cichlids to use different food resources, adapting to different conditions and ecological niches. For example, some feed on plankton located higher in the water column, while others dig for larvae on the muddy bottom of the lake.
The second reason, apparently, was selective mating and the ability to reproduce quickly: cichlids prefer to mate with individuals that have similar characteristics, which contributes to the rapid formation of new species. In addition, hybridization between different species leads to the appearance of offspring with new combinations of genes and accelerates the evolutionary process.
Guppies from the Trinidad River. Image: aquaportail.com
It should be noted that there are other contenders for the title of “fastest”. For example, guppies (Poecilia reticulata), living in a predator-free tributary of a river in Trinidad, have evolved at a rate of between 3,700 and 45,000 Darwins – units of measurement of the speed of evolution. For comparison, artificial selection in mice reaches 200,000 Darwins, and in the fossil record the rate rarely exceeds one Darwin.
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It should be noted that species living in cities are of particular interest to scientists. The fact is that changes in the urban environment also contribute to rapid evolution. For example, lizards in Miami can develop increased resistance to cold, and some plants begin to bloom earlier in response to earlier snow melting.
Climate change and evolution
Michael Lee also notes that the evolution of many species can accelerate due to climate change, as it leads to temperature fluctuations, changes in water salinity, weather conditions and other aspects of the environment.
The world is changing faster than ever before. The evolution we see today is likely to be faster than at any time in history, both in terms of the extinctions that are occurring and in terms of new evolutionary responses to human-induced environmental change, the evolutionary biologist explained.
As you can see, identifying the fastest evolving vertebrate remains a difficult task due to the many factors that have a significant impact on the evolutionary process.
Peppered moths (Biston betularia) have become darker due to industrial pollution in cities. Image: inaturalist-open-data.s3.amazonaws.com
Of course, Lake Victoria cichlids are the most striking example of rapid evolution and adaptation to various ecological niches. Their unique physiological characteristics and behavioral strategies allow them to reproduce quickly and adapt to new conditions.
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However, the rapid genetic changes in tuatara and Adélie penguins show that evolution can occur at the molecular level without noticeable changes in appearance. Guppies and urban species, in turn, demonstrate how quickly organisms can adapt to new environmental conditions, especially under the influence of human activity.
Conclusions and implications for science
Understanding which species are capable of rapid evolution and under what conditions has important implications for biology and ecology, and can help scientists develop strategies for preserving biodiversity and managing ecosystems in the face of rapid climate change.
As research in this area continues, scientists expect that as the environment continues to change, we will see more examples of rapid evolution. This has its benefits for science, as researchers will be able to better understand the mechanisms of evolution and adaptation, as well as how species will respond to future changes in their environment.
Scientists have discovered which vertebrates evolve the fastest. Image: livescience.com
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Amazingly, the vertebrates discussed in this article demonstrate that evolution can happen much faster than we usually think: from molecular changes in the genome to rapid morphological adaptations, the animal world is full of examples of how life on Earth is constantly changing and adapting. Plus, studying rapid evolutionary processes satisfies our curiosity.