Natural Selection | Definition | Types | Example

Definition: Natural Selection

The term “natural selection” refers to a species’ natural evolution through time in which only the genes that help it adapt and survive are present. Charles Darwin, the scholar who gave us many of our contemporary ideas about evolution, reported on this hypothesis.

A population will reveal genetic features over many generations that help it remain best suited to its environment through natural selection. These can be physical, structural qualities like a skeleton or musculature that assist it in surviving in that environment, or physiological traits like the existence of an enzyme in the digestive tract that aids in the breakdown of accessible food sources.

Types of Natural Selection

The pressures put on animals can change in a variety of ways as they diversify and occupy new niches. The functional needs of being a bird are vastly different from those of being a fish. Their diet is different, their environment is different, and they need to get oxygen in a different way. As a result, natural selection favors creatures with a wide range of appearances to fill the ecosystem’s many niches.

Natural selection tends to do one of three things to a population, regardless of the feature. It can keep the trait the same, stabilizing selection, moving the trait in one direction, directional selection, or diversifying selection by selecting for the trait’s extreme values. Natural selection can be defined not only by the effects it creates, but also by the interactions between the organisms that are creating the natural selection, and sometimes by abiotic variables.

Type 1: Stabilizing Selection

In terms of distribution, most features in the animal kingdom may be characterized by a bell curve. The majority of animals in a given species have the same characteristic or features and are of similar size. There are always exceptions to the rule, with stronger or smaller qualities in some people, but most people fall somewhere in the middle.

Stabilizing selection is a type of natural selection that eliminates outliers, or trait exceptions. The screen inhibits those animals from reproducing at the same rate as “normal” or more regular animals. Because of this bias, more “average” kids are born and fewer outliers are noticed in each successive generation. Species can become highly unique from other species in this fashion, yet all members of a species will seem identical.

Type 2: Directional Selection

Directional selection is a sort of natural selection in which one side of a trait’s spectrum is preferred over the other. For example, if the tiniest organisms are devoured while larger organisms are completely protected, the population will swell dramatically. In the event that the contrary is true, the population will shrink over time.

Humans can also use directional selection to develop “miniature” breeds of animals that seem like miniature versions of their larger counterparts. Artificial selection, on the other hand, is limited to a single attribute. Many unfavorable qualities that would have been naturally selected against can now be found in the population.

Type 3: Diversifying Selection

Diversifying selection, like directional selection, pushes the population towards the trait’s extremes. Disruptive selection is another name for this form of selection. In contrast to directional selection, diversifying selection pushes the trait in both directions. This can happen in a variety of ways, but because the populations can become so dissimilar, it frequently leads to speciation. However, if the selection is only done for a brief period of time, it can result in a variety of features that are shared by multiple species.

Type 4: Sexual Selection

Natural selection can be classified in terms of the effects it has on the population, but it can also be viewed as the interaction of organisms with various relationships. Sexual selection is a type of natural selection in which the male and female members of a species exert forces on one another that alter their appearance or features. These qualities, such as vividly colored feathers, the ability to perform a ritualized dance, or certain nesting traits like ornamentation, that don’t appear to serve a function in reproduction, appear random to humans.

Sexual reproduction is a highly competitive process in many organisms. As a result, organisms devote a significant amount of time on finding a spouse who will boost the chances of their children succeeding. In certain creatures, the strongest or largest is the winner. Many organisms, on the other hand, have developed elaborate mating rituals to find potential mates. As demonstrated in many birds, sexual selection in these organisms can produce some strange features.

Type 5: Predator-Prey Selection

Multiple species can impose selection pressures on each other, commonly known as interspecific selection, in the same way that sexual selection is an example of intraspecific selection. While this can take various forms, the predator-prey relationship is one of the most common. Predators will constantly strive to eat the easiest food supply, causing prey to develop to become more difficult to catch. As a result, the predator becomes more nimble and faster. This cycle is never-ending, and predators and prey are always shifting.

Other types of Natural Selection

Natural selection can take on a number of shapes and sizes. Depending on the genes it contains and how those genes interact with the environment, each creature will be more or less successful. Genes can lead to new ways of processing nutrients, the formation of new structures, and the repurposing of old structures. Structures of completely different animals occupying the same niche are frequently discovered to be similar. These structures were formed by the forces of natural selection alone, not by a common ancestor. Natural selection is the major driving factor behind all of Earth’s various shapes and functions.

Natural Selection Explanation

Let’s look at the principles that underpin natural selection. Even if their parents were perfectly adapted to their habitat, if it changes in any way, their children would adapt to the new environment in an attempt to thrive despite restricted resources and to outcompete the other occupants. By that time, the species that are best suited to reproduce will have an advantage. As a result, those that survive will be able to pass on their characteristics or genes to future generations.

Each individual is slightly different due to an organism’s genetic diversity. Because of these distinctions, they are more likely to breed, resulting in individuals who are more suited to succeed. Without these genetic adaptations, the organism will be unable to reproduce. As a result, their lines will gradually vanish.

Natural selection drives populations to grow more adaptable to their surroundings throughout time. Individuals in a group inherit characteristics that help them cope with environmental pressures such as predators and food scarcity.

In comparison to their counterparts, those who received the qualities will have more offspring in the next generation. These beneficial characteristics will help them survive and reproduce more effectively. In nature, resources are limited, thus individuals with desirable features have become more common through generations.

Differential reproduction is how natural selection is defined. Some species with favorable genetic variants that improve survival have better reproductive success than those with undesirable genetic variants. Differences in survival, mating success, development, and fertility lead to the selection.

Natural selection is a process in which an organism’s heritable features improve its chances of survival and reproduction. Beneficial qualities are favored over less advantageous features.

History of Natural Selection

Natural selection is based on actual observation by British naturalist Charles Darwin during the HMS Beagle voyage from 1831 to 1836, which was meant to go around the world. He noticed that the same creature had diverse looks depending on where it was found. By that time, he had proposed that such physical changes were a result of organisms’ adaptation to their surroundings. However, prior to Darwin’s theory of natural selection, there were other evolutionary theories that needed to be explained.

Before Darwin

The world of biology was quite different in 1809. Charles Darwin, the founder of the theory of natural selection, was born in this year. Darwin grew up in a world where transmutation was the prevalent evolutionary theory. Animals changed throughout their lives, according to this hypothesis, and passed these changes down to their progeny. Giraffes, for example, have long necks because each generation stretches as far as it can to reach the leaves.

Darwin, who had previously made some early findings on how creatures pass on their qualities, did not agree with this theory. By 1831, Darwin had been granted a once-in-a-lifetime opportunity. Darwin spent over 5 years gathering specimens and documenting the immense diversity of life aboard the H.M.S Beagle. Darwin had a virtually complete concept of natural selection by 1838.

Darwin’s theory

Throughout Charles Darwin’s journey, he noticed an unusual pattern in the distribution and morphological characteristics of creatures. The species of finches on the Galapagos island were one of the fascinating patterns he discovered.

These birds were not of the same species, but they were all well-suited to their respective environments and roles. Some birds that eat huge seeds, for example, have large, tough beaks. Other insects-eating birds had thin, pointed beaks. Until he gave his sample to an ornithologist, Darwin had no idea that these finches were related (bird biologist).

Gradually, he came up with an explanation for the diverse finch patterns. This pattern, he claims, may have occurred if Galapagos Island had previously been occupied by birds from the mainland.

Finches may have evolved over time to adapt to the local environment, resulting in the emergence of unique species on each island.

Darwin created the Theory of Evolution by Natural Selection based on this concept. It asserts that species can evolve over time and that new species emerge from existing ones. As a result, all species have a common ancestor that split from the original species over time and evolved into a new species.

Natural selection is one of the most well-supported hypotheses in scientific history. There are two primary elements to this idea. To begin with, all life forms on the planet are tied and interconnected. Second, this diversity of life is the result of natural selection, which favors certain features over others in the environment. All of this is based on Charles Darwin’s natural selection theory.

Evolution refers to the processes and events that occur over time, indicating the steady course of changes in a biological population’s genetic composition across generations. Natural selection and genetic drift are two fundamental factors that drive evolution.

The following are the basic concepts in Darwin’s theory of evolution by natural selection:

Traits are frequently inherited. This indicates that organisms have hereditary features that enable them to survive and reproduce in specific environments. When a person has beneficial features, he or she produces more offspring and passes them down to the next generation.

There are more kids than the ecosystem can support. As a result, there is rivalry among the population for limited resources. This competition is exacerbated by a scarcity of food, habitat, and mates. Because advantageous characteristics are heritable, which means that parents can pass them down to their children, they become increasingly common in a population.

Offspring with inherited personalities have the best chance of competing for scarce resources. These individuals will subsequently live longer and have more children than those who have less diversity to compete with. Because qualities are passed down over generations, the characters in question will be represented in the next generation. As a result, the population will shift from generation to generation. Darwin used the phrase “descent with modification” to describe this process.

Principles of Natural Selection

What is natural selection and how does it work? Here are some explanations to help you understand it better.

Natural selection, for starters, is influenced by the environment. It prioritizes features that are favorable for survival and reproduction in a certain area, rather than exceptional traits. Characteristics that are beneficial in one habitat may be detrimental in another.

Second, natural selection operates on heritable features that already exist. This heritable variation is used as a starting point for natural selection to work with. Third, heritable differences are caused by genetic mutations or random alterations. The random mutations of genes result in novel heritable variants of characteristics.

The four main concepts of natural selection stated by Charles Darwin in his book The Origin of Species are listed below:


Individuals within a population differ in their behavior and appearance. Color, height, weight, and other features all play a role in this variety. The frequency of features in the population will alter as a result of each individual with positive variations. However, due to certain environmental factors, some creatures exhibit more variance than others. As a result, these populations develop their own specific traits. Moths of the same species with various wing colors, for example. Moths with colors that are comparable to the tree bark are better at camouflaging themselves than moths with diverse colors. As a result, tree-colored moths have a higher chance of surviving, reproducing, and passing on their genes.


Survival characteristics that are inherited are more likely to be passed down through the generations. A heritable trait that is highly impacted by external factors is required for natural selection to occur. Natural selection is considered to have selected or favored these favorable features. The ineffective features will go away with time, while the successful ones will become more prevalent. When the differences are great enough, though, a new species emerges. Take the Galapagos finches as an example; the variances in their beaks are “chosen” by natural selection. This shift in features was passed down through the generations and became more widespread, resulting in the formation of a new species. In general, better-adapted organisms can pass on their advantageous qualities to their offspring through heredity.

Adaptive Radiation of Darwin’s Finches

Population expansion at a rapid rate: Populations produce more offspring each year than the environment can support, resulting in a resource shortage. As members of the population vie for the limited supply of natural resources, each generation endures high mortality. Only then may the qualities be passed down to the following generation by the surviving individual. Most overproducing species, such as fish, lay millions of eggs at a time, yet only a small percentage of them survive. Sea turtles lay 70 to 190 eggs at a time, but only one out of every 100 will survive. Despite the fact that overproduction looks to be a death sentence, there are advantages to it. Because there are so many predators for fish and turtles, increasing production boosts their chances of survival. It promotes the survival of the fittest, which helps to develop the genetic line. Those who are the most adaptable to environmental problems will be the ones to survive. The strongest genes will be passed down to the next generation, strengthening the species as a whole.

Reproductive advantage

Reproductive advantage refers to the ability of organisms’ visible expressed features to change over time. These favourable qualities are handed down to offspring, providing a reproductive advantage to a population with the trait. Positive qualities suggest that more of these features will be passed down to the next generation. The peacock, for example, has a beautiful long tail that attracts partners and gives them a reproductive advantage. The ability of moths to conceal themselves against predators and reproduce gives them a survival advantage. They broaden the range of potential pollinators for plants, giving them a reproductive advantage. There are aspects to consider in reproductive advantages, such as mate selection and sexual selection, which is why reproductive advantage differs from fitness. Parental care is especially important because taking better care of children typically results in a later life advantage. However, because organisms neutralize the effects of variation in a single year or breeding season, it is measured over generations.

Natural selection is one of evolution’s fundamental driving forces. When an organism’s fitness to its environment improves, natural selection favors features that will be passed down with greater frequency from generation to generation.

30+ Examples of Natural Selection

Examples of Natural Selection Types

Natural selection can be seen in a variety of ways. What are some instances of natural selection? Natural selection, we learn, is the process by which organisms become more adapted to their environment and so more capable of surviving and reproducing. The genetic diversity of animals will be affected by changes in the environment over time. Natural selection has modified organisms to survive in a new environment, thus they may not look like their ancestors. Let’s look at some Natural Selection instances to help clarify things.

1. Example of Stabilizing Selection

Consider a population of mice living in the woods for the purpose of stabilizing selection. Some of the mice are black, while others are white or grey. If there were no predators or other pressures acting on the color of the mouse’s coat, it would have no reason to vary and would only alter at random in response to DNA changes. This is not the case with these mice, though. They are preyed upon by numerous predators.

During the day, foxes and house cats hunt on mice. At night, owls and other predators hunt the darkness for prey. In any case, the mice are in a difficult situation. However, not all mice are at the same risk at all times. Black mice are significantly easier to identify during the day, and predators eat more black mice. At night, the white mice shine out. This means that at night, owls eat more white mice. Only the grey mice had a better chance of surviving both during the day and at night. There will be fewer black and white mice to procreate in the next generation.

The entire population might be grey after a few generations of intense selective pressure. It is fully dependent on the characteristic’s genetic makeup, however in rare circumstances, a single feature gets selected for while the others are lost from the population. In other circumstances, the black and white coat colors may just fade into obscurity. When predators change, keeping the qualities can be advantageous. For example, being black would be more advantageous if all the owls and night predators vanished. The black mice would then spread throughout the population and become more common.

2. Example of Directional Selection

It’s crucial to look at different features in the same animal population. Consider the mouse population in the woods once more. Consider a feature that runs on a continuous scale instead of their color. Assume the mice range in size from a standard mouse to something larger than a rat. Despite the fact that the mice are of the same species, they grow to a variety of sizes. The predators, on the other hand, have a difficult time catching and eating the larger mice. The huge mice are not only heavier, but they can also fight back. The smaller mice are mostly vulnerable, making them the ideal snack size.

If this were the case, and nothing was stopping them, the mice would grow to enormous proportions. This is what is known as directional selection. This is most likely what happened to the capybara, a massive South American rodent. The rigors of their environment have pushed them to grow to be considerably larger than any other mouse known to man, just like our fictitious rodents. Many rodents benefit from remaining small for many reasons, which is why most rodents have kept the same size. These benefits could be as basic as the ability to conceal or the availability of food, but animals of different sizes perform better for various reasons, and populations can alter in size through time.

3. Example of Diversifying Selection

Okay, this is the final time with the mice. But this time, consider a new population feature. Consider the possibility that some of the mice develop skin flaps between their front and hind legs. It essentially functions as a parachute, allowing them to glide away from predators. Mice with completely developed skin flaps fare exceptionally well and virtually always manage to avoid predators. Similarly, mice without flaps avoid trees and open spaces that mice with flaps do, and they are much better at hiding from predators. The mice in the middle face the strongest selective pressure.

Mice in the middle, without the capacity to glide away, are unable to escape predators at a rate that allows them to realize the benefits of the trees. The half-flaps, on the other hand, make it more difficult for them to flee and hide from predators. Many more mice from the middle of the spectrum are eaten as a result of this flaw. As a result, the population begins to be divided into two separate phenotypes. This could eventually result in the mice evolving into a new species.

Bats may have become the only flying rodents as a result of this. There are real rodents that do not fly, some that can glide, and bats, all of which are similar to the hypothetical scenario presented. Despite the fact that the common ancestor of all of these animals was not a rodent, they are all mammals. Diversifying selection could have caused the population of the common ancestor to shift and separate, similar to our hypothetical situation. Selective forces are significantly more complex in the actual world, and we can only speculate on the exact historical relationship between animals.

4. Example of Sexual Selection

Consider a peacock. Try to think of a practical application for that ludicrous tail. Stumped? Until the mechanism of sexual selection was revealed, scientists were in the same boat. Natural selection can sometimes select for functional adaptations, but it also frequently develops odd traits that serve mainly to attract mates. The bright tail of the peacock is employed in a display aimed to attract females. Males with bigger tails and brighter colors are chosen over those with tiny tails. This odd predilection appears to have little influence on the males’ ability to collect food and reproduce, but all male peacocks have enormous, colorful tails as a result of the ladies’ choice.

Interestingly, many bird species follow this pattern of males becoming more ornamented than females. Male ducks, many male tropical birds, and even male common house sparrows are all significantly more ornamented than females. This can also be seen in reptiles. To attract mates, several animals have developed bizarre shows or ways of nest decoration. The selection can go either way, and it primarily relies on which sex is pickier when it comes to choosing a mate.

5. Example of Predator-Prey Selection

The cheetah is the fastest land predator. Cheetahs did not develop their incredible speed for no reason. The antelope, the cheetah’s principal prey, is also quick. It will never be known who was the first to become quick, but the truth remains that these two species are constantly pushing each other to become faster.

Faster cheetahs have an advantage over slower cheetahs in catching more antelope and being able to support a larger family. Slow cheetahs will eventually become extinct, and the number of quick cheetahs will grow, catching antelope. The antelope population is also more successful when they are swift enough to dodge the cheetahs, as a result of the new selection. As a result, the antelope population is being selectively bred for speedier animals.

Many of the predator and prey populations’ defining qualities are thought to be shaped by this give-and-take, according to scientists. Given the paucity of cheetahs in North America, scientists were perplexed as to why the American Pronghorn, a species that resembled an antelope in size and speed, should exist. If you don’t have a predator fast enough to catch you, the extra speed won’t help you much. Scientists were perplexed until the discovery of cheetah-like predator fossils in North America. Unlike cheetahs in Africa, North American cheetahs did not survive human expansion, leaving the pronghorn without a predator.

6. Kin selection

Altruistic behavior is involved in this sort of natural selection. When natural selection promotes qualities or characteristics that benefit related members of the group, this is known as kin selection. Worker bees, for example, demonstrate altruism by spending their life working in the hive but never having the option to reproduce on their own. All of the bees in the hives, however, are related. The queen will pass on the worker bees’ characteristics to the next generation in an indirect manner. As a result, even though the worker bee never reproduces directly, the queen generated more related progeny, resulting in a higher fitness of the worker bee. Natural selection does not appear to be promoting or maintaining worker behavior. Because any element that causes such conduct appears to be vanishing from the population. Because the queen’s reproductive success differs from that of the worker bees.

Other Natural Selection Examples

7. Black-furred vs. tan-furred mice

In the area where the rocks are black, a group of mice with heritable variation in fur color black and tan dwelt. Hawks are the predators that can spot the tan mice quickly. Tan mice are more likely to be eaten than black mice against the black rock in these conditions. In comparison to black mice, a huge number of tan mice will be destroyed. As a result of the significant percentage of black mice that will survive, the next generation will have an increasing number of black mice. The color of one’s fur is inherited. The population of mice could become totally black after several generations of selection. This shift in the mice population’s heritable characteristics is an example of descent with modification.

8. Longer-tailed vs. short-tailed peacocks

The colorful plumage of the peacock, including tail feathers that are 4-5 feet long. Long feathers make it difficult for males to flee predators, but they attract more females who like long, elaborate feathers. As a result, longer-tailed peacocks mated more frequently and produced more offspring than short-tailed peacocks. The feature will subsequently be passed down to the next generation until all males in the peafowl species have lavish plumage. Male tail feather color evolved over time, indicating that peahens (female peacocks) preferred brilliantly colored plumage. It’s vital to remember that natural selection isn’t only about survival; it’s also about reproduction. As a result, natural selection favors features that increase the likelihood of reproduction.

9. White, black, and brown mice

Two rats of white and dark color on a white background

How does evolution occur as a result of natural selection? Natural selection, as previously stated, is the driving factor behind evolution. Natural selection is the term used to describe this type of evolution. Consider a mouse population with different fur colors, such as white, black, and brown. White mice are easy to see, making them vulnerable to predators. As a result, the white color traits will not be handed down to future generations. Brown and brown mice, on the other hand, can hide from predators since they blend in well with their surroundings. That means the black/brown color traits will be passed down to the following generation. Natural selection drives the evolution of mice to be predominantly black or brown in this scenario.

10. Long-necked vs. short-necked giraffes


In a world where some giraffes have long necks and others have short ones. If something occurs in such setting, all low-lying bushes will perish. The short-neck giraffes would therefore be unable to survive due to a lack of food. Only long-neck giraffes will be available in the area after a few generations. Natural selection helps to preserve the group of organisms that are best suited to the biological and physical changes in their environment in this situation.

11. Gray vs. green treefrogs

Gray treefrogs and green treefrogs have a same habitat – the tree bark – and an ecological niche in a wooded environment. Treefrogs are preyed upon by snakes and birds. Gray treefrogs mix in better with tree bark than green treefrogs. Green treefrogs are therefore more noticeable to predators and so more likely to be eaten. Gray treefrogs produce more progeny with time, and their offspring are less likely to be eaten. In this situation, natural selection has benefited treefrogs that reside in more disguised environments. Furthermore, natural selection shapes organisms in a variety of ways.

12. Red vs. green bugs

A habitat is shared by red and green bugs. The area’s predators include birds, which prefer to eat red bugs over green ones. Green bugs will soon outnumber red bugs, which will eventually become extinct in the area. In this situation, the bugs’ differential reproduction is determined by the predator’s feeding preferences. Reproductive success is thought to be a crucial factor of which groups are preferred by natural selection.

13. Penguins, flightless birds

For example, the penguin is a flightless bird that does not appear to be a viable option for survival. Penguins, on the other hand, have evolved to be excellent swimmers rather than flyers. As a result, they have an easier time obtaining food and avoiding predators. Since the area wherein penguins’ lives have no land predators and the source of food is in water. They do not see losing their capacity to fly as a loss.

14. Venus flytrap

Plants like the Venus Flytrap, for example, are subject to natural selection. These plants are carnivorous and thrive in locations with low nitrogen levels in the soil. Plants require nitrogen, a chemical element that is essential for their survival. To thrive in such an environment, the Venus flytrap captures insects in a trap-like manner, as insects contain nitrogen and provide an alternate supply of nitrogen for the plants to survive in the low-nitrogen environment.

15. Green and brown beetles

Green and brown beetles, which reside on the ground, are another example of natural selection. Birds can easily recognize green beetles because they stand out against the brown background. As the green beetles are consumed by the birds, mostly brown insects remain in the population over time. Due to climate change, the earth will be filled with grass as changes occur in the area. The brown beetles are now easily spotted by birds. As a result, their population may fall. The few remaining green beetles, on the other hand, will ultimately expand in numbers as they adapt to their new surroundings. As a result, the beetles’ evolution to adapt to their environment through natural selection is driven by random effects of descent with modification. The qualities that are more adapted to the environment are handed down, while those that are not will die out.

16. Sharks

Closeup View of Gray Nurs Shark With Two Skinny Parasite

Sharks have defensive coloring on the bottom that is white and blue-gray on the top. This colour allows them to blend into the water, where the top merges in with the bluish water seen from below. The white tint of the shark’s underbelly balances the light that shines through the water from above.

17. Galapagos finches 

The beaks of Galapagos finches come in a variety of shapes and sizes. Finches with larger beaks fared better during droughts than those with smaller beaks. More little seeds were generated during rainy periods, and birds with smaller beaks fared better. Both types of beaks survive in the population because the environment supports them.

18. Peacock females

Female peacocks choose their spouse based on the male’s tail. More commonly, the ones with the largest and brightest tails mate. Because most breeding males today have large, vivid tales, finding guys without brilliant feathers is rare. This is due to the fact that adult breeding peacocks pass on their tail features to their young.

19. Peppered moths

The majority of peppered moths used to be white with black markings. The white trees became darker when London’s atmosphere became soot-filled as a result of coal combustion during the Industrial Revolution. As a result, birds were more likely to eat light-colored moths. Most moths turned darker after a few months. Light-colored moths surged in population after manufacturers were forced to minimize soot output.

20. Deer mice

Deer mice that migrated to Nebraska’s sandhills swiftly changed color from dark to light brown, allowing the species to thrive in this environment. According to scientists, this alteration was caused by a single genetic modification. As a result, the deer mice were able to hide from predators in the sand more quickly, helping them to survive in their new surroundings.

The majority of eels feed fish and cephalopods, which do not necessitate a forceful bite. Moray eels evolved a second set of jaws and teeth to help them consume hard-shelled food like crabs and snails.

21. Warrior ants

Warrior ants emit a chemical signal that instructs other ants in the colony not to attack them. Some colonies have adapted and learnt to mimic the chemical signals of other colonies. This permits them to infiltrate and take control of another colony while remaining undetected by the workers.

22. Malaria disease

Malaria is one of the top causes of death all around the world. Those who are genetically predisposed to be more resistant to malaria are less likely to contract the disease. Malaria parasites are incapable of surviving in sickle-shaped blood cells. People with sickle cell anemia have a better chance of surviving in malaria-infected areas, reproducing, and passing on their disease to their children.

23. SARS-CoV-2 Virus

SARS-CoV-2 Virus Disease resistance is a powerful natural selection factor for humans in general, not just malaria. SARS-CoV-2, for example, evolved in bats in such a way that it became a disease capable of causing havoc on the human population. Researchers are currently attempting to figure out what elements influence a person’s ability to combat COVID-19.

25. Strong Immune System

As people moved from rural to urban regions and began to live in crowded quarters, sickness spread rapidly across the population. Humans with powerful immune systems were the only ones who survived. Their kids tended to be born with immune systems that allowed them to survive in a densely populated environment as they multiplied.

25. Shape of human hands

Human hands are thought to have evolved over time, according to scientists. Tossing a spear, manufacturing tools, or throwing a boulder to collect the food they needed to survive gave those with higher manual dexterity an advantage.

26. Biological ecosystem

Giraffes with various neck lengths may live in a biological habitat. The giraffes with shorter necks would not be able to eat enough if low-lying bushes died out. They wouldn’t live long enough to have children. The surviving giraffes would have longer necks after a few generations since that body type is better suited to survive in the environment.

27. Hypothetical species

If a hypothetical species of rats lives in a tree with uniformly spaced branches, natural selection would lead to the rats being the proper size for that tree. Smaller rats couldn’t go from one branch to the next, while larger rodents would break the branches and fall. Rats of the proper size would survive and reproduce. The majority of rodents would soon attain the perfect size for the tree branches.

28. Hypothetical environment

In a hypothetical scenario where predators (such as birds) prefer the taste of red bugs, the green bugs have a better chance of surviving. There will be a lot of green bugs and a few red ones soon. The green bugs will breed and create more green bugs, eventually resulting in a situation where nearly all of the bugs born in this area are green.

29. Hypothetical ecosystem

Lizards with long legs could climb better to avoid floods and seek food in a hypothetical ecology prone to flooding. As a result, most lizards in that type of ecology will eventually acquire lengthy legs. This feature would be handed down from their parents, who were able to live due to their long legs.

30. Resistant to pesticides

Pesticide resistance can develop quickly in insects, often in just one generation. If an insect develops a mutation that renders it resistant to a chemical, some of its offspring will be as well. Insect generations can be as short as a few weeks, therefore insects in a given area might quickly develop resistance to a pesticide. Soon, the pesticide may have no effect on newly born babies.

31. Resistant to antibiotics

Antibiotic resistance can develop in bacteria. Bacteria may produce many generations in a single day, so this can happen quite quickly. Only those with mutations that enable them to withstand antibiotic treatment will survive and reproduce. This results in bacterial strains that are resistant to antibiotics.

What can natural selection teach you?

Charles Darwin, a 19th-century biologist, investigated the principle of natural selection. Natural selection explains how a species’ genetic features change over time. This could result in speciation or the emergence of a new species. Choose from these resources to teach your students about this evolutionary biology subfield.


Natural selection is a scientific theory that states that organisms are more likely to pass on features that improve their chances of survival.

Adaptations are useful qualities that animals evolve over time. Body structures, processes, and behaviors can all be examples. Polar bears, for example, have developed thick, white fur for warmth and camouflage in the cold, snowy arctic climate.

A species with a lot of genetic variation has the best chance of surviving an environmental shift. Individuals with the most advantageous characteristics are more likely to live to reproductive age and pass on those characteristics to the next generation.

Some environmental changes might cause once-beneficial features to become hazardous. Peppered moths, for example, developed white bodies to blend in with the trees they inhabited.

Leave a Comment