Natural Selection - Biology Online Dictionary (2023)

Definition of natural selection

What is natural selection in biology?Natural selection is defined as a process in nature by which living organisms adapt and change in response to an environmental condition. And organisms that are better adapted to their environment tend to survive longer and produce more offspring.

Different conditions tend to acquire a particular organism.adaptive property🇧🇷 These traits are then passed on to the next generations. Over time, these traits will become more common as they outnumber other traits in the population.

Natural selection (biological definition):a process in nature by which organisms possessing certain genotypic characteristics that make them better adapted to an environment tend to survive, reproduce, increase in number or abundance, and thus are able to retain their essential genotypic characteristics for transmission and carry on to future generations.

CorrespondentUrry and others, (2016)Natural selection refers to the differential survival and reproduction of individuals. It is a vital mechanism of evolution, in which the heritable traits of a population change over generations.

The basic idea of ​​natural selection is that individuals are inherently variable, which means that we are all different in some way. This variation exists within organisms and changes occurcasually🇧🇷 It is transmitted to the next offspring.

Natural selection occurs when some of these changes help an organism survive and produce more than others, causing its genes to become more common in the population over time.

Since the environment is constantly changing, no organism can be considered perfectly adequate or absolutely adapted to its environment. It will always act selectively on certain organisms having certain genetic combinations. This makes natural selection a major driving force in evolution.

Explanation of natural selection.

Let's try to understand the underlying principles.natural selection🇧🇷 Even if the parents perfectly adapted to the environment, somehow the environment changes, their children tend to adapt to the changing environment in order to thrive and win despite limited resources.competencewith the other residents. Until then, the most suitable organisms will reproduce preferentially. As a result, those who manage to survive can pass on their traits or genes to the next generation.

The genetic variability of an organism makes each individual slightly different. These differences cause them to reproduce more, creating individuals more in tune with success. The organism without these genetic adaptations will not continue to reproduce. As a result, his lines eventually cease to exist.

Thatnatural selection processcauses populations to adapt to their environment over time. Individuals in a population inherit traits that help them survive environmental stressors, such as the presence of predators and food availability.

Those who inherited traits tend to have more offspring in the next generation compared to their peers. These useful traits allow them to survive and reproduce more efficiently. Resources are of a limited nature, where individuals with favorable traits have increased in abundance over generations.

Natural selection is described asdifferential reproduction🇧🇷 Some organisms that carry favorable genetic variants that tend to increase survival have greater reproductive success than those that carry alternative genetic variants. Selection occurs based on differences in survival, mating success, development, and fertility.

Natural selection is the process by which inherited traits increase an organism's chances of survival and reproduction. Beneficial properties tend to be favored over less favorable properties.

history of natural selection

ThatTheory of natural selectionbased on the direct observation of the British naturalist,charles darwin, during the round-the-world voyage of HMS Beagle from 1831 to 1836. He observed that the same organism had different appearances in different geographical locations. Until then, he had partially suggested that such physical changes were an adaptation of organisms to their environment. But afterDarwin's theory of natural selection, there were also other evolutionary thoughts that deserve explanation.

Pre-Darwinian Theories

Jean-Baptiste Chevalier de Lamarck(1744-1829) was the first evolutionary theorist to publicly proclaim his idea of ​​the process that leads to biological change. He was one of the promoters ofspontaneous generation, a theory that was once widely accepted, believing that living organisms arise spontaneously from non-living materials, gradually transforming into a more complex form as they continuously strive for perfection. 🇧🇷Pre-Darwinian theory of evolution, 2015)

A theory has been attributed to his name. known aslamarckianismothe theory was based on Lamarck's idea that evolution depends primarily on the inheritance of traits as organisms adapt to their environment. 🇧🇷Pre-Darwinian theory of evolution, 2015)

He believed that the human race was his final product.directed development🇧🇷 (Pre-Darwinian Theory of Evolution, 2015)

I'mInheritance of acquired characters, Lamarck asserted that evolution occurs when an organism uses the body part in such a way that it eventually changes during its lifetime. That change could then be passed on to their descendants.

He illustrated this theory using the example of giraffes, which grew over time. He believed that the ancestors of giraffes were originally short-necked. As giraffes continue to stretch out their necks to get leaves to eat, their necks ended up getting longer with each generation. This change in body shape was probably inherited gradually.

Another example is shorebirds like egrets and egrets. They seemed to have developed their long legs by stretching them out to stay dry.

Lamarck also believed that organisms could develop new organs that altered the structures and functions of old ones.

However, this theory is not as popular as it was when it was discredited by more modern evolutionary thought and research. Although his theory was wrong, he was instrumental in directing scientific discoveries toward the foundation.biology of evolutions.

Jorge Cuvier(1769-1832) was a French scientist who discredited Lamarck's theoryInheritance of acquired characters🇧🇷 Despite this, he still believed that a previous life form existed. Cuvier was the first scientist to document the extinction of ancient animals. He was an expert on dinosaurs. Cuvier believed that "The types have been fixed and have not changed.(Braun (2007).

Another pre-Darwinian school of thought wascatastrophism🇧🇷 Its naturalist defenders were Joseph Fourier and Comte de Buffon. The theory was based on the idea that catastrophic events changed the Earth. Disaster researchers believe that Earth began as a hot ball of molten rock that eventually cooled. 🇧🇷Uniformitarismo: Charles Lyell, 2020).

This school of thought has been challenged byKarl Lyell(1797 – 1875), English jurist and geologist, when certain naturalists linked catastrophism with the Bible. 🇧🇷Uniformitarismo: Charles Lyell, 2020).

Lyell wanted to found geology as a science removed from theological aspects. He then resorted to the ideas of James Hutton, which led him to the conception of the school of thought.uniformitarismo.

Lyell claimed that the Earth went through slow processes over time rather than one great cataclysm. These gradual processes like weathering, deposition, petrification, etc. changed the Earth as we see it today. He described these forces of nature as a force that changed the shape of the Earth's surface.

However, both Lyell and Hutton saw Earth's history as vast and directionless. Lyell believed that the processes that alter the Earth were constant over time.

In relation to the history of life, this has no value. However, this revolutionary idea contributed to Charles Darwin's understanding of biological evolution in the 1830s. George Cuvier and Charles Lyell vehemently rejected the idea of ​​biological evolution. Cuvier did not live long enough to know the proof of the evolution of Charles Darwin. However, Lyell discovered and accepted this evidence in the early 1860s and became a friend of Charles Darwin. Today our world is marked by occasional catastrophic events. All of these events could have influenced the speed and direction of biological evolution.

to darwin's theory

Throughout Charles Darwin's expedition, he saw an intriguing pattern in the distribution and physical properties of organisms. One such notable pattern that he noted was the finch species in the Galapagos Islands.

These birds were not identical species, each species was well adapted to its environment and role. For example, some birds that eat large seeds tend to have large, hard beaks. Other insect-eating birds had thin, pointy beaks. However, Darwin did not know that these finches were related until he presented his sample to an ornithologist (bird biologist).

Gradually, he developed an idea that explained the pattern of various finches. In his opinion, this pattern would be possible if the Galapagos island had already been colonized by birds from the mainland.

The finches may have slowly adapted to local conditions over a long period of time, leading to the formation of distinct species on each island.

With this idea, Darwin developed theTheory of evolution by natural selection🇧🇷 It states that species can change over time and that new species arise from existing species. Therefore, the species share a common ancestor that gradually moved away from the original species and became a new species.

File:Darwin and natural selection(Tutorial)

Evolution by natural selection is one of the most validated theories in the history of science. This theory has two main points. First, all life forms on Earth are related and connected to each other. Second, this diversity of life is the product of modification by natural selection, in which some characteristics of the environment have been favored over others. All of this is Charles Darwin's theory of natural selection.

Evolutionrefers to processes and events that occur over time and illustrates the gradual progression of changes in the genetic makeup of a biological population over successive generations. Two main mechanisms driving evolution arenatural selectionmigenetic drift.

Darwin's theory of evolution by natural selection includes the following basic ideas:

• Traits are often hereditary.This means that organisms have inherited properties that allow them to survive and reproduce under certain environmental conditions. When an individual has useful traits, they produce more offspring and pass them on to the next generation.
• More offspring are produced than the environment can support.This creates competition for limited resources among the population. This competition implies a lack of food resources, habitat, and mates. Since useful traits are heritable, where parents can inherit those traits to their children, those traits become more common in a population.
• Offspring with inherited traits allow them to better compete for limited resources.These individuals will survive and have more offspring than those individuals with fewer variations to compete. Since traits are inherited, these characters will be represented in the next generation. As a result, the population will change over the next generation. Darwin called this processoffspring with modification.

Principles of natural selection

How does natural selection work?Here are some explanations that can help you get a better idea.

First, natural selection depends on the environment. Does not favor superior trait, but favors present traitsadvantageousfor survival and reproduction in a given area. Traits that are useful in one habitat may be harmful in another.

seconds, natural selection acts on existing heritable traits. This heritable variation serves as the starting material for natural selection. Third, heritable variations result from accidental changes or mutations in genes. Random gene mutations lead to new variants of traits that are inherited.

Below are thefour basic principles of natural selectionWhat Charles Darwin originally described in his bookThe origin of species:

Variation: Individuals in a population exhibit variations in behavior and appearance. This variation includes color, size, weight, and other characteristics. Each individual with favorable variations changes the frequency of traits within the population. However, some organisms show more variation than others due to the specific conditions of their environment. As a result, these populations develop a very distinctive trait. Like moths of the same species with different colored wings. Moths that are similar in color to tree bark can camouflage themselves better than any other moth. Therefore, tree moths are likely to survive, reproduce, and pass on their genes.

Express: Inherited traits beneficial for survival are more likely to be passed on to subsequent generations. For natural selection to occur, an individual must have a heritable trait that is strongly influenced by environmental conditions. These beneficial traits are said to be selected for or favored by natural selection. Over time, the failed traits will disappear and the successful ones will become more common. However, when the differences are large enough, a new species evolves. Consider the example of the Galapagos finches; beak variations are "selected" by natural selection. This change in characteristics was passed on to subsequent generations and became more frequent, forming a new, distinct species. In general, the most adapted organisms are able to pass on their beneficial characteristics to their offspring through heredity.

high population growth: Populations produce more offspring each year than the environment can support, resulting in a struggle for resources. Each generation experiences significant mortality as members of the population compete for the limited availability of natural resources. Only then can the surviving individual pass the traits on to the next generation. For example, most species considered overproductive lay millions of eggs at a time, but only a fraction of them survive. Sea turtles lay around 70 to 190 eggs at a time, but typically only 1 in 100 survive. While overproduction may seem like a death sentence, it does have its benefits. Fish and turtles have many enemies, so increasing production also increases the chances of survival. It helps to improve the genetic lineage helping the survival of the fittest. Those that can best adapt to environmental challenges can survive. The best genes are passed on to the next generation, strengthening the species as a whole.

reproductive advantage: It means that the visible characteristics of organisms can change over time. These advantageous traits are passed on to offspring, conferring a reproductive advantage on a population with a favorable trait. Having positive traits means that more of those traits will be present in the next generation. For example, the peacock has a magnificently long tail to attract mates, giving them a reproductive advantage. Moths that camouflage themselves with the bark of the tree to avoid predators and to reproduce give the moths a survival advantage. For plants, they broaden their range of potential pollinators and provide plants with a reproductive advantage. Reproductive advantage involves factors such as mate choice and sexual selection, so reproductive advantage is different from fitness. Parental care also plays a role, as better care for the offspring is often beneficial later in life. However, it is quantified across generations, as organisms negate the effects of variation within a single year or breeding season.

Natural selectionit is one of the most important driving forces of evolution. Natural selection selects for traits that are most likely to be passed from one generation to the next, as they improve an organism's adaptation to its environment.

principles of evolution

What are the four principles of evolution? How are these principles implemented in natural selection?Charles Darwin's four principles of evolution are presented below.

competence: Each generation produces more individuals in a given environment. However, these individuals compete with each other for natural resources. Resources that allow them to survive and have the opportunity to pass on their genes to the next generation. Also, competition can beintraspecificointerspecific.intraspecific competitionIt occurs between members of the same species. For example, two lizards of the same species compete to mate in the same territory. This type of competition is the common factor of natural selection that results in an organism with a better population fit. another boy isinterspecific competitionin which members of two different species compete with each other. For example, predators of different species compete for the same prey in the same area. This type of competition can lead to the extinction of other species. When this species is less adapted and receives fewer resources than the two different species require.

hereditary differences: Differences or genetic traits can be found within the individual in the population. These differences are visible and invisible features that may or may not be beneficial. Therefore, variation is preferred and essential as it offers a higher chance of survival for the species. Furthermore, heritability is a concept that involves the amount of variation in a given trait that qualifies for genetic variation. It is said to be specific to a population in the same environment and to change over time as circumstances change. Like, for example, the melanism of moths in England. Industrialization causes air pollution in the area, soot from factories darkens the tree. We know that the peppered moth used to be a light color to blend in with tree bark and lichens. In this case, dark moths became more common than light ones, as the latter became vulnerable to predation.

survival of the fittest: An individual's genetic variation is generally well adapted to its environment for survival and reproduction. Fitness refers to beneficial qualities: stamina, strength, speed, social skills, intelligence, etc. that help organisms survive. Although the forces that affect survival are not the same between individuals, there have always been differences. These variations would confer fitness over the others. We look again at the example of the peppered moth; The dark moth adapts better to the changing environment. As the dark moth's physical fitness increased, it was able to survive and reproduce. Although the light moths are declining in numbers, the physical condition does not bode well for them. Fitness means surviving and reproducing in a specific environment.

offspring with modification: Formation of a new species from a common ancestor due to reproductive isolation. There is a divergence of genetic characteristics that allow organisms to clearly descend from a common ancestor. For example, a population of tortoises on the island of the Galapagos have a longer neck than tortoises living on dry plains. Long-necked turtles are chosen because they can access more leaves and better food. When there is a drought, there are fewer leaves available on the islands. Those who manage to get more leaves have a better chance of survival than those who did not manage to reach the leaves. As a result, long-necked turtles are more likely to have reproductive success. Until then, the long neck characteristic will be passed on to the offspring. Over time, only long-necked turtles will become available in the population. Since traits are inherited, those traits will be present in the next generation. This will lead to a change in a population over generations through a process called descent with modification.

types of natural selection

What types of natural selection are there?Let's find out below.

stabilize selection

It occurs in natural selection.Favors the intermediate stages of character.survive against extreme character variation🇧🇷 Like the height of the plants, the ground floor received less sunlight compared to the upper floor. However, tall plants are susceptible to wind disturbance. Given these two pressures, the plant will remain at medium height. Over time, the number of small and large plants decreases, while the medium-sized plants continue to increase. In this scenario, plants undergo stabilizing selection. Plant diversity decreases when the population stabilizes at a certain level of characteristics: medium-sized plants. This type of selection pushes the trait towards the average rather than towards the extremes. In short, the stabilization cause of selection increases the reproductive success of the intermediate individual. These extreme traits come with a downside one way or another, which is reduced reproduction.

direction selection

Occurs during direction selectionwhen a single phenotype is preferred, causing the frequency to shift in one direction.The distribution of the trait in the population will shift toward the other extreme trait. A classic example in this case is a peppered moth in England. Before the industrial revolution, peppered moths were naturally light in color to blend in with light-colored trees and lichens. However, if air pollution from industry darkens the color of the trees. Light moths in dark trees become vulnerable to predators. Pepper moths darken over time to camouflage dark trees. Dusky moth numbers are increasing as they have a higher survival rate in habitats affected by air pollution. When the environment changes frequently, the population undergoes directional selection. Thus, there is a change in the genetic variation of the population towards a new adaptive variation of the phenotype. If the trait falls on one extreme and the other phenotypic spectrum is preferred over the others, the selection is directional.

Diverse or disruptive options

This type of selection removes an individual from the center of a phenotypic distribution. It occurs through natural selection.favors both extreme continuous variations🇧🇷 With this selection, the distribution becomes bimodal.Two extreme variations will occur more frequently, eventually giving rise to two distinct new species. For example, coloration allows an organism to match or blend its background to avoid detection by predators. With oysters, light-colored oysters are more hidden than medium-colored ones. The dark oysters, on the other hand, blend with the shadows of the rocks. Therefore, crabs are more likely to eat medium-colored oysters. Both light and dark oysters survive and reproduce. This type of selection, which produces more variation, is called polymorphism.

sexual selection

It is said that the organism that is most capable of finding a mate is the one that is best adapted to the environment. The presence of a particular trait in members of one sex may somehow attract the opposite sex.As for example indrosophilaFlies, some of which result in a yellow coloration of the body.spontaneous mutation🇧🇷 Instead, others have normal yellowish gray pigmentation. The yellowish-gray males are more preferred by female flies than the yellow-colored males. Another example is the deer (male deer). Deer antlers increase competition performance. Therefore, in a battle of strength, those with better horns have the advantage to win and secure a mate. Therefore, sexual selection leads to greater size and aggressiveness in males. The ultimate goal of sexual selection is reproduction, where an individual must maximize the ability to find a mate and produce viable offspring. Sexual selection is also known as non-random differential reproduction due to differential access to mating and reproductive labor. For example, if sexual selection favors the development of conspicuous courtship structures in the peacock's tail, this increases mating success.

Predator-prey selection

This type of natural selection is an interaction between organisms in which the predator captures and eats part or all of the body of the other organism: the prey.🇧🇷 Predators and prey often have beneficial traits resulting from natural selection that help them function better in the environment. For example, the prey has a defense setting to evade predators. These defense mechanisms vary in nature and can be chemical, mechanical, and behavioral. For example, the centipede has chemical and bodily defenses. It produces noxious substances and curls up into a defensive ball when threatened. Many organisms used their coloration or body shape to escape predators. For example, the chameleon changes color to blend in with its surroundings. Over time, the process of natural selection can change the organism to make it a better predator and more defensive prey. In both cases, the adjustment alters the overall predator-prey dynamic. If an organism fails to adapt with the proper defenses, it can somehow die. The predator-prey relationship often forms an "evolutionary arms race" that evolves to neutralize the other.

kin selection

This type of natural selection involves altruistic behavior.Kin selection occurs when natural selection favors traits or characters that benefit related members of the group. For example, worker bees display altruistic behavior, spending their lives working in the hive but never getting a chance to reproduce. However, all bees in hives are close relatives. The traits of the worker bees are passed on indirectly to the next generation through the queen. Therefore, the queen produced more related offspring, leading to a higher fitness of the worker bee, although it never reproduced directly. It seems that natural selection would not encourage or support the behavior of workers. Because whatever factors cause such behavior will likely be removed from the population. Because it is not about the different reproductive success of the worker bees, but of the queen.

examples of natural selection

What are some examples of natural selection?We learned that natural selection is the means by which organisms tend to adapt and thus become more adapted to their environment.mechanicin survival and reproduction. Changes in the environment affect the genetic diversity of species over time. Organisms may not look like their ancestors because they have been modified by natural selection to survive in the new environment. To make it clearer, let's consider some examples of natural selection.

Black-skinned rats vs. Brown

A group of mice with the inherited variation of black and brown fur lived in the area where the rocks are black. Hawks are the predator that can easily spot brown rats. With these environmental characteristics, brown mice are more likely to be eaten than black mice against black rock. Large numbers of light brown mice are eliminated compared to black mice. So the large proportion of black mice that will survive means that there will be more and more black mice in the next generation. Coat color is an inherited trait. After several generations of selection, the mouse population may be completely black. This change in the hereditary characteristics of the mouse population is an exampleoffspring with modification.

Long-tailed peacocks vs. short tailed peacocks

The iridescent plumage of the peacock where the tail feathers are 4-5 feet long. These long feathers hinder the males' ability to escape predators, but are more attractive to females, who prefer long, ornate feathers. As a result, the long-tailed peafowl mates more frequently than the short-tailed peafowl and produced more offspring. The trait is then passed on to the next generation to the point where all male peacocks have extravagant plumage. The color of the males' tail feathers evolved, telling us that peacocks (the females) preferred brightly colored plumage. It is important to remember that natural selection is not enough for an individual to survive, but also for it to reproduce. Therefore, traits that increase reproductive probability are critical to natural selection.

White, black and brown mice

How does natural selection lead to evolution?As mentioned above, natural selection is the driving force behind evolution. It is generally known asEvolution through natural selection🇧🇷 Let's take a look at a population of mice with different fur colors: white, black, and brown. White mice are vulnerable to predators because their color is easy to spot. Therefore, the properties of the white color are not passed on to the next generation. However, brown and tan mice can hide from predators as they easily blend in with their surroundings. This means that they can pass on the black/brown color traits to the next generation. In this case, natural selection leads to the evolution of mice to be mostly black or brown.

Long-necked giraffes vs. short-necked

In an environment where some giraffes have long necks while others have short necks. If something happens to this environment, all the low-growing shrubs will die. So the short-necked giraffes would not have enough food to survive. After several generations, only long-necked giraffes will be available in the area. In this scenario, natural selection promotes the conservation of the group of organisms best suited to the biological and physical changes in their environment.

Gray vs green tree frogs

In a wooded area, gray tree frogs and green tree frogs share a common habitat, tree bark, and aecological niche🇧🇷 Snakes and birds are the predators of frogs. On tree bark, gray tree frogs do better than green tree frogs. Therefore, green tree frogs are more visible to predators and are likely to be eaten. Over time, gray tree frogs produce more young that are less likely to be eaten. In this case, natural selection has favored tree frogs that live in habitats where they are better camouflaged. There are also many ways in which natural selection shapes organisms.

red vs green bugs

Red beetles and green beetles share a habitat. Birds are the region's predators, preferring to eat red beetles to green ones. Soon, the number of green beetles will increase, while the red beetles in the area will decrease or disappear. In this case, the differential reproduction of the beetles depends on the food preference of the predator. Reproductive success is considered an important determinant of the groups favored by the process of natural selection.

Penguins, flightless birds

The penguin, for example, is a flightless bird and does not appear to be a viable survivor. However, instead of flying, penguins have adapted to be good swimmers. Which, in turn, greatly benefits them when it comes to finding food and escaping from predators. Since the area where the penguins live has no land predators, and the food source is in the water. The loss of the ability to fly is not a handicap for them.

carnivorous plant

Natural selection also occurs in plants like the Venus flytrap. These plants are carnivorous and grow in areas where the soil is deficient in nitrogen. Plants naturally require nitrogen, a chemical necessary to survive. In order for the Venus Flytrap to survive in such an environment, it captures the insects as a trap, as the insects contain nitrogen and becomes an alternative source for plants to survive in a nitrogen-poor habitat.

green and brown beetles

Another example of natural selection is the green and brown beetles that live in the soil. Green beetles are easy for birds to spot as they are most visible in the brown environment. Over time, most of the brown beetles remain in the population, while the green ones are eaten by birds. As the environment changes, the ground will be covered with grass due to climate change. So brown beetles are now easy for birds to see. Consequently, their population size may decrease. However, the few remaining green bugs will eventually reproduce as they adapt to survive in their new environment. Thus, the random effects of offspring with modification become the evolution of insects to adapt their environment through natural selection. The traits that are best adapted to the environment are passed on, while those that are not well adapted do not survive.

Municipality

Sharks exhibit defensive coloration, with white underparts and bluish-gray upperparts. This coloration makes them camouflaged in the water, where the upper part blends into the bluish water when looking down. The white underside of the shark, on the other hand, balances the lights coming from above the water.

Try taking the quiz below to check what you've learned so far about natural selection.

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