Natural Selection

Natural Selection

Natural Selection, a fundamental concept in evolutionary biology, explains how species adapt and evolve over time. This guide provides a detailed exploration of natural selection, offering easy-to-understand examples and explanations. It’s an invaluable resource for teachers aiming to clarify this complex process to students. From the evolution of antibiotic-resistant bacteria to the diverse beak shapes of Darwin’s finches, this guide demonstrates natural selection in action, highlighting its role in shaping the diversity of life on Earth.

What Is Natural Selection

Natural selection is a scientific theory of adaptation and change that tries to explain why species adapt and change over time in a given environment or setting. Charles Darwin, a famous scientist, postulated that natural selection is the reason why organisms evolve the way they do.

What is the Best Example of Natural Selection?

what is the best example of natural selection

A prime example of natural selection is the evolution of the peppered moth in Britain. During the Industrial Revolution, soot darkened the trees, providing a survival advantage to darker moths over lighter ones, as they were less visible to predators. This change in moth populations, driven by their environment, perfectly illustrates natural selection in action.

20 Natural Selection Examples

natural selection examples

Natural selection, a cornerstone of evolutionary biology, describes how species adapt over time through favorable traits. This list of 20 examples offers a broad perspective on natural selection in various environments, providing a valuable educational resource for teachers. These examples demonstrate the diverse ways in which species have evolved to better survive and reproduce in their specific habitats. Understanding these examples helps students grasp the dynamic and ongoing nature of evolution, reinforcing key biological concepts.

  1. Peppered Moths: Shift from light to dark coloration due to industrial pollution.
  2. Darwin’s Finches: Different beak shapes evolved based on available food sources.
  3. Antibiotic-Resistant Bacteria: Bacteria evolving resistance to antibiotics.
  4. Galápagos Tortoises: Shell shapes varying based on island habitat.
  5. Cane Toads in Australia: Rapid leg length adaptation for better mobility.
  6. Arctic Foxes: White fur as camouflage in snowy environments.
  7. Giraffes’ Long Necks: Adaptation for reaching higher foliage.
  8. Elephant Tusk Size Reduction: Due to selective hunting practices.
  9. Lactose Tolerance in Humans: Evolutionary adaptation to dairy consumption.
  10. Camouflage in Stick Insects: Resembling twigs for predator avoidance.
  11. Mimicry in Butterflies: Non-toxic species mimicking toxic species.
  12. Polar Bears’ Thick Fur: Adaptation for cold Arctic climate.
  13. Sickle Cell Trait in Humans: Offers malaria resistance.
  14. Flowering Plants and Pollinators: Co-evolution for efficient pollination.
  15. Penguins’ Waterproof Feathers: Adaptation for aquatic life.
  16. Cichlids in African Lakes: Diverse jaw structures for specialized diets.
  17. Wildlife in Chernobyl: Adaptations to high radiation levels.
  18. Himalayan Sherpas’ Lung Efficiency: Adaptation to high altitude.
  19. Moths’ Hearing Abilities: Evolved to avoid bat predation.
  20. Desert Plants’ Water Storage: Adaptations for arid environments.

Types of Natural Selection

Natural selection, a key mechanism of evolution, can be categorized into various types, each with distinct characteristics and examples in nature.

Directional Selection: This type favors one extreme phenotype over the average or other extremes. A classic example is Peppered Moth In Britain, industrial pollution darkened tree bark, favoring darker moths that were less visible to predators, leading to an increase in the dark moth population

directional selections

Stabilizing Selection: It favors the intermediate variants and acts against extreme phenotypes. Human birth weight is an example, where very high or low weights are less favored compared to average weights.

stabilizing selectionss

Disruptive Selection: This type favors individuals at both extremes of the phenotypic range. An example is seen in black-bellied seedcracker finches, where individuals with either very small or very large beaks are more successful than those with intermediate-sized beaks.

disruptive selection

Kin Selection: A form of natural selection that favors the reproductive success of an organism’s relatives, even at a cost to the organism’s own survival and reproduction. An example is the altruistic behavior of certain animal species, such as bees, where workers sacrifice their own reproduction to help raise their siblings, enhancing the genetic success of their common genes.

kin selection

Artificial Selection: while not a natural process, is a form of selection where humans actively select for desirable traits in organisms. This has been widely used in agriculture and animal breeding. For instance, dogs have been bred for various traits leading to the wide range of breeds we see today, from the tiny Chihuahua to the large Great Dane, each with characteristics valued by humans.

artificial selection

Principles of Natural Selection

Natural Selection, a foundational concept in biology, explains how species evolve over time through genetic variations and environmental pressures. This guide is tailored to assist teachers in conveying these principles effectively to students, enhancing their understanding of evolutionary biology.

  1. Variation Exists Within Populations: Every species exhibits genetic diversity, meaning individuals within the same population vary in their traits. For example, in a rabbit population, some might have longer ears than others. This variation is crucial for natural selection as it provides the raw material for evolution.
  2. Inheritance of Traits: Traits that offer survival advantages tend to be passed down through generations. Consider the peppered moth; during the Industrial Revolution, darker moths were less visible to predators on soot-covered trees, thus more likely to survive and reproduce, passing on their dark coloring.
  3. Overproduction of Offspring: Species often produce more offspring than the environment can support. Imagine a turtle laying dozens of eggs, yet only a few hatchlings survive to adulthood. This overproduction leads to a struggle for survival, with only the fittest succeeding.
  4. Differential Survival and Reproduction: Not all individuals have an equal chance of survival and reproduction. For instance, a faster gazelle has a better chance of escaping predators and living to reproduce. Those with advantageous traits are more likely to pass these on, influencing the species’ evolution.
  5. Adaptation to the Environment: Over time, traits that enhance survival and reproduction become more common in the population. Consider the Arctic fox’s white fur, which camouflages it against the snow, a critical adaptation for hunting and evading predators in its habitat.

What is the Process of Natural Selection?

Natural Selection is a key mechanism of evolution, where individuals with certain heritable traits are more likely to survive and reproduce, influencing the genetic makeup of future generations. This process is essential for understanding how species adapt and evolve over time.

  1. Genetic Variation: Every population exhibits genetic differences. For instance, beetles in a group may vary in color, influencing their visibility to predators.
  2. Struggle for Existence: Living organisms compete for resources. In a forest, trees vie for sunlight, affecting their growth and survival rates.
  3. Survival of the Fittest: Individuals best adapted to their environment are more likely to survive. A classic example is the giraffe’s long neck, allowing it to reach higher leaves for food.
  4. Reproduction of the Fittest: Surviving individuals pass on their traits. Birds with better camouflage, for instance, are less likely to be preyed upon and thus more likely to reproduce.
  5. Inheritance of Advantageous Traits: Favorable traits become more common in the next generation. Cheetahs, through generations, have developed remarkable speed to catch prey.
  6. Change in Population Over Time: Over generations, a population’s characteristics gradually shift. For example, bacteria may evolve resistance to antibiotics.
  7. Adaptation to the Environment: Species adapt to their surroundings. The Arctic fox’s white fur, blending with the snow, is a survival adaptation in its habitat.
  8. Speciation: Over time, these changes can lead to the emergence of new species. The diverse beak shapes of Darwin’s finches, adapted to different food sources, are a prime example.

Why is Natural Selection Important?

Natural Selection is crucial in shaping biodiversity and the adaptive characteristics of organisms. It explains the diversity of life on Earth and how species adapt to environmental changes, providing a framework for studying evolutionary biology.

  1. Explains Biodiversity: Natural selection accounts for the vast diversity of species. The different species of finches on the Galápagos Islands, each with unique beak shapes suited to specific food sources, demonstrate this.
  2. Adaptation to Changing Environments: It enables species to adapt to environmental changes. Polar bears, for instance, have evolved thick fur and fat layers to survive in Arctic conditions.
  3. Survival and Reproductive Success: It determines which traits are favorable for survival and reproduction. The camouflage of a stick insect, allowing it to blend with its surroundings, is a survival trait.
  4. Influence on Human Evolution: Natural selection has played a role in human evolution, such as the development of bipedalism for efficient locomotion.
  5. Impact on Agriculture and Medicine: Understanding natural selection aids in improving crop varieties and combating antibiotic-resistant bacteria.
  6. Conservation and Wildlife Management: It informs conservation strategies by understanding how species adapt to environmental changes and human impacts.
  7. Educational Importance: Teaching natural selection is vital in biology education, helping students understand the dynamics of ecosystems.
  8. Foundation of Evolutionary Theory: It’s a cornerstone of evolutionary biology, essential for research in genetics, ecology, and conservation biology.

What is Required for Natural Selection to Take Place?

Natural Selection is a fundamental process in evolution, requiring specific conditions to drive the adaptation and evolution of species. Understanding these requirements is crucial for educators to effectively teach the concepts of natural selection and evolution.

  1. Variation in Traits: Populations must have differences in traits, like the various beak sizes in a bird species, providing material for selection.
  2. Heritability of Traits: Traits must be heritable, meaning they can be passed from parents to offspring. For example, fur color in mammals is a heritable trait.
  3. Differential Survival: Individuals with certain traits must survive better or worse than others, like rabbits with better camouflage avoiding predators more effectively.
  4. Differential Reproduction: Those who survive longer tend to reproduce more, passing on their traits. A fast-running antelope, for instance, is more likely to reproduce.
  5. Competition for Resources: There must be competition for resources, such as food or mates. Plants, for example, compete for sunlight.
  6. Environmental Pressure: The environment must exert pressure that affects survival, like climate changes influencing the fur thickness in animals.
  7. Time: Natural selection occurs over many generations. The development of antibiotic resistance in bacteria is a gradual process.
  8. Population Size: Larger populations provide more genetic variation. In a large fish population, there’s a greater chance of varied traits.

What are the Natural Selection Steps?

Natural Selection involves a series of steps that lead to the evolution of species. Educators can use these steps as a framework to help students grasp how natural selection operates in nature.

  1. Presence of Variation: There must be variations in traits within a population, like different shell patterns in a group of snails.
  2. Inheritance of Variations: These variations are inheritable. A bird’s ability to fly is an inherited trait.
  3. Overproduction of Offspring: Species produce more offspring than can survive. Turtles, for example, lay numerous eggs, but not all hatchlings survive.
  4. Struggle for Existence: Limited resources lead to a struggle for survival. In a drought, plants compete for water.
  5. Survival of the Fittest: Individuals best suited to the environment survive. Moths that blend into their background avoid predators more successfully.
  6. Differential Reproduction: Those who survive are more likely to reproduce. A faster deer is more likely to escape predators and reproduce.
  7. Change in the Population Over Time: Over generations, the population evolves. Bacteria can evolve to become resistant to antibiotics.
  8. Adaptation: Populations become better suited to their environment. The thick fur of polar bears is an adaptation to cold climates.

1. Natural Selection and Adaptation

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2. Understanding Causality in Natural Selection


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3. Evolutionary Biology Natural selection

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How to Check If the Organism Can Undergo Natural Selection

Scientists and researchers have posited that organisms must be able to fit into four factors before they can utilize natural selection for their survival. Reproduction is the first factor of natural selection that focuses on the organism’s ability to reproduce offspring and pass down desirable traits. Heredity is the second factor that refers to the offspring’s ability to exhibit and accept desirable traits and characteristics from their parents. The fitness of the organism is the third factor that describes the fertility of both parents and the ability of the mother to reproduce numerous offspring. The last factor of natural selection is the individuality of the organism, which relates to the biodiversity of the species in a given setting.

1.) Create an Outline or a Table With the Four Factors of Natural Selection

Begin by creating an outline or a table with all four factors of natural selection as the x-axis of the table or outline. The four factors of natural selection are reproduction, heredity, the fitness of the organism, and the individuality of the organism.

2.) Research the Species of the Organism

You will then need to research the overall species of the organism. This will help you determine the reproduction and fitness of the organism. Not only that, but it will also provide you with the internal factors of survival for the organism, which could affect the lifespan of the organism.

3.) Note Down the Environment of the Organism’s Habitat

After you have researched the characteristics of the organism’s species, you will not need to note down the habitat or ecosystem of the organism. The habitat or ecosystem will help you obtain data that will provide the external factors that affect the organism’s survival.

4.) Cross Reference the Data With the Four Factors

When you have finished obtaining all the data of the organism, you will now insert it into the table or outline. The completed table or outline will make you determine whether or not the organism has space to undergo natural selection in its lifetime.


Evolution vs. natural selection; what is the difference between evolution and natural selection?

Evolution is the process of change and adaptation where traits, mutations, and genetics are passed down from generation to generation to determine the species’ survival. The phenomenon occurs when an organism adapts to desirable characteristics for survival and passes it on through genetics, which will take some time to observe. Natural selection is the process of change and adaptation that creates new traits or characteristics to survive the current environment and proceed to the next generation. All of this means that evolution is more of a long-term process when compared to natural selection. Not only do the durations differ, but natural selection can create observable changes in the short term compared to the changes incurred by evolution.

Is natural selection a theory or a scientific fact?

Natural selection is still a scientific theory that uses the scientific method to investigate what causes species to change over time. Because natural selection is still a theory, the phenomenon is still not a scientific fact and does not explain how species adapt and change over time. But this does not mean that natural selection is invalid and not an explanation of this phenomenon; instead, this theory just lacks more evidence to prove its existence or inexistence.

Can humans affect the natural selection of different organisms?

Yes, humans can and have affected a species’ adaptation and characteristics. Human intervention and interaction result in the early signs of natural selection and coevolution. An example of this phenomenon is the rampant decrease in the size of hunted animals and fishes. Humans tend to hunt and consume animals that have a bigger size or a more grand appearance, which has caused some animals and fishes to decrease in size and create a less appealing appearance. The phenomenon occurs because the smaller or less appealing animals have more chances of passing their genes to the next generation, thus affecting the future population of the animal species.

Natural selection is the process of adaptation that Charles Darwin proposed and theorized. This process explains what factors are necessary to conduce or induce an observable change in the traits or characteristics of a species.

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