science

Population control

Population control is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Population control rather than just read about it. In short: Population control is the practice of artificially maintaining the size of any population. It simply refers to the act of limiting the size of an animal population so that it remains manageable, as opposed to the act of protecting a species from excessive rates of extinction, which is referred to as conservation biology.

Key takeaways

Population control belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Population control to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Population control from memory before moving on to harder problems.

Reference excerpt

Population control is the practice of artificially maintaining the size of any population. It simply refers to the act of limiting the size of an animal population so that it remains manageable, as opposed to the act of protecting a species from excessive rates of extinction, which is referred to as conservation biology. While many abiotic and biotic factors influence population control, humans are notably influential against animal populations. Whether humans need to hunt animals for food, exterminate a pest, or reduce competition for resources, managing populations involves providing nourishment, or neutering to prevent reproduction, culling individuals or the use of pesticides. Population control plays an important role in wildlife populations. Based on the species being dealt with, there are numerous ways populations of the wild are controlled. Wildlife contraception is the act of preventing reproduction in the wild, which subsequently decreases populations. An example of this includes the maintenance of deer populations with the use of vaccines. Other methods to maintain populations include lethal trapping, live trapping, egg/roost site manipulation, live-ammunition shooting, and chemical euthanization. Lethal trapping, egg/roost site manipulation, live-ammunition shooting, and chemical euthanization are methods used to eliminate animal populations and prevent reproduction, whereas live trapping captures species to remove them from a specific area.

Factors influencing population control

Population control can be influenced by a variety of factors. Humans can greatly influence the size of animal populations they directly interact with. It is, for example, relatively common (and sometimes even a legal requirement) to spay or neuter dogs. Spaying – removing the ovaries and uterus of a female animal – medical term = ovariohysterectomy. Neutering - removing the testes of a male animal – medical term = orchiectomy. Various humans activities (e.g. hunting, farming, fishing, industrialization, and urbanization) all impact various animal populations. Population control may involve culling, translocation, or manipulation of the reproductive capability. The growth of a population may be limited by environmental factors such as food supply or predation. The main biotic factors that affect population growth include:

Food – both the quantity and the quality of food are important. The population growth and decline of species depends on the amount of their food availability. The more available food, the more the population grows to meet it. The less nutritious food, the less fertile a species of reproductive age becomes. Snails, for example, cannot reproduce successfully in an environment low in calcium, no matter how much food there is because they need this mineral for shell growth. Predators – as a prey population becomes larger, it becomes easier for predators to find prey. If the number of predators suddenly falls, the prey species might increase in number extremely quickly. Competitors – other organisms may require the same resources from the environment, and so reduce the growth of a population. For instance, all plants compete for light. Competition for territory and for mates can drastically reduce the growth of individual organisms. Parasites – These may cause disease, and slow down the growth and reproductive rate of organisms within a population. Important abiotic factors affecting population growth include:

Temperature – Higher temperatures speed up enzyme catalysis reactions and increase growth. Oxygen availability – affects the rate of energy production by respiration. Light availability – for photosynthesis. light may also control breeding cycles in animals and plants. Toxins and pollutants – tissue growth can be reduced by the presence of, for example, sulphur dioxide, and reproductive success may be affected by pollutants such as estrogen like substances. Direct human impacts are not the only ways humans can control animal populations. Oftentimes, humans are indirectly controlling animal populations, in other words, the humans are not aware that their actions are controlling animal populations. For example, new infrastructure and roads can lead to animals being displaced from their natural habitat. Their new habitats that they are forced to move to may not provide the same necessities to them that they require for survival. This will result in a decreasing population as a result of human actions.

Methods for active population control Animal euthanasia is often used as a final resort to controlling animal populations. In Tangipahoa Parish, Louisiana, the parish performed mass euthanasia on the entire animal shelter population, including 54 cats and 118 dogs that were put to death due to a widespread disease outbreak that spread among the animals. Neutering is another option available to control animal populations. The annual Spay Day USA event was established by the Doris Day Animal League to promote the neutering of pets, especially those in animal shelters, so that the population remains controllable.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Population control

Start with the simplest possible case. Write down what Population control claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Population control before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Population control ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Population control

In research: Population control appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Population control in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Population control is common in secondary-school and first-year university syllabi. It links to neighbouring topics Animal culling, Animal welfare, Birth control, so understanding it makes those chapters shorter.
In everyday life: Look for Population control outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Population control in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Population control means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Population control out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Population control in simple terms?

Why does Population control matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Population control?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Population control.