Examples Of Biotic Limiting Factors
By now, you're probably familiar with the thought that populations change over time, and these changes are examined through analysis of population size, density, and distribution patterns. The population of organisms rarely grows uncontrolled, though, because certain factors limit it. Now let's delve into population limiting factors!
Population limiting factors examples
Firstly, what exactly are these limiting factors that touch population growth? Allow's wait at the definition of a limiting cistron in population ecology.
Limiting factors are referred to as conditions or resource within an surroundings that restricts population growth.
Population growth is the change in size of a population over a certain flow of fourth dimension.
For example, suppose a population has just a certain corporeality of nutrients available. In that case, information technology will keep growing exponentially until the nutrients are used up, and the population reaches a carrying capacity (Figure 1). When the conveying is reached, the population size remains relatively the aforementioned.
The conveying capacity is the maximum number of individuals of a given species that an environment can support.
Figure one. Logistic Growth Model, Isadora Santos - StudySmarter Originals.
The carrying capacity of a arrangement is limited by limiting factors. Population growth tin exist express by biotic or abiotic factors, and changing these factors can also impact carrying capacity. During natural disasters, for example, ecosystem resource are destroyed. As a effect, the ecosystem is unable to support a large population, resulting in a decrease in carrying capacity.
- Abiotic factors are nonliving factors in an ecosystem such as temperature, sunlight, nutrients, h2o, pH, salinity, and humidity.
- Biotic factors are living factors such as competition for resources, predation, and affliction.
Did you know that microorganisms are also affected by limiting factors? For instance, temperature and pH accept the ability to limit the growth of organisms such as bacteria, yeasts, and molds!
Definition of density dependent limiting factor
Population growth limiting factors are divided into two categories: density-dependent and density-independent . The first blazon of limiting cistron that we will be exploring are density-dependent limiting factors (Effigy ii). Density-dependent factors include competition, predation, resource depletion, and diseases.
Density-dependent factors are biotic factors whose furnishings in population size depend on population density.
Density-dependent factors are subdivided into two groups: negative density dependence and positive density dependence.
- Negative density dependence happens when the rate of population growth decreases every bit population density increases.
- Positive density dependence occurs when the population growth rate increases as population density decreases.
Some textbooks might refer to positive density dependence as inverse density dependence or the Allee issue.
Contest
At this betoken in your biology or ecology course, y'all probably heard of the term competition. Competition occurs when individuals of the same or of unlike species start competing for resources. In some cases, an increased population density tin put a strain on the availability of food, shelter, and water. Due to competition for resource, this could eventually upshot in reduced population growth.
Intraspecific competition is the contest for limited resource between individuals of the same species.
Interspecific competition is the competition for limited resource between individuals of dissimilar species.
Let's look at an example.
The intertidal zones of ocean shores are home to sessile animals like mussels and barnacles. The open space they have is, therefore, an essential resources for their population growth. Withal, these animals' population growth declines equally rocks become crowded and space becomes less available.
Diseases
Diseases and parasitism are considered density-dependent limiting factors considering equally population density increases, they are able to spread more easily inside the population, eventually leading to a subtract in population growth.
Bacillus anthracis is a blazon of pathogenic leaner that causes a series of complications such as respiratory infections, GI infections, and cutaneous infections (black-colored lesions). In Africa, an infection of zebras with B. anthracis is condign a concern. Basically, the pathogen lures zebras into the contaminated area so that they become infected by ingesting the microbe, and spread the infection to other organisms. This disease can be lethal, causing a decline in the population of zebras.
Parasitism is as well a density-dependent limiting gene. For example, the Cordyceps fungi is a blazon of fungal parasite that infects insects, leading to "summit disease". Basically, the cordyceps fungi invaded the insect's body, growing inside and affecting the insect's brain, making it walk to a high part of a tree and jump, releasing fungal spores to greater distances. An increase in the population density of insects volition make it easier for the cordyceps fungi to parasitize. On the other hand, a subtract in insect population density will besides decrease cordyceps infection.
Predation
Predation involves the threatening of a prey population by a predator, keeping their numbers low. A mutual case of predation as a density-dependent limiting cistron is the change in the population of moose and wolves on Isle Royale. But, what are the causes for such dramatic changes in numbers?
Co-ordinate to ecologists, at that place are many factors that limit its population growth. Cold winters can weaken moose, reduce food availability and decrease their population size. Now, when temperature is mild, nutrient is readily available, and the moose population can grow faster.
However, an increment in the moose (prey) population is followed past an increase in the wolves (predator) population. And then, the high predator population causes the prey population to decrease.
Density dependent limiting factors examples
Let'due south take a wait at some interesting examples involving density-dependent limiting factors. African swine fever (ASF) is a very dangerous disease that kills pigs and wild boar, with a fatality rate of 100%. It is considered a density-dependent limiting factor and affects different provinces in Africa.
Another important written report (Figure 3) involving competition as a density-dependent limiting factors was performed by ecologist Joseph Connell to study the interspecific competition between ii barnacle species in the declension of Scotland: Chthalamus stellatus and Balanus balanoides. According to the competitive exclusion principle, no two species tin can occupy the same niche, and this was proved to be true in the case of C. stellatus and B. balanoides.
During this study, Connell removed Balanus from the rocks at several sites to analyze whether the distribution of Chthalamus was a result from competition, and he was right! Conner concluded that interspecific competition makes the realized niche of Chthalamus much smaller than its fundamental niche.
Realized niche is the niche that is actually occupied.
Cardinal niche are all the niches that can be occupied.
Density independent limiting factor definition
At present, let's expect at the definition of density-Contained limiting factors.
Density-contained limiting factors are usually abiotic factors that limit a population size regardless of population density.
Density-independent limiting factors include natural disasters, unusual conditions, seasonal cycles and humans activities such as cutting trees and obstructing rivers (Figure 4).
For example, the effects of temperature in bark protrude population is density-contained. Ecologists accept establish that in warm temperatures, beetles are able to develop faster and produce more than generations per year. Nevertheless, once sudden drib in temperature tin can cause them to die.
Figure iv. Examples of density-contained limiting factors, past Isadora Santos - created with Canva.
Another common example involving density-contained limiting factors is the upshot of weather change in the population of aphid insects (Figure 5). From April to June, these insects abound exponentially. Then, changes in weather causes a sudden decline in the number of aphids. This subtract in aphid population tend to cause a subtract in the ladybug beetle population considering aphids are a popular nutrient source for them!
Limiting factors tin can also bear upon the rate of photosynthesis. For example, decreasing light intensity, lowering temperature, and decreasing carbon dioxide concentration and water supply will lead to a decrease in photosynthesis!
Human intervention is as well a blazon of density-independent limiting factor. For example, cod decease rates have been increasing due to fishing fleets catching more fish every year. Since birth rates cannot surpass cod expiry rates, cod populations have been decreasing in number.
Divergence between density dependent and density independent limiting factors
Lastly, let'southward make a table (Table 1) to review the differences between density-dependent and density-independent limiting factors.
Tabular array 1. Density-dependent vs. density-independent limiting factors, by Isadora Santos - created with canva.
Population Limiting Factors - Key takeaways
- Limiting factors are referred to as conditions or resources inside an surround that restricts population growth.
- Population growth limiting factors are divided into two categories: density dependent or density-independent .
- Density-dependent factors are biotic factors whose effects in population size depend on population density. Examples include contest, affliction, and predation.
- Density-independent limiting factors are usually abiotic factors that limit a population size regardless of population density. Examples include weather changes, and natural disasters.
References
- October 2014, C. Q. C. 01. (n.d.). In Africa, Anthrax Lures Animals to Their Decease. Livescience.com. https://www.livescience.com/48093-anthrax-lures-zebras-to-their-expiry.html
- BD Editors. (2016, Dec 15). Limiting Gene. Biology Dictionary. https://biologydictionary.cyberspace/limiting-factor/
- Dark-brown, Yard. (2021). Everything you need to ace biology in i big fatty notebook : the complete high school study guide. Workman Publishing Co., Inc.
- Relyea, R., & Ricklefs, R. Due east. (2018). Ecology : the economy of nature. Macmillan Didactics.
- Campbell, N. A. (2017). Biological science. Pearson.
- Pack, P. East. (2017). CliffsNotes AP biology. Houghton Mifflin Harcourt.
Examples Of Biotic Limiting Factors,
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