Which Of The Following Density-independent Factors Can Affect The Size Of A Human Population?

Density Independent Factors Definition

Density contained factors, in ecology, refer to any influences on a population's birth or death rates, regardless of the population density. Density contained factors are typically a physical factor of the environment, unrelated to the size of the population in question. Density independent factors vary depending on the population, but always impact the population the same regardless of its size. There are many common density contained factors, such as temperature, natural disasters, and the level of oxygen in the atmosphere. These factors apply to all individuals in a population, regardless of the density.

However, density independent factors are oft confused density dependent factors for a number of reasons. First, density independent factors for ane population of organisms is non the aforementioned for every organism on the planet. While oxygen is a density contained factor for most oxygen breathing organisms, it may be a density dependent cistron for some. Image an obligate anaerobe bacteria, for instance. Oxygen is toxic to these organisms. As they grow in density, the bacteria furthest from the nearest source of oxygen is protected. If these bacteria where to grow thick, oxygen would not bear upon each bacteria, and the consequence on the death rate would be lessened. This would make oxygen a density dependent factor for these particular bacteria.

Analyzing each population specifically allows scientists to identify their unique density contained factors. Beneath are several examples of mutual density independent factors and how they touch on diverse species.

Examples of Density Independent Factors

Natural Disaster

Natural disaster is a perfect example of a density contained gene. Consider a hurricane, slamming into the coastline. While we often see the devastation of these storms on the news, we rarely consider the impacts of such a tempest on wildlife and vegetation in the area. The fact is, hurricanes increment the death rate for many species, while some species encounter a highly increased birthrate after the destruction.

During a hurricane, winds increase to dangerous speeds, tearing large trees out of the basis. Trees similar the 1 in the epitome above would survive whatever regular storm. For many species, a hurricane drastically increases the death rate, as the trees merely cannot withstand the air current and waves. Many animals, such as fish and amphibians, succumb to rapidly rising and falling tides. Many news images evidence pictures of fish done up into roadways. These animals and plants die, regardless of how dumbo their population was. They could accept been the concluding of their species, or ane in a billion.

Nonetheless, hurricanes practise not only bring expiry. Consider the expanse unearthed by the tree in the above epitome. New, smaller plants volition be given an opportunity to abound where they were previously restricted past the shade cast by the large tree. Fungi and insects living on expressionless plant thing volition be able to banquet and reproduce on the dead wood. The standing water left from the hurricane provides many insects, such as mosquitos, ample breeding sites. While this is often a nuisance for humans, it increases the food source of birds and bats, perhaps increasing their birthrates likewise. Still, the hurricane affects all species and individuals inside its path, regardless of how many at that place were.

Pollution

Similar other density independent factors, pollution is a good example of a density independence. While humans are full-bodied in cities around the world, the emissions and chemicals we create are dispersed into the atmosphere. From here, they are carried globally and touch all organisms. Even organisms in the oceans are affected, as pollutants deliquesce from the temper into various h2o sources.

Therefore, whether you are the last pair of endangered clownfish in the ocean or have a huge population like sparrows, your birthrate is still negatively impacted. Density independent factors like these often cause a dull and steady drag on populations over time. Fifty-fifty the human population sees drastic health furnishings from pollution, from lead poisoning exercise to drinking water to increased lung diseases.

Honeybees

Instead of looking at density contained factors in full general, let's plough our view to a population of honeybees and the factors that probable touch the size of their population. Density independent factors for honeybees include things like weather condition and temperature. Regardless of the electric current size of their population, bees demand the temperature and weather condition to stay within certain ranges. If the weather does non stick to this pattern, many bees will dice. For example, if at that place was of a sudden snowstorm in the middle of summer, the bees would be caught off guard and would die in the common cold.

All the same, the bees also face a number of density dependent factors. For instance, their food source and its effects on their population is directly related to the size of their population. If they have a small population, at that place volition be plenty of nutrient for all and the bees will grow. If the population is larger than the amount of food available, bees will starve and the death rate will increase. Nutrient, and other usable biological resources, are density dependent. Density independent factors will impact the bees regardless of how many bees are present.

Quiz

ane. In a modest garden patch nether a small tree, several species of establish are planted in differing numbers. Consider the sunlight as a resource for the plants. Is sunlight i of the density independent factors, or is information technology density dependent?
A. Density Contained Cistron
B. Density Dependent Gene
C. Neither

Answer to Question #ane

B is correct. Equally the plants grow, they will take up a larger and larger surface area, competing for the sunlight. Every bit the years become past, the tree will go larger, and have up more of the sunlight. If more than plants are added to the surface area, there will exist fifty-fifty less sunlight to become around. Density contained factors, such every bit weather events, volition bear upon the plants regardless of how many are in the garden. Sunlight will be more beneficial to the plants if there are less of them in the garden.

2. Practise density independent factors always limit the population? That is, practice they always increase the decease rate or lower the nativity rate?
A. No
B. Yes
C. Only Density dependent factors do that

Reply to Question #2

A is correct. Any factor, density dependent or contained, can be either beneficial or negative. This all depends on the population beingness affected. Some density independent factors, such as hurricanes, help some species while they hurt other species. Hurricanes are a density independent cistron because they generate the same consequence regardless of the electric current population density.

iii. A population of field mice increases later a farmer leaves his field unharvested for a flavour. Which of the following categories does this factor fall into?
A. Density Independent Factors
B. Density Dependent Factors
C. Increased death rate

Answer to Question #3

B is correct. Food is near always a density dependent factor, because if the population gets also big the nutrient affluence volition quickly turn to a food shortage. Density contained factors would be things like temperature and tornadoes, which would affect the mice regardless of their current or future density.

References

Cain, M. Fifty., Bowman, W. D., & Hacker, S. D. (2008). Ecology. Sunderland, MA: Sinauer Associates, Inc.

Feldhamer, G. A., Drickamer, L. C., Vessey, Due south. H., Merritt, J. F., & Krajewski, C. (2007). Mammology: Accommodation, Diversity, Ecology (3rd ed.). Baltimore: The Johns Hopkins Academy Press.

Kaiser, Yard. J., Attrill, 1000. J., Jennings, S., Thomas, D. Northward., Barnes, D. Thousand., Brierley, A. Southward., & Hiddink, J. G. (2011). Marine Environmental: Processes, Systems, and Impacts. New York: Oxford University Printing.