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Wednesday, April 13, 2016

Limiting Factor

The population of any organism will increase exponentially until a limiting factor comes into play. You think the limiting factors would be sunlight, temperature, amount of water. But these factors affect the type of organisms in an environment. Organisms best suited for the amount available for all of these will be more likely to reproduce.

All populations are limited by limiting factors. There are density dependent and there are density independent limiting factors.

An increase in density will cause more stress on the organism in addition to problems living close together such as the transmission of disease being more easily facilitated. Competition between organisms may make some organisms limited to territories with less food resources. With less food, reproduction and/or the nurturing of offspring is less successful. Higher populations of organisms may make them more vulnerable for predation.

Disease, competition and predation are density dependent limiting factors. These are biotic or living factors.

Food/nutrient availability, weather, natural disasters (earthquakes, tornadoes, hurricanes, volcanos, weather shifts, droughts) or pollutants are density independent limiting factors. These are abiotic or non-living factors.

Excessive pollution does not kill off a population. It reduces the number of individuals in addition to the longevity of the individuals. We think of humans when we consider populations. But non-human species are affected. The increase of acidity in water in the Southeast weakens the native Dogwood tree to the affects of the anthracnose fungi. As a result the population of Dogwood trees will have a slow decline in numbers as the anthracnose is spread. Hence a density independent factor enhances a density dependent factor.

This plant is called Carolina Jessamine. It's flowers resemble honeysuckle. There are cases of poisoning from people who
attempt to drink the alkaline nectar produced by this plant. The honey bee which is not native to North America will
be poisoned by this plant's nectar. However, bees native to North America are not affected. 


  1. We think of humans when we consider populations.
    But non-human species are affected.

    One talks of population explosion and decline. Even non-living things just as unwittingly affected. Did not see it this way. Wonderful write Ann!


  2. Fascinating post, Anne. Thank you. My 'creative' mind is whirring about the limiting factor for the human race. Is nature manipulated by man to curb the population? :):)As you can tell, I watch far too many disaster movies and conspiracy theory stories :)


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