In this lesson, we look at how population is an ecological concept just as it is a sociological one.
We will look at wildlife populations by comparing them to human social actions and define key concepts for understanding population from an ecological perspective.
Populations in Ecology
Chances are when you hear the word ‘population,’ you immediately think of the size of a human population. For example, Canada has around 30 million people, China has more than 1.3 billion, or Washington, D.C.
has around 600,000. However, the word ‘population‘ can just as easily be used to describe the numbers of other animals as well.In this lesson, we will look at population as an ecological concept. To do that, we will see what it means for a population to be stable or to be fluctuating, as well as the results of immigration and emigration on a population. (Spoiler alert: there is a difference between immigration and emigration!) Finally, we will examine the idea of a metapopulation, all while referring back to human populations for clarity.
When ecologists say that a population is stable, they are really saying that it is about as big as it’s going to get and is not in any foreseeable danger of mass shrinkage. Stable populations are usually a good thing for ecologists to find because that means that the chances of extreme and sudden changes are unlikely.Remember, too, that everything in ecology is interrelated and can quickly affect other populations. After all, if a population of deer in a given forest is pretty constant, chances are that the bear population is also pretty stable. In humans, a stable population allows for the people who look after our habitats, ranging politicians to farmers, to make sure that there are enough resources to go around.
Fluctuation is what happens when there is no stability.
Fluctuation can result in a rapidly growing population or one that can’t stop shrinking. In any event, fluctuation means that stability is gone. Let’s go back to our example of the deer in the forest. What do you think would happen if the population of deer was to suddenly increase? It could signal that there is more food for the deer in the area, meaning that more fawns are able to reach adulthood.However, more food for the deer means more food for the local bear population; bears eat deer, so a fluctuation in the deer population often creates the same fluctuation in the bear population. But what happens when the deer run out of food? Their numbers rapidly shrink, but so too does the bear population. However, and why we should care as humans, is that mischievous bears could invade human habitats to access our garbage cans and picnic baskets.
For humans, we are seeing the same thing play out right now. Over the last 80 years, our species’ ability to produce more food has meant that the population is growing at a very rapid rate. Some people are afraid of what will happen when our population approaches a point at which we can no longer produce enough food for ourselves. Luckily, not too many of us have to worry about being eaten by bears, so at least we have that going for us.
Immigration and Emigration
Immigration and emigration are also big factors with wildlife populations. Immigration, spelled with an ‘i,’ refers to when an individual or group comes to a new area. Conversely, emigration, spelled with an ‘e,’ refers to when an individual or group leaves an area.
The best example of this that can be seen is how birds migrate every year. If you are in Florida during the winter, chances are that you see many of the same type of birds that you would see in New York or Michigan during the summer. In the fall, the birds emigrate from the north to immigrate to the south.We see the same thing in humans. People follow resources, just as birds follow warm weather and food.
We try to position ourselves where we have the greatest likelihood of survival. Whether it is flying south for the winter or moving to San Francisco for a new job, both ideas are really the same.
Finally, we come to the idea of a metapopulation. A metapopulation is the name given to a group of groups that are physically distant but still show some level of interaction.
For example, salmon return to the streams in which they were born in order to mate and spawn. However, the rest of their lives, they are largely independent of each other.In humans, just about everyone around the world is part of a giant metapopulation. I am writing this lesson on a computer that was built in China, but chances are I’ll never meet the people who built it.
That said, despite being thousands of miles away, we do have some limited interaction.
In this lesson, we looked at the idea of population within ecology, often by comparing concepts back to those of human populations. We saw how population stability is often a sign of the general health of an ecological system, just as population stability allows planners in the human realm to be more effective. Conversely, we saw how fluctuations in population can have long-reaching effects, just like those that some people see as a point of concern with our own rapid population growth.We examined the concept of emigration and immigration as it applies to animals looking for more resources, much like a job seeker moving to a different city. Finally, we examined the idea of metapopulations as wide-ranging groups that have some limited interaction with each other; the same idea behind globalization.
A Look at the Population
Ecologists are scientists who survey ecosystems and assess the different organisms that populate them. There are many different aspects that the ecologist will study in order to be able to accurately represent the data of an area.
After reviewing this lesson, you should be able to define and explain the various terms related to population dynamics in ecology.