Interactions Within the Ecosystem

In the past few weeks you have learned about interactions within ecosystems. For example, you learned that life in a tundra biome is very different from life in a rainforest biome. You also learned last week that within ecosystems there are food webs, which can become very complex. You have also learned that relationships of mutualism, commensalism and parasitism exist in every ecosystem.

Other complex relationships exist in every ecosystem, such as predator/prey relationships and competition for resources. Some relationships that exist in an ecosystem which are not considered symbiotic. For example, predator-prey interactions are not symbiotic because there is no long-term interaction (because one of the species ends up being eaten). Predation is not an example of parasitism because in a parasitic relationship, the parasite typically needs its host to remain alive in order to receive any benefit. Also, competition for resources between species is not considered to be a symbiotic relationship because the focus is on an external resource (e.g. food or water) rather than an interaction between the species themselves.

Each of these interactions can affect one another, making interactions within ecosystems incredibly detailed. The examples on the following pages illustrate the complexity of interactions that take place in Earth's ecosystems. You will see that in a coral reef ecosystem, symbiotic relationships, predation, and competition abound. You will also learn that biotic changes in an ecosystem can have long-term consequences. For example, you will see how invasive weed species can have dramatic effects on an ecosystem, rapidly changing the plant community that exists in the ecosystem. You will also learn that abiotic factors in an ecosystem can sometimes determine which type of organisms can survive and thrive in that particular ecosystem.

For example, a change in water temperature can influence which types of fish species can survive- this has implications for the entire food web of that ecosystem. Additionally, changes in water pH associated with the weathering of rocks can also affect fish species that live in nearby streams. You will also learn how plants in the wild adapt to the availability of key abiotic factors such as soil, water, and sunlight.

The examples on the following pages show just how detailed and numerous the interactions between the abiotic and biotic factors in an ecosystem can be, and how changes in these factors can have lasting effects on an ecosystem.


Source
http://www.teachersdomain.org/resource/nat08.living.eco.humeco.lpsymstra/