Introduction of a New Species into a Stable Ecosystem

Core Standard: Describe the relationship between living and nonliving components of ecosystems and describe how that relationship is in flux due to natural changes and human actions.


What is a niche? The range of physical and biological conditions in which a species lives and the way the species obtains what it needs to survive and reproduce.

·     Organisms have an upper and lower limit of tolerance for every environmental factor.

·     A species’ tolerance determines its habitat (where that species lives).


A niche includes the species “address” and “occupation” in the ecosystem.


What is a stable ecosystem?

An ecosystem is stable when each species occupies its own niche.

·     The Competitive Exclusion Principle states that no two species can occupy exactly the same niche in exactly the same habitat at exactly the same time.


What shapes a stable ecosystem?

·     Competition

·     Predator-prey relationships

·     Herbivore-plant relationships



Keystone species: changes in a keystone species can cause dramatic changes in the community of an ecosystem.


Example: kelp ŕ sea urchins ŕ sea otters

·     Dividing of resources









What are the three primary ways that organisms depend on each other? (three types of symbiosis or “living together”)

·     Mutualism: a relationship in which both species benefit.  Ex: clownfish and sea anemones

·     Parasitism: a relationship in which one species is harmed Ex: tapeworms in mammals

·     Commensalism: a relationship in which one species benefits and the other is neither helped not harmed. Ex: barnacles and whales


What is an invasive species?

1) non-native (or alien) to the ecosystem under consideration and

2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health.


What happens when an apparently harmless plant or animal is introduced into a stable ecosystem?

These organisms often become invasive species that reproduce rapidly because they lack parasites or predators to control their population. Their rapid growth will upset the stable ecosystem.




What are the characteristics of an invasive species?

·     The ability to reproduce both asexually and sexually

·     Fast growth

·     Rapid reproduction

·     High dispersal ability

·     The ability to alter one’s growth form to suit current conditions

·     Tolerance of a wide range of environmental conditions

·     Ability to live off of a wide range of food types

·     Association with humans

What are the results of introducing new invasive species into an ecosystem?

·     take the place of native species

·     change habitats and ecosystems

·     affect recreational and commercial fishing

·     harm human health

·     affect businesses, jobs, and the economy


1.zebra-mussel-largeThe Zebra Mussel arrived in the Great Lakes on the bottom of ships. The Zebra Mussel reproduces so quickly that it is out-competing many native species and pushing them to extinction. Zebra Mussels can also clog water intake pipes and damage boats.

2.2nutriaNutrias (native to South America) invaded coastal areas of the southeastern U.S. They eat water plants that prevent erosion which in turn destroys the habitat of the Comb jelly imagenative species.


3. The comb jellyfish caused the collapse of the fin fishing industry in the Black and Azov Seas in Eastern Europe.