Hi, I'm Jensen Morgan. We're going to talk about some great concepts in environmental science. Today's topic is native and non-native species. So let's get started. We're going to talk about different categories of species, the causes of the introduction of invasive species, and their impacts.
Within an ecosystem or environment, species can be categorized as being either native or non-native. Every species is native to some environment somewhere-- a place where that species adapted and evolved over time to that ecosystem's predators, competitors, and limiting factors. As long as a species remains in their originally adapted environment, they're considered native.
If you remember, habitats are the area that a particular species inhabits. And niches are all the biotic and abiotic factors that influence a species. Well, a native species occupies specifically adapted habitats and niches in they're indigenous environments, which allows for ecosystem balance and keeps that species population stabilized.
Important to note is that human disturbances can lead to an overabundance of native species as a result of removing competitors or other limiting factors. An example of this would be killing of wolves allowing deer populations to soar. Non-native species, also called exotic, introduced, or invasive species, are species living outside their originally adapted environment, either accidentally or intentionally from human activities.
In particular, invasive species are non-native species that are introduced and end up spreading and adversely affecting habitats and biodiversity. This is made possible because invasive species often have few natural predators, competitors, parasites, or diseases outside their original environment. The result is high birth rates and low death rates, allowing them to quickly take over, like this Japanese knotweed here.
Domesticated species such as pets, livestock, and certain game animals are often considered non-native because if, and/or when they escape their domesticated environment, they often become invasive. Exotic or non-native species are often introduced to a new environment accidentally by escaping from zoos or botanical gardens, escaping from domesticated agricultural environments, escaping from fish farming, escaping pets, and released ballast from ships. Examples of such incidences include Purple loosestrife, a plant that escaped from botanical gardens. English ivy was imported as an agricultural ground cover and quickly became invasive.
Other pathways for species introduction include medicinals imported for health benefits, and accidental pollen transported in travelers clothes and belongings. Many invasives have also been introduced intentionally-- people not knowing the potential impacts, such as sparrows, starlings, water hyacinth, and nutria. For example, kudzu was planted by the US Soil Conservation Service to reduce soil erosion, and it wasn't until a decade later people realized it was invasive to the point of smothering many native plants.
Another example would be Norway maple, which was planted as a shade tree, but quickly displaced many native maples and overshaded wild flowers. Remember, non-native species that adversely impact their new environment by altering the balance of their ecosystem in negative or catastrophic ways are termed invasive species.
And their impacts include displacing or killing native species, and contributing to the number of endangered or threatened species, reducing overall ecosystem health and productivity, threatening ecosystem biodiversity, and causing a loss of forest and agricultural products. Such species can expose humans and ecosystems to unknown pathogens as well.
Now let's have a recap. We talked about different categories of species, the causes of the introduction of invasive species and their impacts. Well, that's all for this tutorial. I look forward to next time. Bye.