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High school biology
Course: High school biology > Unit 9
Lesson 7: Human impact on ecosystems- Human activities that threaten biodiversity
- What is a biodiversity hotspot?
- Conservation and the race to save biodiversity
- Introduced species and biodiversity
- How does climate change affect biodiversity?
- Protecting biodiversity: the power of the individual
- Protecting biodiversity: local and global policies
- Human impact on ecosystems review
- Human impact on ecosystems
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Introduced species and biodiversity
This video explores what happens when exotic animal and plant species are introduced into ecosystems, and the impact of introduced species on biodiversity. Created by California Academy of Sciences.
Want to join the conversation?
- Are there any examples of a non-native species actually causing good to the species richness and diversity of an ecosystem due to the invasion?(2 votes)
- Good question!
The best example in which the non-native organism directly improved the stability of an ecosystem that I know of would probably be the western honeybee, which originated in Africa and Eurasia and has been introduced to North America and Australia. It helps to pollinate the native flowers in the areas it lives in.
I hope this helps! Sorry I did not have more info!(4 votes)
- what are some invasive species examples. Are zebra mussels invasive.(1 vote)
- What acts as an invasive species depends on where you live.
In many places outside their native habitat (in Russia and Ukraine) zebra mussels are invasive.
Two other examples:
European (common) starlings are invasive in north america (and a few other places), but native to Eurasia.
Water hyacinth is invasive in Lake Victoria (Kenya) and many other places, but native to South America.
Does that help?
Links:
•https://en.wikipedia.org/wiki/Zebra_mussel
•https://en.wikipedia.org/wiki/Common_starling
•https://en.wikipedia.org/wiki/Eichhornia_crassipes#Invasive_species
•https://www.nwf.org/Educational-Resources/Wildlife-Guide/Threats-to-Wildlife/Invasive-Species
•https://www.nationalgeographic.org/encyclopedia/invasive-species/
•https://en.wikipedia.org/wiki/Invasive_species(6 votes)
- What if biodiversty is needed to save a certain species.(2 votes)
- In most cases, biodiversity is needed for the survival of a particular species. The more biodiversity in a community, the more interactions that will occur between species. Often times, species in the community rely on these interactions to survive. Thus, without biodiversity, it is less likely they will experience these interactions and less likely the species will survive.(1 vote)
- what kind of invasive species(0 votes)
- what are some invasive species examples? Are zebra mussels invasive?(1 vote)
- these include the lionfish that I think came from Japan and is invading the usa corrals um...kudzu, the plant. Yes, zebra mussels are invasive cause they have no natural predator. cats are invasive in australia:((1 vote)
Video transcript
- [Narrator] At first
glance it might seem that introducing new species the human act of taking
species from somewhere else and dropping them in a different area, would be good for biodiversity. Let's face it, if you take
a bunch of beautiful flowers and plant them in your garden you're increasing the biodiversity
in your garden, right? You raised the species
richness in your garden. But it's not a simple additive equation. It's more complicated than that. The term introduced species is synonymous with exotic species. The definition is, any species
that through the activities of humans is knowingly or
accidentally transferred from its native habitat into one in which it doesn't naturally occur. An introduced species is the
opposite of a native species. Which is one that occurs
in an area naturally. Without human intervention. Many introductions are intentional. We do it on purpose. And we've been doing that
for a heck of a long time. Probably ever since
humans came onto the scene and realized that they
could pick something up that was alive and bring it somewhere else to serve their purposes. From goats and pigs to cattle and crops, mostly we transport
organisms that will do some good for us through agricultural means. We've been introducing plants and animals to places where they weren't native for a long, long time. Usually when people think
about introduced species they're really thinking more
about the accidental ones. The things that happen coincidentally alongside human activities. When we introduce a species to a new area, everything that's living
on, in, or with that species comes along with it. If you pick up a cow from one place and move it to another, it's gonna bring along all the parasites that those cows normally deal with. I think people immediately picture images of rats streaming off the
ships when they pull into some beautiful Tahitian paradise. Or the snakes that came into
Guam with military movements during World War Two. These animals are legendary in
doing damage to native birds. They're very obvious ways
that introduced organisms radically change biodiversity,
in a single place. There are so many other
subtle ways that introductions happen and cause problems. The bottom line is that
the world economy is hit with an annual cost of
1.4 trillion dollars dealing with the negative impacts, obvious and not so obvious,
of introduced species. That's a number I have a hard
time wrapping my mind around. If you had an extra 1.4 trillion
dollars to play around with there's a lot of possibility
to do some good in the world. Because humans have been
introducing new species for a long time, the
concept of native habitat is a little bit slippery. The human activities
that caused the transfer can happen long before we recognized that it actually happened. So that sometimes the
history of an introduction can be lost. When we aren't sure of the history, up until the point we are sure, or have some reasonable evidence, we call those species cryptogenic. Crypto means hidden. Genic means origin. Solving the riddles of cryptogenic species underscores another reason why collections are so important. The only way to trace the
origins of introductions is to know what was there beforehand. Collections can preserve
that historical information and collections made today establish baselines for future reference. If those collections are
maintained in perpetuity those baselines are gonna
be good 100 years from now. Or 1,000 years from now, when we see a radically
different and altered environment due to the introductions. So we can use collections
to try and get answers to this problem. Not all species are in fact harmful. Clearly they're not all harmful to us. Because the ones that
we introduce on purpose are ones that are there for our benefit. Some introduced species can
provide new food sources or even habitats for native species. Native species aren't
always helpless and harmed. They can make use of
some of the newcomers. Introduced grasses and corn for example, are eaten by native species. And certain trees that've been introduced can serve as habitats for birds. Some introduced species
live under our radar, we don't even know they're there. Doing little perceivable
damage to the ecosystem, by reducing species richness. But some introduced
species certainly go beyond just living peacefully,
alongside the natives. They can do this because they
have competitive advantages. They lack natural controls, such as the predators or
diseases that keep them in check in their native habitats. Some invasive species are generalists. Which means they can
tolerate, reproduce rapidly, and thrive in a wide range
of environmental conditions. Allowing them to successfully compete with and overwhelm native populations. When introduced species
take over an environment at the expense of native species, they're known as invasive species. All invasive species are introduced, but not all introduced
species are invasive. Here's an example of
consequences for humans as well as for species richness. In 1992, an introduced
species of comb jelly was found in the Black Sea. Comb jellies are weird, transparent, jellyfish-like forms
with a voracious appetite for fish larvae and eggs. Within months that single
introduction resulted in the total collapse of
the anchovie fisherie, in the Black Sea. Comb jellies tolerated the
conditions in the Black Sea and their population exploded, at the expense of the anchovies. The bottom line here is
that introduced species can out compete the natives for food, for space, and other resources. They alter the ecosystems food webs, disturbing crucial
elements and interactions that would otherwise contribute to healthy ecosystem function. The comb jelly is a good example of that. Sure, your species list for the Black Sea is gone up by one, but it
destroyed all the anchovies. You have to take a species off the list. Plus, perhaps whatever else
was eating the anchovies. And before you know it, because there's nothing for the
comb jellies to eat anymore, they're gone, too. So, not only have you not added a species, but in the end you've actually
subtracted a whole bunch. So invasive species are ultimately, organisms that cause decreases
in ecosystem function. That's another definition of invasives that we need to come to grips with. What's worse, invasives very
seldom come by themselves. As I was saying with the cow example, they often come with new diseases, new parasites, new accompanying effects, that we can hardly predict. Another good example of
invasives are pathagens. Something that we don't
often consider as invasives. These include disease-causing
organisms like, fungi, or bacteria, and even viruses. These are things that we also
introduce to wild populations. And there are extinctions
that come from that. In fact, in the past 500
years we've directly caused the extinction of more
than 100 species of birds, partly through the introduction of disease and heck knows what
damage we did to organisms that were depending on those birds. In the forest realm, Dutch Elm disease was something that, when I was growing up was a huge thing and actually it still is. In North America, Dutch Elm
disease left skelatol trees for miles and miles. When I was a kid growing
up in Toronto in the '60s 80% of the elms in the city were killed. And it was really sad. Those trees were not only gorgeous, they were very important lumber. Elm trees were a direct service to us, in so many different ways, from producing shade to furniture. The fungus was introduced by bark beetles, some of which were native and
some of which were introduced. Both of which supported and co-evolved with the fungal pathogen. Which could not be stopped. This idea of being a generalist, the ability to reproduce
and displace natives, the ability to become more
abundant at the expense of other species, to introduce diseases, to proliferate in non-native habitats, that should sound pretty familiar. Because that's us. In some ways, we are the
ultimate invasive species. We don't just introduce ourselves, we are invasive. The difference is that
unlike the comb jellies and the bark beetles and cows, we're capable of recognizing that fact and maybe mitigating our impact. We can look at the world and the problems and start thinking about ways
to control the invasives, to coral them, maybe to reduce their effects and not introduce them in the first place. We have to, not just for
moral reasons, I think, but because ironically,
and as we said earlier, the invasives that we're bringing with us accidentally or on purpose, can do a lot of harm to
species upon which we depend. Worse, they can upset
healthy ecological functions upon which all life depends. Including us.