Introduced species and biodiversity

Summary

The video script delves into the complexities of introducing new species to ecosystems, highlighting the unintended consequences that can arise from both intentional and accidental introductions. It underscores the economic and ecological impact, with an annual cost of $1.4 trillion to the world economy. The script also discusses the concept of native habitats, the role of collections in preserving historical information, and the competitive advantages invasive species have due to lack of natural controls. Examples such as comb jellies in the Black Sea and Dutch Elm disease illustrate the devastating effects of invasive species on native populations and ecosystems, emphasizing the need for human intervention to mitigate these impacts.

Takeaways

• 🌱 Introducing new species to an area can seem like a good idea for increasing biodiversity, but it's more complex than simply adding species richness.
• 🌿 Introduced species, also known as exotic species, are those transferred by human activities to an area where they don't naturally occur.
• 🐄 Many species introductions are intentional, often for agricultural purposes, and have been happening since humans realized they could transport organisms.
• 🚢 Accidental introductions often occur alongside human activities, bringing along parasites and other organisms that can disrupt local ecosystems.
• 💸 Introduced species have a significant economic impact, costing the world economy 1.4 trillion dollars annually to manage their negative effects.
• 🔍 The concept of native habitat is complex due to the long history of human-induced species transfers, with some species' introduction history being unknown or 'cryptogenic'.
• 📚 Collections of species are vital for preserving historical information and establishing baselines to trace the origins of species introductions.
• 🍎 Not all introduced species are harmful; some provide new food sources or habitats and can be beneficial to native species.
• 🐍 Some introduced species become invasive due to competitive advantages and lack of natural controls, leading to negative impacts on native populations.
• 🌊 Invasive species can cause a cascade of ecological disruptions, altering food webs and reducing ecosystem function, as exemplified by the comb jelly in the Black Sea.
• 🦠 Invasive species can also include pathogens, which can lead to extinctions and have far-reaching effects on dependent species and ecosystems.

Q & A

What is the term 'introduced species' synonymous with?

The term 'introduced species' is synonymous with 'exotic species', referring to any species that has been knowingly or accidentally transferred by human activities from its native habitat to one where it doesn't naturally occur.

What is the main difference between an introduced species and a native species?

An introduced species is one that has been moved by human activities to an area where it doesn't naturally occur, while a native species is one that occurs naturally in an area without human intervention.

Why do humans intentionally introduce species to new areas?

Humans intentionally introduce species to new areas primarily for agricultural purposes, such as for food production or to serve other beneficial uses.

What are some examples of accidental introductions of species?

Examples of accidental introductions include rats coming off ships and snakes arriving in Guam with military movements during World War Two, both of which had significant negative impacts on native bird populations.

What is the annual cost to the world economy due to the negative impacts of introduced species?

The annual cost to the world economy due to the negative impacts of introduced species is 1.4 trillion dollars.

What does the term 'cryptogenic species' refer to?

Cryptogenic species refers to species for which the history of their introduction is uncertain or unknown, with 'crypto' meaning hidden and 'genic' referring to origin.

How can collections help in understanding the origins of introduced species?

Collections can preserve historical information about what species were present in an area beforehand, establishing baselines for future reference and helping to trace the origins of introductions.

Can introduced species sometimes have a positive impact on native species?

Yes, some introduced species can provide new food sources or habitats for native species, and native species can sometimes make use of the newcomers.

What are the characteristics of invasive species?

Invasive species are those that have competitive advantages, lack natural controls such as predators or diseases, and can reproduce rapidly and thrive in a wide range of environmental conditions, often overwhelming native populations.

What is the difference between introduced species and invasive species?

All invasive species are introduced, but not all introduced species are invasive. Invasive species are those that take over an environment at the expense of native species, causing significant harm to the ecosystem.

Can you provide an example of how an introduced species can cause a collapse in an ecosystem?

In 1992, an introduced species of comb jelly in the Black Sea led to the total collapse of the anchovy fishery due to the comb jellies' voracious appetite for fish larvae and eggs, demonstrating how introduced species can drastically alter ecosystems and food webs.

How do invasive species affect ecosystem function and why is it important to control them?

Invasive species can cause decreases in ecosystem function by outcompeting natives for resources, altering food webs, and introducing new diseases or parasites. Controlling them is crucial not only for moral reasons but also because these invasives can harm species we depend on and disrupt healthy ecological functions essential for all life, including humans.

Outlines

00:00

🌿 The Complexity of Introducing New Species to Ecosystems

This paragraph discusses the complexities of introducing new species into ecosystems, which at first seems like it could enhance biodiversity. It explains that while planting flowers in a garden might increase species richness, the same isn't true for larger ecosystems. Introduced species, also known as exotic species, are those moved by human activities from their native habitats to new areas where they don't naturally occur. The paragraph highlights that many introductions are intentional, often for agricultural purposes, but can also be accidental. It points out that these introductions can have both obvious and subtle negative impacts, costing the world economy an estimated 1.4 trillion dollars annually. The concept of native habitats is complicated by the long history of human-caused transfers, with some species' introduction histories being lost, leading to the term 'cryptogenic' for those with hidden origins. Collections and baselines are emphasized as essential for tracing species origins and understanding the impacts of introductions. The paragraph also notes that not all introduced species are harmful; some can provide new resources for native species, while others live without noticeable impact. However, some introduced species can outcompete natives due to their competitive advantages and lack of natural controls.

05:03

🐙 The Impact of Invasive Species on Ecosystems and Human Economy

The second paragraph delves into the characteristics and consequences of invasive species, which are a subset of introduced species that can outcompete and displace native populations. Invasive species are generalists, able to reproduce rapidly and thrive in various conditions, leading to their dominance over native species. The paragraph provides the example of comb jellies in the Black Sea, whose introduction led to the collapse of the anchovy fishery due to their voracious appetite for fish larvae and eggs. It explains that invasive species can alter food webs and disrupt ecosystem functions, often introducing new diseases and parasites. The paragraph also discusses the broader implications for human economies and the environment, with the introduction of pathogens causing extinctions and significant ecological damage, such as Dutch Elm disease in North America. It concludes by drawing a parallel between humans and invasive species, suggesting that we are capable of recognizing our impact and taking steps to mitigate it, which is crucial not only for moral reasons but also because the invasive species we introduce can harm the species and ecological functions upon which we depend.

Keywords

💡Introduced species

Introduced species, synonymous with exotic species, refers to any species that has been transferred from its native habitat into a new area where it does not naturally occur, either intentionally or accidentally through human activities. This concept is central to the video's theme, which explores the impacts of introducing species on biodiversity. The script uses examples such as goats, pigs, cattle, crops, and comb jellies to illustrate the various ways in which species are introduced and the subsequent effects on ecosystems.

💡Biodiversity

Biodiversity is the variety of life in all its forms and levels of organization, including the number of species, genetic diversity within species, and the variety of ecosystems. The video discusses how introducing new species might initially seem to increase biodiversity, as in the case of planting flowers in a garden, but it also highlights the complex and often negative consequences that introduced species can have on native ecosystems and biodiversity as a whole.

💡Native species

Native species are those that naturally occur in a particular area without human intervention. The video contrasts native species with introduced species, emphasizing that native species are often at a disadvantage when new species are introduced because the newcomers may not have natural controls like predators or diseases that would keep their populations in check in their native habitats.

💡Invasive species

Invasive species are introduced species that take over an environment at the expense of native species, often due to competitive advantages such as rapid reproduction and the lack of natural controls. The video uses the comb jelly in the Black Sea as an example of an invasive species that led to the collapse of the anchovy fishery, illustrating the detrimental impact of invasive species on both biodiversity and human economies.

💡Cryptogenic species

Cryptogenic species are those for which the history of introduction is unknown or unclear. The term 'crypto' means hidden and 'genic' refers to origin, indicating that the origins of these species are obscured. The video mentions cryptogenic species in the context of the difficulty in tracing the origins of species introductions, emphasizing the importance of collections for preserving historical information and establishing baselines for future reference.

💡Ecosystem function

Ecosystem function refers to the processes and interactions within an ecosystem that contribute to its health and sustainability. The video explains that invasive species can cause decreases in ecosystem function by outcompeting natives for resources, altering food webs, and disturbing crucial ecological interactions. The comb jelly example shows how the introduction of a single species can disrupt the entire ecosystem, leading to the collapse of fisheries and the loss of multiple species.

💡Generalists

Generalists, in the context of the video, are species that can tolerate a wide range of environmental conditions, reproduce rapidly, and thrive, often outcompeting native species. The video points out that some invasive species are generalists, which allows them to successfully establish and spread in new environments, leading to negative impacts on native populations and ecosystems.

💡Economic impact

The video highlights the significant economic impact of introduced species, stating an annual cost of 1.4 trillion dollars to the world economy to deal with their negative effects. This figure underscores the far-reaching consequences of species introductions, affecting not only biodiversity and ecosystems but also human economies and livelihoods.

💡Accompanied effects

Accompanied effects refer to the additional consequences that come with the introduction of species, such as new diseases or parasites. The video uses the example of a cow bringing along parasites to a new area to illustrate how introduced species can have indirect impacts on native ecosystems by introducing new threats to native species.

💡Mitigation

Mitigation, in relation to the video's theme, involves采取措施 to reduce the impact of introduced species on ecosystems and biodiversity. The video suggests that humans, as the ultimate invasive species, have the unique ability to recognize the harm caused by introductions and take steps to control invasive species, prevent new introductions, and protect native habitats and species.

Highlights

Introduced species, also known as exotic species, are those transferred by human activities from their native habitat to a new area.

Introduced species can sometimes increase biodiversity, but it's a more complex issue than just adding species richness.

Many species introductions are intentional, primarily for agricultural purposes, dating back to early human history.

Accidental introductions often occur alongside human activities and can have significant impacts on native species.

When a species is moved to a new area, it brings along parasites and other organisms associated with it.

Introductions can lead to substantial economic costs, with an annual global impact of 1.4 trillion dollars.

The concept of native habitat has become complex due to long-term human-induced species transfers.

Cryptogenic species are those with unknown introduction history, highlighting the importance of collections for tracing origins.

Collections help preserve historical information and establish baselines for understanding species introductions.

Some introduced species can be beneficial, providing new food sources or habitats for native species.

Not all introduced species are harmful; some live under the radar without significantly impacting ecosystems.

Invasive species have competitive advantages and lack natural controls, leading to their dominance over natives.

Invasive species can cause the collapse of native populations and disrupt ecosystem food webs.

The comb jelly introduction in the Black Sea led to the collapse of the anchovy fishery, illustrating the impact of invasive species.

Invasive species can introduce new diseases and parasites, leading to unforeseen ecological consequences.

Humans, as a species, exhibit invasive characteristics, but also possess the ability to recognize and mitigate our impact.

Controlling invasive species is crucial not only for moral reasons but also to protect species and ecological functions we depend on.

Transcripts

- [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.