The threat of invasive species - Jennifer Klos
-
0:08 - 0:11Massive vines that blanket
the southern United States, -
0:11 - 0:17climbing as high as 100 feet as they
uproot trees and swallow buildings. -
0:17 - 0:21A ravenous snake that is capable of
devouring an alligator. -
0:21 - 0:25Rabbit populations that eat
themselves into starvation. -
0:25 - 0:27These aren't horror movie concepts.
-
0:27 - 0:29They're real stories,
-
0:29 - 0:32but how could such situations
exist in nature? -
0:32 - 0:36All three are examples
of invasive species, -
0:36 - 0:39organisms harmful not because
of what they are, -
0:39 - 0:42but where they happen to be.
-
0:42 - 0:43The kudzu vine, for example,
-
0:43 - 0:48had grown quality in its native east Asia,
eaten by various insects -
0:48 - 0:50and dying off during the cold winters.
-
0:50 - 0:52But its fortunes changed
-
0:52 - 0:55when it was imported
into the southeastern United States -
0:55 - 0:59for porch decoration and cattle feed.
-
0:59 - 1:03Its planting was even subsidized
by the government to fight soil erosion. -
1:03 - 1:08With sunny fields, a mild climate,
and no natural predators in its new home, -
1:08 - 1:10the vine grew uncontrollably
-
1:10 - 1:15until it became known as the plant
that ate the South. -
1:15 - 1:19Meanwhile in Florida's Everglades,
Burmese pythons, -
1:19 - 1:22thought to have been released
by pet owners, -
1:22 - 1:26are the cause of decreasing populations
of organisms. -
1:26 - 1:29They're successfully outcompeting
top predators, -
1:29 - 1:31such as the alligator and panther,
-
1:31 - 1:34causing a significant reduction
in their food sources. -
1:34 - 1:36They're not a problem
in their native Asia -
1:36 - 1:42because diseases, parasites, and predators
help to control their population size. -
1:42 - 1:46And in Australia, European rabbits
eat so many plants -
1:46 - 1:50that they wipe out the food supply
for themselves and other herbivores. -
1:50 - 1:52They're a pretty recent addition,
-
1:52 - 1:59intentionally introduced to the continent
because one man enjoyed hunting them. -
1:59 - 2:01Like the Burmese pythons,
-
2:01 - 2:05various factors in their native habitat
keep their numbers in control. -
2:05 - 2:07But in Australia, the lack of predators
-
2:07 - 2:11and a climate perfect
for year-long reproduction -
2:11 - 2:14allows their populations to skyrocket.
-
2:14 - 2:16So why does this keep happening?
-
2:16 - 2:18Most of the world's ecosystems
-
2:18 - 2:22are the result of millennia
of coevolution by organisms, -
2:22 - 2:25adapting to their environment
and each other -
2:25 - 2:28until a stable balance is reached.
-
2:28 - 2:32Healthy ecosystems maintain this balance
via limiting factors, -
2:32 - 2:37environmental conditions that restrict
the size or range of a species. -
2:37 - 2:40These include things
like natural geography and climate, -
2:40 - 2:41food availability,
-
2:41 - 2:45and the presence or absence of predators.
-
2:45 - 2:49For example, plant growth depends
on levels of sunlight and soil nutrients. -
2:49 - 2:53The amount of edible plants affects
the population of herbivores, -
2:53 - 2:56which in turn impacts the carnivores
that feed on them. -
2:56 - 3:01And a healthy predator population keeps
the herbivores from becoming too numerous -
3:01 - 3:04and devouring all the plants.
-
3:04 - 3:08But even minor changes in one factor
can upset this balance, -
3:08 - 3:11and the sudden introduction
of non-native organisms -
3:11 - 3:13can be a pretty major change.
-
3:13 - 3:17A species that is evolved
in a separate habitat -
3:17 - 3:20will be susceptible to different
limiting factors, -
3:20 - 3:21different predators,
-
3:21 - 3:23different energy sources,
-
3:23 - 3:24and different climates.
-
3:24 - 3:29If the new habitat's limiting factors
fail to restrict the species growth, -
3:29 - 3:31it will continue to multiply,
-
3:31 - 3:33out-competing native organisms
for resources -
3:33 - 3:37and disrupting the entire ecosystem.
-
3:37 - 3:41Species are sometimes introduced
into new habitats through natural factors, -
3:41 - 3:42like storms,
-
3:42 - 3:43ocean currents,
-
3:43 - 3:45or climate shifts.
-
3:45 - 3:50The majority of invasive species,
though, are introduced by humans. -
3:50 - 3:52Often this happens unintentionally,
-
3:52 - 3:57as when the zebra mussel was accidentally
brought to Lake Erie by cargo ships. -
3:57 - 4:00But as people migrate around the world,
-
4:00 - 4:04we have also deliberately brought
our plants and animals along, -
4:04 - 4:07rarely considering the consequences.
-
4:07 - 4:09But now that we're learning more
-
4:09 - 4:11about the effects of invasive species
on ecosystems, -
4:11 - 4:16many governments closely monitor
the transport of plants and animals, -
4:16 - 4:19and ban the imports of certain organisms.
-
4:19 - 4:22But could the species with
the most drastic environmental impact -
4:22 - 4:27be a group of primates who emerged
from Africa to cover most of the world? -
4:27 - 4:30Are we an invasive species?
- Title:
- The threat of invasive species - Jennifer Klos
- Description:
-
View full lesson: http://ed.ted.com/lessons/the-threat-of-invasive-species-jennifer-klos
Massive vines that blanket the southern United States, climbing high as they uproot trees and swallow buildings. A ravenous snake that is capable of devouring an alligator. Rabbit populations that eat themselves into starvation. These aren’t horror movie concepts – they’re real stories. But how could such situations exist in nature? Jennifer Klos gives the facts on invasive species.
Lesson by Jennifer Klos, animation by Globizco.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 04:46
Denise RQ commented on English subtitles for The threat of invasive species - Jennifer Klos | ||
Jessica Ruby approved English subtitles for The threat of invasive species - Jennifer Klos | ||
Jessica Ruby accepted English subtitles for The threat of invasive species - Jennifer Klos | ||
Jessica Ruby edited English subtitles for The threat of invasive species - Jennifer Klos | ||
Jessica Ruby edited English subtitles for The threat of invasive species - Jennifer Klos | ||
Jessica Ruby edited English subtitles for The threat of invasive species - Jennifer Klos | ||
Jennifer Cody edited English subtitles for The threat of invasive species - Jennifer Klos | ||
Jennifer Cody edited English subtitles for The threat of invasive species - Jennifer Klos |
Denise RQ
Hi,
Please kindly note some changes are needed at 0:43: quality --->quietly
Thanks