Why should humans worry about species extinction and the
disruption of ecosystems? When
our actions cause a population to become extinct we lose valuable
knowledge, and in some cases, even potential aides to humankind. For
instance, many medicines are discovered in plants. What happens if these
plant species become extinct before scientists discover that they contain
useful chemicals? Also, with every
extinction, many food chains lose valuable links, upsetting the
For these reasons, the
Fish and Wildlife Service Endangered Species Program was created by
the Endangered Species Act of
What do airplanes, trains, automobiles, boats,
telephones, and the internet have in common?
Can we say that they keep us connected to each other?
In nature, many ecosystems, like islands, are isolated from outside
influences. Can humans affect that
isolation? Human commercial and recreational activities can
introduce new populations that are likely to disturb the existing balance.
|For example, in Hawaii, the Jackson’s
chameleon, native to East Africa, was introduced a few decades ago.
Today, this invasive species continues to expand its population to all the
islands. Since a large
part of the chameleon's diet consists of small insects, other
normally feed on insects (small birds, for example), have begun to
decrease in number. Trying
to maintain a balance between natural populations and invasive
species, like the Jackson’s chameleon, costs the United States
over 100 billion dollars per year.
change in bacterial populations is taking place now. The widespread
use of antibiotics is leading to the evolution of new strains of
bacteria that are resistant to antibiotics. In any infection, there
may be a few bacteria that are naturally resistant to the antibiotic
being used to treat it. If these survivors are not killed off
by the body's own
defenses, they can proliferate and continue the
infection. Have you ever had a bad cold or infection where the
doctor prescribed antibiotics. Do you remember being told not
to skip any doses and to take all the doses for a full 5 days or
so? Why do you suppose these instructions were given.