Figure 25.34: A highly endangered Macquarie perch specimen was caught on a lure with
barbless hooks in a high altitude upland river and was carefully released. This species is
now extinct in most of its upland river habitats due to introduced trout species in the same
habitats. Siltation from agricultural practices and flow regulation and thermal pollution by
dams have also caused the extinction of this species in some upland rivers. ( 3 )
Importance of Biodiversity
Does it matter if we are losing thousands of species each year, when the earth holds millions
and life has been through extinction before? The answer is yes; it matters even if we consider
only direct benefits to humans. But there are also lots of indirect benefits, also known as
ecosystem services, in addition to benefits to other species as well.
Biodiversity is important for a number of reasons. Economically, direct benefits include the
potential to diversify our food supply; increase resources for clothing, shelter, energy, and
medicines; a wealth of efficient designs which could inspire new technologies; models for
medical research; and an early warning system for toxicity.
In our food supply, monocultures (large-scale cultivation of single varieties of single species)
are very vulnerable to disease. As recently as 1970, blight affected the corn belt where 80%
of maize grown in the U.S. was of a single type (Figure25.35). Contemporary breeders of
various crop species increase the genetic diversity by producing hybrids of crop species with
wild species adapted to local climate and disease.
As many as 40,000 species of fungi, plants, and animals provide us with many varied types
of clothing, shelter, and other products. These include poisons, timber, fibers, fragrances,
papers, silks, dyes, adhesives, rubber, resins, skins, furs, and more. In addition to these
above raw materials for industry, we use animals for energy and transportation, and biomass
for heat and other fuels.
According to one survey, 57% of the most important prescription drugs come from na-
ture (bacteria, fungi, plants, and animals) (Figure25.36), yet only a fraction of species