Biodiversity growth and extinction

Wilson estimates that 30, species per year or three species per hour are being driven to extinction.

Biodiversity growth and extinction

Oksana Hlodan There are many ways in which the introduction of non-native or exotic species negatively affects our environment and the diversity of life on our planet. The statistics are startling and more attention must be paid to the problem and devising a solution before the cost is more than we can bear.

Invasive species cause more damage than some pollutants. Almost half of the native species in America are endangered because of invasive species. Compared to other threats to biodiversity, invasive introduced species rank second only to habitat destruction, such as forest clearing. In fact, introduced species are a greater threat to native biodiversity than pollution, harvest, and disease combined.

Biodiversity growth and extinction

Of course, some introduced species such as most of our food crops and pets are beneficial. However, others are very damaging.

Introduced species are not good guests The greatest impact is caused by introduced species that change an entire habitat, because many native species thrive only in a particular habitat. When the Asian chestnut blight fungus virtually eliminated American chestnut from over million acres of eastern United States forests in the first half of the 20th century, it was a disaster for many animals that were highly adapted to live in forests dominated by this tree species.

For example, ten moth species that could live only on chestnut trees became extinct. Similarly, the Australian paperbark tree has replaced native plants, such as sawgrass, overacres of south Florida, because it has a combination of traits for example, spongy outer bark and flammable leaves and litter that increase fire frequency and intensity.

Many birds and mammals adapted to the native plant community declined in abundance as paperbark spread. The invasive zebra mussel is depleting the food of marine natives. In similar fashion, aquatic plants such as South American water hyacinth in Texas and Louisiana and marine algae such as Australian Caulerpa in the Mediterranean Sea change vast expanses of habitat by replacing formerly dominant native plants.

The zebra mussel, accidentally brought to the United States from southern Russia, transforms aquatic habitats by filtering prodigious amounts of water thereby lowering densities of planktonic organisms and settling in dense masses over vast areas.


At least thirty freshwater mussel species are threatened with extinction by the zebra mussel. Other invaders, though they do not change a habitat, endanger single species or even entire groups of them in various ways: Trout fishing is almost nonexistent in some American states because of a foreign parasite.

The predatory brown tree snake, introduced in cargo from the Admiralty Islands, has eliminated ten of the eleven native bird species from the forests of Guam. The Nile perch, a voracious predator introduced to Lake Victoria as a food fish, has already extinguished over one hundred species of native cichlid fish there.

A parasite can be similarly devastating.Human Population Growth and extinction. We're in the midst of the Earth’s sixth mass extinction crisis. Harvard biologist E. O. Wilson estimates that 30, species per year (or three species per hour) are being driven to extinction.

Extinction, in biology, the dying out or termination of a caninariojana.comtion occurs when species are diminished because of environmental forces (habitat fragmentation, global change, overexploitation of species for human use) or because of evolutionary changes in their members (genetic inbreeding, poor reproduction, decline in population numbers).

Human population growth and overconsumption are at the root of our most pressing environmental issues, including the species extinction crisis, habitat loss and climate change.

Biodiversity is a contraction of biological diversity. It reflects the number, variety and variability of living organisms and how these change from one location to another and over time. Biodiversity includes diversity within species (genetic diversity), between species (species diversity), and between ecosystems (ecosystem diversity).

The major causes of biodiversity decline are land use changes, pollution, changes in atmospheric CO 2 concentrations, changes in the nitrogen cycle and acid rain, climate alterations, and the introduction of exotic species, all coincident to human population growth.

For . The most widely used methods for calculating species extinction rates are "fundamentally flawed" and overestimate extinction rates by as much as percent, life scientists report May 19 in the.

5) Causes of recent declines in biodiversity « Rainforest Conservation Fund