Question

A long answer question will require one to three paragraphs to answer.

There are five major threats to biodiversity in our time. Define each of the threats and explain their effects on biodiversity. Of the five, which threat is the number one cause of biodiversity loss?

Answer 1

The five major threats to biodiversity in our time are:

1. Habitat loss anf fragmentation:

The most important concept of habitat loss and fragmentation comes from tropical rainforests. The tropical rainforests are being cleared fast for agriculture or building hotels/buildings.

The Amazon rainforest which harbors uncountable species are being cut down for growing soyabeans. They are also being used to grow grasses for raising beef cattle.

2. Over exploitation:

Overexploitation of natural resources have led to many species extinctions in the last 500 years. Examples are the passenger pegion and stellar's sea cow which have been overexploited by humans.

Present day, many marine fishes are being overharvested worldwide for commercial purposes, thereby endangering them.

3. Alien species invasion:

Introduction of alien species might turn out to be invasive and cause a decline/extinction of indigenous species.

Example: Nile perch introduced into Lake Victoria (Africa) has led to the extinction of more than 200 cichlid fishes in that lake.

The illegal introduction of African catfishes in the rivers of India for commercial purposes posed a threat to the native catfishes in these rivers.

4. Coextinctions:

In obligatory relations, extinction of the symbiotic partner leads to the extinction of the other partner.

Example: Coevolved plant-pollinator mutualism - extinction of one species leads to the extinction of the other.

5. Pollution:

Burning of fossil fuels and dumping of garbages in water bodies and soil disrupts the Earth's ecosystem.

Acid rain caused specifically due to burning of fossil fuels changes the environment of local water bodies and soil, thus potentially impacting species habitat.

The most important cause driving animals and plants to extinction are habitat loss and fragmentation.