Question

What are the major causes of species losses in a geographical region?

Answer 1

Hint: Global extinction is the loss of species, where there are no surviving individuals elsewhere. The extinction of any species is an irreversible loss of biological richness of the earth. Extinction can be naturally occurring caused by chronic environmental stress, unpredictable catastrophe or ecological interaction such as competition, predation or diseases.

Complete answer:
Causes of species loss:
Habitat loss and fragmentation. Major cause of extinction.
1. Habitat loss: Expanding population requires more industrial areas, extension of present towns and cities, more area for agriculture, new roads, etc. All these will result in destruction of natural habitats.
2. Habitat fragmentation: Human settlements, digging of canal and other development activities result in fragmentation of large sized habitats like forest tract.
3. Over exploitation: Exploitation results in degradation and extinction of the resource. Excessive tree felling in the forest overgrazing, uprooting of orchids and medicinal plants, hunting of animals etc. have resulted in degradation of habitats and extinction of many species for example Cheetah from India, Dodo from Mauritius, Quagga from South Africa.
4. Alien species invasions: When a new species is introduced into an area its natural biological control is lifted. If it finds the habitat suitable for its growth it will exterminate the native species from that habitat. For example: water hyacinth was introduced by Europeans in India. It has clogged all wetlands, rivers, lakes resulting in the death of many aquatic species.
5. Co-extinction: There are many obligate associations among different species in. When one of them becomes extinct the other connected with it in obligate association would also die.
6. Pollution: Acid rain has destroyed more than 50% of natural forests and several freshwater lakes in many Western countries. Pesticides often enter food chains and undergo biomagnification causing declination of fish eating birds population.

Note:
Some other causes:
Forestry: Forestry means growth of exploitable forest plants. There is therefore a tendency to grow only these plants in almost pure stands. Other economically less important plants are being ignored resulting in their extermination and hence loss of biodiversity.
Intensive agriculture: Extension of agriculture resulted in diminishing of wetlands, grasslands and forests. Intensive agriculture is based on a few crops and their few high yielding varieties. The remaining varieties are disappearing fast.