Chapter 2 : REASONS FOR ENDANGERMENT

 Species become endangered for two main reasons: loss of habitat and loss of genetic variation. 

Let us take a look at them.

1. Loss of Habitat 

Loss of habitat can happen both naturally and influenced by human activities. 

Development for housing, industry, and agriculture reduces the habitat of native organisms. This can happen in a number of different ways.

Development can eliminate habitat and native species directly. In the Amazon rain forest of South America, developers have cleared hundreds of thousands of acres. To “clear” a piece of land is to remove all trees and vegetation from it. The Amazon rain forest is cleared for cattle ranches, logging, and urban use.

Development can also endanger species indirectly. Some species, such as fig trees of the rain forest, may provide habitat for other species. As trees are destroyed, species that depend on that tree habitat may also become endangered. Tree crowns provide habitat in the canopy, or top layer, of a rainforest. Plants such as vines, fungi such as mushrooms, and insects such as butterflies live in the rain forest canopy. So do hundreds of species of tropical birds and mammals such as monkeys. As trees are cut down, this habitat is lost. Species have less room to live and reproduce.

Loss of habitat may happen as development takes place in a species range. Many animals have a range of hundreds of square kilometers. 

Loss of habitat can also lead to increased encounters between wild species and people. As development brings people deeper into a species range, they may have more exposure to wild species. Poisonous plants and fungi may grow closer to homes and schools. Wild animals are also spotted more frequently. These animals are simply patrolling their range, but interaction with people can be deadly. Polar bears, mountain lions, and alligators are all predators brought into close contact with people as they lose their habitat to homes, farms, and businesses. As people kill these wild animals, through pesticides, accidents such as collisions with cars, or hunting, native species may become endangered.

Environmental factors can also contribute to habitat destruction more indirectly. Geological processes, climate change, introduction of invasive species, ecosystem nutrient depletion, water and noise pollution are some examples. 

2. Loss of Genetic Variation

Genetic variation is the diversity found within a species. Genetic variation allows species to adapt to changes in the environment. Usually, the greater the population of a species, the greater its genetic variation.

Inbreeding is reproduction with close family members. Groups of species that have a tendency to inbreed usually have little genetic variation, because no new genetic information is introduced to the group. Disease is much more common, and much more deadly, among inbred groups. Inbred species do not have the genetic variation to develop resistance to the disease. For this reason, fewer offspring of inbred groups survive to maturity.

Loss of genetic variation can occur naturally. For example Cheetahs cannot adapt to changes in the environment as quickly as other animals, and fewer cheetahs survive to maturity. Cheetahs are also much more difficult to breed in captivity than other big cats, such as lions.

Human activity can also lead to a loss of genetic variation. Overhunting and overfishing have reduced the populations of many animals. Reduced population means there are fewer breeding pairs. A breeding pair is made up of two mature members of the species that are not closely related and can produce healthy offspring. With fewer breeding pairs, genetic variation shrinks.

Monoculture, the agricultural method of growing a single crop, can also reduce genetic variation. Modern agribusiness relies on monocultures. 

Let us take a look at the reasons for endangerment shared by our Instagram family:

@aisha_bagha - 

"Invasion of their natural habitat by humans" 

@_nussy.nus_ -

"Degradation & loss of habitat mainly caused by deforestation, natural disasters due to climate change, human over-exploitation of species e.g. hunting & overfishing, pollution and spread of diseases."

@zainab_akadir -

"Degradation of natural habitat like deforestation. Hunting too" 

@_real_rizwana -

"People and their greed"

@souqbazaars -

"Lack of knowledge"

@rewireyourmindsetstrategy -

"Ignorance"

@leafypaths_freya -

"Human corruption"

REFERENCES:

www.natioanalgeoghraphic.org