The teacher asked Ravi that what is the main reason that many. species are becoming endangered[
Answers
Answer:
An endangered species is a type of organism that is threatened by extinction. Species became endangered for two main reasons: loss of habitat and loss of genetic variation. A loss of habitat can happen naturally.
Step-by-step explanation:
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Answer:
An endangered species is a type of organism that is threatened by extinction. Species become endangered for two main reasons: loss of habitat and loss of genetic variation.
Step-by-step explanation:
A Loss of Habitat
A loss of habitat can happen naturally. Dinosaurs, for instance, lost their habitat about 65 million years ago. The hot, dry climate of the Cretaceous period changed very quickly, most likely because of an asteroid striking the Earth. The impact of the asteroid forced debris into the atmosphere, reducing the amount of heat and light that reached Earth's surface. The dinosaurs were unable to adapt to this new, cooler habitat. Dinosaurs became endangered, then extinct.
Human activity can also contribute to a loss of habitat. 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.
Loss Of Genetic Variation
Genetic variation is the diversity found within a species. It's why human beings may have blond, red, brown or black hair. 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. Cheetahs are a threatened species native to Africa and Asia. These big cats have very little genetic variation. Biologists say that during the last ice age, cheetahs went through a long period of inbreeding. As a result, there are very few genetic differences between cheetahs. They 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.
The Red List
The International Union for Conservation of Nature (IUCN) keeps a "Red List of Threatened Species." The Red List defines the severity and specific causes of a species' threat of extinction. The Red List has seven levels of conservation: least concern, near threatened, vulnerable, endangered, critically endangered, extinct in the wild and extinct. Each category represents a different threat level.
Species that are not threatened by extinction are placed within the first two categories — least concern and near-threatened. Those that are most threatened are placed within the next three categories, known as the threatened categories — vulnerable, endangered and critically endangered. Those species that are extinct in some form are placed within the last two categories — extinct in the wild and extinct.
Classifying a species as endangered has to do with its range and habitat, as well as its actual population. For this reason, a species can be of least concern in one area and endangered in another. The gray whale, for instance, has a healthy population in the eastern Pacific Ocean, along the coast of North and South America. The population in the western Pacific, however, is critically endangered.
Least Concern
Least concern is the lowest level of conservation. A species of least concern is one that has a widespread and abundant population. Human beings are a species of least concern, along with most domestic animals, such as dogs and cats. Many wild animals, such as pigeons and houseflies, are also classified as least concern.