[Biology Class Notes] on Species Diversity Pdf for Exam

It is defined as the number of species and population of species that live in that particular environment. The population of species of that particular location is called species richness. There are approximately 1.8 million different species classified on Earth. Of all the total species, about one million belong to insects. New species are being discovered each year. Scientists estimate that there may be between 5 to 30 million species that actually live on Earth. Due to this wide diversity, there are different species diversity in different locations as different species are present in different locations depending upon their ability to adapt in that particular environment.

There Are Two Different Terms Regarding Species Diversity

• Species Richness: The number of different species present in an ecosystem. Different areas have different populations as per their adaptive capability. Tropical areas have greater species richness as the environment is suitable and adaptable for a large number of species.

• Species Evenness: Relative abundance of individuals of each of those species. If the number of a particular species is constant across the communities then they are called to have a high evenness and if the number of individuals varies from species to species, it is said to have low evenness. High evenness always leads to greater species diversity.

With the change in adaptive ability and geographical distribution, there are two types of species diversity, they are

Importance of Species Diversity

There are so many positive reasons behind species diversity. Each species has a crucial role in ecosystem management. Example: Saprophytes act as decomposers, imagine if these saprophytes are not present in the ecosystem there will be no composting which will lead to several environmental problems like disruption of various ecosystem chains. 

Some of the major importance are listed below:

• Various species are helpful in the purification of water, purification of air, enhanced fertility of soils, maintaining climatic stability, and various other environmental factors.

• It contributes to a healthy ecosystem. As each species has a specific link with a wealthy ecosystem. 

• More the species more will be the productivity in the ecosystem which will form a stable ecosystem.

• The specific reason will be the ability to fight against any disaster.

• More the diversity among species, the more will be their ability to respond against natural disasters like drought.

• Because of high species, diversity people get various products like fruits, cereals, meat, wood, fiber, etc.

• The Amazon forest contributes approximately 20 percent of the total oxygen in the earth’s atmosphere.

• They maintain the soil fertility of ecosystems.

• Pollination, symbiotic relationship, decomposition play a very unique role in the ecosystem.

• Good biodiversity is necessary for the survival of mankind.

• Apart from these, there are other benefits such as recreation and tourism, education, and research.

• They are also prime destinations for tourists.

Threats to Species Diversity

Today’s ecosystem is witnessing a large number of extinction of species due to several human activities which are harming our ecosystem. There are four main causes for the loss of diversity called the Evil Quartet.  These are loss of habitat and fragmentation, invasion of any alien species, overexploitation, co-extinctions.

• Overexploitation: Over harming or exploiting natural resources leads to the extinction of many species of biodiversity. Example: Many marine fishes are overharvested which leads to their extinction. 

• Loss of Habitat: Due to industrialization, urbanization various species lost their shelter and food which ultimately leads to the extinction of various species.
  
  Example: the Amazon rainforest which is also called the lungs of Earth and house many millions of species are being cut down and cleared for different purposes. Likewise, tropical rainforest that once covered 14% of the land is not more than 6% left currently.

• Introduction of New Species: When new species are being introduced they start harming previous species which causes their extinction.
  
  Example: Introduction of catfish in water reservoirs leads to the extinction of various existing species.

• Co-extinction: When species are interdependent on each other, extinction of one species leads to the extinction of another also.
  
  Example: when a host fish is extinct parasites that are dependent on them also get extinct. Likewise, species that are involved in mutualistic relationships such as plant pollinators where if one species becomes extinct the other species becomes extinct too.

Steps Taken for Conservation of Biodiversity

There are several steps that are taken by the government to conserve biodiversity as they are getting depleted day by day. Some of the major steps taken by the government are listed below.

• Rich biodiversity areas are protected as biosphere reserves, national parks, and sanctuaries, and this type of conservation is called in-situ conservation. In this type of conservation, various endangered species are protected from getting extinct in their natural habitat. Example: Royal Bengal tiger is native to the Indian subcontinent and is mainly conserved in National parks and Biosphere reserves.

• Hotspot biodiversity areas are rich in species population. These areas are mainly determined on the basis of endemism, a threat to habitat, species diversity, and degree of exploitation. All over the world, there are a total of 34 hotspots. Example: Western ghat and Eastern Himalayas are two biodiversity hotspots of India.

• India has various celebrations on protecting and planting trees. One of the famous among them is the Chipko movement.

• In various lab and research areas, gametes of threatened species are preserved by cryopreservation techniques.

• Ex-situ conservation is the type of conservation in which endangered species are given full protection and care for their conservation outside their natural habitat.