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In this article, we will define the terminologies ecosystem and niche. Moreover, we will explain that biodiversity can be evaluated at various levels like the number and range of different ecosystems and habitats, the number of species and their relative abundance, and the genetic variation within each species. Understanding Ecosystems and Niches
What are Ecosystems?
Species form communities by interacting with other species. It implies that they do not exist by themselves in their own secluded environment. An ecosystem is formed when these communities interact with each other and their surroundings.
Comparatively, an ecosystem is a self-reliant community of interacting organisms and the environment they inhabit and interact with. An ecosystem has a flow of energy and the nutrients within it are used again and again, i.e. they are recycled.
Components of an ecosystem
An ecosystem has both living and non-living components. Living components are known as biotic, whereas non-living components are called abiotic.
Size and scale of an ecosystem
The size and scale of an ecosystem can be different. This is because a tiny pond in your garden as well as an ocean can be referred to as ecosystems. We as humans are also ecosystems because thousands of species of bacteria are living on us.
The complexity of an ecosystem
The complexity of an ecosystem can vary. For example, a desert can be described as a simple ecosystem, whereas a tropical rainforest can be described as an extremely complex ecosystem.
Remember that ecosystems are not completely self-reliant because organisms from one ecosystem are dependent on the organisms in another ecosystem. For instance, birds can fly long distances from multiple ecosystems for feeding purposes.
Example of an ecosystem
One of the best examples of a complex ecosystem is a forest. In a forest, a large community of organisms lives which include birds, trees, small and large mammals, insects, and fungi. The non-living (abiotic) components of the ecosystem in a forest include dead leaves, soil, rainwater and streams, rocks, and other chemical and physical factors. The community of organisms is influenced by the non-living components of the ecosystem.
What is a Niche?
Habitat refers to the place where the species lives within an ecosystem. A niche can be defined as:
The role that species plays within an ecosystem is referred to as its niche.
The niche includes:
- The place in the environment where an organism lives
- How it obtains its energy
- How it interacts with other species and its physical environment
Example of a Niche
A dung beetle takes an extremely specific niche within its ecosystem. This organism exploits the dung of animals as a resource. Dung beetles have a special behaviour of rolling the dung into balls before carrying it to their underground burrow so that it can be stored there as food. Their behaviour indirectly affects their environment and other organisms living in it. The burrows and tunnels created by them turn over and aerate the soil and their buried dung releases essential nutrients into the soil. Both of these factors are beneficial for other organisms living in that ecosystem. Transporting the dung underground also assists in keeping the fly population under control.
In the next section of the article, we will discuss that biodiversity can be evaluated at different levels such as the number and range of different ecosystems and habitats, the number of species and their relative abundance, and the genetic variation within each species.
What is Meant by Biodiversity?
We can think of biodiversity as a study of all the existing variations within and between all life forms. Biodiversity encompasses a range and variety of genes, species, and habitats within a specific region. We can evaluate the biodiversity at the following three levels:
- The number and range of various ecosystems and habitats
- The number of species and their relative abundance
- The genetic variation with each species
Biodiversity is critical for the resilience of ecosystems because it enables them to resist changes in the environment.
Ecosystem or Habitat Diversity
It refers to the range of various habitats or ecosystems within a specific area or region. If an area or region includes a huge number of different habitats, then we say that the area has high biodiversity. A coral reef is the best example of this concept as they are highly complex with several microhabitats and niches that can be exploited.
We can say that an area has low biodiversity if it has only one or two different habitats. Usually, the large sandy deserts have extremely low biodiversity because the conditions are the same throughout the entire region.
Species Diversity
An ecosystem, for example, a tropical rainforest that contains an extremely high number of different species can be called species-rich. Species richness refers to the number of species within an ecosystem.
Species diversity not only observes the number of different species within an ecosystem, but also the evenness of abundance across different species that are present. The species diversity is greater if there are a large number of species in an ecosystem and the number of organisms is evenly distributed among each species. For instance, there can be a large number of different species in an ecosystem, however, some species can have only 3 to 4 members. Consequently, this ecosystem does not have a greater species diversity.
High Vs Low Diversity
Ecosystems that have high species diversity usually have more stability as compared to those having low species diversity. This is because they are more resilient to changes in the environment. Take an example of the pine forests of Florida. One or two tree species constitute most of this ecosystem. If a pathogen targets one of the two dominating species of trees, then the entire population can be wiped out and the ecosystem can collapse.
Genetic Diversity
The genetic diversity within a species refers to the diversity of alleles and genes in the genome of the species.
Although individuals of the same species can have the same genes, however, they don't need to have the same alleles for each gene. We can measure genetic diversity by computing the proportion of genes that have more than one allele and the number of possible alleles present in each gene.
There can be genetic diversity or genetic differences between populations of the same species. This might be due to the two populations occupying somewhat different ranges in their habitat. Hence, they are subjected to somewhat different selection pressure that influences the frequencies of an allele in their populations.
Genetic diversity is also present within a single population. The diversity in a species is critical because it helps the population in adapting and endure the changes in the environment. These changes can be in:
- Biotic factors like new predators, pathogens, and competition with other species
- Abiotic factors such as temperature, humidity, and rainfall
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