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What is Species Diversity? Examples, Threats, Conservation

Our planet is home to various life forms. Species diversity examples range from the tiniest bugs to the tallest giraffes. Different ecosystems have varying levels of flora and fauna richness that interact with one another and their environment.

The existence and interaction of these species help to balance our ecosystems, and understanding this topic is crucial for monitoring our planet’s status. Read on as we discuss what species diversity means, why it is essential, and a few examples of species diversity.

Related Read: Components Of Biodiversity, Genetic Diversity, Ecosystem Diversity.

What is Species Diversity?

elephant and zebra
Photo by Filiz Elaerts on Unsplash.

Species diversity is the number of species found in a particular area (this could be habitats, biomes, or the entire biosphere) and the relative abundance of each species.

Species diversity is one of the three parts of biological diversity, of which the other two are ecosystem diversity, which is the various ecosystems found on our planet, and genetic diversity, which is the various inherited traits within species.

Environmental conditions play a significant role in species diversity. So you will find locations like Antarctica with low species diversity and others like tropical forests with higher species diversity. 

Locations near the equator tend to have greater species diversity compared to locations near the poles. One explanation for this is that there are more habitats and ecological niches near the equator. 

Components of Species Diversity

clownfish on anemone
Photo by David Clode on Unsplash.

The greatest species diversity within an area is when all the species present are equally abundant within that area. Here are the two components of species diversity: 

Species richness

Species richness refers to how many species live within a habitat or ecosystem. Some ecosystems, like tropical regions, have greater species richness because they are more conducive for a large number of species. 

Species evenness 

Species evenness is the relative abundance of each of the many species within a particular habitat or ecosystem. In other words, species evenness refers to the representation of species relative to the total number of individual species within a location. 

So, if a particular location fairly represents individuals within a species, there is high species evenness. But if only a few individuals are within a species, there is a low species evenness.

You can find ecosystems with the same species richness but necessarily the same species' evenness and vice versa. 

For example, you may find many species within an ecosystem (high species richness) and only a few individuals of each species. On the flip side, you may find only a few species (low species richness) and a huge number of each species (high species evenness). 

Levels of Species Diversity

According to Robert Harding Whittaker, an American plant ecologist, we can study a diverse group of species in an area at three different levels or scales:  

Alpha diversity

Alpha diversity looks at species within one ecosystem or a small scale within a community. The species richness or number of species within that ecosystem typically expresses it. 

Beta diversity 

Beta diversity looks at the change in species diversity between ecosystems or communities. Unlike Alpha diversity, you can compare species diversity between two separate regions.  

Gamma diversity   

Lastly, Gamma diversity measures the total diversity in a geographical region. In other words, the total diversity of every ecosystem within a region. This is typically on a very large scale, measuring areas like the entire slope of a mountain or an entire seashore. 

How to Calculate Species Diversity?

Scientists can measure species diversity in communities using proportional abundance-based indices: the Shannon-Wiener Index and Simpson's Diversity Index. 

Shannon-Wiener Index    

This index helps ecologists study the diversity in environments and can provide useful information about a given community. It takes into account the number of species in an environment as well as their relative abundance. The formula is:

H = -Σpi * ln(pi)

Where:

Σ: A Greek symbol that means “sum.”

ln: Natural log

pi: The proportion of the entire community made up of species i

With a higher value of H comes an increase in the diversity of species in a specific community. Values can range between 0 and 5 but specifically between 1.5 and 3.5.

Simpson's Diversity Index

Some environments have more abundant species than others. The Simpson’s index measures dominance and gives the probability that two individuals randomly selected from a community will belong to the same species.  The formula is:

D = Σni(ni-1)  /  N(N-1)

Where:

ni: The number of organisms of a specific species i

N: The total number of organisms

Simpson’s Diversity Index ranges between 0 and 1, and a higher value typically indicates a high diversity of species. 

Why is Species Diversity Important?

butterfly sitting on top of a flower
Photo by viswaprem anbarasapandian on Unsplash.

Each species plays an essential role in maintaining functional and healthy ecosystems. Different species (plant species and animal species) within an ecosystem depend on each other to thrive and maintain ecological stability. Here are reasons why high species diversity is important: 

  • Different species exist to increase the stability and productivity of our ecosystems. As species interact, they form a stable ecosystem. 
  • Species richness increases the ability of our ecosystem to withstand adverse environmental conditions like drought. 
  • Species diversity is essential for the survival of humans. It helps purify our water and air, increase our soil fertility, and maintain our climate. 
  • Species diversity is vital for ecological processes like pollination, decomposition, and the food web. This helps to prevent overpopulation of one species over other species. 
  • The diversity of species also contributes to resources like fruits, vegetables, and more for human consumption. 
  • Many social and cultural backgrounds use certain plant species because of their medicinal properties. Also, pharmaceutical companies use natural compounds from plants to produce new drugs. 
  • Plants and bacteria are crucial in the nitrogen cycle, and earthworms contribute to soil fertility. 
  • Species diversity helps to provide habitats for living organisms, which in turn helps plants and animals survive. 

Different Types of Species Based on Ecological Niche

In every ecosystem, different species play different roles. An ecological niche is the role species play in our ecosystem. Here are different types of species based on ecological niche: 

  • Generalist species: Rats, cockroaches, flies, and humans are examples of generalist species. These types of species live in various environments, eat various foods, and can adapt to various changing conditions. 
  • Specialist species: These species can only live in one type of environment and are more sensitive to environmental changes. They consume limited types of food and thrive more in more constant environments. For example, the Koala, native to Australia, only feeds on the leaves of the eucalyptus tree and lives in environments that support eucalyptus trees. 
  • Native species: These are indigenous or endemic species that live and thrive in a specific ecosystem. For example, kangaroos are native to Australia. 
  • Non-native species: Also called invasive species, non-native species are species that migrate to another ecosystem by chance or on purpose.
  • Indicator species: Indicator species act as a warning for environmental deterioration. For example, birds could be an indicator of habitat loss and fragmentation. 
  • Keystone species: Keystone species contribute to biodiversity within a local community by suppressing populations that will otherwise dominate the community. These types of species also supply vital resources to a diverse group of species. For example, the starfish Pisaster ochraceous, a predatory starfish on the Northwest coast of North America, feeds on mussels and preserves biodiversity in these communities. 
  • Foundation species: Foundation species help to create or maintain environments that other species need. For example, corals make coral reefs that a variety of species need. 

Examples of Species Diversity

Here are a few examples of ecosystems with both high and low species diversity: 

A. Tropical rainforests    

tropical rainforest
Photo by Jonathanking on Wikimedia Commons licensed under CC BY-SA 3.0 (Cropped from original).

Did you know that tropical rainforests are home to half of the world’s species? This includes some endemic species that you won’t find anywhere else in the world. For example, the Amazon rainforest contains 10% of the species on the earth. 

Tropical forests in countries like Brazil and Madagascar are also home to thousands of undescribed species.  

B. Coral reefs  

coral reef
Photo by Oleksandr Sushko on Unsplash.

Coral reefs have many species, from fish to invertebrates and other organisms, that live both in and around the reefs. The largest coral reel, the Great Barrier Reef of Australia, is home to over a thousand species of fish.

C. Wetlands

You can find birds, fish, amphibians, and other species in wetlands. For example, The Florida Everglades has over 400 bird species, including herons, ibises, and endangered species like snail kites. You can also find plant species like sawgrass, marsh plants, mangroves, and more.

D. Grasslands   

grassland
Photo by Yang on Unsplash.

Grasslands are rich in biodiversity, being home to many plant and animal species. For example, the African Savanna has diverse plants like grasses, flowering plants, and tree species like acacia and baobab trees. It also has diverse animal species like elephants, envelopes, zebras, ostriches, butterflies, bees, and other species. 

E. Coastal forests    

Coastal forests are also rich in biodiversity, with diverse plant and animal species that can adapt to the unique environmental conditions of the coast. 

For example, in the Pacific Northwest rainforest located in North America, you can find coniferous and deciduous trees as well as animals like bears, bald eagles, Pacific tree frogs, salmon, and more.  

Threats to Species Diversity

trees cut down
Photo by gryffyn m on Unsplash

Today, species diversity in biodiversity comes with many threats, including human activities like deforestation, habitat destruction, pollution, and so on. Let’s look at a few threats to species diversity: 

  1. Habitat loss: Activities like pollination, industrial development, and urbanization push plants and animals out of their habitat and into extinction. For example, in the Amazon Rainforest, clearing lands for agriculture, including cattle ranching, is a major driver of deforestation, leading to habitat destruction. 
  2. Overexploitation: Unsustainable harvesting of species for medicine, food, and other uses can reduce populations and lead to lower species diversity within an area.
  3. Invasive species: When new species get introduced into an ecosystem directly or indirectly, it can lead to the extinction of indigenous species. For example, Cichlid species became extinct in Lake Victoria because the predatory Nile Perch invaded the Lake. Initially, this was introduced to improve fishing. However, it led to the extinction of the Cichlid species and a breakdown of the Lake.  

Conserving Species Diversity

Today, species diversity faces many threats that can lead to extinction and distort the balance of our ecosystems. 

Conservation efforts, from habitat restoration to government legislation, have become more critical to reducing these threats. Here are a few conservation strategies that can lead to greater species diversity: 

  1. Restore degraded habitats: When a habitat or ecosystem degrades as a result of human activities, the plant and animal species in these regions lose their homes and are dispersed to other regions. Many biologists agree that one way to restore these habitats to their original state is to bring back the plants and animals that live there.  

One example of habitat restoration was the reintroduction of grey wolves into the Yellowstone National Park. Before this, there was distorted food distribution, affecting beavers. The beaver population has increased thanks to the restoration project, and food distribution has become more stable within the area.

  1. Protect habitats with government legislation: The government can control what exactly happens to and within certain territories in the country. The government can outlaw the harvesting of some natural resources, as well as other activities to protect biodiversity. 

For example, the Endangered Species Act in the United States protects species with an endangered conservation status.

  1. Protect biodiversity hotspots: Biodiversity hotspots are home to endemic species which you cannot find anywhere else in the world. These hotspots also have high species richness. 

We currently have over 30 hotspots in different parts of the world, and conserving them will help secure global diversity.

  1. Raise public awareness: The more people are aware, the more they become actively involved, increasing initiatives geared towards biodiversity conservation. 

Wrapping up

Species diversity is a significant aspect of biodiversity and is crucial in maintaining balanced ecosystems. Restoring and preserving our species' diversity ensures a harmonious coexistence of all life on our planet. 

Jen’s a passionate environmentalist and sustainability expert. With a science degree from Babcock University Jen loves applying her research skills to craft editorial that connects with our global changemaker and readership audiences centered around topics including zero waste, sustainability, climate change, and biodiversity.

Elsewhere Jen’s interests include the role that future technology and data have in helping us solve some of the planet’s biggest challenges.

Fact Checked By:
Isabela Sedano, BEng.

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