Patterns of Biodiversity: Types & Patterns

Patterns of Biodiversity: Do you know why are there so many uncommon species in the polar regions? Many factors contribute to species diversity. The variety of life forms that exist on Earth is referred to as Biodiversity. Patterns of Biodiversity can exist within various species, communities, regions, habitats, biomes, ecosystems, and the entire Earth. The study of biodiversity can provide us with species-area connections. 

The various patterns of biodiversity differ globally, locally, and over time. The increase in temperature enhanced species diversity to some extent, but as we moved up from sea level to the mountain, it started to decline. Read this article for a detailed and easy-to-understand explanation of Patterns and Levels of Biodiversity.

What is Biodiversity?

Biodiversity refers to the different types of ecosystems, different species of organisms with the whole range of their variants and genes adapted to different climates and environments, along with their interactions and processes that sustain life.

Types of Biodiversity

The term “biodiversity” was coined by sociologist Edward Wilson to describe combined diversity at all the levels, which are divided into three interrelated hierarchical levels:

1. Genetic Diversity

Genetic diversity refers to the sum of genetic information present in the genes of individual plants, animals, and microorganisms. Increases in variation in genes of the species take place with the increase in size and environmental parameters of the habitat. This diversity is useful in adaptation to changes in environmental conditions.

2. Species Diversity

Species diversity is the product of both species richness and evenness or equitability. The amphibian species diversity in the western ghats is abundantly enriched compared to the eastern ghats.

3. Ecosystem and Community Diversity

Within the geographical area, there may be a variable number of ecosystems present, which measures the biodiversity of that region. It is again of three types:
a. Alpha Diversity (Within community diversity)
b. Beta Diversity (Between community diversity)
c. Gamma Diversity (Index diversity)

Number of Species on Earth and in India

We have all the published records of all the species discovered till now, but it is very much hard to answer the question of how many species there are on earth. According to the International Union for Conservation of Nature and Natural Resources (IUCN) (2004), the total number of plant and animal species recorded is slightly more than 1.5 million.

1. Among the total recorded species, the number of animal species is 70%. At the same time, plants cover not more than 22% of all the species.
2. The abundance of insects is maximum among invertebrates. Among vertebrates, the abundance of fishes is maximum.
3. The maximum biodiversity takes place in the tropical Amazon rainforest of South America.
4. India has only 2.4% of land area compared to the total land area of the world, but it shares an impressive 8.1% of global species diversity.
5. India is rich in biodiversity, so it is considered a mega diversity nation. The biodiversity-rich regions of India are the Himalayas, Western Ghats, Indo-Burma region, and Sundaland.
6. In India, more than 45,000 species of plants and 91,000 species of animals have been discovered.

Patterns of Biodiversity

Several biodiversity patterns can occur within various species, communities, regions, habitats, biomes, ecosystems, and the entire earth. The ecologists studied biodiversity in the environment and observed a regular pattern in which diversity is distributed over the entire area of the earth. Charles Robert Darwin described three different patterns and levels of biodiversity.

1. Global Patterns of Biodiversity

In this pattern of biodiversity, species living in similar ecosystems but in different parts of the world make them distantly related as they act and look quite similar. They look and act similarly; for example, Emus found in Australia, Rheas found in South America, and Ostriches found in Africa. They are all flightless birds.

Fig: Species vary globally

2. Species Vary Locally

In this pattern of biodiversity, animal species often occupy different habitats within a local area. The Galapagos Islands are a group of islands relatively close to each other but having different climates. Darwin saw differences in the ecological conditions of the islands along with the differences in the shell shape of tortoises.

Isabela Island contains high peaks, higher rainfall, and contains rich vegetation. The tortoise of this Island has a short neck and dome-shaped shell. Hood Island has lower elevations very much with a dry climate and contains less vegetation. The tortoise of this Island has a long neck and saddle-backed shell. Darwin also observed that different Islands contain different varieties of mockingbirds.

3. Species Vary Over Time

Through the studies of fossils, it was found that some were enormous versions of modern-day species. For example, the modern-day armadillo (50cm long) and the fossil remains of glyptodont (3m long) resemble each other.

Spatial Patterns of Biodiversity

Throughout the world, biodiversity is not uniform. Biodiversity varies with the changes in latitude and altitude and also with time. It is the most well-defined pattern of biodiversity.

Spatial Patterns of Biodiversity: Two patterns are defined in which diversity varies with space changes; they are:

I. Patterns of Biodiversity Latitudinal Gradients

Species diversity is maximum near the equator and decreases as we move away from the equator towards the pole. It means biodiversity is more at lower latitudes near the equator and less at higher latitudes near the poles. There might be some exceptions to a few species. India, located in a tropical territory, has good species richness. Amazon rainforests have maximum biological diversity with regard to the number of species inhabiting this region.

Tropics (latitudinal range of 23.5⁰ N to 23.5⁰ S) have firm climate conditions in contrast to temperate areas. So, species do not need to keep adapting to a changing season, so we can see enriched species diversity in this region.

Unlike temperate areas subjected to regular glaciations in the past, tropical latitudes have remained quite intact for millions of years and thus, got a long evolution time for species diversification.

II. Species-area Relationships

Alexander Von Humboldt figured out research that explained that species richness grows with expanding investigated area but only within a limit. On a logarithmic scale, the relationship is a straight line narrated by the following equation:

log S = log C + Z log A

Where,
S = Species richness 
A= Area 
Z = slope of the line (regression coefficient) 
C = Y-intercept

The value of Z lies between 0.1 to 0.2, despite any taxonomic group or area. But, if we analyse It for very large areas like the entire continents, then we found the slope of the line to be much steeper (Z values in the range of 0.6 to 1.2).

Biodiversity Patterns in Time

Three different types of recognised patterns in time are discussed below:

1. Seasonal Pattern: During different seasons, the diversity of species varies. In the rainy season, the diversity of insect species increases and decreases during winter. Bird diversity is related to the migratory activity and breeding season.
2. Successional Pattern: After a disturbance, plants and animal species begin to reoccupy the habitat. They grow and get replaced by other species. This pattern of the temporal shift in the species composition of a community is called succession.
3. Evolutionary Pattern: Over 600 million years of animal evolution, increasing biodiversity have been found over each regime and era. Some animals have been extinct, some are still found as living fossils, and some are represented as missing links or existing links in the history of evolution.

Summary

Biodiversity introduces the total volume of diversity that exists at all extents of biological organisation. According to Charles Darwin, species diversity can vary globally, locally, and over time. The basic patterns of biodiversity depend on latitude, altitude, and species-area relationships. Species diversity also shows variation in patterns over time, such as seasonal and successional patterns. We should take care of our biodiversity so that our future generation gets the opportunity to witness this rich diversity present on earth and also get benefitted.

FAQs on Patterns of Biodiversity

Let’s look at some of the commonly asked questions about biodiversity patterns:

Q.1: Mention different patterns of biodiversity?
Ans: Charles Darwin described three different patterns and levels of biodiversity, which are:
1. Global patterns of biodiversity
2. Species vary locally
3. Species vary over time

Q.2: Write down the equation of the species-area relationship?
Ans: Species-area relationship equation is mentioned below:
log S = log C + Z log A
Where,
S = Species richness
A= Area
Z = slope of the line (regression coefficient)
C = Y-intercept

Q.3: How many species of plants and animals have been recorded from India till now?
Ans: More than 45,000 species of plants and more than 91,000 species of animal have been discovered in India.

Q.4: What do you mean by alpha diversity?
Ans: It is a species diversity in each community and dependent upon species richness and evenness.

Q.5: What are the different patterns of time species biodiversity?
Ans: The different patterns of time species biodiversity are seasonal, successional, and evolutionary patterns.

Now that you have a detailed article on Patterns of Biodiversity, we hope you study well for your CBSE Biology. If you get stuck somewhere, do let us know in the comments sections. We will get back to you at the earliest.

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