Basic Concepts of Biodiversity

Imagine the Earth as one enormous library. But instead of books, this library contains living organisms—plants, animals, microbes, fungi, corals, insects, everything. The sheer variety of life found here is what we call Biodiversity.

The Amazon Rainforest is like the “central library” of this biodiversity—home to the most extraordinary variety of species on the planet.

How many species actually exist?

Scientists estimate that the Earth hosts around 8.7 million species:

• 6.5 million on land
• 2.2 million in oceans

But here’s the surprising part:

• 86% of land species and
• 91% of ocean species
  are yet to be discovered!

Most of these undiscovered species live in tropical regions, where conditions support abundant and diverse life forms.

Yet, until now, only 1.2 million species have been formally described by science.

Share of different groups in known biodiversity

• Animals → Over 70% of described species
• Plants (including algae, fungi, bryophytes, and so on) → About 22%

Among animals, insects dominate overwhelmingly—accounting for over 70% of all known animal species.

Key Terms Related to Biodiversity

Biodiversity (WHO Definition)

According to the World Health Organization, biodiversity is the foundation of all life on Earth. It includes:

• Variations in genes
• Variations in species
• Variations in ecosystems
• Even cultural diversity

To measure biodiversity, two components are crucial:

1. Species Richness
2. Species Evenness

Species Richness

This simply refers to the number of species present in a given area.

The most species-rich ecosystems are:

• Tropical Rainforests (on land)
• Coral Reefs (in oceans)

These act like “hotspots” of life.

Species Evenness

Species evenness tells us how evenly the individuals are distributed among different species in an area.

Think of two sample forests:

Forest A

• Tigers: 10
• Deer: 5
• Rabbits: 5

Forest B

• Tigers: 2
• Deer: 1
• Rabbits: 17

Both forests have:

• Same species richness: 3
• Same total individuals: 20

But Forest A has higher evenness because the population of each species is more balanced. In Forest B, rabbits dominate, so evenness is lower.

Types of Diversity – Alpha, Beta, Gamma

These three terms help us understand biodiversity at different spatial scales.

Alpha Diversity

Diversity within a particular ecosystem.
Example: Number of species inside a single forest.

Beta Diversity

Diversity between ecosystems.
Example: Comparing species of a forest and a nearby grassland.

Gamma Diversity

Overall diversity of a region having multiple ecosystems.
Example: Total diversity of the Western Ghats (forests, grasslands, rivers, etc.)

Genetic Diversity

This refers to the variations in the genetic makeup among individuals of a species.

Example: Humans (Homo sapiens) show genetic diversity across populations—Chinese, Indians, Africans, etc.

Why is genetic diversity important?

• It enables species to adapt to changing environments.
• It ensures that some individuals survive during extreme conditions.
• Closely related species share many genes.
  Example: Humans and chimpanzees share about 98.4% of their genes.

Species Diversity

This considers:

• Species Richness (number of species)
• Species Evenness (distribution of individuals)

It is measured as the ratio of:

Population of one species
——————————————————
Total organisms across all species

A value:

• 0 → Very high diversity
• 1 → Only one species present

A general rule in ecology:

Species diversity decreases from equator to poles.

Ecological Diversity

This refers to the variety of habitats or ecosystems.

Example:
India has deserts, rainforests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows—far more variety than a country like Norway.

Endemism

A species is called endemic if it is found only in a particular region and nowhere else.

For example:

• Nilgiri Tahr is endemic to the Western Ghats.

Opposite of endemism: Cosmopolitan distribution (species found everywhere).

Bioprospecting

This refers to the scientific search for:

• valuable genetic resources,
• useful biochemicals, and
• potential commercial products from biodiversity.

Countries rich in biodiversity often conduct bioprospecting to discover new medicines, cosmetics, enzymes, etc.

Biopiracy

Biopiracy occurs when:

• Traditional knowledge or genetic resources of local communities are taken without permission, and profits are made without compensating them.

Example:

Patent attempts on neem, turmeric, and basmati.

The Nagoya Protocol (under Convention on Biological Diversity) ensures:

• fair and equitable sharing of benefits
• when genetic resources or traditional knowledge are used.

Types of Species

1. Keystone Species

A keystone species is like the “pillar” of an ecosystem.
If you add or remove it, the entire ecosystem changes dramatically.

Key Features:

• Their presence or absence affects many other species.
• Losing a keystone species can lead to ecosystem collapse.
• They often regulate population numbers of other species.

Typical examples:

• Top predators (lions, tigers, crocodiles)
• Elephants (shape forest structure)
• Coral species (form reef ecosystems)

They maintain ecological balance.

2. Indicator Species

Indicator species act like environmental warning signals.

Key Features:

• Their presence, absence, or abundance reflects the health of the environment.
• They are very sensitive to pollution or habitat changes.
• Also called Sentinel Species because they “alert” us to ecological stress.

Common examples:

• Frogs → sensitive to water & air pollution
• Lichens → indicators of air quality
• Salmon → reflect river health

If indicator species decline, it means the ecosystem is under stress.

3. Endemic Species

These species are native to one specific geographical location and found nowhere else in the world.

Key Features:

• Restricted to a particular region, such as an island, state, or mountain range.
• Vulnerable to habitat destruction because they have limited distribution.
• Alternative term: ‘precinctive species’.

Indian examples:

• Lion-tailed macaque – Western Ghats
• Nilgiri Tahr – Western Ghats
• Red Panda – Eastern Himalayas
• Flying Squirrel – Eastern Ghats
• Civet species – Eastern Ghats

Endemism is highest in biodiversity hotspots.

4. Invasive Alien Species

These are non-native species introduced intentionally or unintentionally into a new area.

Key Features:

• They spread fast, dominate the ecosystem, and displace native species.
• Cause ecological and economic damage.
• Alter soil chemistry, fire patterns, food webs, and habitats.

Examples:

• Lantana
• Fall Army Worm
• Eucalyptus
• Wattle (Acacia species)
• Prosopis juliflora
• Common Water Hyacinth

These species often create monocultures and reduce biodiversity.

5. Flagship Species

These species are chosen to represent a conservation cause or campaign.
They are usually charismatic and attract public attention.

Key Features:

• Symbolic species used to promote conservation.
• Selected because they are attractive, vulnerable, or culturally iconic.

Examples:

• Indian Tiger
• African Elephant
• Giant Panda (China)
• Kangaroo (Australia)

Saving flagship species helps generate large-scale support for conservation.

6. Umbrella Species

These are species whose protection automatically protects many other species that share the same habitat.

Key Features:

• Conserving them indirectly saves a whole ecosystem.
• Often species with large home ranges.

Examples:

• Tigers
• Giant Pandas

Protecting tiger landscapes also saves deer, boars, antelopes, monkeys, and many other species.

7. Foundational Species

These are dominant primary producers that create or maintain an ecosystem.

Key Features:

• Support a large part of the ecosystem’s structure and function.
• High abundance + high influence
• Removing them affects the entire food web.

Examples:

• Kelp → forms kelp forests
• Corals → form coral reef ecosystems

Without foundational species, entire habitats collapse.