Ecologybiodiversity And Conservation

Biodiversity#

Biodiversity, short for biological diversity, refers to the variety of life forms present on Earth. It encompasses the diversity of species, their genetic variability, and the variety of ecosystems and habitats in which they live. Biodiversity is essential for the health and stability of ecosystems.

Levels of Biodiversity: Biodiversity can be examined at various levels:

• Genetic Diversity: The variation in genes within a population or species.
• Species Diversity: The variety of species within an ecosystem or on the planet.
• Ecosystem Diversity: The range of different ecosystems and habitats, such as forests, grasslands, and aquatic systems.

Magnitude of Biodiversity: 1. Known Species:

• Approximately 1.5 million species have been described so far
• Total estimated species could be around 7 million (conservative estimate)
• Some estimates range from 20-50 million species

2. Distribution of Known Species:

• Animals: >70% of all recorded species
• Plants: About 22% (including algae, fungi, bryophytes, gymnosperms, angiosperms)
• Insects: Make up 70% of all animal species
• Fungi: More species than fishes, amphibians, reptiles, and mammals combined

India’s Biodiversity: India has 2.4% of world’s land area but 8.1% of global species diversity classified as one of 12 mega diversity countries currently recorded: 45,000 plant species and 90,000 animal species estimated undiscovered species: 100,000+ plants and 300,000+ animals.

Patterns of Biodiversity#

Latitudinal gradients : Species diversity is highest near the equator and decreases towards the poles.

Examples of this gradient: Colombia (near equator): 1,400 bird species New York (41°N): 105 bird species Greenland (71°N): 56 bird species India (tropical): 1,200+ bird species

The Amazon rainforest’s biodiversity: 40,000+ plant species 3,000 fish species 1,300 bird species 427 mammal species 427 amphibian species378 reptile species 125,000+ invertebrates Estimated 2 million undiscovered insect species

Reasons for higher tropical diversity: Longer evolutionary time due to less glacial disturbance more stable and predictable environments leading to niche specialization higher solar energy availability contributing to greater productivity.

Species-Area relationships:

Alexander von Humboldt observed that within a region species richness increased with increasing explored area, but only up to a limit. In fact, the relation between species richness and area for a wide variety of taxa (angiosperm plants, birds, bats, freshwater fishes) turns out to be a rectangular hyperbola. On a logarithmic scale, the relationship is a straight line described by the equation log $S = log C + Z log A$ where $S$= Species richness $A$= Area $Z$ = slope of the line (regression coefficient) $C = Y$-intercept Ecologists have discovered that the value of $Z$ lies in the range of $0.1 to 0.2$,regardless of the taxonomic group or the region (whether it is the plants in Britain, birds in California or molluscs in New York state, the slopes of the regression line are amazingly similar). But, if you analyse the species-area relationships among very large areas like the entire continents, you will find that the slope of the line to be much steeper ($Z$ values in the range of $0.6 to 1.2$). For example, for frugivorous (fruit-eating) birds and mammals in the tropical forests of different continents

Importance of biodiversity#

• Ecologists have long debated whether more species in a community leads to better ecosystem functioning.

• A stable community should maintain consistent productivity, recover from disturbances, and resist invasive species.

• Rich biodiversity is crucial for both ecosystem health and human survival.

• Paul Ehrlich’s ‘rivet popper hypothesis’ explains biodiversity importance: Each species is like a rivet in an airplane Losing some species might not show immediate effects Continuous loss of species weakens the ecosystem Loss of key species (like rivets on wings) has more severe impacts

• Species extinction rate is currently alarming, and even seemingly insignificant losses can have cumulative effects on ecosystem stability

Loss of Biodiversity#

Species Loss:

• Earth is experiencing rapid decline in biodiversity
• Human activities are the main cause
• 784 species became extinct in last 500 years
• Recent examples include dodo, quagga, and certain tiger subspecies

Current Threats:

• Over 15,500 species worldwide face extinction
• Threatened species include:
  • 12% of birds
  • 23% of mammals
  • 32% of amphibians
  • 31% of gymnosperms

Sixth Extinction:

• Current extinction rate is 100-1,000 times faster than pre-human times
• Unlike previous five mass extinctions, this one is caused by human activities
• Could result in loss of half of Earth’s species within 100 years

Causes of biodiversity losses: The accelerated rates of species extinctions that the world is facing now are largely due to human activities. There are four major causes (‘ The Evil Quartet’ is the sobriquet used to describe them).

Habitat loss and fragmentation: Most significant cause of species extinction Example: Tropical rainforests reduced from 14% to 6% of Earth’s surface amazon rainforest being cleared for agriculture and cattle ranching Habitat fragmentation affects migratory animals and those needing large territories.

Over-exploitation: Results when human ’need’ becomes ‘greed’ caused extinctions like Steller’s sea cow and passenger pigeon currently affecting marine fish populations worldwide threatens commercially important species

Alien species invasions: Introduction of non-native species example: Nile perch in Lake Victoria led to extinction of 200+ cichlid fish species Invasive weeds like Parthenium, Lantana, and water hyacinth African catfish threatening native catfish species

Co-extinctions When one species dies out, dependent species also go extinct Affects host-parasite relationships Impacts plant-pollinator relationships creates chain reaction of extinctions.

Reasons for conserving biodiversity

Narrowly Utilitarian Arguments:** Direct economic benefits from nature Food sources (cereals, pulses, fruits) Construction materials and firewood Industrial products (tannins, lubricants, dyes, etc.) Medicinal value (25% of current drugs from plants) Potential for bioprospecting

Broadly Utilitarian Arguments: Ecosystem services Oxygen production (e.g., Amazon forest - 20% of Earth’s oxygen) Natural pollination services Aesthetic benefits Recreational value Intangible benefits (like enjoying nature)

Ethical Arguments: Moral duty to protect other species Intrinsic value of all species Responsibility to future generations Sharing the planet with other life forms Preservation of biological legacy

Biodiversity Conservation#

In situ conservation Protected Areas: Biosphere reserves (14 in India) National parks (90 in India) Wildlife sanctuaries (448 in India)

Biodiversity Hotspots: 34 global hotspots identified Cover less than 2% of Earth’s land area Harbor extremely high species diversity Three hotspots in India: Western Ghats and Sri Lanka, Indo-Burma, and Himalaya Protection could reduce mass extinctions by 30%

Traditional Conservation: Sacred groves protected through religious and cultural traditions Found in various regions like: Khasi and Jaintia Hills (Meghalaya), Aravalli Hills (Rajasthan), Western Ghats (Karnataka and Maharashtra) ,Sarguja, Chanda, and Bastar (Madhya Pradesh)

Significance: Helps preserve species in their natural environment Protects both target species and associated ecosystems Maintains traditional ecological knowledge and cultural practices Serves as refuge for rare and threatened species

Ex situ Conservation Methods: Zoological parks Botanical gardens Wildlife safari parks Cryopreservation of gametes In vitro fertilization Tissue culture propagation Seed banks

Important Features: Provides special care and protection Preserves species extinct in the wild Maintains genetic diversity Enables long-term storage of biological materials

International Efforts: 1992 Rio Earth Summit: Convention on Biological Diversity 2002 Johannesburg Summit: 190 countries committed to reducing biodiversity loss

Benefits: Protects endangered species, Maintains genetic resources,Enables scientific research, Supports breeding programs, Facilitates species recovery.