Understanding Biodiversity

• Biodiversity refers to the variety of life on Earth
• This includes diversity at the genetic, species, and ecosystem levels

Biodiversity

• Enormous diversity exists within the biosphere at all levels of biological organization, from macromolecules to biomes
• Edward Wilson popularized the term biodiversity
• A single species might exhibit high diversity at the genetic level across its distribution
• Rauwolfia vomitoria shows genetic variation in the potency and concentration of reserpine in different Himalayan ranges
• India has over 50,000 genetically distinct rice strains and 1,000 mango varieties
• The Western Ghats have greater amphibian species diversity compared to the Eastern Ghats
• Deserts, rainforests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows contribute to India's greater ecosystem diversity than Norway
• It would take millions of years to replenish biodiversity

Estimating Species Numbers

• It is known how many species have been recorded and named
• It is harder to estimate the total number of species on Earth
• According to IUCN in 2004, about 1.5 million plant and animal species have been described
• The total number of species is unknown
• Existing estimates are educated guesses
• Statistical comparisons are made of insect groups from temperate regions
• Figures between 20 to 50 million are extreme estimates
• Robert May estimates about 7 million global species

Biodiversity Distribution

• Animals account for over 70% of recorded species
• Plants make up no more than 22%
• Insects comprise over 70% of all animal species
• Fungi species outnumber the combined species of fishes, amphibians, reptiles, and mammals
• Prokaryote figures are unavailable
• Identifying microbial species and culturing are problematic

Indian Biodiversity

• India accounts for 2.4% of the world's land area
• India contributes 8.1% of global species diversity
• 45,000 plant species and twice as many animal species have been recorded in the country
• May's global estimates show only 22% of species have been recorded
• There are more than 1,00,000 plant and 3,00,000 animal species in India to be discovered and described

Patterns in Biodiversity - Latitudinal Gradients

• Plant and animal diversity is unevenly distributed globally
• Species diversity decreases from the equator towards the poles
• Tropics (23.5° N to 23.5° S) have more species than temperate/polar regions
• Colombia has approximately 1,400 bird species
• New York has 105 bird species at 41° N
• Greenland has 56 bird species at 71° N
• India has over 1,200 bird species in tropical latitudes
• Ecuador rainforests have 10 times more vascular plant species than the Midwest USA
• The Amazon rainforest holds the most biodiversity on Earth
• There are 40,000 plant species, 3,000 fish species, 1,300 bird species, 427 mammal species, 427 amphibian species, 378 reptile species and 125,000 invertebrate species
• There may be at least two million insect species

Hypotheses for Greater Tropical Biodiversity

• Speciation takes time but tropical latitudes have remained undisturbed
• Tropical environments are less seasonal, constant, and predictable
• Niche specialization is promoted
• The tropics receive more solar energy, which increases productivity

Species-Area Relationships

• Alexander von Humboldt noted that species richness increases up to a limit when increasing explored area within a region
• For angiosperms, birds, bats, and freshwater fish the relation between area and species richness is described by the equation: log S = log C + Z log A
• S equals species richness and A is area
• The line slope indicates the regression coefficient with C as the Y-intercept
• The Z value ranges from 0.1 to 0.2
• A steeper line slope means larger areas like entire continents have Z values from 0.6 to 1.2, such as frugivorous birds/mammals slope = 1.15

Importance of Species Diversity

• Ecologists have not been able to definitively determine if the number of species matters
• A stable community shows little productivity variation yearly while being resistant
• David Tilman’s experiments revealed higher productivity and less biomass variation in plots with more species
• Rich biodiversity maintains ecosystem health and human survival
• Paul Ehrlich's "rivet popper hypothesis" uses an airplane as an ecosystem analogy
• Loss of rivets (species) may initially not affect flight safety, but over time threatens the plane

Loss of Biodiversity

• While speciation may be rare, biodiversity loss is ongoing as a result of human activity
• Colonization of Pacific Islands led to the extinction of over 2,000 native bird species
• The IUCN Red List (2004) notes 784 extinctions in the last 500 years
• Includes 338 vertebrates, 359 invertebrates, 87 plants
• Dodo (Mauritius), quagga (Africa), thylacine (Australia), Steller’s Sea Cow (Russia), and three tiger subspecies (Bali, Javan, Caspian) included
• The last twenty years have seen 27 disappearances
• Amphibians more likely face extinction
• Over 15,500 species face extinction worldwide
• 12% of bird species, 23% of mammal species, 32% of amphibian species, and 31% of gymnosperm species are threatened
• There were five mass extinction episodes before humans

Sixth Mass Extinction

• The current extinction rate is 100 to 1,000 times faster than pre-human times
• Human activities are responsible
• Half of all species may be wiped out in the next 100 years
• Losing biodiversity can decline plant production
• Loss can also lead to decreased drought resistance

Causes of Biodiversity Losses - The Evil Quartet

• Habitat loss and fragmentation is a major factor
• Tropical rainforests were 14% of Earth, now 6%
• Deforestation occurs rapidly
• The Amazon rainforest is being cut for soy cultivation or beef cattle
• Pollution degrades habitats
• Fragmented habitats affect mammals/birds needing large habitats
• Over-exploitation occurs when need turns to greed
• The introduction of Alien species causes decline in native species
• Lake Victoria had 200 cichlid fish species go extinct due to the Nile perch
• Carrot grass (Parthenium), Lantana, and water hyacinth (Eicchornia) are invasive weeds
• African catfish Clarias gariepinus threatens indigenous catfish
• Co-extinctions result in the loss of species associated with an extinct one
• An example is a plant-pollinator relationship

Biodiversity Conservation

• There are diverse reasons to conserve biodiversity such as: narrowly utilitarian, broadly utilitarian, and ethical
• Humans benefit directly from nature in the form of food, firewood, fiber, construction materials, industrial products like tannins, lubricants, dyes, resins, and perfumes
• 25% of drugs are from plants
• Native people use 25,000 plant species for traditional medicines
• Bioprospecting explores molecular, genetic, and species-level diversity for economic opportunities and benefits
• Biodiversity plays a role in many ecosystem services
• The Amazon rainforest produces 20% of Earth's oxygen supply
• Ecosystems use pollination

The Importance of Ethic

• The need to save millions of species
• Every species has value
• People have a moral duty to care
• We must ensure that earth's biodiversity stays intact for the next generation

Biodiversity Conservation Methods

• In situ conservation protects the whole ecosystem
• In the case of endangered animals/plants, ex situ conservation is desirable
• In situ conservation occurs when faced with the conflict between development and conservation as nations find it challenging to conserve all species
• Maximum conservation is achieved in biodiversity hotspots
• Hotspots are regions of high species richness and endemism
• There are 34 biodiversity hotspots
• Western Ghats, Sri Lanka, Indo-Burma, and the Himalayas constitute India's biodiversity regions
• Hotspots account for 2% of land and strict protection could reduce mass extinction by 30%
• India protects biodiversity-rich regions as biosphere reserves, national parks, and sanctuaries
• India has 14 biosphere reserves, 90 national parks, and 448 wildlife sanctuaries
• Sacred groves are found in Khasi and Jaintia Hills, Meghalaya, Aravalli Hills, Rajasthan, Western Ghats, Sarguja, Chanda, and Bastar
• Meghalaya harbors many rare plants

Ex Situ Conservation

• Threatened animals and plants are taken from their habitat
• They are put in special settings to be protected and given special care
• This includes zoological parks, botanical gardens, and wildlife safari parks
• Some animals are extinct in the wild, but maintained in parks
• Cryopreservation and in vitro fertilization have advanced conservation
• Seeds are stored in seed banks
• There was a Convention on Biological Diversity ("The Earth Summit") in 1992
• Appropriate conversation measures were called upon
• A World Summit on Sustainable Development occurred in 2002
• 190 countries pledged to reduce biodiversity loss by 2010