Biodiversity Measurement and Loss

Biodiversity Measurement and Loss

• Biodiversity encompasses biological variety at various levels (genes, populations, ecosystems).
• Traditional measures include species count and individual counts per species.
• Loss of species like the passenger pigeon, dodo, and woolly mammoth might seem inconsequential, but current accelerated extinction rates threaten thousands of species.
• Tropical rainforests, rich in biodiversity, are heavily impacted by deforestation for timber and agriculture, potentially harming human welfare.
• Ecosystem collapse and increased costs for food production, clean water/air, and human health are likely consequences.

Types of Biodiversity

• Species diversity is a basic measure, counting species in an area (e.g., 2078 bird species in North/Central America).
• More complex measures consider species abundance (a forest with equally common species is more diverse than one dominated by one species).
• Scientists have documented ~1.5 million species, but estimate many more (potentially 10 million+) remain undiscovered (especially microorganisms).

Genetic and Chemical Biodiversity

• Genetic diversity drives a species' adaptability.
• A species' future adaptability depends on the genetic variation within its populations.
• Genetic diversity is also linked to chemical diversity, as different genetic makeups lead to distinct cellular chemical compositions (proteins, metabolic products).
• Chemical diversity is crucial for humans, potentially yielding new medicines (e.g., eptifibatide from rattlesnake venom).

Ecosystem Diversity

• Ecosystem diversity refers to the range of ecosystems in an area.
• Ecosystem loss impacts species interactions and coadaptation.
• Examples of lost ecosystems are North American prairies.
• The loss of ecosystem functions (e.g., soil productivity) often outweighs direct species loss.

Patterns of Biodiversity

• Biodiversity is unevenly distributed.
• Lake Victoria's high cichlid diversity contrasts with Lake Huron's lower diversity.
• Geographic factors (like latitude and age) influence biodiversity patterns.
• Tropics tend to have greater biodiversity (more endemic species and biodiversity hotspots), but knowledge about tropical species is limited and human activity poses a high risk of biodiversity loss.

Importance of Biodiversity

• Biodiversity is crucial for human health, food security, and other aspects.
• Human health benefits from natural medicines found in diverse organisms (e.g., plant secondary compounds).
• Many contemporary medicines are derived from plant compounds (e.g., aspirin, codeine, digoxin, atropine, vincristine).
• Antibiotics are derived from fungi/bacteria.
• Humans benefit from psychological well-being in biodiverse environments.

Agriculture

• Human agriculture relies on crop diversity.
• Wild relatives of crops are essential for breeding improvements.
• Ecosystem services are crucial for crop growth (e.g., nutrient cycles in soil, pollination).
• Loss of wild relatives or ecosystem health can reduce crop production capacity.
• Honeybee and other pollinators are vital; colony collapse disorder impacts food production.

Wild Food Sources

• Aquatic resources (fish) are primary food sources for billions globally.
• Overfishing can lead to ecosystem restructuring and negative impacts on local communities.
• Fish stocks are often shifting towards smaller species.

Threats to Biodiversity

• Human population growth and resource use are the central threats.
• The three main proximate threats are habitat loss, overharvesting, and invasive species.
• Anthropogenic climate change is a growing threat with predictions of increased extinction rates.

Habitat Loss

• Human modification and habitat destruction disproportionately affect certain species that cannot adapt to human alterations.
• Forest loss is a significant threat in Sumatra and Borneo, impacting orangutans and other species.
• Habitat loss is a major cause of biodiversity decline.

Overharvesting

• Overharvesting, particularly in fisheries, is a key threat.
• The tragedy of the commons is a major driver.
• Overfishing has led to significant declines in some fisheries (e.g., the western Atlantic cod fishery).

Invasive Species

• Invasive species pose a significant threat via competition, predation, or disease.
• Ships' ballast water often introduces aquatic invasive species (e.g., zebra mussels in the Great Lakes).
• Disease-carrying invasive species can decimate native populations (e.g., chytridiomycosis in amphibians, white-nose syndrome in bats).

Climate Change

• Climate change (anthropogenic global warming) is a major threat.
• Climate shifts impact species ranges and timing of seasonal events.
• Range shifts are observed in various species.
• Rising sea levels endanger coastal species and ecosystems.

Preserving Biodiversity

• Preserving biodiversity requires understanding, behavioral change, and conservation strategies.
• Biodiversity is a dynamic balance between speciation and extinction.
• Mass extinctions (including the one that wiped out dinosaurs) have happened repeatedly throughout history.
• Human activities are driving a sixth mass extinction.

Conservation Efforts

• Legislation, preserves, and habitat restoration are main strategies.
• CITES (Convention on International Trade in Endangered Species) restricts international trade of threatened species.
• Endangered Species Act (USA) aims at protecting, but is sometimes ineffective.
• Preserves (protected areas) are fundamental, but face challenges due to political/economic limitations.

Biodiversity Hotspots

• Biodiversity hotspots are areas with high concentrations of endemic species.
• Conservation efforts can protect large numbers of species.

Role of Zoos and Captive Breeding

• Zoos are increasingly involved in conservation but face limited successes in species reintroduction to the wild.
• Education programs play a role in changing people's attitudes towards conservation.

Extinction Rates

• Current extinction rates are higher than background rates.
• Estimates vary but often are significantly higher (e.g., 100 E/MSY, up to 1500 E/MSY) than the background rate and often higher than historical values, highlighting the impact of humans.

Habitat Restoration

• Habitat restoration can help restore biodiversity in degraded ecosystems; examples include reintroducing key species to affected areas.