IBESS Topic 3.3: Threats to Biodiversity

Overview

• Focuses on biodiversity and conservation
• Estimated 8.7 million species on Earth
• Only 1.2 million are formally described
• Variability in species count estimates; could be up to 100 million
• Techniques include mathematical modeling and taxonomy challenges

Challenges in Estimating Species

• Financial constraints for research
• Small or remote species are underreported
• Requires substantial time and money

Extinction

• Defined as a species, genus, or family's permanent disappearance
• 99% of all species have gone extinct
• Current extinction rates much higher than historical ones

Historical vs. Current Extinction Rates

• Pre-human extinction rate: 1 per 1 million species per year
• Current rate: 100 to 60,000 extinctions per million species per year
• Potential for 20% of current species extinct by 2030

Human Impact

• IUCN records show increased extinction rates due to human activities
• Around 40% of amphibians, 25% of mammals, 34% of conifers, etc., are threatened

Causes of Extinction

• Natural causes: volcanic eruptions, earthquakes, etc.
• Human causes: HIPPO acronym
  • H: Habitat Destruction
  • I: Introduced Species
  • P: Pollution
  • P: Practices of Agriculture
  • O: Overhunting

Examples of Human Impact

• Habitat fragmentation and destruction
• Invasive species like Asian carp, kudzu, starlings, rabbits, cane toads
• Pollution from agriculture, overfishing, hunting
• Over-exploitation of resources leads to tragedy of the commons

Factors Making Species Prone to Extinction

• Specialized niche (e.g., pandas, koalas)
• Low reproductive potential (e.g., blue whales, gorillas)
• Narrow distribution (e.g., lemurs, midges)
• Large territory needs (e.g., tigers)
• Fixed migratory patterns (e.g., wildebeest)
• Ground nesting vulnerable to predators
• Higher trophic level subject to biomagnification
• Economically valuable species (e.g., elephants)

Conservation Status (IUCN Red List)

• Categories include extinct, extinct in the wild, critically endangered, endangered, vulnerable, least concern
• Determined by factors like population size, reduction rate, geographic range

Key Takeaways

• Mathematical modeling is used to estimate biodiversity, with limitations
• Extinctions are driven by natural and human causes; HIPPO is a useful acronym
• Human activities exacerbate extinction rates
• Conservation involves understanding species vulnerabilities and using IUCN classifications

Resources

• Presentation adapted from William Green's and Dave Hoover's materials
• Additional learning resources: IBESS textbook, online platforms like Cognate

Note: This summary is intended as a study aid and should be used in conjunction with other resources for comprehensive understanding.