Biodiversity: Study Notes
Definition and Scope
- Biodiversity refers to the variety and variability of life on Earth, encompassing the diversity within species (genetic diversity), between species (species diversity), and between ecosystems (ecosystem diversity).
- It includes all living organisms: plants, animals, fungi, and microorganisms, as well as the ecosystems they form.
Historical Context
- The term “biodiversity” emerged in the 1980s, but the study of biological variety dates back to early naturalists like Alexander von Humboldt (18th-19th centuries).
- Early cataloguing efforts, such as Carl Linnaeus’s taxonomy (18th century), laid the groundwork for understanding species diversity.
- The 20th century saw the rise of ecology as a discipline, focusing on the interactions between organisms and their environments.
Key Experiments
1. The Cedar Creek Biodiversity Experiment (1994–present)
- Location: Minnesota, USA.
- Aim: To study how plant diversity affects ecosystem processes.
- Findings: Plots with higher plant species richness showed greater productivity, stability, and resistance to invasive species.
2. Island Biogeography Theory (1967)
- Developed by Robert MacArthur and E.O. Wilson.
- Hypothesis: The number of species on an island reflects a balance between immigration and extinction rates, influenced by island size and distance from the mainland.
- Impact: Provided a framework for understanding habitat fragmentation and species loss.
3. DNA Barcoding (2003–present)
- Technique: Uses a short genetic sequence from a standardized region of the genome to identify species.
- Result: Accelerated species discovery and monitoring, especially for microorganisms and cryptic species.
Modern Applications
- Conservation Planning: Biodiversity data guide the establishment of protected areas and wildlife corridors.
- Agriculture: Crop genetic diversity is crucial for food security and resilience to pests, diseases, and climate change.
- Medicine: Many pharmaceuticals are derived from natural compounds found in diverse ecosystems.
- Biotechnology: Enzymes from extremophiles (organisms thriving in extreme environments) are used in industrial processes.
Recent Breakthroughs
- Environmental DNA (eDNA): Allows detection of species presence in water, soil, or air samples without direct observation. This non-invasive method is revolutionizing biodiversity monitoring.
- Global Biodiversity Assessment using AI: Machine learning models are now used to predict species distributions and identify at-risk habitats.
- Plastic Pollution in Deep Oceans: Recent research (Peng et al., 2020, Nature Geoscience) revealed microplastics in the Mariana Trench, showing that human impact reaches the planet’s most remote ecosystems.
Case Study: Plastic Pollution in the Deep Sea
- Discovery: In 2018, scientists found plastic debris in the Mariana Trench, the world’s deepest oceanic trench. Subsequent studies confirmed microplastics in sediment and organisms at depths over 10,000 meters.
- Implications: Deep-sea biodiversity is threatened by pollutants previously thought to be confined to surface waters. Microplastics can enter food webs, affecting species health and ecosystem functions.
- Research Example: Peng et al. (2020) documented microplastic accumulation in the deepest marine sediments, indicating global circulation and deposition patterns.
Biodiversity and Human Health
- Disease Regulation: Diverse ecosystems can buffer the spread of infectious diseases (the “dilution effect”), as higher species diversity can reduce the prevalence of disease vectors.
- Nutrition and Medicine: Biodiverse diets provide essential nutrients. Many drugs (e.g., antibiotics, anticancer agents) are derived from natural sources.
- Mental Health: Access to biodiverse green spaces is linked to improved psychological well-being.
- Risks from Biodiversity Loss: Reduced biodiversity can lead to ecosystem instability, increased disease outbreaks, and diminished food security.
Recent Research
- Reference: Peng, X., Chen, M., Chen, S., Dasgupta, S., Xu, H., Ta, K., Li, J., Guo, Z., Bai, S., Li, Y., & Shi, S. (2020). Microplastics contaminate the deepest part of the world’s ocean. Nature Geoscience, 13, 345–350. https://www.nature.com/articles/s41561-020-0615-2
- Key Findings: Microplastics are present in the deepest ocean sediments, raising concerns about their impact on deep-sea organisms and food webs.
Summary
- Biodiversity encompasses the full range of life on Earth, from genes to ecosystems.
- Its study has evolved from basic cataloguing to sophisticated genetic and ecological analyses.
- Key experiments have shown that biodiversity enhances ecosystem productivity, stability, and resilience.
- Modern applications span conservation, agriculture, medicine, and biotechnology.
- Recent breakthroughs, such as eDNA and AI-based assessments, are transforming biodiversity monitoring.
- Plastic pollution, now found in the deepest ocean trenches, highlights the vulnerability of even remote ecosystems.
- Biodiversity is intimately linked to human health, affecting disease regulation, nutrition, and mental well-being.
- Ongoing research underscores the urgent need to protect and restore biodiversity for planetary and human health.