Biodiversity

The Importance of Biodiversity

What You Need to Know

• Define relevant terminology.

• Describe how organisms interact with each other and with their physical environment, using examples.

• Explain how biodiversity is critical for ecosystem and human health.

• Analyze human population growth trends and our proximity to carrying capacity.

• Analyze and describe the impact keystone species have on the food web and ecological balance.

What is Ecology?

34.1 The Scope of Ecology

• Definition of Ecology: The study of the interactions of organisms with each other and with their physical environment.   - Focus on how organisms adapt to their environment.

• Niche Concept: Each organism fills a niche (its role in the environment).   - Questions associated with each organism's niche:     - What do they eat?     - What are they food for?     - Where do they live?     - What resources do they need?     - What resources do they provide?     - What jobs do they perform?

Ecology in Our Course

• Common perceptions of ecology typically include trees, lakes, and nature, but ecological concepts have been explored throughout the course.

• Relevant topics discussed:   - Survival of the fittest/Microevolution   - Predator and prey dynamics (e.g., peppered moths)   - Populations and disease   - Environmental change and macroevolution   - Role of microbes in breaking down organic material into nutrients for ecosystems.

Ecology and Health

• Ecology directly impacts human health through various means:   - Microbiome: The good and bad bacteria and microorganisms in the human body.   - Medicinal sources: Many medications are derived from natural substances (e.g., Penicillin - antibiotic).   - Stress reduction: Exposure to nature can alleviate stress and may introduce additional beneficial microbes to the body.   - Environmental health impacts: Pollution affects human health.

The Difference between Genetic Diversity and Biodiversity

• Comparison: Both genetic diversity and biodiversity are critical for survival but are not synonymous.

• Genetic Diversity Importance: Species require genetic diversity to maximize the chance of survival against natural adversities.

• Biodiversity Importance: Different species rely on each other for food, shelter, nutrients, etc., thereby sustaining life.   - Questions posed to highlight biodiversity's necessity:     - What would you eat without biodiversity?     - What materials would one use to build without biodiversity?     - What would one breathe in absence of biodiversity?     - How would organic waste be managed without biodiversity?

North Pacific Kelp Forests

• **Role in Ecosystem: **   - Provide food and nutrients.   - Offer shelter.   - Produce oxygen.   - Function in waste management.

Case Study: Sea Otters and their Ecological Impact

• Impact of Sea Otter Removal:   - The Loss: If sea otters are removed (due to hunting or habitat loss), the sea urchin population explodes since their main predator is gone.   - The Collapse: Sea urchins overgraze on kelp, leading to the disappearance of kelp forests and creating "Urchin Barrens" - biological deserts.   - Consequences of Collapse: Without kelp, fish lose habitat and food, oxygen production declines, and nutrient recycling is disrupted.

Ecosystems

The Biotic Components of Ecosystems 35.1

• Components of Biodiversity: Healthy ecosystems require a mix of abiotic and biotic components.   - Abiotic Components: Nonliving elements include sunlight, inorganic nutrients, soil type, water, temperature, and wind.   - Biotic Components: Living organisms categorized based on their food source.

Autotrophs (Producers)

• Definition: Autotrophs are self-feeders requiring inorganic nutrients and an external energy source.

• Photosynthesis: Green plants and algae (photoautotrophs) absorb solar energy through photosynthesis and can produce most of the organic nutrients and energy for living organisms.

• Role: Called "producers" due to their ability to create their own food.

Heterotrophs (Consumers)

• Definition: Heterotrophs are organisms that need an external source of organic nutrients ("other feeders").

• Categories of Heterotrophs:   - Herbivores: Feed on plants/algae (Primary consumers)   - Carnivores:     - Secondary consumers: Feed on herbivores     - Tertiary consumers: Feed on carnivorous animals   - Omnivores: Feed on both plants and animals (e.g., humans).

Decomposers

• Function: Break down nonliving organic matter (dead organisms and waste) and return inorganic nutrients (e.g., nitrogen, phosphorus) back to the environment.

• Types of Decomposers: Heterotrophic bacteria, some protists, fungi, and detritivores who eat partially decomposed matter (e.g., earthworms, beetles, termites, maggots).

Energy Flow and Nutrient Cycling

• Key Phenomena in Ecosystems:   1. Energy Flow: Begins when producers absorb solar energy.   2. Chemical Cycling: Initiated when producers uptake inorganic nutrients and cycle them through the ecosystem, transitioning from soil to plants to consumers and back to soil via decomposers.

• Sunlight as an Energy Source: Energy comes exclusively from the sun and is lost at each step of the food chain.

Energy Balances

• Energy Transfer: Approximately 10% of the organic nutrients made by an autotroph is passed on to heterotrophs.

• Nutrient Availability: Only a portion of the nutrients consumed by heterotrophs are accessible for further consumers.

Food Webs and Food Chains

• Food Webs: Diagrams showing interconnecting energy flow paths within ecosystems.   - Each organism likely has more than one predator.

• Food Chains: Diagrams showing a singular path of energy flow, categorized into trophic levels.   - Example Food Chain: Nuts → Birds → Hawk   - Energy Transfer: Only about 10% of energy is transferred to each subsequent trophic level.

Ecological Pyramids

• Foundation of Biodiversity: A diverse and extensive base of producers is essential for stabilizing the entire ecosystem.

• Biomass Pyramid: Represents the total mass of organisms at various trophic levels. Higher energy loss results in fewer carnivores supported in a food web.

Biodiversity

Definition and Importance

• Biodiversity: The variety of life on Earth; describes the number of species in a given area or ecosystem.

• Species Diversity: Approximately 2.3 million species have been cataloged, with insects comprising about half. Estimates suggest there may be 8.7 million total species.

• Human Dependence on Biodiversity:   - Plants and animals for food, pollinators for crops, and materials for construction.   - Medicinal sources from plants and fungi, and a healthy microbiome supported by bacteria.   - Natural environments boost mental health and provide leisure activities.

The Value of Biodiversity 37.2

• Direct Value: Individual species provide tangible services and resources such as:   - Medicinal Use: Antiseptic chemicals in horseshoe crab blood assist in bacterial contamination prevention in vaccines.   - Agricultural Use: North American grape roots resistant to pests (Phylloxera) help sustain crops.   - Direct Consumption: Food sources, timber, and other natural products such as honey and fruits.

Indirect Value of Biodiversity

• Understanding Indirect Value: Often not apparent through service purchases. The functionality of ecosystems and the services they provide must be recognized.

• Examples:   - Biogeochemical Cycles: Ecosystems recycle elements effectively (e.g., carbon sequestration helps in climate regulation).   - Waste Management: Wetlands filter out pollutants acting as natural water treatment systems.   - Climate and Flood Control: Diverse ecosystems act as buffers against natural disasters, with healthy forests preventing flooding and various species aiding pollination.

Extinction and Biodiversity

• Current Status: About 41,000 species globally are endangered (endangered species face immediate extinction risks, while threatened species are at risk of becoming endangered).

• Local Example: The endangered Jefferson salamander is impacted by habitat destruction due to human expansion.   - Environmental regulations in Kitchener reflect biodiversity's influence on development.

Human Population Growth

• Patterns of Population Growth 34.2:   - Each population exhibits a specific growth pattern based on the rate of natural increase.   - Example Growth Calculation: A population of 1,000 with a birth rate of 30 and death rate of 10 results in a growth rate of 0.02 (2.0% per year).

Biotic Potential

• Definition: The theoretical maximum growth rate for a population.

• Factors Affecting Growth:   - Number of offspring that survive to reproduce.   - Competition within the population.   - Age distribution of reproductive partners.   - Presence of diseases and predators.  

Exponential vs. Logistic Growth

• Exponential Growth: Occurs under optimal conditions, leading to a J-shaped growth curve with two phases:   - Lag Phase: Initial slow growth.   - Exponential Growth Phase: Accelerated growth reflecting biotic potential.

• Logistic Growth: Eventually unsustainable due to environmental resistance, leading to an S-shaped curve with:   - Four Phases: Lag phase, exponential growth, logistic growth phase, and stable equilibrium.

• Carrying Capacity: The maximum number of individuals that an environment can support; identified at the stable equilibrium phase.

Current Trends in Human Population Growth

• Phase transitions in human growth trends:   1. Lag Phase: Pre-1800s; balance of high birth and death rates.   2. Exponential Phase: 1800 - 2011; rapid growth from 1 billion to 7 billion due to technology and medicine.   3. Logistic Phase: Current; growth peaking and slowing (approx. 2.1% in the late 1960s to under 1% today).   4. Stable Equilibrium: Projections suggest leveling of the population around 2100 between 10 and 11 billion.

The Significance of Biodiversity in Ecosystems

• Biodiversity's Critical Role: Food webs rely on all species; the loss of one can lead to significant damage.

• Keystone Species Impact: The grey wolf serves as an example of a keystone species, demonstrating the cascading effects of its removal.

The Story of Grey Wolves in Yellowstone Park

• Historical Extirpation: Grey wolves were driven out due to predation on livestock in the early 1900s.

• Ecosystem Consequences: Following the wolves' removal, the coyote population increased, leading to reductions in other species (e.g., badgers, pine martens), and elk populations thrived without natural predation, causing overgrazing.

• Ecosystem Restoration: Introduction of wolves in 1994 rebalanced the ecosystem, demonstrated the critical role of keystone species in maintaining ecological integrity.

Human Population Dynamics

• Growth Disparities: Less-developed countries are still in an exponential growth phase, while more-developed countries have stabilized.   - Doubling Time: Human population doubling is approximately every 40 years.

• Consequences of Growth: Increased resource consumption leads to declining biodiversity and potential for a 6th mass extinction, with current rates of species extinction significantly higher than historical averages.

Conclusion

• Biodiversity is vital for ecosystem health, human survival, and sustaining ecological balance. As populations grow, understanding and mitigating the impact of human actions on biodiversity will be critical to prevent irreversible ecological damage.