Partial Final Review

Chapter 18 – Human Impact on the Environment

Biodiversity and Its Levels

Biodiversity refers to the variety of life in all its forms and at all levels of organization. It is essential for ecosystem resilience and human well-being.

• Ecosystem Diversity: The variety of ecosystems in a given region.

• Community Diversity: The variety of species and their interactions within a community.

• Genetic Diversity: The variety of genetic information within and among populations of species.

Human Impacts on Ecosystems

• Pollution: Introduction of harmful substances into the environment, affecting air, water, and soil quality.

• Habitat Destruction: Conversion of natural habitats to urban, agricultural, or industrial areas, leading to loss of species.

• Over-exploitation: Unsustainable harvesting of natural resources, such as overfishing or deforestation.

• Climate Change: Alteration of global or regional climate patterns, primarily due to increased greenhouse gases from human activities.

• Introduction of Non-native Species: Species introduced by humans to new areas can become invasive, outcompeting native species.

Biodiversity Hotspots

Biodiversity hotspots are regions with exceptionally high levels of species richness and endemism that are under significant threat from human activities. Preserving these areas is crucial for maintaining global biodiversity.

Landscapes, Edges, and Movement Corridors

• Landscape: A mosaic of interconnected ecosystems in a region.

• Edges: Boundaries between different ecosystems; can increase or decrease species diversity depending on the context.

• Movement Corridors: Strips of habitat that connect isolated populations, facilitating gene flow and migration.

Bioremediation and Sustainable Development

• Bioremediation: The use of living organisms (such as bacteria or plants) to detoxify polluted environments.

• Sustainable Development: Economic development that meets present needs without compromising the ability of future generations to meet their own needs.

Chapter 19 – Population Ecology

Abiotic vs. Biotic Factors

• Abiotic Factors: Non-living components of the environment (e.g., temperature, water, sunlight, soil).

• Biotic Factors: Living components of the environment (e.g., plants, animals, bacteria).

Adaptations to the Environment

• Physiological Adaptations: Internal body processes that help an organism survive (e.g., thermoregulation).

• Anatomical Adaptations: Physical features (e.g., thick fur, long roots).

• Behavioral Adaptations: Actions or behaviors (e.g., migration, nocturnal activity).

Population Description and Dynamics

• Population: A group of individuals of the same species living in a specific area.

• Population Density: Number of individuals per unit area or volume.

• Population Dispersion Patterns: The spatial arrangement of individuals (clumped, uniform, random), shaped by interactions among individuals.

• Population Growth: Change in population size over time.

Population Growth Rate Equation:

$\text{Growth Rate} = \text{Birth Rate} - \text{Death Rate}$

Exponential vs. Logistic Growth

• Exponential Growth: Population increases rapidly under ideal conditions; represented by a J-shaped curve.

• Logistic Growth: Population growth slows as it approaches the carrying capacity (K); represented by an S-shaped curve.

Logistic Growth Equation:

$\frac{dN}{dt} = rN \left(1 - \frac{N}{K}\right)$

• Carrying Capacity (K): Maximum population size that an environment can sustain.

• Limiting Factors: Environmental factors that restrict population growth.

  • Density-dependent: Effects increase with population density (e.g., competition, disease).

  • Density-independent: Effects are unrelated to population density (e.g., natural disasters).

Age Structure and Survivorship Curves

• Age Structure: Distribution of individuals among different ages in a population; affects growth potential.

• Survivorship Curves: Graphs showing the proportion of individuals surviving at each age.

  • Type I: High survivorship until old age (e.g., humans).

  • Type II: Constant survivorship throughout life (e.g., some birds).

  • Type III: Low survivorship for the young, high for survivors (e.g., many fish, plants).

Chapter 20 – Communities & Ecosystems

Biological Communities and Their Properties

• Biological Community: All the populations of different species living and interacting in a particular area.

• Diversity: Includes species richness (number of species) and species abundance (relative number of individuals per species).

• Vegetation: The plant life present, which shapes community structure.

• Stability: The ability to resist or recover from disturbances (events that change community structure).

• Trophic Structure: The feeding relationships among organisms (food chains and food webs).

Community Relationships

1. Competition

   • Intraspecific: Competition among individuals of the same species.

   • Interspecific: Competition between different species.

   • Limiting Factors: Competition arises due to limited resources.

   • Ecological Niche: The role and space an organism occupies in its environment.

   • Competitive Exclusion Principle: Two species competing for the same resources cannot coexist indefinitely.

   • Ecological Species Concept: Species defined by their ecological niche.

2. Predation (Predator-Prey Relationships)

   • Predator Adaptations: Claws, speed, camouflage, acute senses.

   • Prey Adaptations: Camouflage, warning coloration, defensive behaviors.

   • Co-evolution: Reciprocal evolutionary adaptations between predators and prey.

   • Mimicry: One species resembles another.

     • Batesian Mimicry: A harmless species mimics a harmful one.

     • Müllerian Mimicry: Two or more harmful species resemble each other.

3. Symbiosis

   • Symbiotic Relationship: Close, long-term interaction between different species.

   • Parasitism (+/-): One organism benefits, the other is harmed (e.g., tapeworms in mammals).

   • Mutualism (+/+): Both organisms benefit (e.g., bees and flowering plants).

   • Commensalism (+/0): One organism benefits, the other is unaffected (e.g., barnacles on whales).

Trophic Levels, Food Chains, and Food Webs

• Producers: Organisms (usually plants or algae) that produce organic molecules from inorganic substances via photosynthesis.

• Consumers: Organisms that obtain energy by eating other organisms.

• Food Chains: Linear sequences showing who eats whom.

• Food Webs: Complex networks of interconnected food chains.

• Biomass: Total mass of living organisms in a given area.

• Primary Productivity: The rate at which producers convert solar energy to chemical energy.

Biogeochemical Cycles

• Carbon Cycle: Movement of carbon among the atmosphere, biosphere, oceans, and geosphere.

• Nitrogen Cycle: Movement of nitrogen through the atmosphere, soil, and living organisms.

• Phosphorus Cycle: Movement of phosphorus through rocks, water, soil, and living organisms.

• Roles: Producers, consumers, and detritivores (decomposers) all play roles in recycling nutrients.

• Human Disruption: Activities such as burning fossil fuels, fertilizer use, and deforestation alter these cycles.

Biomes and Climate

• Biome: Major type of ecological community defined by its climate and dominant vegetation (e.g., tundra, rainforest, desert).

• Climate: Long-term patterns of temperature and precipitation; determines biome distribution.