Ecology and Conservation Biology: Study Guide

Ecological Hierarchy and Organization

Levels of Ecological Organization

• Organism: An individual living entity (e.g., a single Homo sapiens).

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

• Community: All populations of different species living and interacting in an area.

• Ecosystem: The community plus the abiotic (non-living) environment.

• Landscape: A mosaic of connected ecosystems.

• Biosphere: The global sum of all ecosystems; the zone of life on Earth.

Ecosystems: Structure and Function

Components and Processes

• Biotic factors: Living components (plants, animals, microbes).

• Abiotic factors: Non-living components (climate, soil, water, sunlight).

• Energy flow: Movement of energy through trophic levels; energy enters as sunlight and exits as heat.

• Nutrient cycling: Movement of elements like carbon, nitrogen, and phosphorus through biotic and abiotic components.

Trophic Levels, Food Chains, and Food Webs

Energy Transfer and Organization

• Trophic level: Each step in a food chain or web (producers, primary consumers, etc.).

• Food chain: Linear sequence of energy transfer (e.g., grass → rabbit → fox).

• Food web: Interconnected food chains showing complex feeding relationships.

• Energy transfer efficiency: Typically, only about 10% of energy is transferred from one trophic level to the next.

Formula:

$\text{Trophic Efficiency} = \frac{\text{Energy at higher trophic level}}{\text{Energy at lower trophic level}} \times 100\%$

Population Ecology

Population Characteristics

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

• Dispersion: Pattern of spacing among individuals (clumped, uniform, random).

• Range: Geographic area where a species is found.

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

Population Growth Models

• Exponential growth: Population increases under ideal conditions; J-shaped curve.

• Logistic growth: Population growth slows as it approaches carrying capacity; S-shaped curve.

Formulas:

Exponential: $\frac{dN}{dt} = rN$

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

Survivorship Curves

• Type I: High survival early, most die late (e.g., humans).

• Type II: Constant death rate (e.g., birds).

• Type III: High death rate early, survivors live long (e.g., oysters).

Biomes and Aquatic Zones

Major Terrestrial Biomes

• Tropical Rainforest: High rainfall, biodiversity.

• Boreal Forest (Taiga): Coniferous trees, cold climate.

• Chaparral: Shrubland, mild wet winters, hot dry summers.

• Conifer Forest: Dominated by cone-bearing trees.

• Tundra: Cold, permafrost, low vegetation.

• Savannah: Grassland with scattered trees.

• Desert: Low precipitation, extreme temperatures.

Aquatic Zones and Features

• Wetland: Area saturated with water, high productivity.

• Littoral zone: Near shore, shallow, well-lit.

• Estuary: Where freshwater meets saltwater.

• Riparian area: Interface between land and river/stream.

• Coral reef: Marine, high biodiversity, built by corals.

• Photic zone: Sunlit upper layer of water.

• Benthos: Organisms living on/in the ocean floor.

• Thermocline: Layer with rapid temperature change in water.

• Pelagic zone: Open water away from shore.

• Limnetic zone: Well-lit, open surface water in lakes.

• Intertidal zone: Area between high and low tide.

• Deep-sea vent: Hydrothermal vent communities.

Climate, Water Cycle, and Environmental Factors

Water Cycle

• Evaporation: Water changes from liquid to vapor.

• Condensation: Vapor forms clouds.

• Precipitation: Water returns as rain/snow.

• Runoff: Water moves over land to bodies of water.

Climate and Related Factors

• Atmosphere: Layer of gases surrounding Earth.

• Prevailing winds: Consistent wind patterns due to Earth's rotation.

• Rain shadow: Dry area on leeward side of mountains.

• Latitude and longitude: Coordinate system for Earth's surface.

• Seasons: Caused by Earth's tilt and orbit.

Energy Flow and Productivity

Primary and Secondary Production

• Primary production: Amount of light energy converted to chemical energy by autotrophs.

• Gross primary productivity (GPP): Total primary production.

• Net primary productivity (NPP): GPP minus energy used by producers for respiration.

• Secondary production: Energy converted to new biomass by consumers.

• Standing crop: Total biomass of producers at a given time.

• Limiting factors: Elements that restrict productivity (e.g., nutrients, light).

• Conversion efficiency: Proportion of energy transferred between trophic levels.

Formulas:

$\text{NPP} = \text{GPP} - R$

where $R$ is energy used in respiration.

Biogeochemical Cycles

Nitrogen Cycle

• Nitrogen fixation: Conversion of N2 gas to usable forms (ammonia, nitrate) by bacteria.

• Nitrifying bacteria: Convert ammonia to nitrate.

• Reservoirs: Atmosphere, soil, living organisms.

Carbon Cycle

• Photosynthesis: Plants convert CO2 to organic molecules.

• Respiration: Release of CO2 by organisms.

• Reservoirs: Atmosphere, fossil fuels, biomass, oceans.

Phosphorus Cycle

• Weathering: Releases phosphate from rocks.

• Uptake: Plants absorb phosphate.

• Reservoirs: Rocks, soil, water, organisms.

Community Interactions and Biodiversity

Types of Interactions

• Autotroph: Organism that produces its own food (e.g., plants).

• Heterotroph: Organism that consumes others for energy.

• Mutualism: Both species benefit (e.g., bees and flowers).

• Parasitism: One benefits, one is harmed (e.g., tapeworms).

• Scavenger: Consumes dead organisms (e.g., vultures).

• Decomposer: Breaks down dead material (e.g., fungi, bacteria).

Biodiversity Levels

• Genetic diversity: Variation within a species.

• Species diversity: Number of species in an area.

• Ecosystem diversity: Variety of ecosystems in a region.

Threats to biodiversity: Habitat loss, introduced species, overharvesting, human activity.

Conservation Biology

Key Concepts and Approaches

• Bioremediation: Using organisms to detoxify polluted environments.

• Biological augmentation: Adding essential materials to degraded ecosystems.

• Fire and fire suppression: Fire can maintain ecosystem health; suppression can lead to fuel buildup.

• Extinction vortex: Small populations are vulnerable to extinction due to inbreeding and genetic drift.

• Small population approach: Focuses on increasing population size and genetic diversity.

• Declining population approach: Identifies and addresses causes of population decline.

• Edge species: Thrive in habitat boundaries; fragmentation can increase edge effects.

• Movement corridors: Strips of habitat connecting isolated populations.

• Critical load: Maximum level of a nutrient that can be added without damaging the ecosystem.

• Sustainable development: Using resources to meet current needs without compromising future generations.

Examples

• Red-cockaded woodpecker: Requires mature pine forests; threatened by habitat loss.

• Flying fox: Important pollinator; threatened by hunting and habitat loss.

• Costa Rica: Model for conservation and sustainable development.

Threatened and Endangered Species

• Endemic species: Found only in a specific location.

• Threatened species: Likely to become endangered.

• Endangered species: At risk of extinction.

Human Impacts and Environmental Issues

• Air pollution: Release of harmful substances into the atmosphere.

• Fossil fuels: Nonrenewable energy sources; burning releases CO2.

• Eutrophication: Nutrient enrichment leads to algal blooms and oxygen depletion in water bodies.

Table: Comparison of Population Growth Models

Model	Curve Shape	Equation	Key Feature
Exponential	J-shaped	$\frac{dN}{dt} = rN$	Unlimited growth
Logistic	S-shaped	$\frac{dN}{dt} = rN \left(1 - \frac{N}{K}\right)$	Growth slows near carrying capacity

Table: Levels of Biodiversity

Level	Description	Threats
Genetic	Variation within species	Inbreeding, small populations
Species	Number of species	Extinction, habitat loss
Ecosystem	Variety of ecosystems	Fragmentation, climate change

Key Terms and Definitions

• Biophilia: Human affinity for nature and living things.

• Conservation: Protection and management of biodiversity.

• Ecology: Study of interactions among organisms and their environment.

• Range changes: Shifts in species distributions due to environmental changes.

• Fragmented forests: Large habitats broken into smaller patches.

• Brown-headed cowbird: Example of nest parasitism; lays eggs in other birds' nests.

Additional info: Some examples and case studies (e.g., Costa Rica, red-cockaded woodpecker, flying fox) are referenced for further reading in the textbook or lecture materials.