Ecology Basics

Ecology Basics

• Ecology is the study of interactions between organisms and their environment.
• The four basic levels of ecological research are organismal, population, community, and ecosystem.

Abiotic vs. Biotic

• Biotic components include all living organisms and their interactions.
• Abiotic components are non-living physical and chemical factors like water, soil, sunlight, and temperature.
• Living organisms rely on non-living things for survival.
• Abiotic factors are, in turn, affected by biotic factors.

Ecological Organization

• A population is the number of people or inhabitants in a country or region.
• A community is all the different populations of living organisms in a specific area.
• An ecosystem is a system formed by living organisms and their physical environment interacting as a functional unit.
• Biogeography is the study of the geographical distribution of plants and animals.
• Flora refers to the plants of a particular region or period.
• Fauna refers to the animals of a particular region or period.
• A biome is a large geographical area characterized by specific plant and animal life.
• Endemic refers to a species confined to a specific area, found nowhere else.

Abiotic Factors & Distribution

• Abiotic factors affecting the global distribution of plant and animal species include temperature, water availability, sunlight, soil type, and wind.
• Aquatic ecosystems are shaped by salinity, water flow, and depth.
• Terrestrial environments are influenced by temperature, sunlight, and soil type.
• Temperature and precipitation determine terrestrial biome types.
• Temperatures, precipitation patterns, and dominant vegetation distinguish the characterized biomes.
• Abiotic factors determine which species can survive and thrive in specific areas of aquatic biomes.

Ocean Zones

• Intertidal Zone: Area along the coastline covered and exposed by tides, marked by changing salinity and temperature.
• Neritic Zone: Shallow, coastal ocean above the continental shelf, with abundant sunlight and nutrients.
• Pelagic Zone: Open ocean water column, from the surface to the deepest parts.
• Abyssal Zone: Deepest part of the ocean, with extreme pressure, darkness, and cold temperatures.

Freshwater Biomes & Estuaries

• Freshwater biomes have low salt content.
• Estuaries are transitional zones where freshwater meets saltwater.

Population Size & Density

• Population size (N) is the total number of individuals in a population.
• Population density is the number of individuals per unit area or volume.
• Ecologists measure size and density through techniques like quadrat sampling for stationary organisms and mark-recapture methods for mobile ones.

Population Distribution

• Clumped distribution: individuals grouped.
• Uniform distribution: individuals evenly spaced.
• Random distribution: individuals scattered with no pattern.

Demography

• Demography is the study of the size, structure, and distribution of populations, and how they change over time due to births, deaths, migration, and aging.
• Three factors that change populations over time are birth rates, death rates, and migration.

Survivorship Curves

• Type I: high survival until late age.
• Type II: constant mortality rate.
• Type III: high early mortality, followed by higher survival.

Fecundity & Parental Care

• Fecundity is the potential number of offspring an organism can produce.
• Fecundity is often inversely related to the amount of parental care provided.

Life History

• Focuses on the timing, quantity, and frequency of key life events like reproduction and survival.
• Some species prioritize early reproduction with many offspring, while others focus on later reproduction with fewer, larger offspring, and parental care.
• Semelparity is often favored in harsh environments
• Iteroparity often favored in more stable environments.
• Two types of reproductive strategies: iteroparity versus semelparity
• Exponential growth depicts rapid, unlimited population increase.
• Logistic growth acknowledges resource limitations, leading to a leveling off at the carrying capacity, resulting in an S-shaped curve.
• Carrying capacity of a habitat may change due to increased food supply, habitat destruction, or natural disasters.
• Density-dependent growth regulation limits population growth based on population density.
• Density-independent regulation affects populations regardless of their density.
• Competition and disease are examples of density-dependent regulation.
• Natural disasters are examples of density-independent regulation.

Community Interactions

• A community is the effect that a pair of organisms living together have on each other.
• Mechanical defenses: thorns or shells.
• Chemical defenses: toxins or bad tastes.
• Behavioral defenses: camouflage or mimicry.
• Two species can't coexist if they occupy exactly the same niche.

Niche

• The specific role and position a species has within its environment, including how it interacts with biotic and abiotic factors.

Symbiotic Relationships

• Clownfish and sea anemones: mutualism.
• Remoras and sharks: commensalism.
• Tapeworms and their hosts: parasitism.

Community Structure

• Species create or modify habitats, influencing the physical environment and thus the structure and function of the entire community.
• Positive interactions where one species benefits another, potentially creating new habitats or reducing stress, and plays a crucial role in shaping community composition and biodiversity.
• Keystone species have a disproportionately large impact on the structure and function of the community.
• Invasive species can significantly alter community structure by disrupting ecological interactions.
• Succession describes the predictable changes in community structure over time, driven by disturbances or habitat formation.

Biodiversity

• Crucial for healthy ecosystems and human well-being, providing resources, regulating vital processes, and supporting resilient communities.
• Two measures of biodiversity are species richness and species evenness.

Invasive Species

• Factors include resilience to environmental changes, ecosystem services, food security, and livelihoods.
• Non-native organisms that, when introduced to a new environment, can cause significant harm to ecosystems, economies, and human health.

Ecological Succession

• Primary succession occurs on newly formed or exposed land lacking soil.
• Secondary succession happens in areas where soil exists but vegetation has been disturbed or removed.

Ecosystem Types

• Basic ecosystem types are terrestrial and aquatic.
• Food chains represent a single, linear path of energy transfer in an ecosystem.
• Food webs show the interconnected, complex relationships between multiple food chains.
• The different trophic levels found in an ecosystem are producers (plants), followed by primary consumers (herbivores), secondary consumers (carnivores/omnivores), and potentially tertiary and quaternary consumers.

Energy Transfer

• The process of energy being moved from one place or form to another, either by mechanical work, electrical work, heating, or radiation.
• Coastal ecosystems support diverse life, provide essential resources and services, and help regulate the global climate.
• Predation by higher trophic levels affect the accumulation of biomass at lower trophic levels.