Ecology Flashcards

A food chain is a single linear energy pathway; a food web is a network of interconnected food chains showing all feeding relationships in an ecosystem.

Only ~10% of energy at one trophic level transfers to the next; the rest is lost mainly as heat from respiration.

Primary succession starts on bare substrate with no soil (e.g., after volcanic eruption); secondary succession starts where soil remains after a disturbance, so it proceeds faster.

First colonizers in primary succession (e.g., lichens, mosses) that break down rock into soil and enable later species to establish.

Exponential growth (J-curve) is unlimited (dN/dt = rN). Logistic growth (S-curve) slows as the population approaches carrying capacity K (dN/dt = rN[(K-N)/K]).

The maximum population size an environment can sustain indefinitely given available resources.

Factors whose impact increases with population density (e.g., competition, predation, disease).

Factors that affect populations regardless of density (e.g., natural disasters, extreme weather, pollution).

Biotic factors are living components (organisms, interactions). Abiotic factors are non-living components (temperature, water, sunlight, soil pH).

Mutualism (both benefit), commensalism (one benefits, other unaffected), and parasitism (one benefits, other harmed).

A species with a disproportionately large ecological impact relative to its abundance (e.g., sea otters preventing urchin overgrazing of kelp).

Photosynthesis removes CO2 from the atmosphere and fixes it into organic molecules; cellular respiration releases CO2 back.

N2 has a strong triple bond. Nitrogen-fixing bacteria (e.g., Rhizobium) must convert it to ammonia or nitrate before plants can use it.

GPP is total energy fixed by producers; NPP = GPP minus producer respiration, representing energy available to consumers.

The full range of conditions and resources a species uses to survive and reproduce, including habitat, diet, and interactions.

Two species competing for the same limited resources cannot coexist indefinitely; one will outcompete the other or they must partition resources.

Progressive increase in concentration of persistent toxins (e.g., DDT, mercury) at each higher trophic level in a food chain.

High year-round temperatures, heavy rainfall (200-400+ cm), extremely high biodiversity, stratified vegetation layers, and nutrient-poor soil.

Extremely cold temperatures, low precipitation, permafrost, short growing season, low biodiversity, and no trees.

r-selected: many small offspring, little parental care, thrive in unstable environments. K-selected: few large offspring, extensive care, thrive near carrying capacity.

Evaporation, transpiration, condensation, precipitation, infiltration, and runoff, driven by solar energy.

Phosphorus has no significant atmospheric phase. It cycles through rock weathering, soil uptake by plants as phosphate, food chains, and decomposition.

A change at one trophic level that ripples through others (e.g., wolves reducing elk, allowing vegetation recovery in Yellowstone).

Population: same species in one area. Community: all species interacting in an area. Ecosystem: community plus abiotic factors, linked by energy flow and nutrient cycling.

Excess nutrient runoff (N, P) causes algal blooms; decomposition of dead algae depletes oxygen, creating dead zones that kill aquatic life.