Ecology: Biomes, Trophic Interactions, and Population Dynamics

What is ecology?

The scientific study of interactions between organisms and the environment.

What primarily determines an ecosystem?

Climate, particularly temperature and precipitation; soil and elevation also affect its organisms.

What is weather?

Short-term atmospheric conditions over hours or days.

What is climate?

Long-term prevailing weather conditions in an area.

What is macroclimate?

Climate patterns at global, regional, or landscape scales.

What is microclimate?

Fine-scale climate conditions, such as those beneath a fallen log.

What is a biome?

A major life zone characterized by vegetation or physical environment, strongly influenced by climate.

What determines the distribution of terrestrial biomes?

Temperature and precipitation, including how they vary through the year.

Which biomes are named on the biome map?

Tropical forest, savanna, desert, chaparral, temperate grassland, temperate broadleaf forest, coniferous forest, arctic tundra, high mountains, and polar ice.

How do latitude and elevation affect biomes?

Changes in sunlight and temperature across latitude and elevation affect vegetation and biome patterns.

What is a food chain?

A sequence of food transfers between trophic levels.

What is a food web?

A network of interconnected food chains within a community.

What is trophic structure?

The feeding relationships among species in a community.

What is a producer or autotroph?

An organism that makes organic food and supports other trophic levels.

What is a primary consumer?

An herbivore that eats producers.

What is a secondary consumer?

A carnivore that eats primary consumers.

What is a scavenger?

An organism that feeds on carcasses, such as a crow or vulture.

What is a detritivore?

An organism that consumes dead organic material, such as an earthworm or millipede.

What is a decomposer?

An organism, such as a fungus or prokaryote, that breaks down organic matter.

What is predation?

A + / - interaction in which a predator kills and eats prey.

What is cryptic coloration?

Camouflage that helps prey hide from predators.

What is warning coloration (aposematism)?

Bright coloration signaling an effective chemical defense.

What is mimicry?

A defensive resemblance in which one species looks like another.

What is mutualism?

A + / + interaction in which both species benefit.

What is commensalism?

A + / neutral interaction in which one species benefits and the other is unaffected or the effect is unknown.

What is interspecific competition?

A - / - interaction in which different species compete for resources.

What is the competitive exclusion principle?

Species with ecological niches that are too similar cannot coexist in the same place indefinitely.

What is a parasite?

An organism living in or on a host from which it obtains nutrients.

What is a pathogen?

An agent that causes disease.

What is symbiosis?

An ecological relationship between species living in close proximity.

What is convergent evolution in biomes?

Similar traits can arise in organisms in distant biomes with similar conditions.

What is a population?

Individuals of the same species living in the same general area.

What is a community?

Interacting populations living in the same area.

What is an ecosystem?

One or more communities plus the abiotic environment.

What is demography?

The statistical study of populations to predict population changes.

What are the three key population features?

Size, density, and dispersion.

What is population size?

The number of individuals in an area.

What is population density?

Number of individuals per unit area or volume.

How do you calculate population density?

Number of individuals divided by the unit of space.

What is dispersion?

The spacing of organisms relative to one another.

What are the three dispersion patterns?

Clumped, uniform, and random.

What is immigration?

Movement of individuals into a population.

What is emigration?

Movement of individuals out of a population.

What increases population size?

Births and immigration.

What decreases population size?

Deaths and emigration.

How do you calculate natural increase?

Birth rate (b) minus death rate (d) equals r.

How do you calculate change in population size?

Births minus deaths plus immigration minus emigration.

What are density-dependent factors?

Factors whose effects increase with population density, such as disease, competition, and parasites.

Give examples of density-dependent limits.

Limited food or shelter, toxic waste, infectious disease, predation, stress, and emigration.

What are density-independent factors?

Factors that affect populations regardless of density, such as storms, floods, and earthquakes.

Give examples of density-independent limits.

Severe storms, flooding, extreme cold, earthquakes, volcanoes, and meteorite impacts.

What is exponential population growth?

Rapid accelerating population growth represented by a J-shaped curve.

What is logistic population growth?

Population growth that slows and levels off near carrying capacity, forming an S-shaped curve.

What is carrying capacity (K)?

The maximum population size supported by available resources.

What causes negative feedback on population growth?

Resource limitation in crowded populations reduces reproduction and slows growth.

What is intraspecific competition?

Competition among members of the same species.

What is a survivorship curve?

A graph showing the number of individuals in a cohort still alive at each age.

What describes Type I survivorship?

Most survive early and middle life; mortality rises late in life. Example: humans.

What describes Type II survivorship?

A roughly constant mortality rate across ages. Example: squirrels.

What describes Type III survivorship?

High mortality early in life. Example: oysters.

What are r-strategist traits?

Short lifespan, small body, rapid reproduction, many young, little parental care.

What are K-strategist traits?

Long lifespan, large body, slow reproduction, few young, parental care.

Give examples of r-strategists.

Cockroaches, weeds, and bacteria.

Give examples of K-strategists.

Humans and elephants.

What is age distribution?

The distribution of males and females among age groups, used to predict population growth.

What growth pattern does the human population lecture emphasize?

J-curve growth; the lecture also discusses cultural, agricultural, and industrial-medical changes.

What is soil made of?

Minerals from rock, water, organic matter, air spaces, and living organisms.

What mineral particle types are found in soil?

Sand, silt, and clay.

What do soil pores contain?

Air or water.

What soil composition percentages are shown on the slide?

48% mineral particles, 25% air, 25% water, and 2% organic matter.

What are the three key processes of soil formation?

Weathering, accumulation of organic matter, and transformation of organic matter.

What five factors influence soil formation?

Climate, organisms, topography, parent material, and time.

What is parent material?

The original geological material from which soil forms.

What is bedrock?

The continuous mass of solid rock forming part of Earth's crust.

What is weathering?

Physical or chemical breakdown of rock.

What is erosion?

Transport of weathered particles by water, ice, or wind.

Give examples of physical weathering.

Heating and cooling, water/ice/wind abrasion, and actions of plants and animals.

Give examples of chemical weathering.

Hydrolysis, hydration, acid weathering, and oxidation.

What is the O soil horizon?

Surface organic layer.

What is the A soil horizon?

Topsoil, important for agriculture and soil life.

What is the E soil horizon?

A layer where materials have been leached out.

What is the B soil horizon?

Subsoil.

What is the C soil horizon?

Parent material.

What is the R soil horizon?

Bedrock.

What are ecosystem services of soil?

Habitat, air quality, temperature regulation, carbon and nutrient cycling, water cycling and quality, and decomposition.

Why does soil matter for air quality?

Well-covered soil resists erosion and reduces airborne dust.

How does soil support carbon and nutrient cycling?

It stores carbon and influences carbon, nitrogen, phosphorus, and other materials.

How much carbon does soil store compared with plants according to the lecture?

Nearly five times as much carbon as the plants growing in it.

How does soil help water quality?

Soil particles and organisms help retain, process, and filter water.

How does soil provide habitat?

It supplies a growing environment, nutrients, water, and habitat for organisms.

What is one environmental consequence of expanding farmland?

Farmland replaces forests and grasslands, affecting natural ecosystems.

What agricultural change raised yields according to the slides?

A combination of agricultural technologies increased yields and reduced pressure to expand cropland.

What is a GMO?

A living organism whose genetic material has been artificially manipulated through genetic engineering.

What GMO traits are highlighted in the slides?

Herbicide tolerance, insecticide production, and reduced browning in apples.

What GMO concern is raised in the slides?

Questions about herbicide use and claimed environmental, yield, or nutritional benefits.What is ecology? The scientific study of interactions between organisms and the environment.

What primarily determines an ecosystem?

Climate, particularly temperature and precipitation; soil and elevation also affect its organisms.

What is weather?

Short-term atmospheric conditions over hours or days.

What is climate?

Long-term prevailing weather conditions in an area.

What is macroclimate?

Climate patterns at global, regional, or landscape scales.

What is microclimate?

Fine-scale climate conditions, such as those beneath a fallen log.