Module 1, p1

Community ecology

Study of interactions among species.

Symbiosis

Close, long-term association between two species in an ecosystem.

Abiotic factors

Nonliving conditions such as temperature, rainfall, and nutrients.

Biotic factors

Living organisms like plants, animals, fungi, and bacteria.

Ecosystem boundaries

Divided by biotic and abiotic components or by human definitions.

Climate influence

Local temperature and precipitation determine ecosystem type.

Soil water

Amount present controls whether trees or grasses dominate.

Cave ecosystem

System with distinct boundaries, unique species, and defined stream flow.

Cave energy source

Bat feces provide nutrients for invertebrates and salamanders.

Aquatic ecosystems

Defined by land-water boundaries, such as lakes or streams.

Subjective boundaries

Often based on species ranges or topography rather than strict edges.

Managed ecosystems

Areas defined by human decisions, such as national park borders.

Yellowstone example

Park's original borders too small to manage species like grizzly bears.

Greater Yellowstone Ecosystem

Expanded 20 million ha region beyond park's administrative boundaries.

Small ecosystems

Tiny systems like tree holes support microbes and aquatic insects.

Ecosystem interactions

Exchange of energy and matter between adjacent systems.

Biosphere

Earth's 20-km layer where life exists between ocean bottom and mountain peaks.

Competition

Struggle of individuals or species to obtain limited resources.

Gause experiment

Two Paramecium species grown together showed one outcompeted the other.

Competitive exclusion principle

Two species cannot coexist if competing for the same limiting resource.

Goldenrods

Dominate New England fields due to superior ability to capture sunlight.

Wild oat

Plant that outcompetes crops by germinating earlier on Great Plains.

Resource partitioning

Species reduce overlap by dividing resources through traits or behaviors.

Temporal partitioning

Use of the same resource at different times of day or year.

Spatial partitioning

Use of different habitats or root depths to minimize overlap.

Morphological partitioning

Evolution of body differences, such as beak shapes in finches.

Wolves and coyotes

Reduce conflict by hunting during different times of day.

Flowering time

Plant species avoid competition for pollinators by blooming at different seasons.

Desert roots

Different root systems allow plants to access water at varying depths.

Black grama grass

Shallow roots spread widely to capture rainfall near soil surface.

Tarbush

Deep roots reach underground water sources in desert regions.

Darwin's finches

Single ancestor evolved into many species specialized for different foods.

Large ground finch

Specialized on cracking large seeds.

Small ground finch

Adapted to eat small seeds.

Woodpecker finch

Uses its beak to feed on insects.

Vegetarian finch

Consumes plant buds as main food source.