Chapter 1: The Living World: Ecosystems

Ecosystem

A community of living (biotic) organisms interacting with the non-living (abiotic) components of their environment as a system through various nutrients and energy cycles.

Organism

A living thing that can function on its own.

Species

Organisms that resemble each other; are similar in genetic makeup, chemistry, and behavior; and are able to interbreed and produce fertile offspring.

Interspecific

Means between different species.

Population

Organisms of the same species that interact with each other and occupy a specific area.

Community

Population of different species.

Ecological Niche

A particular area within a habitat occupied by an organism, as well as the function of that organism within its ecological community.

Physical environment

It influences how organisms affect and is affected by resources and competitors.

Niche

It reflects the specific adaptations that a species has acquired through evolution.

Generalists

Able to survive on a wide variety of food resources

Generalists

Able to withstand a wide range of environmental conditions

Generalists

Live in broad niches

Specialists

Specific/limited number of prey

Specialists

Prone to extinction, sensitive to environmental change

Specialists

Live in narrow niches

Symbiosis

A term used to describe any type of close and long-term biological interaction between two different biological organisms of the same or different species.

Amensalism

The interaction between two species whereby one species suffers and the other species is not affected.

Commensalism

The interaction between two species whereby one organism benefits and the other species is not affected.

Competition

It can be either intraspecific and interspecific. It is the driving force of evolution whether it is for food, mating partners, or territory.

Intraspecific

Competition between members of the same species.

Interspecific

Competition between members of different species.

predator–prey relationships

Competition is prominent in ________, with the predator seeking food and the prey seeking survival.

Mutualism

The interaction between two species whereby both species benefit.

Parasitism

The interaction between two species whereby one species is benefited, and the other species is harmed.

Opportunistic predators

These predators kill and eat almost anything.

Specialist predators

These predators only prey upon certain organisms.

Saprottrophism

Saprotrophs obtain their nutrients from dead or decaying plants or animals through the absorption of soluble organic compounds.

Law of Tolerance

It states that the existence, abundance, and distribution of species depend on the tolerance level of each species to both physical and chemical factors.

Limiting Factor

Any abiotic factor that limits or prevents the growth of a population.

**Predator-prey cycles**

**These** are based on a feeding relationship between two species:

* If the prey species rapidly multiply, the number of predators increases until the predators eventually eat so many of the prey that the prey population dwindles again.

Morphological partitioning

It occurs when two species share the same resource but have evolved slightly different structures to utilize the same resource

Spatial partitioning

It occurs when competing species use the same resource by occupying different areas or habitats within the range of occurrence of the resource

Temporal partitioning

It occurs when two species eliminate direct competition by utilizing the same resource at different times

Biomes

These are major regional or global biotic communities characterized by dominant forms of plant life and the prevailing climates

*average air temperature*

*amount of rainfall*

The geographical distribution of the various terrestrial biomes is controlled primarily by the *______* and the *_______* the biome receives.

Deserts

Defined in terms of the amount of rainfall they receive, not temperature.

Deserts

They cover about 20% of Earth’s surface and occur where rainfall is less than 20 inches (50 cm) per year.

Arctic tundra

It is a cold desert due to the low amount of rainfall it receives yearly.

Succulents

Plants that have fleshy leaves or stems that store water.

Cactus

• They have sharp spines that create shade, reduce drying airflow, discourage herbivores and reflect sunlight.

• They also secrete toxins into the soil to prevent interspecific completion.

Wildflowers

• They are dependent on water for germination;

• They have short life spans;

• They perform their entire life cycle from seed to flower to seed within a single growing season

Desert animals

• They are generally small.

• They are often nocturnal.

• They have small surface areas.

• They spend time in underground burrows where it is cold.

Aestivation

A summer hibernation.

Forests

It cover about one-third of Earth's land surface, mostly in North America, the Russian Federation, and South America, and account for 75% of gross primary productivity and plant biomass.

Ecozones

_____ like boreal forests near the poles and tropical forests near the equator are formed by forests at different latitudes and elevations.

Closed canopy

Tree crowns cover more than 20% of the ground’s surface.

Open canopy

Tree crowns cover less than 20% of the ground surface.

Tropical Rainforests

• Animals include numerous birds, bats, small mammals, and insects.

• Decomposition is rapid and soils are subject to heavy leaching.

• Distinct seasonality where winter is absent and only two seasons are present.

Tropical Rainforests

• The length of daylight is 12 hours and varies a little year-round

• Large diversity of species.

• Occur near the equator.

• Annual rainfall exceeds 80 inches (200 cm) and is evenly distributed.

• Plants are highly diverse.

Tropical Rainforests

• Tree canopy is multilayered and continuous, allowing little light penetration.

• Trees have buttressed trunks, shallow roots, and large, dark green leaves.

**Overstory**

The uppermost trees in a forest.

**Understory**

Layer made up of young trees, short species of trees, shrubs, and soft-stemmed plants.

Temperate Deciduous Forests

• Occur in eastern North America, northeastern Asia, and western and central Europe.

• Have a distinct winter, moderate climate, and a 140–200-day growing season during four to six frost-free months.

Temperate Deciduous Forests

• Temperature varies from –20°F to 85°F (–30°C to 30°C).

• Precipitation averages 30–60 inches (75–150 cm) per year.

• Fertile soil is enriched by decaying leaf litter.

Temperate Deciduous Forests

The tree canopy allows light to penetrate, resulting in well-developed and diverse understory vegetation and animal stratification.

Temperate Coniferous Forest

• Found in temperate regions with warm summers, cool winters, and enough rainfall to support forests.

• Common in coastal areas with mild winters and heavy rainfall, or inland in drier climates or mountains.

Temperate Coniferous Forest

• These forests have cedar, cypress, fir, juniper, pine, redwood, and spruce.

• These forests have two layers:

  • Overstory

  • Understory

• Some forests have a shrub layer.

Temperate Coniferous Forest

• In winter, when food is scarce, many animals hibernate to conserve energy and build fat in summer.

• Birds have feathers and many animals have thick fur to protect them from cold weather.

• Some animals migrate to warmer climates during the winter months.

Taiga

Largest terrestrial biome; found in northern Eurasia, North America, Scandinavia, and two-thirds of Siberia.

Southern Taiga

Also known as *boreal forest*, consists primarily of cold-tolerant evergreen conifers with needle-like leaves, such as pines, spruces, and larches.

Northern Taiga

It is more barren as it approaches the tree line and the tundra biome.

Grasslands

These are characterized as lands dominated by grasses rather than by large shrubs or trees.

Savannas

These are grasslands with scattered individual trees and cover almost half the surface of Africa and large areas of Australia, South America, and India.

Temperate Grasslands

Here grasses are the dominant vegetation, while trees and large shrubs are absent.

Tundra

It has extremely low temperatures, large repetitive population changes, limited soil nutrients, little precipitation, low biotic diversity, poor drainage, short growing and reproductive seasons, and simple vegetation structure.

Arctic tundra

Due to the ________’s unique conditions, the biota is highly specialized and sensitive to environmental change.

Arctic tundra

It circles the North Pole and extends south to the taiga, is cold, dry, and desert-like.

Permafrost

A layer of permanently frozen subsoil.

Alpine tundra

It is located on mountains throughout the world at high altitudes where trees cannot grow.

Aquatic Biomes

Antarctic, marine, lakes, wetlands, and rivers

Antarctica

It has the coldest climate on Earth.

ice sheet

It is formed from compressed snow that rarely melts.

Krill

These are key food sources in this ecosystem and serve as food for many predators.

75%

Oceans cover approximately ____ of Earth’s surface and have a salt concentration of about 3%.

Evaporation

______ of seawater is the primary source of most of the world’s rainfall.

Convection

The circular motion that occurs when warmer air or liquid rises, while the cooler air or liquid sinks.

conveyor belt

Thermohaline currents drive a "_____" of ocean water that moves constantly, unlike most surface currents, which are driven by winds.

Littoral Zone

Also known as the *intertidal zone*, it is the part of the ocean that is closest to the shore.

Neretic Zone

Also known as the *sublittoral zone*, this zone extends to the edge of the continental shelf.

Photic Zone

The uppermost layer of water in a lake or ocean that is exposed to sunlight down to the depth where 1% of surface sunlight is available.

Photic Zone

The layer just above the depth where the rate of carbon dioxide uptake by plants is equal to the rate of carbon dioxide production by animals.

Corals

These are marine invertebrates that typically live in compact colonies of many identical individual polyps.

Polyps

Small, sac-like animals with a set of tentacles surrounding a central mouth opening and an exoskeleton made of calcium carbonate at the base.

zooxanthellae

Most corals obtain the majority of their energy and nutrients from photosynthetic unicellular dinoflagellates, commonly known as _______, that live within their tissues.

Fringing reefs

• They grow near the coastline around islands and continents and are separated from the shore by narrow, shallow lagoons.

• They are the most common type of reef.

Barrier reefs

• These are also parallel to the coastline but are separated by deeper, wider lagoons.

• At their shallowest point, they can reach the water’s surface, forming a “barrier” to navigation.

Atolls

• These are rings of coral that create protected lagoons and are usually located in the middle of the sea.

• They usually form when islands, often the tops of underwater volcanoes, surrounded by fringing reefs, sink into the sea, or the sea level rises around them.

Lakes

These are large natural bodies of standing freshwater formed when precipitation, runoff, or groundwater seepage fills depressions in Earth’s surface.

Artificial lakes

These are constructed for hydroelectric power generation, recreational purposes, industrial and agricultural use, and/or domestic water supply.

Benthic Zone

The bottom of lake, organisms can tolerate cool temperatures and low oxygen levels.

Limnetic Zone

A well-lit, open surface water, farther from shore, extends to a depth penetrated by light, occupied by phytoplankton, zooplankton, and higher animals; produces food and oxygen that supports most of a lake’s consumers

Littoral Zone

It is shallow, close to shore, extends to depth penetrated by light; rooted and floating plants flourish

Profundal Zone

It is deep, no-light regions, too dark for photosynthesis; low oxygen levels; inhabited by fish adapted to cool, dark waters

Oligotrophic (Young Lake)

Deep, cold, small surface area relative to depth; nutrient-poor, phytoplankton are sparse; not very productive; doesn’t contain much life; waters often very clear; and sediments are low in decomposable organic matter.

Mesotrophic (Middle-Aged Lake)

Moderate nutrient content and moderate amounts of phytoplankton; reasonably productive.

Eutrophic (Old Lake)

Shallow, warm, large surface area relative to depth; Waters often murky;

stratification

The ______ or layering of water in lakes is the result of density changes caused by shifts in temperature.

hypolimnion

Deep water is insulated from the sun and stays cool and denser, forming a lower layer called the _______.

Seasonal turnover

_______ refers to the exchange of surface and bottom water in a lake or pond that happens twice a year.

Fall Turnover

• With the arrival of fall and cooler air temperatures, water at the surface of a lake begins to cool and becomes heavier.

• During this time, strong fall winds move the surface water around, which promotes mixing with deeper water.