Chapter 4: Ecosystem and Biodiversity

Princeton

Ecosystem

A system of interconnected elements: a community of living organisms and its environment; result of biotic and abiotic components interacting.

Biotic

Refers to living organisms.

Abiotic

Refers to non-living components.

Evolution

Change in a population’s genetic composition over time; results in biodiversity of all forms.

Phylogenetic Tree

A figure used to model evolution.

Species

A group of organisms that can breed with one another and are incapable of breeding with other species.

Speciation

The formation of new and distinct species in the course of evolution.

Evolutionary Fitness

The ability of individual organisms that are better adapted to their environment to live and reproduce, ensuring their genes are passed to the next generation.

Natural Selection

A process where habitat selects certain organisms to live and reproduce, passing beneficial traits to the next generation.

Survival of the Fittest

The concept that organisms that produce offspring successfully will ensure their continued existence.

Genetic Drift

Changes in allele frequencies over time due to random chance, more pronounced in small populations.

Microevolution

Small-scale changes in a population over a relatively short period of time.

Macroevolution

Large-scale patterns of evolution within biological organisms over a long period of time.

Extinction

Occurs when a species cannot adapt quickly enough to environmental changes, leading to the death of all members.

Biological Extinction

The true extermination of a species; there are no individuals left on the planet.

Ecological Extinction

Occurs when there are too few individuals of a species to perform its ecological function.

Commercial / Economic Extinction

When a few individuals exist, but the cost of harvesting them outweighs the benefits.

Population

A group of organisms of the same species.

Community

Populations of different species occupying the same geographic area.

Niche

The total sum of a species’ use of biotic and abiotic resources in its environment.

Habitat

The area or environment where an organism or ecological community normally lives.

Specialist

A species with a narrow niche that can only live in specific habitats.

Generalist

A species with a broad niche that is highly adaptable and can live in varied habitats.

Competition

Arises when two individuals compete for resources in the environment.

Intraspecific Competition

Competition between two individuals of the same species.

Interspecific Competition

Competition between individuals of different species.

Competitive Exclusion

Phenomenon where one species outcompetes another for resources.

Gause's Principle

No two species can occupy the same niche simultaneously, and the less fit species will relocate or die out.

Realized Niche

The actual niche a species occupies due to competition.

Fundamental Niche

The niche a species would occupy in the absence of competition.

Resource Partitioning

Avoidance of direct competition by using different parts of a habitat.

Predation

Occurs when one species (the predator) feeds on another (the prey), affecting population sizes.

Symbiotic relationship

Close, prolonged associations between different species, which may benefit both, one, or neither.

Mutualism

A symbiotic relationship where both species benefit.

Commensalism

A relationship where one organism benefits and the other is neither helped nor hurt.

Parasitism

A relationship where one species is harmed while the other benefits.

Biomes

Ecosystems based on land.

Ecotones

Transitional areas where two ecosystems meet.

Ecozones / Ecoregions

Smaller regions within ecosystems sharing similar physical features.

Aquatic Life Zones

Ecosystems in aqueous environments categorized by water salinity.

Epilimnion

Uppermost and most oxygenated layer of freshwater.

Hypolimnion

Lower, colder, denser layer of freshwater.

Thermocline

The demarcation line between epilimnion and hypolimnion where temperature shifts dramatically.

Littoral Zone

Shallow water zone where sunlight is abundant and plants grow; ends where rooted plants stop.

Limnetic Zone

Surface of open water extending to where sunlight penetrates, inhabited by short-lived organisms.

Profundal Zone

Deep water zone where sunlight cannot reach; lacking photosynthesizing life.

Benthic Zone

Surface and subsurface layers of water bodies characterized by low temperatures and oxygen levels.

Estuary

Area where freshwater meets saltwater, rich in nutrients and diverse species.

Wetlands

Areas along shores of fresh bodies of water, characterized by temporary and permanent water bodies.

Mangrove Swamp

Coastal wetlands found in tropical and subtropical regions.

Barrier Islands

Landforms off coastal shores created by sediment buildup, acting as buffers.

Coral Reef

A type of barrier island formed from a community of living corals.

Cnidarians

Organisms that create coral reefs by secreting a hard shell.

Coastal Zone

Ocean water closest to land; rich in diversity due to sunlight and nutrient availability.

Euphotic Zone

Warmest and photic upper ocean layers with high levels of dissolved oxygen.

Bathyal Zone

Middle ocean region; colder, darker, less dense of organisms.

Abyssal Zone

Deepest ocean region; cold, low oxygen but high nutrients from decaying matter.

Upwelling

Seasonal movement of nutrient-rich water from the bottom to the surface.

Algal Bloom

Rapid growth of algae populations, can produce toxins affecting aquatic life.

Red Tide

Toxic algal bloom caused by dinoflagellates.

Biogeochemical Cycle

Nutrient cycles that move through the environment.

Reservoir

A large quantity of a nutrient stored for a long time.

Exchange Pool

Site where a nutrient exists for a short time.

Residency Time

Amount of time a nutrient spends in a reservoir or exchange pool.

Law of Conservation of Matter

Matter cannot be created or destroyed.

Precipitation

Water that condenses and falls to Earth due to gravity.

Groundwater

Water that infiltrates and percolates through soil and rock.

Runoff

Water that travels over land to enter bodies of water.

Evaporation

Water returned to the atmosphere from Earth's surface and organisms.

Transpiration

Process of plants releasing water into the air.

Respiration

Process where organisms breathe in oxygen and release carbon dioxide.

Photosynthesis

Process where plants use carbon dioxide, water, and sunlight to create carbohydrates.

Fossil Fuels

Natural resources formed from ancient biological material under heat and pressure.

Carbon Cycle

Cycle that describes the movement of carbon through the environment.

Nitrogen Cycle

Cycle that describes the movement of nitrogen through the environment.

Nitrogen Fixation

Process that converts atmospheric nitrogen into a biological usable form with the help of certain soil bacteria

Nitrification

Soil bacteria convert ammonia into nitrites and nitrates usable by plants.

Assimilation

Process by which plants absorb ammonia, ammonia ions and nitrate iond through their roots.

Ammonification

Decomposing bacteria convert dead organisms and other waste to ammonia (NH3) or ammonium ions (NH4+), which can be reused by plants or volatilized (released into the atmosphere).

Denitrification

Conversion of ammonia back to nitrates and nitrites and then to nitrogen gas and nitrous oxide by specialized bacteria.

Deciduous forest (temperate and tropical)

• Annual Rainfall: 75–250 cm

• Rich soil  with high organic content

Tropical Rainforest

• Annual Rainfall: 200–400 cm

• Poor quality soil

Grasslands

• Annual Rainfall: 10–60 cm

• Rich soil

 Coniferous Forest (Taiga)

• Annual Rainfall: 20–60 cm

• Mostly in summer, soil is acidic due to vegetation

Tundra

• Annual Rainfall: Less than 25cm

• Soil is permafrost

Chaparral (Scrub forest/ Shrubland)

• Annual Rainfall: 50–75 cm

• Mostly in winter, soil is shallow and infertile

Deserts (cold and hot)

• Annual Rainfall: Less than 25 cm

• Soil has a coarse texture

Temperate Rainforest

• Annual Rainfall: Over 140 cm

• Soil richer than that in tropical rainforests

 Savanna

• Annual Rainfall: 10–30 cm almost all in rainy season

• Soil is porous and has only a thin layer of humus

Phosphorus

a major component of nucleic acids, ATP (cellular energy), cell membranes, and other important biological molecules

Phosphorus

found in soil, rock, and sediments; released from rock forms through chemical weathering in the form of phosphate (PO₄^3-), which is soluble and can be absorbed from the soil by plants. 

Mycorrhizae

fungi that have a symbiotic relationship with the roots of a plants, which increases water and nutrient absorption capabilities of plant, while the plant provides the fungi with carbohydrates formed from photosynthesis. 

Eutrophication

occurs when a body of water receives excess nutrients which can cause an overgrowth of algae and deplete the oxygen

Sulfur

One of the components that make up proteins and vitamins; it is absorbed by plants when dissolved in water and taken up through roots and is obtained by animals by consuming it.

Sulfur dioxide (SO₂) ; Hydrogen sulfide (H₂S)

Sulfur enters the atmosphere through human activity, mainly via industrial processes that produce _________ and _____ gasses.

Autotrophs

organisms that can produce their own organic compounds from inorganic chemicals

Heterotrophs

obtain food energy by consuming other organisms or products created by other organisms.

Producers

organisms that are capable of converting radiant energy, or chemical energy, into carbohydrates

Chemosynthesis

process by which a few autotrophs make food from inorganic chemicals in anaerobic environments

Chemotrophs

a specialized bacteria that carries out chemosynthesis; found in hydrothermal vents deep in ocean