Ecology

Abiotic Factors

Non-living elements of an ecosystem like temperature, water, light

Biotic Factors

Living elements of an ecosystem

Things like plants, animals, etc

Species

A group that can interbreed and have viable, fertile offspring

Population

A specific species living in a specific location

Habitat def

The type of environment where a specific organism lives

• Includes other biotic and abiotic factors

Ecological Community

All the populations in a specific geographic area

Ecosystem

System of all the organisms (biotic factors) in an ecological community and their interactions with the abiotic factors

Density Dependent Factors

• Examples

Depend on population density

• Disease, resources, competition

Density independent factors

Climate, weather

Biome

A large area of land or water defined by its biotic factors, which are adapted to the climate and geography of that region

Ecological Niche

A species’ unique position and role within its ecosystem

• Defines how the species interacts with its environment and other species to survive and reproduce successfully

Fundamental Niche

Encompasses the full range of ecological conditions in which a species could theoretically survive

Realized Niche

The environment in which the species actually lives

Gause’s Law → Competitive Exclusion Principle

Gause’s law (competitive exclusion principle):

Two species cannot occupy the same niche and maintain

their population levels

One species will out-compete the other

Resource Partitioning

Resource partitioning: Species may coexist by utilizing resources in different ways, at different times, or in different places

Competition

Two species or individuals compete for the same resources

Intraspecific Competition

Members of the same species compete for resources

• Ex: Two giraffes competing for leaves

Interspecific competition

Individuals from different species compete for resources

• Ex: Lions and hyenas hunting the same prey species

Exploitation Competition

Indirect competition that occurs when resources are depleted

• Ex: Leopards deplete the warthog population, leaving less available for tigers

Apparent Competition

Apparent competition: Indirect competition that occurs between two species of prey that share a common predator

• Ex: Increased warthog population allows for increased leopard population, which increases antelope predation

Interference Competition

Interference competition: Occurs when one species directly prevents the establishment of another that would compete for mutual resources

Allelopathy

Plants that secrete toxic chemicals

Symbiosis

A close, long-term interaction between two organisms (symbionts)

Mutalism

Both organisms benefit

Ex: Oxpecker birds eating ticks off of a rhino

Commensalism

Commensalism (+/0): One organism benefits and the other is unaffected

• Ex: Barnacles attach to whales and filter feed

Parasitism

One organism benefits at the other’s expense

• Ex: Ticks feed off of a dog’s blood

Food chain

Linear depiction of what eats what

• Ex: Carrot → rabbit → fox → lion

Food Web

More complex diagram depicting interconnections between food chains

Trophic Level

An organism’s position within a food chain or food web

Ecological Pyramid

Graphical representation of the accumulation of biomass at each trophic level

Autotrophs

Autotrophs: Produce organic compounds from abiotic factors (sunlight, water, CO2, etc.)

Heterotrophs:

Must ingest organic compounds to generate energy and survive

Predation def

• Predation: Relationship between predator (hunter) and prey (hunted - plant or animal)

Herbivore

• what makes their digestion different

• Herbivore: Organism that eats plants

• Has a long intestinal tract and cecum to digest plants

Carnivore

• Organism that eats meat

Omnivore

Organism that eats plants and meat

Invasive Species

Non-native species that outcompetes native species and overtakes the ecosystem

Non-invasive species

Non-native species that survives in but does not overrun the ecosystem

Naturalized species:

Non-native species that spreads beyond its origin and reproduces sufficiently to maintain its population

Exotic Species

Non-native species that lives outside of its native distributional range due to human activity

Primary Producers

The lowest trophic level

• Autotrophs undergoing energy production to generate the biomass of an ecosystem

• Consumers eat producers and other consumers

Primary Consumers

Just above primary producers

• Often herbivores

Secondary consumers

Prey on primary consumers

• Carnivores

Tertiary Consumers

Prey on secondary consumers

• Carnivores

Apex Predator

At the top of the food chain

• Tertiary consumer or higher

Movement of energy moving through trophic levels.

• Only 10% of energy stored in a given trophic level is converted into organic tissue in the next trophic level

• 90% of energy stored in a given trophic level is lost as heat due to inefficient energy transfer

Scavengers

Consume dead plants or animals

Decomposers

Break down and recycle material from dead organisms

• Fungi (saprophytes)

• Worms (detritivores)

Detritus

Decaying organic matter

Photoautotrophs

• Energy source

• Carbon Source

• Energy source: Light

• Carbon Source: CO2

Chemoautotrophs

• Energy source

• Carbon Source

• Energy source: Inorganic Compounds

• Carbon Source: CO2

Photoheterotrophs

• Energy source

• Carbon Source

• Energy source: Light

• Carbon Source: Organic Compounds

Chemoheterotrophs

• Energy source

• Carbon Source

• Energy source: Organic Compounds

• Carbon Source: Organic Compounds

Autotrophs

• How do they get their carbon

They can fix carbon.

Use inorganic CO2 as primary carbon source.

Heterotrophs

• How do they get their carbon

Derive their carbon from organic compounds

Population Dynamics

Population dynamics: The study of how populations change in space and time and how they interact with their environment

Biotic Potential

A species’ ability to achieve its highest population growth

• Occurs when conditions are ideal

• Highest birth rates and lowest death rates

Carrying Capacity

The maximum population size an ecosystem can sustain

Principle of Population Theory

Any living species increases exponentially while food production increases linearly

• Food production will not be able to keep up with population growth

• Proposed by Thomas Malthus

K - selected species

• Population size

• Reproductive rates

• Parental care

• Length of development and gestation

• Survival rates

• Offspring amounts

• Example species

K-selected species: Type I survivorship curves

• Produce fewer offspring with higher survival rates

• Long gestation periods with slow development and late maturation

• High parental care and investment in offspring to ensure survival and competitive success

• Population size is relatively stable and near the carrying capacity

  • Ex: Elephants, humans

R - selected species

• Reproductive rates

• Parental care

• Length of development and gestation

• Survival rate

• Offspring amounts

• R-selected species:

  • Type III survivorship curve

• Produce more offspring with lower survival rates

• High number of offspring ensures some survive

• Short gestation periods with quick development and early maturation

• Low parental care in unstable environmental conditions

R selected species polpulation size

• Population densities are well below carrying capacity of the enviroment.

• Example species

• Population size fluctuates wildly

• Population densities are well below carrying capacity of the environment

• Ex: Insects, frogs

Type II survivorship species

• Mortality rate is roughly constant throughout the organism’s life span

• Survival chances do not significantly increase or decrease at any stage of life

• Ex: Many birds, small mammals, and some reptiles

Ecological Succesion

Ecological Succession

The predictable change and development of an ecological community over time

• Occurs primarily in new habitats or after a disturbance

• There are primary and secondary succession patterns

Primary Succession

• Example

• What causes it to occur

Occurs after a large disturbance in an area that has never supported life

EX: An example of a large disturbance is a volcanic eruption

What kicks of the of primary succession areas?

• Example

Pioneer species

• EX: Lichen, fungi, algae

Order of colonization species for primary succession

Pioneer species → thin soil → vascular plants (e.g., grasses, shrubs) → larger plants (e.g., trees) → animals

Climax Community

End result of primary succession

• A steady state is reached and a balance of species is achieved

Secondary Succesion

• What are the disasters that cause it.

Occurs on terrain that has previously supported life and has experienced destruction following a disturbance

• Examples of such disturbances include floods and fires.

Colonization pattern of secondary succesion

Secondary succession begins with grasses and shrubs (i.e, vascular plants)

Keystone Species:

Maintain ecological balance, even when abundance is low

Examples:

• African elephants (landscape remodeling)

• Wolves (elk population control)

• Beavers (wetland creation)

Keystone Predators

Hunt animals and prevent overabundance

Eutrophication

The process by which a body of water becomes enriched with minerals and nutrients

Algal Bloom

• What causes it

A rapid increase in the population of algae and/or cyanobacteria, commonly resulting from eutrophication

• Algae: Photosynthetic eukaryotes

• Cyanobacteria: Photosynthetic prokaryotes

What do algae blooms cause?

• Algal bloom leads to the depletion of oxygen in the water, causing the death of aerobic organisms in the area (e.g., fish)

• The death of these organisms damages the natural aquatic ecosystem

Common cause of eutrophication

• Industrial nitrogen-rich fertilizer is a common cause

• Dissolves in rainwater and accumulates in an aquatic biofilm, supporting the algal bloom

Aquatic Biomes take up how much of the earth’s surface?

75%

What type of phtosynthetic organism contributes the most to earth’s atmospheric O2

Photosynthetic algae

Split of freshwater and saltwater

Divided into freshwater biomes (~3%) and saltwater biomes (~97%)

Ocean Layers

• Euphotic zone

• Littoral zone

• Disphotic Zone

• Aphotic Zone

Euphotic Zone

Euphotic zone: Closest to the surface, where strong irradiance allows plant survival and photosynthesis

ELDA

Littoral Zone

Where Sunlight penetrates all the way to the ocean floor (very shallow)

Disphotic Zone

Semi-irradiated with sun

• Insufficient sun to support vegetation

• Bioluminescent species live here and produce light

Aphotic Zone

• Aphotic zone: No light or photosynthetic species

• Some bioluminescent species

• Select fish can survive off of dead matter descending to the ocean floor

Tropical Rainsforest

• Temperature

• Rainfall

• Fun Fact

• EX

● Consistent, hot temperatures

● Consistent, heavy rainfall

● Biome with the greatest amount of diversity

Amazon

Savannas

• Temperature

• Rainfall

• Fun Fact

• EX

● Savannas: Tropical grasslands with diffuse trees

● High temperatures and small amounts of rainfall (seasonal)

● Seasonal droughts and fires

Temperate Grasslands

• Temperature

• Rainfall

• Fun Fact

• EX

Temperate grasslands:

● Cool winters and hot summers

● Seasonal rain (less rain than savannas)

● Seasonal droughts and fires

EX: North American Prarie

Temperature Deciduous Forests

• Temperature

• Rainfall

• Vegetation

• EX

• Warm summers and cold winters

• Moderate precipitation; snow during winter

• Trees shed leaves in the winter due to poor growing conditions

EX: Eastern North America

Chaparrals

• Temperature

• Rainfall

• Vegetation

• EX

• Mild winters with hot, dry summers

• Scattered vegetation, often with small tough leaves to conserve water

• Common droughts and fires

EX: Mediterranean coast

Deserts

• Temperature

• Rainfall

• Vegetation

• Fun fact

• EX

• Hot days and cold nights with extreme temperature fluctuations

• Very little rain, with plant growth occurring after rainfall

• Animals are often nocturnal and water conservative (concentrated urine)

• Plants have leather leaves or spines to conserve water

Arizona

Taigas (coniferous forests)

• Temperature

• Rainfall

• Fun fact

• EX

• Cold winters with snowfall and warm, rainy summers

• Largest terrestrial biome

Canada and alaska

Tundras

● Tundras:

● Cold with very little precipitation (mostly snow)

● Ground freezes during winter

● Topsoil thaws during summer, but deeper soil is permafrost (stays frozen)

Iceland

What decomposers externally digest dead organic matter

SAPROPHYTES

They secrete digestive enzymes outside their bodies, breaking down complex organic material into simpler compounds, and then absorb the nutrients.