DAT Biology: Ecology

Abiotic Factors

Non-living elements of an ecosystem

Example: temp, light, water, etc.

Biotic Factors

Living Elements of an Ecosystem

Example: Plants, animals, etc.

Species

A group that can interbreed and have viable, fertile offspring

Population

A specific species living in a specific location

Habitat

The type of environment where a specific organism lives, including other biotic/abiotic factors

Ecological Community

All 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

Dependent on population density factors impacting things like disease, resources, competition

Density-Independent Factors

Things that do not depend on population density like climate, weather

Biome

a large area of land or water defiend by its biotic factors which are adapted to the climate/geography of the region

Niche

A species’ unique position and role within its ecosystem, defining how a 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

Example: there is an upper and lower level of the sea, occupy technically all of it even if they actuality-wise only choose one area

Realized Niche

The environment in which the species ACTUALLY lives

Example: lower level of sea floor

Gause’s Law

Aka Competitive Exclusion Principle

Two species cannot occupy the same niche and maintain their population levels—one species will out-compete the other for resources

Resource Partitioning

Species may coexist by utilizing resources in differen ways, times, or places, different perspective to Gause’s Law

Competition

Two species or individuals competing for the same resources

Intraspecific Competition

Members of the same species compete for resources

Example: 2 giraffes competing for leaves

Interspecific Competition

Individuals from different species compete for resources

Example: Lions and hyenas hunting the same prey species

Exploitation Competition

Indirect competition that occurs when resources are depleted

Example: Increasing leopard population causes them to deplete the warthog population, leaving less available for tigers. This is indirect as the increase in leopard population is not directly attacking the tigers, but rather, causing a depletion of a mutually shared food source, causing tigers to decline in population

Apparent Competition

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

Example: Warthogs and Anteloeps are both prey to Leopards. Increasing the Warthog Population allows for increased Leopard Population, which means more predators, which increases antelope predation decreasing their overall population

Interference Competition

When one species directly prevents the establishment of another species that would compete for mutual resources

Example: allelopathy

Allelopathy

A type of interference competition in which plants secrete toxic chemicals so no other plants could settle there

Symbiosis

a close, long-term interaction between two organisms/symbionts, broader umbrella for more specific types of relationships

Mutualism

(+/+) Both organisms benefitting in a symbiosis relationship

Example: oxpecker birds eating ticks off a rhino

Commensalism

(+/0) One organism benefits, another is unaffected

Example: barnacles attach to whales and filter feed

Parasitism

(±) One organism benefits at another’s expense

Example: Ticks feed off of a dog’s blood

Food Chain

Linear depiction of what eats what

Food Web

More complex diagram depicting interconnections between food chains

Trophic Level

Organism’s position within a food chain/web

Ecological Pyramid

Graphical representation of the accumulation of biomass at each trophic level

Top has a much smaller apex than the base pyramid (highest biomass)

Autotrophs

One method of food acquisition

Produce organic compounds from abiotic factors like sunlight, water, CO2, etc. by fixing carbon, using inorganic CO2 as their primary carbon source

Heterotrophs

One method of food acquisition

Must ingest organic compounds to generate energy and survive, cannot fix carbon molecules, derive their carbon from organic compounds

Predation

Relationship between predator (hunter) and prey (hunted: plant/animal)

Herbivore

Organism that eats plants—has a long intestinal tract and cecum to digest plants, allowing for a longer duration to break down the fibrous material

Carnivore

Organism that eats meat

Omnivore

Organism that eats plants and meat

Invasive Species

Non-native species that outcompete native species and overtake the ecosystem

Non-Invasive Species

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

Naturalized Species

Non-native species that spread beyond its origin and reproduce sufficiently to maintain its population

Exotic Species

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

Primary Producers

Lowest trophic level, typically autotrophs undergoing energy production to generate the biomass of an ecosystem, highest biomass

Consumers

Eat producers and other consumers, depending on where on the chain

Primary Consumers

Just above primary producers, often known as herbivores

Secondary Consumers

Prey on primary consumers, carnivores

Tertiary Consumers

Prey on secondary consumers, carnivores

Apex Predator

Top of the food chain, must be a tertiary consumer or higher, has no natural predators, hunts without fear of being hunted

Scavengers

Consume dead plants/animals

Decomposers

Consume dead plants/animals AND break down and recycle material from dead organisms to replenish soil w/ nutrients

Example: fungi/saprophytes

Example: worms/detritivores

Detritus

Decaying organic matter, what decomposers target

Photoautotroph

Energy Source: light

Carbon Source: CO2

Chemoautotroph

Energy Source: inorganic compounds

Carbon Source: CO2

Photoheterotroph

Energy Source: Light

Carbon Source: Organic Compound

Chemoheterotroph

Energy Source: Organic Compound

Carbon Source: Organic Compound

Population Dynamics

Study of how populations change in space/time and how they interact with their environment

Biotic Potential

A species’ ability to achieve its highest population growth, occurs when conditions are ideal, ability to undergo highest possible birth rate and lowest possible death rate, resulting in maximal population growth

Carrying Capacity

Max pop size an ecosystem can sustain

Principle of Population Theory

Proposed by Thomas Malthus, any living species increases exponentially while food production increases linearly, showing that food production will not be able to keep up with population growth

r/k Selection Theory

There are predictable ways to express how different species will survive within the environment via a graph

K-Selected Species

Type I survivorship curve, fewer offspring, higher survival rates

Example: elephants, humans

R-Selected Species

Type III survivorship curve, more offspring, lower survival rates

Example: insects, frogs

Type II Survivorship Species

Mortality rate is constant throughout the organism’s lifespan, survival chances do not significantly increase nor decrease, straight line

Ex: Many birds, small mammals, small reptiles

Ecological Succession

Predictable change and development of an ecological community over time , after a disturbance or in new habitats

There are primary and secondary succession patterns

Primary Succession

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

Example: Volcanic Eruption

Pioneer Species

Lichen, fungi, algae, first phase of primary succession

Secondary Succession

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

Example: floods, fires

Keystone Species

Species maintaining ecological balance, even when abundance is low, they have a disproportionately high impact on ecosystem, without them, it would collapse

Examples: African elephants (landscape remodeling), wolves (maintain elk population), beavers (wetland creation)

Keystone Predators

Hunt animals and prevent overabundance

Eutrophication

Process by which a body of water becomes enriched with minerals/nutrients

Algal Bloom

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

Algae

Photosynthetic eukaryotes

Cyanobacteria

Photosynthetic prokaryotes

Euphotic Zone

Closest to surface, where strong irradiance allows plant survival and photosynthesis

Littoral Zone

Zone where sunlight penetrates all the way to the ocean floor

Disphotic Zone

Semi-irradiated from the sun zone

Insufficient sun to support vegetation, murky, but bioluminescent species live here and produce light, and other adaptations to navigate

Photosynthetic species present here but they cannot thrive on that alone

Aphotic Zone

No irradiance from the sun zone, no light or photosynthetic species

Some bioluminescent species

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

Tropical Rainforest

Consistently hot temperatures and heavy rainfall

Biome with the greatest amount of diversity

Example: Amazon Rainforest

Savannas

Tropical grasslands with spread out trees

High temperatures and small amounts of rainfall

Seasonal droughts and fires

Example: African Safari

Temperate Grasslands

Cool winters, hot summers

Seasonal rain (less than savannas), droughts, and fires

Example: North American Prairie

Temperate Deciduous Forest

Warm summers and cold winters

Moderate Precipitation, snow during winter

Trees shed leaves in the winter due to poor growing conditions

Example: Eastern North America

Chaparrals

Mild winters with hot, dry summers

Scattered vegetation, often with small tough leaves to conserve water

Common droughts and fires

Example: Mediterranean Coast

Deserts

Hot days, cold nights, extreme temp flux

Very little rain, with plant growth occurring after rainfall

Animals are often nocturnal and water conservative, meaning they have concentrated urine

Plants have leather leaves or spins to conserve water and make sure none escapes

Example: Arizona

Taigas

Aka Coniferous Forest

Cold winters with snowfall and warm, rainy summers

Largest terrestrial biome

Example: PA, Canada, and Alaska

Tundras

Cold with very little precipitation (mostly snow)

Ground freezes during winter

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

Example: Iceland