Bio FINAL

BI 223 final, 2026

What is a community?

A group of populations of different species living in an area that interact with each other.

What is a population?

A group of same species that live and interact with each other.

What is the difference between a community and a population?

Communities are multiple species while populations are same species.

What are the 4 types of interactions?

Competition, exploitation, mutualism, and commensalism.

What is competition?

When individuals use a resource that limits survival and reproduction of both individuals (negative/negative).

What are intraspecific interactions?

Interaction/competition WITHIN two of similar

What are interspecific interactions?

Competition/interactions between, ecological niche of two species overlap.

What is density dependent growth?

A populations growth dependent on density of population, think carrying capacity.

How do intra-specific interactions relate to density dependent growth?

Competition for limited resources can slow down the population. The more individuals there are that need the same resources, the less resources that are available.

Why does inter-specific interaction occur?

Niche of two species overlap,

What happens if the niche of two species completely overlaps?

The realized niche of one species becomes more realized.

What is a realized niche?

The “actual” space, resources, and things a species needs to survive in an environment.

What is resource partitioning?

Can be short-term changes in behavior or long-term evolution, species use limited resources in different ways.

What is character displacement?

When two species reduce similarity when living in the same area.

What is a realized niche?

Restricted and actual space a species occupies and needs to occupy for survival.

What is a fundamental niche?

The maximum range of resources a species COULD occupy without any limiting factors.

What core concept is character displacement most closely related to?

Core concept of structure function.

Morphology defensive adaptation example

(Physical features) Spines provide mechanical defenseP

Physiology defensive adaptation example

(Internal biological processes) Skunks synthesize a pungent spray

Behavioral defensive adaptation example

(Actions) octopus mimics a venomous animalDe

Define exploitation

A positive negative interaction when one side benefits from the other.

What are the three main types of exploitation?

Herbivory, predation, and parasitism

What two things contribute towards a species diversity?

Species richness (# of species in a community) and species evenness (relative abundance of the different species).

How can diversity affect community stability?

Makes it more stabilizing and increases interactions

Define disturbance

A strong, short lived disruption to a community that can disrupt both biotic and abiotic resources.

What levels of disturbance lead to higher levels of diversity?

Intermediate disturbances instead of small or large ones.

What is ecological succession?

Pattern of colonizatiion and species replacement that occurs in a community following a severe disturbance.

Traits of early-succession species

short-lived, small in size, and have high rates of reproduction.

Traits of late succession communities

Long-lived, large, and good resource competitors.

What is primary succession?

Patterns of colonization in an area that was virtually lifeless before, following a catastrophic event. Ex. Glacier Bay

What is secondary succession?

Ecological succession following a disturbance that removed some or all of the organisms - soil left intact. Ex. burning of yellowstone forests.

What is the equillibrium model?

Proposed a community will reach a stable climax community that will persist indefinitely

What is the nonequillibrium model?

Proposed that communities continually change due to periodic disturbances. Also suggests that there are different types of communities possible.

What are the two different proposed outcomes to disturbances?

The equillibrium model and nonequillibrium model.

How does latitude influence species diversity?

Closer to the equator (smaller latitudes) have greater diversity and richness

Where can have a greater diversity of habitats?

Larger geographic areas.

Why do rates of extinction and immigration matter on an island?

As # of species increases, competition increases and cuases reduced immigration of new species and increased extinction of existing species.

How does the biogeography model apply to conservation?

Many protected areas are considered to be “islands.”

What do ecosystem engineers do?

Create or dramatically alter their physical environment (Ex. beavers).

What do foundation species do?

strong effects to food chain and environment due to their large size or high abundance. (ex. kelps, elk)

What do keystone species do?

Have critical roles, usually few and predators.

What is a trophic level?

A feeding position in the food chain/web. W

What is a trophic cascade?

When a predator has an effect on multiple trophic levels, can change the abundance of species even if it doesn’t directly interact with it.

What is the role of keystone predators in trophic cascades?

Changing the abundance of species, which then has an effect on all species that interacted with that one and so on and so forth. W

What is top-down control?

Abundance of higher trophic levels controls abundance of lower trophic levels.

What is bottom-up control?

Abiotic factors limit abundance of trophic levels. Such as: availability of resources at lower trophic levels can limit # of trophic levels in a food chain.

What is primary production?

Converts sunlight energy into chemical energy to be passed up the trophic levels.

What is gross primary production

An ecosystems TOTAL amount of primary production.

How much of GPP is used by plants during cellular respiration?

~1/2

What is Net primary production?

Amount of new biomass

What is secondary production?

Consumers produce new biomass by ingesting food. Lost energy is used in cellular respiration and new growth.

Define an ecosystem

All living organisms and abiotic factors that occupy a habitat/enviornment

What can affect NPP productivity globally?

Annual precipitation positively correlates with NPP, and NPP is dependent on biomes, ex. terrestrial vs. aquatic. Terrestrial biomes have higher NPP.

Example of exception to 10% rule

Transfer of energy from Phytoplankton to zooplankton, can transfer up to 20% or more.

Why do nutrients cycle within an ecosystem?

Matter and energy cannot be created nor destroyed, so it must be circulated.

Nutrient cycles involve?

Biotic and abiotic components, called biochemical cycles.

What is a reservoir?

Large pool of a particular nutrient.

What do decomposers do in nutrient recycling?

Decomposers consume nonliviing organic matter for eneryg.

What are the four key biochemical cycles?

Water, carbon, nitrogen, and phosphorus.

What are nutrient cycling rates influenced by?

Climate and latitudes.