Interactions in ecosystems Chp14

Niche

How an organism lives in its habitat, its role

Habitat

The area where an organism lives, including biotic and abiotic factors that affect the organism

Competitive exclusion principle

No 2 species can occupy the same niche in the same habitat at the same time

Symbiosis

A close ecological relationship between 2 or more different species that live in direct contact with one another

Niche partitioning

when organisms divide a niche

Divergent evolution

When organisms move away genetically into their own species

Ecological equivalents

species that occupy similar niches but live in different regions

What does ecological equivalents result from?

Convergent evolution

Mutualism

A symbiotic relationship in which both species benefit

Commensalism

When one species benefits and the other neither benefits nor is harmed

Parasitism

When one species benefits but the other is harmed

Competition

When two fight for the same limited resource

Predator

An organism that hunts, captures and eats another organism

Population Density

A measurement of the number of individuals living in a defined space

What is the population density equation?

# of individuals divided/area (units2)

What is population dispersion?

How a population is spread in an area

What is clumped dispersion?

Individuals live close together in groups

What is uniform dispersion?

Individuals in a population living at specific distances from each other

What is random dispersion?

individuals in a population spread randomly throughout an area

What is a survivorship curve?

A diagram showing the number of surviving members over time from a measured set of births

What is survivor ship type I?

Low level of infant mortality and an older population. Common to large mammals and humans

What is type II?

Survivorship rate is equal at all stages of life. Common to birds and reptiles

What is type III?

Very high birth rate, very high infant mortality. Common to invertebrates and plants.

What are four factors that affect population size?

Immigration, births, emigration, and deaths

Immigration

Movement into a population

Emigration

Movement out of a population

Exponential growth

a rapid population increase due to an abundance of resources

When does exponential growth occur?

When a population inhabits a new area with lots of resources and no predators

What is a carrying capacity?

The maximum number of individuals in a population that the environment can support

Population crash

A dramatic decline in the size of a population over a short period of time

What causes a population crash?

Seasonal weather changes, natural disasters, introduction to new species

Limiting factor

A factor that limits population size

Examples of Density dependent limiting factors

Competition, predation and parasitism/disease

Examples of Density independent limiting factors

Natural disasters, human activities and unusual weather

Intraspecific competition

Occurs among members of the same species

Interspecific competition

Occurs among members of different species