Ecology BI303

Biotic Interactions

How interactions between individuals and populations effect the species composition and functioning of habitats ecosystems and biomes

Density-dependent

When the mortality rate and selection increases with increasing population size

Density-independent

When the rate of mortality is constant regardless of population size

Competition

An interaction between individuals where there is a struggle for limited resources resulting in a reduction of growth/reproduction

Intraspecific competition

Competition within a species

Carrying capacity

The total number of individuals a region can support without environmental degradation

Facilitation

When dominance of one species provides circumstances for another species to establish itself

Succession

One group of organisms in a location is replaced by another gradually due to biotic interactions and environmental changes

Primary succession

New biological habitat formed

Secondary succession

Existing biological habitat transformed

Interspecific competition

Individuals of one species suffer reduction in survivourship due to resource exploitation by another species

Gause's Law

Every species has its an individual niche, 2 species competing for exact same resources cannot co-exist

Niche

The unique set of habitat resources a species requires and its effects on an ecological system

Fundamental niche

The physiologically optimal range of conditions where a species can survive

Realised niche

Where the species actually lives

Niche/resource partitioning

the differentiation of niches that enables similar species to coexist in a community

Character displacement

The tendency for two species to diverge in morphology and thus resource use because of competition

Predation

the attack and consumption of a living organism

Lotka-Volterra Model

Predator and prey influence each other such that population growth stops once one of them exceed a critical threshold

Positive biotic interactions

encounters that benefit at least one participant but harm neither

commensalism

A relationship between two organisms in which one organism benefits and the other is unaffected

Phoresy

one organism uses another for transportation

Inquilinism

one organism uses another organism for housing

Metabiosis

One organism creates a suitable envioronment for another

Mutualism

A relationship between two species in which both species benefit (usually goods or services)

Dispersive mutualism

species receives food in return for transporting pollen or seeds

Symbiosis

A relationship between two species that usually helps both usually physically close and long term

Zonation

the distribution of plants or animals into specific zones according to such parameters as altitude or depth, each characterized by its dominant species.

Herbivory

consumption of plant material by animals

Fecundity

the ability to produce an abundance of offspring or new growth; fertility

optimal defense theory

the more important an organ or tissue is, the better protected it will be

Parasite

an organism that gets nutrients from one or small number of hosts normally causing harm but not death

Holoparasites

lack chlorophyll and are totally dependent on the host plant for energy

Hemiparasites

can photosynthesize but depend on host for water and nutrients

Allopatric

geographically separate

Sympatric

geographically overlapping

Biomass

total amount of living tissue within a given area

Trichome

hairlike projections that extend from a plant's epidermis; help reduce water evaporation and may provide protection from herbivores