Biology - Unit 1: Ecology and natural systems

Tolerance

describes an organism’s ability to survive variation in abiotic factors

Tolerance range

describes the values for an abiotic factor within which an organism can survive

Limits of tolerance

describes the lower and upper bounds of values for an abiotic factor between which an organism can survive

Terrestrial biomes

land-based biomes that are defined by their climate (temperature and precipitation)

Aquatic biomes

water-based biomes and are defined by their water depth and salinity

Microbiome

a group of microbes (such as bacteria) that naturally live on or within another organism

Community

a group of different species that interact with one another within a specific area

Population

a group of individuals from the same species, living in the same general area

Population’s density

refers to the number of individuals within a specific area

Dispersion

describes how individuals are spread throughout their habitat

Types of dispersion

• Clumped

• Uniform

• Random

Clumped dispersion

occurs when many individuals are packed closely together into groups

Uniform dispersion

occurs when individuals are spaced evenly from one another

Random dispersion

occurs when individuals have an unpredictable distribution throughout their habitat

Immigration

individuals move into a population from elsewhere

Emigration

when individuals leave a population

TRUE OR FALSE: Populations grow if immigration is greater than emigration

TRUE

Exponential growth

• occurs when a population grows exponentially; the larger the population becomes, the faster it grows

• produce a J-shaped curve

Logistic growth

• occurs when a population grows exponentially at first, but then slows

• produce an S-shaped curve

Carrying capacity (K)

maximum population size of a species that a particular environment can support

Limiting factors

abiotic and biotic factors that control population growth

Density-independent factors

• limit growth regardless of population’s density

• volcanic eruptions, earthquakes, fires, droughts

Density-dependent factors

• affect growth in relation to a population’s density

• competition, predation, herbivory, disease

r-selected traits

have a short lifespan and produce many offspring that require little to no parental care

K-selected traits

are long-lived and tend to produce fewer offspring that require increased parental care

Competition

occurs when the same or different species compete directly or indirectly for the same limited resources

Predation

involves one organism (the predator) that kills and eats another organism (the prey)

Scavengers

predators who consume the remains of dead organisms

Herbivory

occurs when a non-plant species feeds on a plant species

Symbioses

close, long-term associations between two or more species

Mutualism

occurs when all species involve benefit from a symbiotic association

Faculative mutualism

a species benefits from a symbiotic association with another species but are not dependent on it

Obligate mutualism

the survival of a species is dependent on their symbiotic association with another species

Commensalism

occurs when one species benefits from a symbiotic association while the other is neither harmed nor helped

Parasitism

when a species (parasite) lives in or on another species (the host) and the parasite obtains its nutrition by feeding on the host’s tissues or fluids

Endoparasites

found within a host

Ectoparasites

occur on the host’s body