Ch 44 Population ecology

Ecology

study of organisms among all organisms and their physical environment

organism

an individual living thing, can be one or more cells

population

all individuals of a species in a particular place and time

community

all populations of multiple species interacting at a locale

ecosystem

community interacting with the environment

hábitat

place where an organism lives

biosphere

the zones of the Earth’s soil, water and air (all of earth that is inhabited by life)

demography

statistical study of a population; includes population density, distribution and growth

Clumped dispersion pattern

resources are often unequally distributed and individuals are grouped in patches

uniform dispersion pattern

individual so are most likely interacting and equally spaced in the environment

random dispersion pattern

individuals in a population are spaced in an unpredictable way

Rate of natural increase

determined by the number of individuals born each year minus the individuals who die each year

bionic potential

max rate of increase for a population and depended on the factors that influence the population’s reproduction

factors affecting bionic potential

• reproductive age

• competition

• reproductive opportunities

• disease and predators

Cohort

All the members born in a population at the same time

Life tables

show how many members of a cohort are still alive after certain intervals of time

survivorship

the probability that a newborn individuals of a cohort will survive to a particular age

survivorship curve

plot of the number of organisms surviving at each age

Type 1 curve

few offspring but increased likelihood of surviving to maturity

Type 2 curve

intermediate, survivorship is constant, no stage that is more vulnerable

Type 3 curve

low survivorship of the young followed by a period when survivorship is high for the few who live to a certain age

Semelpairity

members only have a single reproductive event

• unstable environment

iteropairity

members reproduce multiple times

• stable environment

carting capacity

how many individuals the environment can support

Density dependent factors

limiting factors linked to population density

• disease

• competition

density independent factors

unrelated to population density

• abiotic factors

population “boom”

rapid exponential growth

population bust

population falls back to minimal level after a boom

Life history

made up traits that affect an organism’s schedule of reproduction and death

What does r represent?

rate of natural increase

What does K represent?

carrying capacity

r-selected populations

• density independent

• opportunistic

• lots of offspring, small, early maturation, short life

• ex) mosquitoes, mice and flies

K-selected populations

• density dependent

• equilibrium species

• less offspring, large body, mature late, long lives

• ex) humans, cattle and whales