Chapter 20 — Population Ecology

textbook and lecture

ecology

study of interactions among and between organisms and their noliving environment

population ecology

the study of population numbers, including how population size and growth change

population

a group of individuals of the same species living in an area

population density

the number of individuals per unit area

distribution pattern

the way individuals in a population are spatially arranged

random distribution

individuals in a population are distributed randomly

Ex; pine tree seeds spread by gusty winds

clumping distribution

individuals occur in groups

Ex: wolves circling prey, defensive grouping in fish

uniform distribution

individuals are spaced relatively evenly

Ex: nesting birds

Population growth

change in population growth overtime

density-dependent factors

factors whose influence on population size and growth depends on the number and crowding of individuals in a population

density-independent factors

factors that can influence population size and growth regardless of number and crowding

biotic

relating to living components/factors

abiotic

relating to nonliving components/factors

Biotic, density dependent factors examples

predation/predators, food, disease

Abiotic , density-independent influence examples

Precipitation, fire, temperature

carrying capacity

the maximum population size that an environment. Can sustainably support

exponential growth

population growth that increases rapidly when conditions allow continued growth

logistic growth

population growth that slows as the population approaches carrying capacity

isle royale wolf and moose study

a long running predator-prey study observing the dynamic fluctuations of Isle Royale’s gray wolves and moose

Isle Royale is ideal: no humans live there, protected as a national park, nearly natural environment (no settlement, hunting, logging, etc.), far from shore- not other predators or prey on the island, size (not too big or small)

predator-prey relationship

a relationship in which predators consume prey (Isle Royale’s gray wolves and moose study)

ecological detectives

using evidence such as urine-soaked snow, droppings/scat, moose kill sites, and bones to learn more about the moose and wolves

sampling methods

methods used to estimate population size/characteristics; different lifestyles require different sampling strategies

warming climate and ticks

warmer temperatures lead to increased tick infestations, resulting in loss of hair and weakened populations in wolves and moose