Ecology - Chapter 5 Flashcards
What are the four important characteristics of a population?
population size, population density, population growth, and geographic distribution
Geographic distribution
describes the area inhabited by a population.
Population density
is the number of individuals per unit area.
What are three factors that affect the population size?
number of births, number of deaths, number of individuals that enter or leave the population
A population can ________ when its birthrate is greater than its death rate.
grow
If the birthrate __________ the death rate, the population stays more or less the same size.
equals
If the death rate is greater than the birthrate, the population __________.
shrinks
Immigration
The movement of individuals into an area is a factor that can cause a population to grow.
Emigration
the movement of individuals out of an area, can cause a population to decrease in size.
The J-shaped curve indicates that the population is undergoing ____________.
Exponential growth
Under ideal conditions with unlimited resources, a population will grow ___________.
exponentially
As ___________ become less available, the growth of a population slows or stops.
resources
The S-shaped curve indicates that the population is undergoing ___________.
logistic growth
___________ of the environment for a particular species is the largest number of individuals that a given environment can support.
Carrying capactiy
The primary productivity of an ecosystem can be reduced when there is an insufficient supply of a particular nutrient. Ecologists call such substances _____________.
limiting nutrients
A ____________ is a factor that causes population growth to decrease.
limiting factor
A limiting factor that depends on population size is called a _____________.
density-dependent limiting factor
Density-dependent limiting factors
include competition, predation, parasitism, and disease.
Competition among members of the same species is a _______________.
density-dependent limiting factor
The regulation of a population by predation takes place within a ______________, one of the best-known mechanisms of population control.
predator-prey relationship
Parasitism and disease are ______________________.
density-dependent limiting factors
Like predators, ________ take nourishment at the expense of their hosts, often weakening them and causing disease or death.
parasites
___________ affect all populations in similar ways, regardless of the population size. Unusual weather, natural disasters, seasonal cycles, and certain human activities - such as damming rivers and clear-cutting forests - are all examples of this.
Density-independent limiting factors
Like the populations of many other living organisms, the size of the human population tends to __________ with time.
increase
