Chapter 15.1 Flashcards
study of the interactions among organisms and between organisms and their environment
ecology
all the individuals of a species in a given area
population
characteristics of a population
population structure
Population ecologists estimate the size of population of interest by using a _____ _______.
Direct Census
Individuals are counted or surveyed
Direct Census
Estimates the size of more mobile or inconspicuous species
mark-recapture method
how organisms are distributed in space
population dispersion
Three types of dispersions are
1.
2.
3.
clumped distribution
uniform distribution
random distribution
high densities in resource-rich areas
clumped distribution
Low densities elsewhere
clumped distribution
Globally, humans are clumped around resources (waterways).
clumped distribution
Plants and animals _____ around food and energy sources.
clump
spacing between individuals tends to be equal
uniform distribution
spacing between human houses on a local level
uniform distribution
territorial species
uniform distribution
shown by nonsocial species with ability to tolerate wide range of conditions
random distribution
No competing factor brings individuels together or pushes them apart
Random distribution
trees with windblown seeds
random distribution
Historians have determined human population sizes over past 10,000 years by
1.
2.
archaeological evidence
written records
Human population growth shows exponential growth.
true
Shows exponential growth: occurring in proportion to the _______ total.
Current
Graph of exponential growth shows a ____ shaped curve
j
Growth rate = ________ - ________.
Birth rate - death date
Current growth rate per year is:
1.2%
Current population is:
7.3 billion people
the period when birth rates are dropping toward lowered death rates
demographic transition
Studies show that no population can grow to unlimited numbers.
True
Norway lemmings: Every 5-7 years massive migrations lead to deaths from what?
Overcrowding
the maximum population that can be supported indefinitely in a given environment
carrying capacity
populations may grow _________.
exponentially
Carrying capacity is limited by environmental resources 1. 2. 3. 4.
- food
- water
- shelter
- space
Pattern of growth seen in populations limited by environmental resources
logistic growth
observed in lab populations of flour beetles, water fleas, and protists
logistic growth
Graph of resource-limited growth has _________ Curve
S - shaped
population limiting factors that increase with population size
Density-dependent factors
Limited food supply
density dependent factor
increased risk of disease
density dependent factor
increase in waste levels
density dependent factor
Results in
1. Decrease in birth rates
2. increase in death rates
or both
Density-dependent factors
influence population growth rates regardless of population
Density- independent factors
Droughts
Density-independent factors
Temperature extremes
Density-independent factor
Natural disasters
Density-independent factor
Severity of effects of density-independent factors may depend on population size.
1. competition for resources
Density-independent factors
Current growth rate is:
1.2%
