Ecology
study of the interaction among organisms and between organisms and their environment
Population
all the individuals of a species in a given area
Mark-Recapture Method
some individuals trapped, marked released, note number of marked individuals in later captures
Clumped Distribution
high densities in resource-rich areas, low densities elsewhere
Uniform Distribution
spacing between individuals tends to be equal
Random Distribution
no compelling feature pushing individuals together or apart
Exponential Growth
- example: human population
- is in proportion to population size
- as population grows, growth also increases
Growth Rate
- human population growth rate has been low
- growth rate was 0.1% per year 2000 years ago
- by 1750 growth rate was 2% per year
- currently growth rate is 1.2% per year
- current population of earth 6.6 billion, at 1.2% growth rate, which means the population will increase by 77 million people per year
Demographic Transition
- generally in human populations, a decrease in death rate is followed by a decrease in birth rate
- less developed countries
Carrying Capacity
the maximum number of individuals that can be supported indefinitely in a given environment
Density-Dependent Factors
factors that increase with population size
Density-Independent Factors
not influenced by population numbers
Net Primary Productivity
- Earth’s resources can be measured through this
- the total amount of plant growth
Non-Renewable Resources
- many essential supplies
- USA accounts for 5% of world’s population, but consumes 24% of resources
Population Cycle
the cycle of growth beyond carrying capacity
Population Pyramid
a large base that indicates the majority of the population is young and that the population is still growing
