Ecology (Ch 5 & 6)
Populations
Group of the same species living in the same area
Important Features Geographic Distribution Density Growth Rate Age Structure
Geographic Distribution
Range of Locations that the species is found in
Controlled by tolerances for the species
Also controlled by geographical barriers
Population Density
# of individuals of a species within a unit area Different in different species and ecosystems Based on biotic and abiotic factors
Population Growth
Change in size of a population Factors that affect growth
Birth rate- # of births in a population over a period of time
Death rate- # of deaths in a population over a period of time
Immigration (moving in) and Emigration (moving out)
Job Offer
Job #1 Starting salary= $10,000 Raise= increased $10,000/day
Job #2 Starting salary= $0.01 Raise= Salary doubled every day
Exponential Growth
Seen in populations with unlimited resources
Logistic Growth
Population shows exponential growth until a resource becomes limited
Growth is slowed or stopped when population size reaches carrying capacity
Carrying capacity (k)- amount of individuals of a population that an area that support
Limiting Factors
Factor that limits growth Density-dependent factors
Affect of factor increases with increasing population density
Competition Predation Parasitism and Disease
Density-independent factors Affect of factor does not depend of population density Climate changes, natural disasters, and human
disturbances
Demography
Study of the size of human populations Growth rates are controlled by the
same factors Birth Rate Death Rate Immigration and Emigration Age Structure
Historical Demography
Human population used to be low and relatively stable Limited by
resources and disease
Past 500 years Exponential growth
as limits have been removed
Age Structures
Histogram depicting the number of people in each age category within a population
Can be used to predict future growth
Biodiversity
Variety of Life Important because
Provides varied resources Food Products Medicines
Creates stability Species Diversity-
number of different species
Geographic Distribution of Biodiversity
Threats to Biodiversity
Habitat Loss Deforestation
Habitat Fragmentation Pollution Introduction of Invasive species
Habitat Loss
Resourses
Non-renewable- cannot be remade (or only can be remade over a long time period)
Renewable- can be remade Sustainable Development- use of
renewable resources in a way that does not deplete future supplies
Habitat Fragmentation
Pollution
Water Chemicals, Trash,
Temperatures, Noise
Land Chemicals, Trash
Air Chemicals and
Noise
Effects of Pollution: Acid Rain
Effects of Pollution: Ozone Depletion
Effect of Pollution: Biomagnification
Chemical pollutant becomes more concentrated as it moves up the trophic levels within a food chain or web
Very dangerous for top level predators
Invasive Species
Also called non-native species
Introduced to new habitat
Often grows without check because of lack of natural predators or disease in the area
Losing Biodiversity
Species experiences a decline in growth Threatened
Canadian lynx Prairie dog
Endangered Bald Eagle Many Marine Mammals
Extinct Dodo Passenger Pigeon
Top Related