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