1. organism
population
community
ecosystem
biosphere
Population Ecology

2. Life takes place in populations
group of individuals of same species in same area at same time
rely on same resources
interact
interbreed
Population Ecology: What factors affect a population?

3. Why Population Ecology?
Scientific goal
understanding the factors that influence the size of populations
general principles
specific cases
Practical goal
management of populations
increase population size
endangered species
decrease population size
pests
maintain population size
fisheries management
maintain & maximize sustained yield

4. Factors that affect Population Size
Abiotic factors
sunlight & temperature
precipitation / water
soil / nutrients
Biotic factors
other living organisms
prey (food)
competitors
predators, parasites, disease
Intrinsic factors
adaptations

5. Characterizing a Population
1937
1943
1951
1958
1961
1960
1965
1964
1966
1970
1956
Immigration
from Africa
~1900
Equator
Describing a population
population range
pattern of spacing
density
size of population
range
density

6. adaptations to polar biome adaptations to rainforest biome
Population Range
Geographical limitations
abiotic & biotic factors
temperature, rainfall, food, predators, etc.
habitat
adaptations to polar biome
adaptations to rainforest biome

7. Changes in range Range expansions & contractions changing environment
aspen
oak, maple
white birch
sequoia
Woodlands
Grassland, chaparral,
and desert scrub
15,000 years ago
glacial period
Alpine tundra
Spruce-fir forests
Mixed conifer forest
0 km
2 km
3 km
1 km
Elevation (km)
Present
Grassland,
chaparral, and
desert scrub
result of competition

8. At risk populations Endangered species limitations to range / habitat
places species at risk
Socorro
isopod
Devil’s hole
pupfish
Iriomote cat
Northern white rhinoceros
New Guinea
tree
kangaroo
Iiwi
Hawaiian
bird
Catalina
Island
mahogany

9. Population Spacing Dispersal patterns within a population
Provides insight into the environmental associations & social interactions of individuals in population
clumped
Within a population’s geographic range, local densities may vary substantially. Variations in local density are among the most important characteristics that a population ecologist might study, since they provide insight into the environmental associations and social interactions of individuals in the population. Environmental differences—even at a local level—contribute to variation in population density; some habitat patches are simply more suitable for a species than are others. Social interactions between members of the population, which may maintain patterns of spacing between individuals, can also contribute to variation in population density.
random
uniform