Population Ecology

-Study of the Interactions
-Organisms with other organisms
-Organisms physical Environment (Habitat)

Ecology and Evolution
-Ecology and evolution are connected
-Interactions are selection pressures(annoying cause harm)
-Evolutionary change affect interactions

Levels of Interaction
Factors that inlfuence interactions:
-Abiotic factors (Non living) (Temperature, Soil and Air)
-Biotic Factors (Living Things)
-Ecological studies divided into five levels.

Levels of Ecological Studies
-Organismal Ecology
-Population Ecology
-Community Ecology

Organismal Ecology
how individual organisms adapt to their habitat

Population Ecology
All organisms of same kind of species living in an area
-Focus on factors that affect growth & regulation of population size.
-same species
– live in same area

Community Ecology
all populations interacting at a particular area.
-Focus on how interactions like predation and competition of organisms in community
-dif populations
– share resources
-interaction with in dif populations.

study of the community of populations and abiotic environments include energy flow and chemical cylces
– all biotic and abiotic factors

the zone of the earths soil water and air in which living things organisms are found
-sum of all earths ecosystem

Population Characteristics
1. Density
2. Distribution
3 Population Size
4.Intrinsic rate of natural increase or growth rate

Population Density
Density-number of individuals per unit are or volume

Population Distribution
-Population Distribution-pattern of dispersal of individuals with in an area
-Uniform distribution-due to territoriality and food distribution
-Random Distribution, Clumped distribution.

Distribution causes
abiotic factors like moisture, temp, soil, nutrients which can be limiting factors

Population size
-Emigration (-)

Environmental resistance
-control population biotic potential
-limited food
-increased competition
-accumulation of wastes
-predation, parasites

population growth
Exponential “J” Shaped growth
-Biotic potential -reached only if there is no resource limitation

Logistic growth
“S”Shaped growth curve or sigmoid growth
-lag phase-exponential growth , decrease phase -stable equilibrium

Carrying Capactiy
(K) environmental resistance
-max pop. size a particular area can sustain

Mortality patterns
Cohort-group born at same time
-Survivorship-probablility of individuals to cohort surviving to a spec. age
—–Types I II III

Age structure
Give into a past and future history of a population

Population Regulation
Density- Dependent factors
Density- Independent factors (Competition, parasites and weather)

Life history patterns
-They vary
-# of births
-Age of reproduction
-Life Span
-The probability of living the whole life span

K selection-
-K selections or K strategists
-Equilibrium species – Large individuals, long life span, slow to mature, few offspring, much care of offspring
-Allocate energy to their own growth and survival of their off spring
-Competitions and exclude opportunists

r selection
R strategies
-Opportunists species-insects and annual plants
-Small, short life span, fast to mature, many offspring, little or no care of off spring

Human Population
-Doubling time
-More developed countries(MDCs)
-Less deveoloped countries (LDCs)
-Demographic transision
-Zero population
-Replacement population