Ecology

What is Ecology? The study of the interaction of living organisms with one another and their environment.

Levels of Ecology Species  Population  Community  Ecosystem  Biomes  Biosphere

Population: All the individuals of a species living together in one place at one time

Demography is - Demography: the statistical study of populations So what is a Demographer? Demography: the statistical study of populations So what is a Demographer?

Features of a Population Population Size : # of individuals in a population Population Density : # of individuals that live in a given area Dispersion : the way individuals of a population are arranged in space Population Size : # of individuals in a population Population Density : # of individuals that live in a given area Dispersion : the way individuals of a population are arranged in space

Dispersion Even Random Clumped

Distribution clumped

Distribution even

Distribution random

How do populations grow?

Population Growth Model Used to study how populations change 3 stages of complexity to population growth 1. Birth rate: when more organisms are born than die. Used to study how populations change 3 stages of complexity to population growth 1. Birth rate: when more organisms are born than die.

2. Growth Rate Relationship between number of births and deaths

Births > Deaths Immigration: individuals move into area Births > Deaths Immigration: individuals move into area Population Growth

Population Decline Deaths > Births Emigration: individuals move out of area Deaths > Births Emigration: individuals move out of area

Graphing Populations J curve: Infinite growth of a population S curve: Has a carrying capacity! J curve: Infinite growth of a population S curve: Has a carrying capacity!

Stage IStage IIStage III time Population size Births > DeathsExponentialLogistic Carrying capacity (K) Which graph represents human population growth? Which graph represents bacteria population growth with unlimited food? Which graph represents elephant population growth? Which is it?

Limitations to population growth Abiotic Factors (nonliving things): space, water, disease, weather, fire Biotic factors: (living things): predators, prey, plants Abiotic Factors (nonliving things): space, water, disease, weather, fire Biotic factors: (living things): predators, prey, plants

Limiting factors can be….. a. Density-Independent Factors (entire population would die) Weather (tornado, floods), climate, clear- cutting, fires b. Density-Dependent Factors (portion of population affected depends upon how individuals are dispersed) Limited resources ( Food, water, land), Disease

Characteristics of growth curves What would A,B,C, and D represent?

Terms: ____________________________: The population size that an environment (ecosystem) can sustain ____________________________: Any factor limiting the survival and productivity of organisms, for example, the lack of water could limit grass in a grassland biome.

_______________________: Limited resources whose rates of depletion depend on the density of the population using them. Examples include: food, water, mates, competition for resources! _______________________: Factors such as, climate and weather that affect the growth of populations =. These factors are unaffected by the density of populations hence the term

Reproductive Strategies r-strategists Fast growing Exponential Short life span Reproduce early Many offspring No parental care Ex.Bacteria, insectsK-strategists slow growing Near carrying capacity Long life span Reproduce late Few offspring Parental care Ex:Tigers, gorillas humans

World Population Growth Human numbers through time

The End

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