Ch. 8 Env. Science Ch. 5 Biology Population Dynamics Ch. 8 Env. Science Ch. 5 Biology 1

Population Dynamics Population: all the individuals of a species that live together in an area

Population Dynamics Demography: the statistical study of populations, make predictions about how a population will change

Population Dynamics Three Key Features of Populations Size Density Dispersion (clumped, even/uniform, random)

Three Key Features of Populations Size: number of individuals in an area Estimate by sampling Mark-Recapture Method Ok so 5

2. Density: measurement of average population per unit area or unit volume Formula: Dp= N Pop. Density = # of individuals (population size) ÷ unit of space S

Whitetail Deer Population Density

Three Key Features of Populations 3. Dispersion:describes their spacing relative to each other clumped even or uniform random

clumped even (uniform) random

Population Dispersion

Population Size Growth Rate: Birth Rate (natality) - Death Rate (mortality) How many individuals are born vs. how many die Birth rate (b) − death rate (d) = rate of natural increase (r).

POST-REPRODUCTIVE REPRODUCTIVE PRE-REPRODUCTIVE

Population of a Stable Country Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. 14

Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. 15

You decide!

Factors That Affect Future Population Growth Immigration + + - Population Mortality Natality Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. - Emigration 17

Factors that affect growth 3. Immigration- movement of individuals into a population 4. Emigration- movement of individuals out of a population Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. 18

Growth Rate : Reproductive Potential Reproductive Potential = maximum number of offspring that each member can produce Darwin proposed that it would take elephants 750 years for elephants to produce 19 million descendants. Bacteria can do this in a few days

Growth Rate : Reproductive Potential Increases: more offspring at a time reproduce more often earlier in life (generation time)

2 Types of Growth Curves Exponential Growth - grow faster and faster Logistic Growth - levels off due to limited resources

Exponential Growth population increases rapidly only occurs in nature when there is plenty of food and space, and have little or no competition or predators.

Logistic Growth population decreases as resources become scarce leveling off when the carrying capacity of the environment is reached resulting in an S-shaped curve.

Growth Curves

Carrying Capacity Carrying Capacity- the maximum population size that can be supported by the available resources There can only be as many organisms as the environmental resources can support

J-shaped curve (exponential growth) Carrying Capacity N u m b e r J-shaped curve (exponential growth) Carrying Capacity (k) S-shaped curve (logistic growth) Time 26

Limiting Factors Limiting factor- any biotic or abiotic factor that restricts the existence of organisms in a specific environment. EX.- Amount of water Amount of food Temperature

2 Types of Limiting Factors 1. Density-dependent factors- Biotic factors in the environment that have an increasing effect as population size increases   Ex. disease competition parasites Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat. 28

2 Types of Limiting Factors 2. Density-independent factors- Abiotic factors in the environment that affect populations regardless of their density   Ex. temperature storms habitat destruction drought