2. Measurement in Population Dynamics

• Habitat- an ecological or environmental area that is inhabited by a particular species of animal, plant or other type of organism

• Species- taxonomic group whose members can interbreed

• Population Size (#/area)- number of individual organisms in a population

• Crude density- The number (or biomass) per unit total space

• Ecological density- the number (or biomass) per unit of habitat space (available area or volume that can actually be colonized by the population-where organisms exist)

• Population Dispersion- the general pattern in which individuals are distributed through a specific area

• Clumped• Random• Uniform

• Mark-Recapture SamplingM/N=m/n

• Example: There is a fish population of unknown size in a lake. 26 fish are captured, marked, and released back into the lake. After 10 days 21 fish are captured of which 3 are marked...How do we use this information to figure out the population size?

Answer

• Carrying Capacity- population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment.

Factors that affect Population Growth

• Population dynamics- changes in population characteristics determined by natality, mortality, immigration, and emigration

• Fecundity- the potential for a species to produce offspring in one life time

Factors that affect Population Growth

• Natality- birthrate: the ratio of live births in an area to the population of that area; expressed per 1000 population per year

• Mortality- deathrate: the ratio of deaths in an area to the population of that area; expressed per 1000 per year

• Emigration- migration from a place (especially migration from your native country in order to settle in another)

• Immigration- migration into a place (especially migration to a country of which you are not a native in order to settle there)

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• Closed Population- A population that is closed to genetic material from the outside (zoo)

• Open population- a population that is open to genetic material from the outside (forest)

Biotic Potential

• the maximum rate a population can increase under ideal conditions

Biotic Potential

• Birth potential- maximum reproductive capacity of a population if resources are unlimited. Full expression of the biotic potential of an organism is restricted by environmental resistance, any condition that inhibits the increase in number of the population.

• Capacity for survival• Procreation- the sexual activity of conceiving and

bearing offspring• Length of reproductive cycle

Exponential Growth:• If a population has a constant birth rate

through time and is never limited by food or disease, it has what is known as exponential growth. With exponential growth the birth rate alone controls how fast (or slow) the population grows.

Logistic Growth

• In most real populations both food and disease become important as conditions become crowded. There is an upper limit to the number of individuals the environment can support. Ecologists refer to this as the "carrying capacity" of the environment. Populations in this kind of environment show what is known as logistic growth.

Logistic Growth1. Lag Phase2. Log Phase3. Stationary Phase

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