Chap 11 Population Growth and Regulation

Population Size

equals population size at time + the number of births + number of imigrants - number of deaths - number of emigrants

Geometric growth

Exponential growth from one discrete time period to the next in organisms reproducing in synchrony at regular time intervals

Exponential Growth

change in the size of a population of a species with continuous reproduction by a constant proportion at each instant in time

Density-independent factors

Their effects on population size or growth rate are independent of the number of indivduals in the population

Density-dependent factors

Their effects are dependent on the number of individuals in the population

Example of Denisty-Dependent Factors

Amount of resources, habitat influence population size, birthm, death, and dispersal rates change as density of population changes. As density increases, birth rates decrease, death rates incresase, and dispersal increases which all tend to decrease population size

Logistic Growth

Models denisty dependent population growth; when density are low, logistic growth is similar to exponential growth. On the other hand, when density increases, growth rate approaches zero as population is near the carrying capacity

Logistic vs Exponential

As both do begin growing rapidly, logistic tend to slow down when reaching carrying capacity while exponential growth continues to grow rapidly.

Life table

A cohort life table follows the fate of a group of individuals all born at the same time, including survivorship of individuals from birth to age X, Fecundity which is the average number of offspring produced per surviving adult per age class, and a net reproductive rate due to the Survivorship x Fecundity

How to find population growth through geometric growth

Population size after # generations x geometric population growth

How to find population growth through exponential growth

Population size at each instant in time x exponential growth rate

How to find population size at each instant in time

Original population x e^ (exponential population growth rate x time)