Population Dynamics

A group of individuals of a single species inhabiting a specific area at the same time

Area in population ecology concerned with factors influencing the expansion, decline, or maintenance of populations
Includes the effects of: births, deaths, immigration, and emigration

For the Conservation of diverse plants and animals * Determines whether or not a species is going extinct
For the Control of noxious pests, including human parasites and pathogens
For the Maintenance of economically important animal and plant populations

Describes changes in population throughout the life cycle of the organism
Commonly used in human population, but can also be used for general purposes
Populations are affected by: * Birth (Natality) * Death (Mortality) * Immigration → new members of the population entering the population but not through birth * Emigration → leaving the population and decreasing population size * Emigration happens due to some dispersal mechanisms of certain populations * Ex: Spiderlings → produce silk and hang on to the tips of leaves, waiting for wind to take them to other places (they balloon themselves to occupy new environments) * Allows for the species to be dispersed and prevents competition * Dispersal can either increase or decrease local population densities * Can lead to population expansion, resulting to an increase in their geographic range * Normally happens when environmental conditions in the original habitat become unfavorable
Biotic Potential * Property or capacity of populations to multiply; maximum reproductive rate of an organism * Normally high in most species * Influenced by sex ratio and age distribution * Favorable environmental conditions enable species to realize their full biotic potential → leads to population increase

Exponential Growth Model * Represents growth of a population without environmental resistance factors * No limits to population growth (such as predators, food, etc.) * A continuous population increase in an unlimited environment * Represented by a J-shaped curve * Exponentially rises
Logistic Growth Model * Shows that when resources are diminished, population growth rate will ultimately plateau * Takes into consideration Carrying Capacity * The total number of individuals the environment can support * Represented by an S-shaped curve * Lag-Phase * Population size small, resources abundant * Log (Exponential) Phase * Rapid growth and fast resource utilization * Stationary Phase * Zero population growth; carrying capacity is reached * Death (Decline) Phase * Population has exceeded carrying capacity and slowly decreases

Limiting factors (ex: raw materials, energy supply and accumulation of waste products)
Influenced by the Carrying Capacity of the environment
Density-dependent factors * Biotic factors, such as diseases and predation, that limit population growth
Density-independent factors * Abiotic factors, such as temperature and weather, that also influence population growth