chap+5


 * Poplulation density**: a measurement of population per unit area or unit volume.



I**mmigration**: is the arrival of new individuals into a habitat or population. It is a biological concept and is important in population ecology, differentiated from emigration and migration.




 * Emigration:** is the act of leaving one's native country or region to settle in another.




 * Exponential growth**: occurs when the growth rate of a mathematical function is proportional to the function's current value.




 * Logistic growth:** Population growth in which the growth rate decreases with increasing number of individuals until it becomes zero when the population reaches a maximum.




 * Carrying capacity:** of a biological species in an environment is the population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment.




 * Limiting Factor:** is a factor that controls a process, such as organism growth or species population, size, or distribution.




 * Denity-dependent limiting factor:** Limiting factor that depends population size.




 * Predator prey relationship:** Predation is used here to include all "+/-" interactions in which one organism consumes all or part of another. This includes predator-prey, herbivore-plant, and parasite-host interactions.




 * Density-independent limiting factor:** Liiting factor that affect all populations in similar ways, regerdless of population size.




 * Demography:** is the statistical study of all populations. It can be a very general science that can be applied to any kind of dynamic population, that is, one that changes over time or space (see population dynamics).




 * Demographic transition:** is a model used to represent the process of explaining the transformation of countries from high birth rates and high death rates to low birth rates and low death rates as part of the economic development of a country from a pre-industrial to an industrialized economy.




 * Age-structure diagram:** Graph of the numbers of males and females within defferent age of a population.