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types of overpopulation - people overpopulationpeople overpopulation refers to a situation where there are more people than the supplies of food
four distinct phases of demographic transitiondemographic transition takes place in four distinct phases1 re-industrial stage in which harsh living
demographic transitionas we saw earlier death rates and birth rates have been nearly equal throughout much of human history however in western europe
total fertility ratetotal fertility rate tfr is the total number of children a women can be expected to bear in a given population if birth rates are
age-sex distribution while studying exponential growth we need to know more than just the birth and death rates because these rates vary with age and
archaeological records of human campsitesarchaeological records of human campsites indicate that early humans started out as small bands of hunters
evolutionary implications of natural regulationmany changes in abundance can be attributed to changes in extrinsic factors such as weather disease or
genetic diversity of populationthe biological diversity of animals plants and microorganisms is of fundamental importance to human survival the term
density independent factors density independent factors are the extrinsic factors which tend to regulate the density of a population in ways that are
density dependent factors - population regulationthe density dependent factors are intrinsic or biotic factors and they depend on interactions
population regulationthe number of individuals in a natural population varies with time if the size of a population declines too drastically due to
factors affecting biotic potential - population growthbiotic potential differs from one species to another eg bacterial populations can grow faster
population growth - population parameters and regulationthe size of a population depends upon the balance between natality and immigration through
age distribution - population parameters and regulationit is obvious that individuals in a population will be of different age groups relative
migration - population dispersaldispersal is affected by the presence or absence of the barrier and vagility which means inherent power of movement
mass dispersal - population dispersal a population is inherently dynamic in nature since individuals are always leaving or entering the populations
population dispersal population dispersal is the movement of individuals into or out of the population or the population area it occurs in three
mortality - population parameters and regulationthe death of an individual in a population is known as mortality mortality rate like natality
natality rate - natalitynatality rate or birth rate is determined by dividing the number of individuals born by unit time and is expressed as
natality - population parameters and regulationnatality is the ability of a population to increase natality rate is equivalent to birth rate which
density - population parameters and regulationdensity is defined as number of individuals or population biomass per unit of area or volume at any
population parameters and regulationpopulation can be defined as a group of organisms of same species occupying a specific area at a particular time
crustose lichen stage - xerarchon bare rocks conditions are inhospitable for life as there is extreme deficiency of water and nutrients great
foliose lichen stage - xerarchas mentioned earlier the weathering of the rocks and the decaying of the crustose lichens results in the formation of
moss stage - xerarchthe accumulation of soil particularly in the crevices and depressions of rock favours the growth of certain xerophytic mosses eg