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POPULATION BIOLOGY Chapter 5 Population Dynamics • Population _________ = increase in ________ of population over time (Fig. 4.1, p. 95) – growth of organisms is not _____________ but ______________ – as population get larger it also grows ___________ J-shaped curve • Initially, the increase in number of organisms is _____________ – number of ____________________________ is small – rate increases rapidly because ________________________ of organisms increases – results in population __________________ Limits of population growth • Populations cannot grow ____________________! – Limiting factors will cause population to stop increasing – results in ________________ growth curve Carrying Capacity ______ • Number of organisms of one ________________ that an environment can support – if population is __________ its carrying capacity, then _____________ >deaths (until k is reached) – if population is _____ its carrying capacity, then _____________ > births (until k is reached) * Thus….population levels __________________. Patterns of population growth • Most important factor determining population growth is organism’s _______________ ________________________ – – – – how fast how ________________ how early how _______________ • _____________ reproductive rates found in organisms with ___________ body size and short _______________________ – populations increase/decrease ____________________ as conditions change – ie. mosquitoes • __________________ reproductive rates found in organisms with ______________ body size and longer life span – species live in more ___________________ environments – ie. elephants, ___________________ Environmental Limits Two main kinds of limiting factors 1. ______________________________ 1 2. ______________________________ Limiting Factors • Density-dependent – have increased effect as population __________________ – ________________, competition, parasites, food – ex: disease spreads more quickly in large populations – _____________________ can also limit population • Density-independent – affect _______ populations regardless of size/density – ___________________, storms, floods, drought, habitat disruption, ____________ Human Population Growth • __________________--study of human population growth characteristics – growth rate, _______________________, geographic distribution – world wide human population has ________________ exponentially over past several ___________________ years – humans can reduce/limit environmental effects by __________________ competing organisms, increasing food production and controlling ______________ Birth/Death Rates Growth rate of population = Birth rate - Death rate • In US, people are _______________ longer, waiting until their _________ to have kids , and having fewer kids (__________________ rate is decreasing) • When fertility rates are high, populations grow ________________ unless death rate is also high Age Structure • Proportions of population that are at different ____________ levels • Rapid growth countries have ___________ base (lots of _________________ people) • Stable populations have fairly _____________ categories (Fig. 4.11, p. 107) • _______________ of people affects population size • Immigration vs. Emigration 2