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Chapter 5-6 Population Lecture Notes When describing a population three factors come into play. Geographic distribution, density, and growth rate. Geographic distribution describes the range of habitat. Density refers to the number of individuals in a given amount of space. D= N/S # of people in room Area of room Density _________ _________ __________ Population Growth When hunting sea otters became illegal, the otter population soared. It eventually went back down to normal levels because killer whales preyed upon them. _______________—Birth Rate _______________—Death Rate _______________- moving into a geographic area by migration. This increases the population. _______________- leaving a geographic area. This decreases the population. What could cause animals to Immigrate? Emigrate? What could cause Humans to Immigrate? Emigrate? 2000 Natality Immigration Mortality Emigration 200 300 150 200 Population _150___ 2004 250 180 180 150 _100_ change= final-initial time (_____________________ 4 years) Exponential Growth If there is enough food, water, reproduction, space, and no diseases, populations will increases exponentially. On pg. 121 there is a graph of exponential growth. It’s a _______________curve. Of course, there are limiting factors. There is never an unlimited amount of food and space in any population. As these limiting factors (resources) become less available, the population decreases. Carrying capacity: The _______________population an ecosystem can support. On a graph the carrying capacity shows an _______________ _______________curve. Pg. 122. This type of graph indicates a_______________, stable population. This would indicate that birth and death rates are about _______________and immigration and emigration are about the same. Limiting Factors—limit the _______________ of a population. Competition Predation Disease Drought/Natural disaster Humans Density Dependent Factors—depends on size of population. Density Dependent factors only affect the population size, when it gets too _______________. Competition: The larger the population, the more _______________ is the amount of food/water space. This can be between individuals as well as other_______________. Predation: vital to help control populations and keep them healthy. Pg. 126. When the moose population increases, so does the wolf. Parasite/Disease: when a population gets too large (or lives too close together) disease spreads killing off many individuals. This is even true of human populations. Density Independent Factors *Size of population is irrelevant. _______________is a density independent factor. Human activity, such as building Human Populations Humans have been increasing in population size. We are in exponential growth. Pg. 129. Demography studies human population sizes. What is the shape of the graph for human population?_____________________________________ Pg. 131 graph What does the Rwanda graph show with natality? _______________ Mortality? _______________ What does the U.S. population show with natality? _______________ Mortality? _______________ India has the fastest growing population. Pg. 132 Ch 6-2 Renewable Resources- can be regenerated in limited amounts List: Nonrenewable- limited supply never regenerated. List: Sustainable use- using a resource at a _______________rate that can be replaced. You cannot donate blood every week. Land resources- limited amount of space and quality soil. Crop rotation______________________________ Soil erosion______________________________ Overgrazing______________________________ Ocean resources Over fishing______________________________ Pollution______________________________ Biodiversity is the Earth’s greatest natural resource. _______________ _______________ _______________ Humans Interrupt biodiversity Habitat Destruction Pollution (pg 152) Introduced species- rats on Hawaiian Islands, brought in mongoose, brought in cats. There aren’t any predators for an introduced species. Zebra muscles from Europe are in the Great Lakes, killing off natural aquatic creatures. Leafy spurge—replaces natural grasslands Varroa mites on honeybees Fire ants, Dutch elm, Asia beetle on maple trees, Eurasia milfoil chokes lakes, Mexican Bull weevil on cotton, cheat grass-in pastures What happens to the ocean and land that is open to everyone? Pg 144 What is the tragedy of the commons?
