Biology1001FinalExam ChAPTER18-

# Biology1001FinalExam ChAPTER18- - November18,2009

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November 18, 2009 Gene flow makes population more genetically similar Which of the following is the first step in process of allopatric speciation? Geographic isolation Population Growth and Regulation Chapter 39 Ecology The study of the interrelationships among living things and their nonliving environment Population Members of a particular species within an ecosystem Actually or potentially interacting How does population size change? Biotic potential Maximal growth rate given ideal conditions Produces exponential growth if not restrained Environmental resistance Factors that limit population growth E.g. food availability, space, access to mates, environmental factors Population growth=biotic potential-environmental resistance Population change=(births-deaths)+(immigrants-emigrants) If we ignore migration Growth rate (r )= birth rate(b)-death rate(d) To determine the number of individuals added to a population in a given time period, the growth  rate(r ) is multiplied by the current population size Population growth=r*N Time current N population growth T=0 N 0 n/a T=1 N 1 N 0 +r*N 0 T=3 N 2 N 1 +r*N 1

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Exponential population growth Kirk says, “there must be thousands!”{ Spock says, “there are 1,771,561” Spock’s calculation assume 1. Initial population=1 2. 3 days 3. No deaths 4. Unlimited food 5. 10 offspring each 6. 12 hour between generations 7. All Tribbles breed Exponential Growth Curves Characterized by “J-shaped curve” Death rate<birth rate exponential growth Just takes longer Death rate= or > birth rate  no growth Equilibrium or decline Figure 39-2 How is population growth regulated? Populations can’t grow exponentially forever Finite amount of resources available Once they are limiting, population growth stops  o Can reach equilibrium or population may crash Figure 39-3 Lemming Population cycles Conditions good, boom; conditions bad, bust Figure 39-4 Environmental resistance limits population growth  Decreases birth rate, increases death rate Density-dependent factors  o Predation o Parasitism
o Competition(inter-and intraspecific Density independent factors o Weather, natural disasters, pesticides, pollutants Causes populations to stabilize at or below carrying capacity o Maximum population size an area can support long term November 20, 2009 Population growing exponentially has j shaped growth and has a per capita growth of more than zero A j shaped growth curve is converted to a s-shaped one…. When the carrying capacity is reached.

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## This note was uploaded on 09/08/2010 for the course BIOL BIOL 1001 taught by Professor Ah during the Spring '09 term at LSU.

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Biology1001FinalExam ChAPTER18- - November18,2009

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