BIO 373 1st Edition Lecture 12 Outline of Last Lecture I. Populationsa. Consequences of exponential growthb. Life tablesi. Cohort life tableii. Static life tableiii. Growth patterns1. Rapid, zero, negativeOutline of Current Lecture I. Influences on Population Sizea. Weatherb. Intraspecific competitionc. Density dependent factorsII. Logistic Growtha. Carrying capacityb. Compare to exponential growthIII. Simple and complex population dynamicsa. Exponential and logistic growthb. Population fluctuationsCurrent LectureInfluences on Population Size- Weathero Density independent factors Drought, flood- Intraspecific Competitiono Density dependent factors As competition in females increases, birth rates of females decreasesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Negative correlation- Less resources for female to give offspring As egg density increases, mortality rate increases- Lack of resources Increasing population size, increasing mortality- Decrease in resources As population density increases, competition increases in general- Density dependent factorso Vegetation Competition for light as e- resourceo Predation Competition for food sourceo Parasitism Increased population density when increased parasitismo Population regulation Density dependent factors cause population to increase when density is low and decrease when density is highLogistic Growth- carrying capacityo B= births d= deaths N= population density K= carrying capacityo How many individuals can a site support with available resourceso Initially, logistic growth is similar to exponentialo Eventually, a population that grows logistically will level off at carrying capacity- Compare logistic to exponentialo Logistic growth is a downward curve when graphed as dN/dt and population density Peak is at half of carrying capacityo Exponential growth is positive linearo Comparing per capita growth rate, we assume birth and death rate are affected linearly by density dependence in logistic growth and we assume birth and death rate are constant in exponential growthSimple and Complex Population Dynamics- Exponential and logistic growtho Example: birds went from Africa to South America and began growing exponentially This was because conditions and resources were optimal In Florida, now they are growing logistically because they are reaching their carrying capacity- Population fluctuationso Sometimes increase or decrease precipitously in just a few days How population growth changes occur in nature Can be because of changes in upwelling, temperature, salinity, etc.o Above and below max sustainable population sizeo Fluctuation occurs within general growth patterns Within the general trend of exponential or logistic growth, there are fluctuations in growtho Can be caused by outbreaks or peaks and declines within population cycles Maybe temperature affected organisms’ metabolism or resourceso Delayed density dependence Logistic equation is modified to include time
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