Biol 301 1nd Edition Lecture 4 Outline of Last Lecture I. DemographyII. Population growthIII. Age structureOutline of Current Lecture II. Population growth modelsIII. Density dependent growth modelIV. Carrying capacityCurrent LecturePopulation Growth Models – A. Density independent limitations: factors that limit population size regardless of the population’s density. Common factors include climactic events (ex: tornadoes, droughts, floods).B. Density dependent limitations: factors that affect population size in relation to the population’s density (ex: food, nesting sites, physical space).- Negative density dependence: when the rate of population growth decreasesas population density increases- As a population’s size increases, resources are divided among more individuals, and per capita resources decline to a level at which individuals find it difficult to grow and reproduce.- Positive density dependence (aka. Inverse density dependence or Allee effect): when the rate of population growth increases as population density increases.- Typically occurs when population densities are low, which may make it hard to find mates, particularly when sex ratios are uneven.C. Density Dependent Logistic Growth Model: dN/dt=rN- Adds carrying capacity—the maximum number of individuals that an environment can sustain indefinitely. Depends on resource availability- Logistic growth model: a growth model that describes slowing growth of populations at high densities: These 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.D. S-shaped curve: the shape of the curve when a population is graphed over time using the logistic growth model.E. Inflection point: the point on a sigmoidal growth curve at which the population has its highest growth
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