NAU Biology BIO 326
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BIO326 : Population : Population Characteristics : Lesson

Population Characteristics: Lesson

Glossary terms that are important in this lesson:

Age structure, allele, bottleneck, cline, density, dispersion, ecotype, founder, gene flow, gene pool, genetic drift, habitat, ideal free distribution, inbreeding, inbreeding depression, landscape concept, MHC, modeling, mutation, outbreeding, patchiness, population growth rate, self incompatibility, stable age distribution, survivorship curve

Use the outline below to guide your study of the material in this lesson. The outline follows the book, but indicates those topics the instructor feels are most important for you to learn in the course. You should read all the pages that are assigned, but the outline will help you focus your study.

Individuals occupying the same habitat and sharing the same gene pool make up a population. A population is dispersed in its environment, it has a growth rate, it has an age structure and can be identified as an ecological unit.

I. Population

  1. Introduction

  2. Population structure

  3. Habitat and distribution

  4. Population density

  5. Populations in heterogeneous landscapes

  1. Ideal free distributions - apparent quality of patch depends on:
    • Intrinsic patch quality
    • Exploitation
    • Migratory birds, stickleback
    • Sense the environment - know the resources
    • Behavioral flexibility and freedom to choose; dominance

  2. Source and sink populations
    • Good habitats produce surplus populations
    • Poor habitats receive immigrants
    • Blue tits in southern European oak forests
Blue tit

  1. Dispersion

  2. Spatial coherence
II. Genetic Structure of Populations

  1. Genetic variation (Review from prerequisite classes)

  2. Mating systems

  1. Genetic changes in small populations
    • Genetic diversity is less (in small populations)
    • Large genetic differences between populations
    • Chance effects are important: genetic drift in allele frequencies
    • Fixation is inversely related to population size
    • Founder event: colony established from a reduced gene pool
    • Population bottleneck: cheetahs; gene pool restricted
    • Probability of extinction increases

  2. Geographic variation in the gene pool
    • Cline: gradual change in allele frequency from differential selection
    • Ecotype: genetic basis; Göte Turesson
    • Achillea, toxic metals, Teleogryllus, Bradybaena, Linanthus
Linanthus parryae
III. Population Growth

  1. Age structure and population growth rates

  2. Population age structure: birth rates (fecundity) and death rates (mortality) are dependent on the age of individuals

  3. Stable age distribution

  4. The life table - a model

When you have completed this lesson, go on to Review Questions

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