1. Introduction
   1. A. What is a population?
      1. Group of potentially interbreeding individuals
      2. Continuity over time
      3. Groups of populations that actually or potentially interbreed with each other = species
   2. Characteristics of populations
      1. Size (numbers)
      2. Density (numbers per unit area or host)
      3. Distribution in space (clumped, random, uniform)
      4. Variation (e.g., size, density, distribution,..)[Range, mean, variance, skewness]
      5. Social behavior (interactions among members)
      6. Genetics (gene pool)
         1. Genotype - genetic makeup
         2. Phenotype - interaction between genotype and the environment
      7. Evolution (speciation)
      8. Extinction
2. Demography: Vital statistics: Natality (births); Mortality (deaths)
   1. Survivorship (actuarial) curves:
      1. Type I- Most live to old age (humans, deer)
      2. Type II- Constant mortality (adult butterflies, mice)
      3. Type III- High infant mortality (most insects, oysters)
   2. Generation time (T) - Time between generations (egg to egg)[Female only]
   3. Net Replacement Rate (R_o)/generation - number of daughters that replace an average female in the course of a generation.
      1. R_o > 1 Growing
      2. R_o = 1 Stable
      3. R_o < 1 Decreasing
      4. R_o - not a useful statistic for comparison between species as generation times vary greatly.
   4. Intrinsic Rate of Natural Increase (r_m)
      1. r_m > 0 Growing (Natality > Mortality)
      2. r_m = 0 Stable (Natality = Mortality)
      3. r_m < 0 Decreasing (Natality < Mortality)
      4. r_m - the rate of increase in a population growing under optimal conditions; useful statistic for comparing growth rates of populations of different species.
   5. What factors influence r?
      1. Generation time: Increase (lengthen), decreases r
      2. Immature survival: Increase early, increases r
      3. Fecundity patterns of female:
         1. Few additional eggs early has more impact than-
         2. Many additional eggs later
      4. Little or no effect:
         1. Males
         2. Longevity of female beyond reproductive period.
3. Population Growth
   1. Exponential growth
      1. Malthus (1798)
      2. In unlimited environment, growth rate is exponential (r )
   2. Logistic growth
      1. Carrying capacity (K)
      2. Populations exceed carrying capacity; populations decrease or "crashes"
      3. New resources; populations recover
4. Factors Influencing Populations (Fluctuations over time; Natural Controls)
   1. Density-Dependent - Governing factors-proximate role, usually biotic, feedback
      1. Competition - Two or more organisms requiring the same resources when these are limited
         1. Interference competition- Direct interaction
         2. Exploitation competition- Indirect, one reduces shared resource availability
         3. Intraspecific vs. interspecific (Within vs. between species)
      2. Predation
      3. Parasitism
      4. Disease
   2. Density-Independent
      1. Legislative factors-ultimate role, usually abiotic
      2. Unpredictable, catastrophic (e.g., weather, insecticides)
5. Life History Characteristics [Not discrete categories, but ends of a continuum]
   1. Opportunistic populations or r-strategists
      1. Many insects, rapid reproductive rate
      2. Catastrophic density-independent mortality
      3. Adapted for rapid adjustment
   2. Equilibrium populations or K-strategists
      1. Few insects, low reproductive rate
      2. Constant density-dependent mortality
      3. Adapted for efficient use of resources
   3. Characteristics of extremes of r-selected and K-selected species:

      Characteristics	r-selected	K-selected
      Reproduction	rapid	slow
      Egg number	high	low
      Generation time	short	long
      Generations/year	>1 (Multivoltine)	1 (Univoltine)
      Development	Rapid	Slow
      Competition	Usually reduced	Usually intense
      Mortality	catastrophic (density-independent)	constant (density-dependent)
      Population size	variable	fairly constant
      Brood care	absent	sometimes present
      Dispersal ability	very high	often low
      Body size	often very small	often larger
      Habitat	unstable (temporary)	stable (climax)
      Emphasis on	high productivity (reproduction)	efficient use of resources
      Examples	Aphids, locusts	Tsetse flies, specialized feeders

6. Numerical vs. Functional Response
   1. Numerical Response - Response of predators or parasites to host densities by increase in their population density.
   2. Functional response - Response of predators or parasites in increasing their rate of kill of their prey.

Other background reading: Evans, H.E. (1984). Insect Biology: A Textbook of Entomology: pp. 336-377

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