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Chapter 4

Chapter 4. Section 1 Population Dynamics. Populations…. Reminder… A population is a group of species (all the same type) that live together in the same area at the same time. How can we describe a population? Density Spatial distribution Growth rate. 1. Population Density.

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Chapter 4

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  1. Chapter 4 Section 1 Population Dynamics

  2. Populations… • Reminder… • A population is a group of species (all the same type) that live together in the same area at the same time. • How can we describe a population? • Density • Spatial distribution • Growth rate

  3. 1. Population Density • The number of organisms per unit are • This means how saturate is the population • Look at Figure 2 on Pg 93 in your book • Population density of the Black Bear is: • 1 bear per several hundred square kilometers • 1 bear/km2 • Population density of the American Bison is: • 4 bison/km2 • Population density of the White-tailed Deer is: • 10 deer/km2

  4. Population Density Thinking Critically PD = # of organisms/square area • If 15,000 bass, 275 turtles, 148,070 minnows lived in a pond 100,000 m2: • PD of bass: • 0.15 bass/m2 • PD of turtles: • 0.00028 turtles/m2 • PD of minnows: • 1.48 minnows/m2

  5. 2. Spatial Distribution • Distribution = how is something spread out or arranged. • Dispersion is the pattern of spacing of a population. • Look at Figure 2 on Pg 93: • Black Bear = Uniform • American Bison = Clumped group • White-tailed Deer = random

  6. 3. Population Ranges • The distribution of a species: • Means where it lives and reproduces. • A species might now be able to expand its population range because it may not be able to survive, due to Abiotic Factors/Conditions. • Temperature • Precipitation • Sunlight • Others also - ??? • Also Biotic Factors present threats. • Predators, competitors, parasites

  7. Population Ranges Look again at Figure 2 on Pg 93 • Black Bears ARE found in Michigan. • Where? • Northern lower peninsula • Entire upper peninsula • White-tailed Deer ARE NOT found in Alaska. • The American Bison range includes the entire state of Texas.

  8. Population Limiting Factors • What limits the growth of a population? • Density-Independent factors (DIF) • Density-Dependent factors (DDF) • Remember a limiting factors is a biotic or abiotic factor that keep the population from growing indefinitely. (indefinitely = does not stop)

  9. Density–Independent Factor (DIF) • Any factor in the environment that does NOT depend on the number of members in a population. • DIF – are usually abiotic factors • Drought/flooding • Fire • Tornados/hurricanes • Human alterations to landscaping • Pollution • Why? • Because, abiotic factors do not depend on the number of organisms in a population.

  10. Density-Dependent Factors (DDF) • Any factor in the environment that depends on the number of organisms in a population. • DDF – are usually biotic factors • Predation • Disease • Competition • Parasites • Why? • Because, biotic factors need other organisms.

  11. Density-Dependent Factors (DDF) Look at Figure 5 on Pg 96 • The approximate ratio of moose to wolves: • In 1965 _______ • In 1980 _______ • In 1995 _______ • In 2000 _______ • Between 1980 and 1995: • the wolf population decreased form about_________. • the effect that it had on the moose population was an increase from about___________.

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