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Ch. 52 Warm-Up

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Title: Nerve activates contraction Author: Karl Miyajima Last modified by: Gabor takacs Created Date: 12/11/2000 1:39:32 AM Document presentation format – PowerPoint PPT presentation

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Title: Ch. 52 Warm-Up


1
Ch. 52 Warm-Up
  1. (Review) Sketch an exponential population growth
    curve and a logistic population growth curve.
  2. What is an ecological footprint?
  3. What are ways that you can reduce your ecological
    footprint?
  • Define
  • Demography
  • Semelparity
  • Iteroparity
  • Carrying capacity
  • Exponential growth curve
  • Logistic growth curve
  • K-selection
  • r-selection
  • Ecological footprint

2
Population Ecology
  • Chapter 52

3
You Must Know
  • How density, dispersion, and demographics can
    describe a population.
  • The differences between exponential and logistic
    models of population growth.
  • How density-dependent and density-independent
    factors can control population growth.

4
Introduction
  • Population group of individuals of a single
    species living in same general area
  • Density individuals / area
  • Dispersion pattern of spacing between individuals

5
Determining population size and density
  • Count every individual
  • Random sampling
  • Mark-recapture method

6
Patterns of Dispersal
  1. Clumped most common near required resource
  2. Uniform usually antagonistic interactions
  3. Random not as common as you would think

7
Demography the study of vital statistics that
affect population size
  • Additions occur through birth, and subtractions
    occur through death.
  • Life table age-specific summary of the survival
    pattern of a population
  • Represent data with a survivorship curve.
  • Plot of individuals in a cohort still alive at
    each age.

8
Life Table
9
Survivorship Curves
  • Type I curve low death rate early in life
    (humans)
  • Type II curve constant death rate over lifespan
    (squirrels)
  • Type III curve high death rate early in life
    (oysters)

10
Life History traits that affect an organisms
schedule of reproduction and survival
  • 3 Variables
  • Age of sexual maturation
  • How often organism reproduces
  • offspring during each event
  • Note These traits are evolutionary outcomes, not
    conscious decisions by organisms

11
Semelparity
  • Big-bang reproduction
  • Many offspring produced at once
  • Individual often dies afterwards
  • Less stable environments

Agave Plant
12
Iteroparity
  • Repeated reproduction
  • Few, but large offspring
  • More stable environments

Lizard
Critical factors survival rate of offspring and
repeated reproduction when resources are limited
13
Change in Population Size
  • ?N/?t B-D
  • N population size
  • t time

14
  • Zero population growth B D
  • Exponential population growth ideal conditions,
    population grows rapidly

15
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16
  • Unlimited resources are rare
  • Logistic model incorporates carrying capacity
    (K)
  • K maximum stable population which can be
    sustained by environment
  • dN/dt rmax((K-N)/K)
  • S-shaped curve

17
Laboratory Populations
18
Factors that limit population growth
  • Density-Dependent factors population matters
  • i.e. Predation, disease, competition,
    territoriality, waste accumulation, physiological
    factors
  • Density-Independent factors population not a
    factor
  • i.e. Natural disasters fire, flood, weather

19
  • K-selection pop. close to carrying capacity
  • r-selection maximize reproductive success

K-selection r-selection
Live around K Exponential growth
High prenatal care Little or no care
Low birth numbers High birth numbers
Good survival of young Poor survival of young
Density-dependent Density independent
ie. Humans ie. cockroaches
20
  • Populations fluctuate due to biotic and abiotic
    factors

1975-1980 peak in wolf numbers 1995 harsh
winter weather (deep snow)
21
  • What do you notice about the population cycles of
    the showshoe hare and lynx?

22
Boom-and-bust cycles
  • Predator-prey interactions
  • Eg. lynx and snowshoe hare on 10-year cycle

23
Human Population Growth
  • 2 configurations for a stable human population
    (zero population growth)
  • High birth / high death
  • Low birth / low death
  • Demographic transition occurs when population
    goes from A ? B

24
Age-Structure Diagrams
25
Global Carrying Capacity
  • UN predicts 7.8 to 10.8 billion people by the
    year 2050
  • 2012 7 billion
  • Estimated carrying capacity 10-15 billion?
  • Ecological footprint total land water area
    needed for all the resources a person consumes in
    a pop.
  • 1.7 hectares (ha)/person is sustainable
  • U.S. 10 ha/person ? over K??
  • Limitations? Consequences? Solutions?

26
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27
Map of ecological footprint of countries in the
world (proportional sizes shown)
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