Population Dynamics Chapters 8 and 9, Miller 15th Edition - PowerPoint PPT Presentation

About This Presentation
Title:

Population Dynamics Chapters 8 and 9, Miller 15th Edition

Description:

... we are all in it together. 1949 1964 Habitat fragmentation in northern Alberta 1982 1991 * Population dispersion is the spatial pattern of ... – PowerPoint PPT presentation

Number of Views:82
Avg rating:3.0/5.0
Slides: 50
Provided by: homeLcus
Category:

less

Transcript and Presenter's Notes

Title: Population Dynamics Chapters 8 and 9, Miller 15th Edition


1
Population Dynamics Chapters 8 and 9, Miller
15th Edition
  • AP Environmental Science
  • LCHS
  • Dr. E

2
Population Dynamics Outline
  • Characteristics of a Population
  • Population Dynamics and Carrying Capacity
  • Reproductive Strategies
  • Conservation Biology
  • Human Impacts
  • Working with Nature

3
Characteristics of a Population
  • Population - individuals inhabiting the same area
    at the same time
  • Population Dynamics Population change due to
  • Population Size - number of individuals
  • Population Density - population size in a certain
    space at a given time
  • Population Dispersion - spatial pattern in
    habitat
  • Age Structure - proportion of individuals in each
    age group in population

4
Population Size
  • Natality
  • Number of individuals added through reproduction
  • Crude Birth Rate - Births per 1000
  • Total Fertility Rate Average number of children
    born alive per woman in her lifetime
  • Mortality
  • Number of individuals removed through death
  • Crude Death Rate Deaths per 1000

5
Population Density
  • Population Density (or ecological population
    density) is the amount of individuals in a
    population per unit habitat area
  • Some species exist in high densities - Mice
  • Some species exist in low densities - Mountain
    lions
  • Density depends upon
  • social/population structure
  • mating relationships
  • time of year

6
Population Dispersion
Population dispersion is the spatial pattern of
distribution There are three main
classifications Clumped individuals are lumped
into groups ex. Flocking birds or herbivore
herds due to resources that are clumped or
social interactions most common
http//www.johndarm.clara.net/galleryphots/
7
Population Dispersion
http//www.calflora.net/bloomingplants/creosotebus
h2.html
8
Age Structure
  • The age structure of a population is usually
    shown graphically
  • The population is usually divided up into
    prereproductives, reproductives and
    postreproductives
  • The age structure of a population dictates
    whether is will grow, shrink, or stay the same
    size

9
Age Structure Diagrams
Positive Growth Zero Growth
Negative Growth (ZPG) Pyramid
Shape Vertical Edges Inverted
Pyramid
10
Population Dynamics Outline
  • Characteristics of a Population
  • Population Dynamics and Carrying Capacity
  • Reproductive Strategies
  • Conservation Biology
  • Human Impacts
  • Working with Nature

11
(No Transcript)
12
  • Biotic Potential
  • factors allow a population to increase under
    ideal conditions, potentially leading to
    exponential growth
  • Environmental Resistance
  • affect the young more than the elderly in a
    population, thereby affecting recruitment
    (survival to reproductive age)

13
Biotic Potential
  • Ability of populations of a given species to
    increase in size
  • Abiotic Contributing Factors
  • Favorable light
  • Favorable Temperatures
  • Favorable chemical environment - nutrients
  • Biotic Contributing Factors
  • Reproductive rate
  • Generalized niche
  • Ability to migrate or disperse
  • Adequate defense mechanisms
  • Ability to cope with adverse conditions

14
Environmental Resistance
  • Ability of populations of a given species to
    increase in size
  • Abiotic Contributing Factors
  • Unfavorable light
  • Unfavorable Temperatures
  • Unfavorable chemical environment - nutrients
  • Biotic Contributing Factors
  • Low reproductive rate
  • Specialized niche
  • Inability to migrate or disperse
  • Inadequate defense mechanisms
  • Inability to cope with adverse conditions

15
(No Transcript)
16
Population Growth
  • Population growth depends upon
  • birth rates
  • death rates
  • immigration rates (into area)
  • emigration rates (exit area)
  • Pop Pop0 (b i) - (d e)
  • ZPG
  • (b i) (d e)

17
Population Growth
  • Populations show two types of growth
  • Exponential
  • J-shaped curve
  • Growth is independent of population density
  • Logistic
  • S-shaped curve
  • Growth is not independent of population density

18
Exponential Growth
  • As early as Darwin, scientists have realized that
    populations have the ability to grow
    exponentially
  • All populations have this ability, although not
    all populations realized this type of growth
  • Darwin pondered the question of exponential
    growth. He knew that all species had the
    potential to grow exponentially
  • He used elephants as an example because elephants
    are one of the slowest breeders on the planet

19
Exponential Growth
One female will produce 6 young over her 100 year
life span. In a population, this amounts to a
growth rate of 2 Darwin wondered, how many
elephants could result from one male and one
female in 750 years? 19,000,000 elephants!!!
20
(No Transcript)
21
Exponential Growth Graph
22
Population Dynamics and Carrying Capacity
  • Basic Concept Over a long period of time,
    populations of species in an ecosystem are
    usually in a state of equilibrium (balance
    between births and deaths)
  • There is a dynamic balance between biotic
    potential and environmental resistance

23
Carrying Capacity (K)
  • Exponential curve is not realistic due to
    carrying capacity of area
  • Carrying capacity is maximum number of
    individuals a habitat can support over a given
    period of time due to environmental resistance
    (sustainability)

24
(No Transcript)
25
Logistic Growth
  • Because of Environmental Resistance, population
    growth decreases as density reaches carrying
    capacity
  • Graph of individuals vs. time yields a sigmoid or
    S-curved growth curve
  • Reproductive time lag causes population overshoot
  • Population will not be steady curve due to
    resources (prey) and predators

26
(No Transcript)
27
(No Transcript)
28
Population Dynamics Outline
  • Characteristics of a Population
  • Population Dynamics and Carrying Capacity
  • Reproductive Strategies
  • Conservation Biology
  • Human Impacts
  • Working with Nature

29
Reproductive Strategies
  • Goal of every species is to produce as many
    offspring as possible
  • Each individual has a limited amount of energy to
    put towards life and reproduction
  • This leads to a trade-off of long life or high
    reproductive rate
  • Natural Selection has lead to two strategies for
    species r - strategists and K - strategists

30
r - Strategists
  • Spend most of their time in exponential growth
  • Maximize reproductive life
  • Minimum life

K
31
R Strategists
  • Many small offspring
  • Little or no parental care and protection of
    offspring
  • Early reproductive age
  • Most offspring die before reaching reproductive
    age
  • Small adults
  • Adapted to unstable climate and environmental
    conditions
  • High population growth rate (r)
  • Population size fluctuates wildly above and below
    carrying capacity (K)
  • Generalist niche
  • Low ability to compete
  • Early successional species

32
K - Strategists
  • Maintain population at carrying capacity (K)
  • Maximize lifespan

K
33
K- Strategist
  • Fewer, larger offspring
  • High parental care and protection of offspring
  • Later reproductive age
  • Most offspring survive to reproductive age
  • Larger adults
  • Adapted to stable climate and environmental
    conditions
  • Lower population growth rate (r)
  • Population size fairly stable and usually close
    to carrying capacity (K)
  • Specialist niche
  • High ability to compete
  • Late successional species

34
Survivorship Curves
  • Late Loss K-strategists that produce few young
    and care for them until they reach reproductive
    age thus reducing juvenile mortality
  • Constant Loss typically intermediate
    reproductive strategies with fairly constant
    mortality throughout all age classes
  • Early Loss r-strategists with many offspring,
    high infant mortality and high survivorship once
    a certain size and age

35
(No Transcript)
36
Population Dynamics Outline
  • Characteristics of a Population
  • Population Dynamics and Carrying Capacity
  • Reproductive Strategies
  • Conservation Biology
  • Human Impacts
  • Working with Nature

37
Conservation Biology
  • Careful and sensible use of natural resources by
    humans
  • Originated in 1970s to deal with problems in
    maintaining earth's biodiversity
  • Dedicated to protecting ecosystems and to finding
    practical ways to prevent premature extinctions
    of species

38
Conservation Biology
  • Three Principles
  • Biodiversity and ecological integrity are useful
    and necessary to all life on earth and should not
    be reduced by human actions
  • Humans should not cause or hasten the premature
    extinction of populations and species or disrupt
    vital ecological processes
  • Best way to preserve earths biodiversity and
    ecological integrity is to protect intact
    ecosystems that provide sufficient habitat

39
Habitat Fragmentation
  • Process by which human activity breaks natural
    ecosystems into smaller and smaller pieces of
    land
  • Greatest impact on populations of species that
    require large areas of continuous habitat
  • Also called habitat islands

40
(No Transcript)
41
1949 1964 Habitat fragmentation in northern
Alberta 1982 1991
42
Population Dynamics Outline
  • Characteristics of a Population
  • Population Dynamics and Carrying Capacity
  • Reproductive Strategies
  • Conservation Biology
  • Human Impacts
  • Working with Nature

43
Human Impacts
  • Fragmentation and degrading habitat
  • Simplifying natural ecosystems
  • Strengthening some populations of pest species
    and disease-causing bacteria by overuse of
    pesticides
  • Elimination of some predators

44
Human Impacts
  • Deliberately or accidentally introducing new
    species
  • Overharvesting potentially renewable resources
  • Interfering with the normal chemical cycling and
    energy flows in ecosystem

45
Population Dynamics Outline
  • Characteristics of a Population
  • Population Dynamics and Carrying Capacity
  • Reproductive Strategies
  • Conservation Biology
  • Human Impacts
  • Working with Nature

46
Working with Nature
  • Learn six features of living systems
  • Interdependence
  • Diversity
  • Resilience
  • Adaptability
  • Unpredictability
  • Limits

47
Basic Ecological Lessons
  • Sunlight is primary source of energy
  • Nutrients are replenished and wastes are disposed
    of by recycling materials
  • Soil, water, air, plants and animals are renewed
    through natural processes
  • Energy is always required to produce or maintain
    an energy flow or to recycle chemicals

48
Basic Ecological Lessons
  • Biodiversity takes many forms because it has
    evolved over billions of years under different
    conditions
  • Complex networks of and feedback loops exist
  • Population size and growth rate are controlled by
    interactions with other species and with abiotic
  • Organisms generally only use what they need

49
Four Principles for Sustainable
  • We are part of, not apart from, the earths
    dynamic web of life.
  • Our lives, lifestyles, and economies are totally
    dependent on the sun and the earth.
  • We can never do merely one thing (first law of
    human ecology Garret Hardin).
  • Everything is connected to everything else we
    are all in it together.
Write a Comment
User Comments (0)
About PowerShow.com