Brief idea on the Impact of ongoing human development on our environment and Describing and understanding population ecology - Patterns of dispersion, Survivorship curve, Population growth, Exponential growth, ecological footprint etc

1. Impact of Development On Environment
By Surabhi Tanwar

2. Human Impacts…

3. All Species Impact Environment
 Understanding how humans interact with the biosphere is
crucial to protecting the natural resources.
 Humans Impact the Environment more than any species !

4. Human
Activities
that have changed the biosphere include
may have once caused often relies on the methods of the
have resulted in
which increased
Food supply Pesticide use
Monoculture
use
Hunting and
gathering
Agriculture
Industrial
growth
Urban
development
Extinctions of
large animals
Green
revolution
High standard
of living
Increased
pollution

5. Industry
Industrial
Revolution
mid 1800’s.
Economy, Conveniences and Productivity advances
More “Stuff” More Waste
Increase use of Tools, Technology and Sciences
Use of Fossil Fuels Release of CO2 Green
House Effect
Chemical and waste by products of manufacturing

6. Physical
change of
Ecosystems.
Soil, Flore and
Fauna…
Concrete
Suburban Sprawl –
Commuters to urban
areas
Increase drive time to
work & air pollution.
Biodiversity
Oxygen
Production
Decreases
Increases
Water Run Off, Pollution,
Heat, Habitat Problems
(Destruction,
Degradation and
Fragmentation)
Urban Development

7. Green House Effect and Global Warming
CO2 keeps heat radiation in Blanket
Carbon Dioxide is a primary green house gas,
responsible for 60% of global warming.

8. Breathing Problems Irritation of Membranes
Burning Fossil Fuels is the BIGGEST Source
(SMOG)
Ozone Layer is being broken down by CFC’s
Found in Refrigerators, Coolants; this allows radiation
to reach earth, causing genetic defects and cancer.
Air Pollution

9. Industry Transportation Ore smelting
Power generation

11. Abiotic and Biotic Issues of Fragmentation
Def.: Breaking up of a habitat into unconnected patches
Some Organisms need large area for gathering food
No migratory routes to reestablish populations lost due to
natural disasters.
Climate change

12. Biological magnification
• Biological magnification– toxins may be concentrated from one
trophic level to the next.
• DDT is an example
• DDT is a pesticide that was used extensively
• DDT is not biodegradable
• Organisms do not eliminate it

13. Fish-Eating Birds
Large
Fish
Small Fish
Zooplankton
Producers
Water
10,000,000
1,000,000
100,000
10,000
1000
Magnification of
DDT Concentration

14. So what do we do?
 On an Individual Level
 Carefully use both renewable and non renewable resources :
SUSTAINABLE USE .
 Reduce, Reuse, Recycle.

15. References
http://www.niehs.nih.gov/research/programs/geh/climatechange/health_impa
cts/human_developmental/
https://en.wikipedia.org/wiki/Human_impact_on_the_environment

16. Presentation by: Surabhi Tanwar
Student of Masters in Environmental Science- Institute of Science,
Mumbai

17. POPULATION ECOLOGY
 Population ecology is the study of populations in relation to
environment, including environmental influences on density
and distribution, age structure, and population size
By Surabhi Tanwar

18.  Populations have size and geographical boundaries.
 The density of a population is measured as the number of individuals per unit
area.
 The dispersion of a population is the pattern of spacing among individuals within
the geographic boundaries.
The characteristics of populations are
shaped by the interactions between
individuals and their environment

19. MEASURING DENSITY
•Determination of Density
•Counting Individuals
•Estimates By Counting Individuals
•Estimates By Indirect Indicators
•Mark-recapture Method
N = (Number Marked) X (Catch Second Time)
Number Of Marked Recaptures
Density – Number of individuals per unit
of area.

20.  Measuring density of populations is a difficult task.
 We can count individuals; we can estimate population numbers.
Fig. 52.1

21.  Density is the result of an
interplay between processes
that add individuals to a
population and those that
remove individuals

22.  Patterns of dispersion.
Within a population’s geographic range, local
densities may vary considerably.
Different dispersion patterns result within the
range.
Overall, dispersion depends on resource
distribution.

23. Clumped. For many animals, such as these wolves,
living in groups increases the effectiveness of hunting,
spreads the work of protecting and caring for young,
and helps exclude other individuals from their territory.

24. Uniform. Birds nesting on small islands, such as these
king penguins on South Georgia Island in the South
Atlantic Ocean, often exhibit uniform spacing, maintained
by aggressive interactions between neighbors.

25. Random. Dandelions grow from windblown seeds that
land at random and later germinate.

26.  Additions occur through birth, and subtractions occur through death.
Demography studies the vital statistics
that affect population size.
 Life tables and survivorship curves.
A life table is an age-specific summary of
the survival pattern of a population.
Demography is the study of factors
that affect the growth and decline of
populations

27.  The best way to construct life table is to follow
a cohort, a group of individuals of the same
age throughout their lifetime.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Table 52.1

28. A graphic way of representing
the data is a survivorship
curve.
This is a plot of the number of
individuals in a cohort still alive at
each age.
A Type I curve shows a low death
rate early in life (humans).
The Type II curve shows constant
mortality (squirrels).
Type III curve shows a high death
rate early in life (oysters).

29. Survivorship Curve

30.  Reproductive rates.
Demographers that study populations
usually ignore males, and focus on
females because only females give birth
to offspring.
A reproductive table is an age-specific
summary of the reproductive rates in a
population.
For sexual species, the table tallies the
number of female offspring produced by
each age group.

31. Table 52.2
Reproductive Table

32.  The traits that affect an organism’s
schedule of reproduction and survival
make up its life history.
 Life histories are a result of natural
selection, and often parallel environmental
factors.
 Some organisms, such as the
agave plant, exhibit what is known as big-bang
reproduction, where large numbers of offspring
are produced in each reproduction, after which the
individual often dies. This is also known as
semelparity.
Life histories are very diverse, but they
exhibit patterns in their variability
Agaves

33.  By contrast, some organisms produce only a few eggs during
repeated reproductive episodes.
 This is also known as iteroparity.
Most weedy plants, such as this dandelion, grow quickly and produce a
large number of seeds, ensuring that at least some will grow into plants
and eventually produce seeds themselves.

34. Some plants, such as this coconut palm, produce a moderate
number of very large seeds. The large endosperm provides
nutrients for the embryo, an adaptation that helps ensure the
success of a relatively large fraction of offspring.

35.  The life-histories represent an evolutionary resolution of several
conflicting demands.
 Sometimes we see trade-offs between survival and reproduction when resources
are limited.
Limited resources mandate trade-offs between
investments in reproduction and survival
For example,
red deer show a
higher mortality rate in
winters following
reproductive episodes.

36.  We define a change in population size based on the
following verbal equation.
Change in population = Births during – Deaths during
size during time interval time interval time interval
The exponential model of population
describes an idealized population in an
unlimited environment

37.  Using mathematical notation we can express this relationship as
follows:
If N represents population size, and t
represents time, then N is the change is
population size and t represents the
change in time, then:
N/t = B-D
Where B is the number of births and D is the
number of deaths

38. We can simplify the equation and use r to
represent the difference in per capita birth
and death rates.
 N/t = rN OR dN/dt = rN
If B = D then there is zero population
growth (ZPG).
Under ideal conditions, a population grows
rapidly.
 Exponential population growth is said to be happening
 Under these conditions, we may assume the maximum growth rate for the population
(rmax) to give us the following exponential growth
 dN/dt = rmaxN

39. Fig. 52.9

40. Typically, unlimited resources are
rare.
Population growth is therefore
regulated by carrying capacity (K),
which is the maximum stable
population size a particular
environment can support.
The logistic model of population
growth incorporates the concept
of carrying capacity

41. Example of Exponential Growth
Kruger National Park, South Africa

42. LOGISTIC GROWTH RATE
Assumes that the rate of population
growth slows as the population size
approaches carrying capacity, leveling
to a constant level. S-shaped curve
CARRYING CAPACITY
The maximum sustainable population
a particular environment can support
over a long period of time.
POPULATION GROWTH RATE

43. Figure 52.11 Population growth predicted by the logistic model

44.  How well does the logistic model fit the growth of real populations?
The growth of laboratory populations of
some animals fits the S-shaped curves
fairly well.
Stable population Seasonal increase

45. Some of the assumptions built into the logistic
model do not apply to all populations.
It is a model which provides a basis from which we
can compare real populations.
Severe Environmental Impact

46.  The logistic population growth model and life histories.
 This model predicts different growth rates for different populations, relative to
carrying capacity.
Resource availability depends on the situation.
The life history traits that natural selection favors may
vary with population density and environmental
conditions.
In K-selection, organisms live and reproduce around K,
and are sensitive to population density.
In r-selection, organisms exhibit high rates of
reproduction and occur in variable environments in
which population densities fluctuate well below K.

47. K-Selected Species
 Poor colonizers
 Slow maturity
 Long-lived
 Low fecundity
 High investment in care for
the young
 Specialist
 Good competitors
r-Selected Species
• Good colonizers
• Reach sexual maturity rapidly
• Short-lived
• High fecundity
• Low investment in care for the
young
• Generalists
• Poor competitors

48. Populations are regulated by a
complex interaction of biotic and
abiotic influences
 There are two general questions about regulation of population
growth:
 What environmental factors stop a population from growing?
 Why do some populations show radical fluctuations in size over time,
while others remain stable?

49. Density-Dependent
Factors
 limiting resources (e.g., food
& shelter)
 production of toxic wastes
 infectious diseases
 predation
 stress
 emigration
Density-Independent
Factors

50.  Density-dependent factors
increase their affect on a
population as population
density increases.
 This is a type of negative
feedback.
 Density-independent
factors
are unrelated to population
density, and there is no
feedback to slow population
growth.
Fig. 52.13

51.  A variety of factors can cause negative feedback.
 Resource limitation in crowded populations can stop population growth by
reducing reproduction.
Negative feedback prevents unlimited
population growth

52. Intraspecies competition for food can also cause
density-dependent behavior of populations.
Territoriality.
Predation.

53. Waste accumulation is another
component that can regulate population
size.
In wine, as yeast populations increase, they
make more alcohol during fermentation.
However, yeast can only withstand an
alcohol percentage of approximately 13%
before they begin to die.
Disease can also regulate population
growth, because it spreads more rapidly
in dense populations.

54.  Carrying capacity can vary.
 Year-to-year data can be helpful in analyzing population growth.
Population dynamics reflect a complex
interaction of biotic and abiotic influences

55.  Some populations fluctuate erratically, based on many factors.
Fig. 52.18

56.  Other populations have regular boom-and-bust cycles.
There are populations that fluctuate
greatly.
A good example involves the lynx and
snowshoe hare that cycle on a ten year
basis.

57. Regional Patterns of Population Change
 No population can grow indefinitely, and humans are no
exception
 To maintain population stability, a regional human population
can exist in one of two configurations:
 Zero population growth =
High birth rate – High death rate
 Zero population growth =
Low birth rate – Low death rate
 The demographic transition is the move from the first state
toward the second state
 The demographic transition is associated with various factors in
developed and developing countries

58. Birthordeathrateper1,000people
50
40
30
20
10 Sweden
2050
Year
20001900 19501850
0
18001750
Birth rate
Death rate
Mexico
Birth rate
Death rate

59. Age Structure
 One important demographic factor in present and future growth
trends is a country’s age structure
 Age structure is the relative number of individuals at each age
 It is commonly represented in pyramids
 Age structure diagrams can predict a population’s growth trends
 They can illuminate social conditions and help us plan for the
future

60. Rapid growth
Afghanistan
AgeMale
Percent of population
Female
8 6 4 2 2 4 6 80
45–49
40–44
35–39
30–34
25–29
20–24
15–19
10–14
5–9
0–4
85+
80–84
75–79
70–74
65–69
60–64
55–59
50–54
Slow growth
United States
AgeMale
Percent of population
Female
6 4 2 2 4 6 80
45–49
40–44
35–39
30–34
25–29
20–24
15–19
10–14
5–9
0–4
85+
80–84
75–79
70–74
65–69
60–64
55–59
50–54
8
Decrease
Italy
Male
Percent of population
Female
6 4 2 2 4 6 808

61. Infant Mortality and Life Expectancy
 Infant mortality and life expectancy at birth vary greatly among developed and
developing countries but do not capture the wide range of the human condition
Infantmortality(deathsper1,000births)
Developed
countries
Developing
countries
Developing
countries
Developed
countries
Lifeexpectancy(years)
60
60
50
40
4030
20
20
10
0 0

62. Ecological Footprint
 How many humans can the biosphere support?
 The carrying capacity of Earth for humans is uncertain
 The ecological footprint concept summarizes the aggregate
land and water area needed to sustain the people of a nation
 It is one measure of how close we are to the carrying capacity of
Earth
 Countries vary greatly in footprint size and available ecological
capacity

63. Bibliography
http://www.cfr.washington.edu/classes.esrm.450/lecture11/harvest.pdf
http://www.csun.edu/~msteele/classes/marine_ecology/lectures/4_po
pulation%20ecology%201.pdf
http://warnercnr.colostate.edu/~gwhite/fw662/web_docs/Winkelman
%20Lecture%201.pdf

64. This presentation is
compiled by:-
Surabhi Tanwar
Masters Student in the Environmental Sciences
Institute of Science, Mumbai