The document discusses ecological conditions and limiting factors that affect organisms. It covers: - Each organism has a range of conditions it can survive in, and conditions outside this range prevent survival. - Organisms occupy a wide range of temperatures, from arctic to desert to thermal vents. - A species' ecological niche is the range of conditions it is adapted to. Different niches allow multiple species to coexist. - Limiting factors define the viability of life, and any single factor outside its optimum range can stress an organism.

1. BIO 107 Lecture 2
THE INDIVIDUAL ANDTHE INDIVIDUAL AND
ITS ENVIRONMENTITS ENVIRONMENT
Ecological Conditions andEcological Conditions and
Limiting FactorsLimiting Factors
Instructor: Angeli A. Valera – Mag-aso

2. All organisms are limited in their
distribution by abiotic factors
• Each organism has a range of
conditions within which it can survive
• If conditions are outside this range
the organism cannot survive

3. Organisms occupy a wide rage of
conditions
• Arctic and Antarctic (Temp < - 40 °C)
• Deserts and tropics (Temp >+40 °C)
• Extreme conditions in thermal vents
support extensive biologicalsupport extensive biological
communities
• Water temperature 400 °C
• Extreme pressure prevents boiling
• No light

4. Niche
• The range of conditions to which a
species is adapted is called its ecological
niche
• Different species will evolve different
adaptations depending on theadaptations depending on the
environmental conditions they face
• As a result, different species will tolerate
different ranges of environmental
conditions depending on their
evolutionary history

5. Species coexist
• Because they are adapted to different
conditions
• They occupy different niches
• No single species dominates everywhere• No single species dominates everywhere
because conditions vary from place to
place

6. Fundamental Niche
• the range of conditions to which a species
is adapted
range of conditions actually occupied by arange of conditions actually occupied by a
species
often smaller than fundamental niche
as organisms approach the extremes of their
tolerances, they may be able to tolerate the
conditions but they are often inferior
competitors

7. Niche

8. Limiting Factors
•define the viability of life.
•Only one limiting factor need be out of its optimum range to
cause stress for an organism.
•Each factor necessary for survival has an ideal range.
Zones of Stress
Each factor has a range of values that are above or belowEach factor has a range of values that are above or below
the ideal but not outside the range allowing survival.
Limits of Tolerance
Each factor has an upper and a lower limit beyond which the
organism cannot survive.
Range of Tolerance Each factor has a range of values that
includes the zones of stress and the optimum levels. These
values do not include the upper or lower limits beyond which
the organism cannot survive.

9. Quantities of any
single factor above or
below optimum levels
necessary for
Law of Limiting FactorsLaw of Limiting Factors
necessary for
organism growth,
reproduction, or
survival will limit
growth, reproduction,
or survival.

10. Temperature Relations
CONCEPTS:
• Most species perform best in a fairly
narrow range of temperatures
• Many organisms have evolved ways to
compensate for variations in
environmental temperature by regulating
body temperature
• Many organisms survive extreme
temperatures by entering a resting stage

13. Heat-shock proteins (Hsps)
Animals living in hot deserts are at risk of overheating,
which results in denaturation of enzymes and other
essential proteins.
Levels of Hsps in cells rise rapidly after exposure to
abnormally high temperatures, Hsps are importantabnormally high temperatures, Hsps are important
for species at risk of exposure to high T a because of
their role as chaperone proteins that ‘rescue’
proteins whose tertiary structure has been disrupted
by overheating.
Chaperone proteins bind to denatured regions of a
protein and alter the misfolded structure so that the
correct three-dimensional structure is regained.

14. Temperature and Bacterial Activity
Thermophilic bacteria = heat-loving

15. Human vs. Thermophile
high temperature causes cell membranes
to leak and enzymes to stop working

16. ATPase activity plotted against
temperature for four species of lizard
Since Dipsosaurus has enzymes that are stable even at high
T b it needs to expend less energy for thermoregulation

17. Regulating body
temperature:
Heat transmittance
Acclimation = involves physiological, not genetic changes in
response to temperature; generally reversible with changes in
environmental conditions.environmental conditions.
Metabolic Heat = energy released by an organism during the
process of cellular respiration
Conduction = movement of heat between objects in physical
contact
Convection = process of heat flow between a solid body and a
moving fluid/ wind
Radiation = heat transfer through electromagnet ic radiation
Evaporation = heat loss by an organism

18. Temperature Regulation
by Plants
DESERT PLANTS
•Decrease heating by
conduction: leaves far
enough above groundenough above ground
•Increase rates of convective
cooling: small leaves
•Reduce rates of radiative
heating: orient leaves parallel
to sunlight, reflective leaves

20. Temperature Regulation
by Plants
ARCTIC and ALPINE PLANTS
• Increase rate of radiative heating: leaves
absorb light , oriented perpendicular to
sun’s rays, “cushion” growthsun’s rays, “cushion” growth
• Decrease rate of convective cooling:
compact, hemispherical growth form
(decrease exposure to surface wind )
• Many evolved to do both= can heat up to
temperatures above that of air

21. Sun-tracking behavior of Dryas
Air temperature=15 °C Sunlight reflected
inward by parabolic-
shaped flowers heats
interior
Sun tracking by
Dryas flowers keeps
Flower
temperature=25 °C
Dryas flowers keeps
flowers facing the
sun for several hours
each day
Basking insect
temperature=25 °C

22. Temperature Regulation
in Animals
• Poikilotherms = cold-blooded
=temperature varies directly with environment
• Ectotherms = rely mainly on external sources
• Homeotherms = warm-blooded
=endotherms that use metabolic energy to
maintain a constant body temperature
• Endotherms = rely heavily on internal
metabolic heat energy
• Heterotherms =may regulate by endothermy/
ectothermy

23. High Temperature
The gradients of temperature across the coat of (a) open-
woolled Awassi sheep, (b) short-coated camels and (c)
Merino sheep with dense fleece. All the animals are
exposed to sunlight as shown and T a of 40°C

24. Heat exchange with the environment in a
terrestrial reptile on a hot sunny day

26. Temperature and Pigmentation

27. Costs and benefits of homeothermy
• Costs
• Increased energy requirements
• Increased susceptibility to thermal stress
• Benefits
• Ability to be active in otherwise
inhospitable environments
• Freedom from dependence on sunlight to
regulate body temperatuure
• Increased ability to sustain a high level of
activity

28. A diagram of a temporal counter-current heat exchanger: the nasal
heat exchanger. Inspired air draws heat and water from the walls of the
respiratory tract (i) and gives both back again at exhalation (ii). The
figures represent approximate temperatures varying from those in the
deep body tissues (40°C) to those near the surface. The red arrows
show the direction of heat transfer

29. Simplified diagrams of the venous drainage from
the nasal regions and the arterial supply to the
brain and nose in (a) a monkey and (b) an oryx

30. •The operation of the
nasal counter-current
heat exchanger.
Temperatures (°C)
within the dog's nasal
passages and at the
mucosa during
inhalation and
exhalation indicate the
conservation of heat
when the mouth is
closed. The small
arrows show thearrows show the
direction of heat
transfer from the
mucosa to the air on
inhalation (a) and in
the reverse direction at
exhalation (b)
•Bypass of the dog's
nasal counter-current
heat exchanger by
opening the mouth, an
indication of how heat
loss is enhanced.

32. Balancing heat gain against heat loss
Decreased heart rate
Shivering suppressed
Respiration rate reduced
Oxygen consumption
reduced
Vasoconstriction of
periphery

34. Countercurrent heat exchange
in marine organisms

36. Behavioural thermoregulatory
strategies

37. Water Relations
CONCEPTS:
• The movement of water down
concentration gradients in terrestrial andconcentration gradients in terrestrial and
aquatic environments determines the
availability of water to organisms
• Marine and freshwater organisms use
complementary mechanisms for water
and salt regulation

38. A gradient of water potential
Water potential = concentration gradient of water plus other factors
related to water movement

40. Water Regulation

41. Terrestrial plants and animals regulate
their internal water by balancing water
acquisition against water loss
• Regulation by terrestrial animals:
Wia = Wd+Wf+Wa-We-Ws
• Regulation by terrestrial plants:
Wia = Wd+Wf+Wa-We-Ws
Wip = Wr+Wa-Wt-Ws

42. Root pressure
Roots absorb water from the soil by
osmosis or diffusion. Once the
water is inside the roots, it travels
either through the intercellular
spaces or from cell to cell and
ultimately enters the xylem. Thus, theultimately enters the xylem. Thus, the
xylem in the root develops a positive
water potential and the water is
pushed up the tubes formed by the
xylem elements. The pressure with
which the water is pushed up by the
xylem of the roots is called the
root pressure.

43. Pathway of Water from the Soil into the Xylem
Root pressure explains
the transport of water
to the leaves and other
parts in the case of
short plants like the
herbaceous plants.herbaceous plants.
However, in tall trees
the root pressure
(about 1 atmosphere)
is not sufficient to send
the water up to the
leaves. In these trees,
transpiration pull
transports water.

44. Wilting and the Transpiration Stream
Transpiration pull results in a continuous
stream of water called the transpiration
stream= a continuous stream of water
extending from the xylem of the leaves to
the xylem of the roots. Transpiration pull
can occur only when there is a continuous
column of water. This continuity is
maintained by the cohesive and adhesive
properties of water.
Adhesion= causes the water molecules to
adhere to the xylem walls
Cohesion= water molecules remain
together and move up as a stream.
Any break in this column, makes ascent of
sap difficult. When a stem is cut, the water
column moves away from the cut end of
the xylem making conduction of water from
the cut end difficult.

45. Experiments to Prove that Water Rises
Upwards in the Plant Through Xylem

46. Soil moisture and root
development
Dense network
of deeply
penetrating
roots
Sparse
network of
shallow roots
roots

47. Fog harvesting by a beetle

49. Classification of desert animals based
on body size and rate of evaporation

50. Cutaneous Evaporative Water Loss
Sweating, an extreme form of CEWL in mammals, is important for cooling in
many species. Sweating is the secretion of water plus some salts from special
sweat glands in the skin, which occurs as a response to an increase in T b.

51. An ecological puzzle
How does a cicada remain active
when environmental
temperatures exceed its lethal
maximum?
EVAPORATIVE COOLING
It compensates for high
evaporative water loss by high rate
of drinking

52. Disssimilar Organisms with
Similar approaches

53. Water availability in aquatic organismsWater availability in aquatic organisms
Freshwater
Saltwater

54. Water and salt balance in aquatic
environments

56. AbioticAbiotic factor: Lightfactor: Light
• Solar spectrum - made up of short wave radiation, light and long
wave radiation short wave radiation are cosmic rays, X-rays and
ultraviolet rays, which have wavelengths shorter than 0.4mm.
• Ultraviolet radiation: absorbed by ozone layer, only a small fraction
reaches the earth's surface;
3 types: uv-C, uv-B and uv-A.
• Light has wavelengths of 0.4 to 0.7 mm and it is called photo• Light has wavelengths of 0.4 to 0.7 mm and it is called photo
synthetically active radiation (PAR). The infrared rays have longer
wavelengths, longer than 0.74 mm.
• Electromagnetic spectrum of solar radiation:

57. Effect of Light on Plants
•Phenology: timing of seasonal activaties of plant in relation to changes
in environmental condition.
•Sciophytes = shade loving or photophobic plants, which have best
growth under low intensities of light. Examples: beech, spruce, firs
•Heliophytes or photophilous plants = best grow in full sunlight.
Examples: Pine, willows and birch.
•Photoperiodism = actual duration or length of the day (photoperiod) is
a significant factor in the growth and flowering of a wide variety of
plants.
In this basis, angiosperms are divided into 3 categories.
•Long day plants bloom when light duration is more than 12 hrs per
day. Examples: Beet roots, carrot, oats and rye.
•Short day plants bloom when light duration is less than 12 hrs per day.
Examples: Tobacco, Dahlia, hemp and cosmos.
•Day neutral plants show little response to length of day light.
Examples: Cucumber, cotton and potato.
•Heliotropism or phototropism = effect on movement in some plants

58. - Light promotes the
growth in most of the
plants by promoting the
development of
chlorophyll,
photosynthesis,photosynthesis,
synthesis of growth
hormone and stomatal
opening.
- Competition, shade
tolerance for plants

59. Effect of Light on Animals
Color
• Differentiate light colours; well marked in fish, birds and
primates due to the presence of cones in the retina of the
eye.
Pigmentation
• Light intensity induces chemical changes leading to pigment
formation in the cells. Cave animals lack skin pigments. If
• Light intensity induces chemical changes leading to pigment
formation in the cells. Cave animals lack skin pigments. If
they are kept out of darkness they regain skin pigmentation.
Tanning occurs in human beings in response to prolonged
exposures to bright sunlight.
Bird Migration
• In the northern hemisphere, birds migrate towards the north
during spring (increasing photoperiod) and towards the
south during autumn (decreasing photo period). It also
controls the migration of fishes like eels and salmon.

60. Light and aquatic LifeLight and aquatic Life
- Photic zone, different
wavelengths for aquatic
organisms

61. Ground color and Temperature

62. Biological Rhythms
Circadian Rhythm
•Operating on an 24 hours day - night cycle of the earth's rotation. The
simplest form of this is the alternating periods of activity and sleep
which correlate with dark and light cycle. In this cycle, some animals
remain most active at sunrise and sunset times. Such animals are
known as crepuscular, some animals are active during the night
(nocturnal) but most animals are active during the day time and called(nocturnal) but most animals are active during the day time and called
as diurnal.
Circatidal Rhythm
•The biological rhythms synchronized with the low and high tides in the
sea are called as circatidal rhythms. Thus the organisms living in the
inter tidal zone are alternatively submerged and exposed to air. The
other rhythms are circa lunar rhythms, semi lunar rhythm and
circannual rhythms.

63. Photoperiod
Effect on Reproductive Activities
•Breeding behavior of insects, certain birds and mammals. For example
in some birds, gonads become active during summer. Starlings breed
in spring (longer photoperiod) while deer breed in autumn (decreasing
photoperiod).
Effect on Development
•Light in some cases, for example in Salmon larvae, accelerates
development where as in Mytilus larvae it retards it.development where as in Mytilus larvae it retards it.
Metabolism
•Light increases the enzymatic activities and general metabolic rate. It
also increases photo - oxidation and respiration rates. Animals found in
caves have low rate of metabolism.
Locomotion
•The regulation of speed of locomotion by light is called photokinesis.
For example blind larvae of mussel crab moves faster in light
intensities. The orientation of animals during locomotion in response to
light is called phototaxis. For example Euglena is positively phototactic
while earthworms, slugs are negatively phototactic.

64. AbioticAbiotic factor: Windfactor: Wind
• exacerbates the
effects of
temperature and
water losswater loss
• also exerts forces
on organisms
(waves act in the
same manner)

65. Prevailing wind patterns,
set ocean currents in motion.
• The patterns of wind flow Land
masses can interrupt these
patterns at a local or regional
level.
• Ocean currents are created by the
flow of winds, and cause greatflow of winds, and cause great
patterns of circular flow in the
oceans. The Gulf Stream is one
such current. Without the heat in
this mass of water, the climate of
northern Europe would be much
cooler. This would alter the
biological communities found
there.

66. Abiotic Factor: Pressure

67. 1,400
1,200
1000
800 25.2
24
22.8
22.8
Adiabatic Cooling
800
600
400
200
0 30
28.8
27.6
26.4
25.2
Elevation Temp ºC

68. CLIMATIC FACTORS
• The properties of temperature, pressure,
humidity, rainfall, sunshine and wind in a given
place and time is called weather. The average
weather conditions of an area, which includes
atmospheric conditions, seasons. etc. constitutes
the climate. Weather refers to the daily orthe climate. Weather refers to the daily or
weakly changes, while climate refers to
atmospheric conditions over longer periods, such
as seasons. The main climatic regions are:
1) Tropical 3) Temperate and
2) Sub tropical 4) Arctic and Antarctic

69. Climate
• Four abiotic factors determine climate
• Sunlight
• Temperature
• Wind
• Precipitation• Precipitation
• Macroclimate
• Global, regional, local climate
• Microclimate
• Details of environmental conditions in small
spaces
• Forest floor
• Under rock or log

70. • Temperature
is partly
determined by
the amount ofthe amount of
solar radiation
hitting an area
• Depends on
latitude, angle
of incidence

71. Seasons are caused by the tilt of the
earth as it revolves about the sun.

72. Water holds heat:
Sea & land breezes

73. Ocean currents

74. Air circulation

75. Coriolis Effect

76. Wind patterns interact with mountains to
cause increased rain on windward
sides, rain shadows on leeward sides.

78. The atmosphere has a tremendous effect on the distribution of plants
and animals. Global patterns of circulations affect rainfall patterns and
the prevailing wind directions. Changes in air circulation over the
Pacific Ocean can lead to events,
such as El Nino, which have global repercussions
(i.e. torrential rains in the Andes and severe drought in Australia)

79. The physiognomic method = a technique used to
analyze climate and elevation. This method describes
common characteristics of leaves and forests found in
each climate type.

80. Certain characteristics,
such as smooth margins
indicate a plant is from a
Botanical Climate
Indicators
indicate a plant is from a
tropical to subtropical
climate.

81. Tropics
-Leaf margins between 57% and 89% entire:
-Leaves with driptips common on understory evergreens.
- Vines are common in the understory
Subtropics
-Leaf margins between 39%-55% entire
-Broad-leaved evergreens often with conifers and broad-Broad-leaved evergreens often with conifers and broad
leaved deciduous.
Warm Temperate
-Leaf margins between 30%-38% entire
-Broad-leaved deciduous with conifers.
-Evergreens present, but not dominant
Cool Temperate
-Leaf margins less than 20% entire
-Conifer with some broad-leaved deciduous.

82. Microclimates

83. Microclimates

84. Aquatic Microclimates

85. The Soil

86. The Soil