Transcript File

CHAPTER 6
Factors Affecting Distribution and Abundance :
4)ABIOTIC
FACTORS
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Learning Outcome
• Define abiotic factors
• Acquire knowledge on the influence of
non living factors towards living organism
• Understand the application of abiotic
factors in nature
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What is abiotic factors?
• Abiotic factors = the non-living factors
• which affect the ability of living organisms to survive in
an environment. These can include both physical and
chemical factors.
• Some examples of physical abiotic factors are soil,
weather, and the availability of consumable water.
Natural disasters can also be considered abiotic.
• Examples of chemical factors include the amount of
sunlight and the pH level of the soil.
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How Organisms Tolerate Temperature &
Moisture?
1. Each organism has a range of temperature.
2. Organisms also acclimate physiologically.
3. Temperature & moisture limit distribution.
4.
Organisms respond differently to the same
environmental variables during different phases of
their life cycles (eg. udang putih/kertas – Penaeus
merguiensis; Siakap, sea bass – Lates calcarifer)
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Penaeus merguiensis, Udang putih
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•
How temp or moisture can limits distribution of
organism?
i.
determine the phase of the life cycle that is most
sensitive (juvenile white prawn is sensitive to high
salinity)
i.
determine the physiological tolerance range of the life
cycle phase (mature white prawn can reproduce and
responsive at high salinity/marine)
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Example 1- Passerine birds
tolerate with temperature
• The range limits of endotherms (warm blooded)
correlates with climatic variables.
• The distribution of passerine birds in North America
correlates with minimum temperature.
• The northern temperature limit of the phoebe (passerine
bird) is -4oC.
–
linked with the energetic demand associated with
temperature.
– lower temperature requires higher metabolic rates to
maintain body temperature and also there is a limit to
feeding rates.
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Example 2- Red kangaroo
tolerate with moisture
• The distributional boundary of the red kangaroo
(Megaleia rufa) coincides with the 400 mm
rainfall contour and do not spread outside the
rainfall contour
– the red kangaroo feed generally on arid zone
grasses that are restricted to low rainfall areas.
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Example 3- Plants
tolerate with moisture
•
Plants resistance to drought is achieved by:
i.
ii.
iii.
Improvement of water uptake by roots – deeper roots
Storage of water – cacti
Prevention during drought season:
- reduce water loss via stomata or
- reduce cuticular respiration, thick cuticles in cacti
- reduction of leaf surface area – small leaves,
- peeling of leaves during drought (xerophytes)
- orientation of leaves
- succulent/moist leaves and stem in Bryophyllum and
Euphorbia
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Interaction Between Temperature &
Moisture
• Drought can restrict plant distribution. Two
types of drought:
1) soil drought
ii) frost drought/winter drought
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Example 1
• Loblolly pine (Pinus taeda)
• Northern limit set by winter
– winter drought
– rate of water uptake in loblolly pine
decreases rapidly in winter
– water not available in liquid form
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Northern limit- winter
temperature and rainfall
Western
limit- winter
temperature
and rainfall
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Example 2 – Intertidal Zone
• 2 species of barnacles dominate the British
coast:
– a) Chthamalus stellatus
– b) Balanus balanoides
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Balanus balanoides
Chthamalus stellatus
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• a) Chthamalus stellatus - southern species –
dominant in the upper intertidal zone and high
tolerance to long exposure to air
• Its upper limit is set by desiccation.
• Its lower limit set by competition for space with
Balanus balanoides.
• C. stellatus can survive in the Balanus zone if the
latter is removed.
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• b) Balanus balanoides - (northern species) has
(1) faster growth as compared to C. stellatus and
so force out the latter from the middle intertidal
zone.
• Its upper limit is determined by temperature and
dessication – it (2) has lower tolerance for higher
temp and dessication, that’s why it cannot
occupy C. stellatus space.
• Its lower limit is set by competition of space with
algae and predation by a gastropod – Thais
lapillus
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Adaptation to
Temperature & Moisture : Ecotype
• There are certain physiological tolerances built into all
individuals of a particular species.
• Local adaptation can occur and that genetic and
physiological uniformity cannot be assumed throughout
the range of the species (e.g. as shown by Aurelia aurita)
Aurelia aurita
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• Species can extend their distribution by
local adaptations to limiting
environmental factors.
• Turreson (1922) demonstrated the concept
of ecotype – genetic varieties within a
single sp (Example : Aurelia aurita)
• He also show variations associated with
climate and soil in a plant species, Plantago
maritima.
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Example : Ecotype
• Turreson (1925) collect plants
(Plantago maritima) from a variety
of areas and grow them in field
or laboratory plots at one site.
• He worked with 2 varieties
• tall & robust ones grow
along the marshes along
the coast
• dwarf plant on exposed
sea cliffs on Island.
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Experimental design:
• He planted the seeds side by side
Result:
• the plants from the coast (tall and robust) were
significantly taller than those from the cliffs
• this showed ecotypes, populations adapted to
local conditions
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As a conclusion….
•
Plants of the same species growing in diverse
environments can differ in morphology and
physiology in 3 ways:
1. all differences are phenotypic – seeds transplanted
from one situation to the other they will respond
exactly as the resident
2. all differences are genotypic – seeds are
transplanted, mature forms will retain as in original
habitat. E.g. Plantago maritima
3. some combination of phenotypic and genotypic
determination produces an intermediate result – in
nature this is most usually observed.
E.g. P. glandulosa
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Light as factor that brings about
Distribution & Abundance
Importance:
1. Cue for timing of day/night (plants) essential for
photosynthesis
2. Cue for timing seasonal rhythms (animals) –
spawning/breeding season
Light as a cue
• some organisms use light as a cue for activity cycles
– response to day length changes. Day and night
length are vary and not constant.
• Behavior and physiological reaction towards variation
in duration of day/night – photoperiodism
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Example 1
• Plant response differently towards day light.
• The rate of photosynthesis can be measured by the rate
of CO2 uptake.
• sunlight- energy absorption by plant-restrict
photosynthesis at certain level, restrict the glucose
production
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Light as Factor that Brings about
Distribution & Abundance
2. Light as a cue for animals:
- Many organisms use day length as a behavioral
cue.
- Birds can be brought to breeding condition in
mid winter by increasing day length artificially.
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Example 2
• Breeding seasons have evolved to
occupy part of the year in which
offspring have the greatest
chances of survival
• Birds in temperate zones use
spring time
- increasing/longer day length in
spring
- to begin nesting cycle at a point
when adequate food resources
will be available for their young
in nest and as fledglings.
• light as a cue- bird can predict
the perfect time for breeding
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Why light is important for plant?
• Plant species become adapted to live in a certain
kind of habitat
• Prevent them from occupying other habitats
- Eg Hemlock – shade tolerant – seedlings can survive in
forest understorey under very low light levels
– grow slowly/low metabolic rates.
- One consequence – they die easily in drought – roots
do not grow quickly to penetrate deep into the soil to
look for water.
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• Adaptations to live in one ecological
habitat make it difficult or impossible to
live in a different habitat.
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Light Adaptation – Example 1
• Seaweeds
adaptation.
show a variety of response to light
• 2 types of seaweeds occur
(1) monolayered, flat, wide thalli
(2) highly dissected (multilayered), narrow thalli,
• Morphological adaptation:
– 1) Monolayered seaweeds would be advantage at low light
levels in deeper waters
– 2) Multilayered seaweed would be advantage at high light
intensity in shallow water
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2
1
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Example 2- Rate of photosynthesis
•
•
1.
2.
3.
The rate of photosynthesis under given light
conditions can affect whether the plant can
survive in different environments
One reason why photosynthetic rate varies
among plants is that there are 3 different
biochemical pathways by which
photosynthesis reactions can occur:
C3 (most plants) – CO2 converted to 3-phosphoglyceric
acid (3 carbon molecule, C3);
C4 plants (sugar cane) – CO2 fixed as malic and aspartic
acid (4 carbons molecule, C4)
CAM (Crassulean Acid Metabolism)- cacti and any
desert plant
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Differences between C3 and C4 leaves
• Leaf anatomy of C3 and C4 plants differ.
• Chlorophyll in C3 plants are found throughout
the leaf
• Chlorophyll in C4 plants it is concentrated in
Krantz Anatomy and they have a high
concentration of mitochondria
• C4 plants do not reach saturation light levels
even in bright sunlight and produce more
photosynthetic per unit area of leaf than do C3
plants
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Anatomical differences between C3 and C4 leaves.
C3 LEAF
Photosynthesis occurs within the
mesophyll cells in C3 plants, which
form a dense layer on the upper
surface of the leaf and a spongy layer
on the lower surface. Bundle-sheath
cells surrounding the veins are not
photosynthetic.
C4 LEAF
Dense layers of mesophyll cells
surround the bundle-sheath cells of
C4 plants. Both the bundle-sheath
cells and the rings of mesophyll
cells are photosynthetic.
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•
The C4 anatomy is more efficient – C4 plants are at an
advantage when photosynthesis is:
1. occurs under high light intensity and high temp
- C4 grasses are at a selective advantage in warmer areas
with high solar radiation
2. limited by CO2 concentration and water is in short supply
•
Type C4 grasses, sedges and dicotyledons are all more
common in tropical area, North America than in temperate
or polar regions (Fig. 7.15)
•
On mountains in Hawaii, which have small seasonal
changes in temp, C3 grasses predominate at high elevations
(low temperature) and C4 at low elevations (high
temperature)
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Water Chemistry
• Studies on freshwater Rotifers – pH and
bicarbonate ions seem to be most
important
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Salinity Tolerance Adaptation
High
salinity
Low
salinity
Salt Marsh Plant Distribution in Relation to Salinity Tolerance
A salt marsh is a type of marsh that is a transitional
intertidal between land and salty or brackish water
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