Biology Form 4 Chapter 8 :Dynamic Ecosystem Part 2

DYNAMIC ECOSYSTEM
PART 2
Part 2

4 types
 Symbiosis
 Saprophytism
 Prey-Predator
 Competition

 A symbiotic relationship is an interaction
between two or more species that live
together in direct contact
 Types of symbiotic relationships:
–Mutualism
– Parasitism
– Commensalism

Symbiosis – “living together”
Relationship
Type Species A Species B
Commensalism + 0
Mutualism + +
Parasitism + -

 is a close relationship between two living
organisms of different species which is
beneficial to both
In legumes:
Rhizobium (nitrogen-fixing
bacteria)
receive protection
and nutrients
The plant gets
usable nitrogen.

 Hermit crab gets
protection from sea
anemone’s tentacles
 Sea anemone gets
food scraps &
transportation

 Protozoa produce cellulase enzyme to digest
celluose
 Termites provide food & shelter.

Mutualism (+/+)
• Ex: Pollinators and flowers.
Bees and birds visit flowers in search of pollen and
nectar. In the process flowers are pollinated
• Seed dispersal by birds, bird gets food

Mutualism [+/+]
The rhinoceros has parasites (ticks) removed.

 Aphids are small, soft-bodied, near defenseless insects
that feed on plant sap.
 The ants feed on the sugary fluid released by the
aphids.
 The aphids are protected by the ants from predators
and parasites.
 In some cases ants tend colonies almost like ranchers
with their cattle, not only protecting the aphids, but
moving them around from plant to plant.

 A lichen is a combination of two separate organisms: an alga and
a fungus.
 Most lichens are three-layered organisms, with an algal layer
sandwiched between two layers of fungus.
 The alga produces the food for the lichen through photosynthesis,
while the fungus absorbs water and other nutrients.
 Neither the fungus nor the alga can live independent of the other.

 between a fungus and a plant root
Fungus gets:
organic nutrients
[carbohydrates
and vitamins]
Plant gets:
mineral salts +
water which the
fungus absorbs

Mutualism
Mycorrhizal fungi (threads) covering aspen roots:
fungi aid in water and nutrient absorption by the aspen and the aspen
provides sugars and other food molecules to the fungi.

The ant keeps predators away
from the acacia tree.
Ant Acacia tree
The acacia provides shelter
and food for the ant.

Ant hollows out the
large thorns of the
plant for nests.
Ant ffeeeeddss oonn nneeccttaarr aatt tthhee bbaassee ooff
eeaacchh ppeettiioollee aanndd oonn tthhee pprrootteeiinn rriicchh
BBeellttiiaann bbooddiieess ffoouunndd oonn tthhee ttiippss ooff
tthhee lleeaavveess

Sea anemone
gets scraps of
food from
clownfish
Clownfish is
protected by
tentacles of
sea anemone

 a close relationship between two living
organisms of different species which is
beneficial to one and harmful to the other
Head louse
Flea Mosquito

Parasitism
one organism, the Parasite derives its nourishment
from another organism, its host, which is
harmed in the process
2 groups
 Ectoparasite (lives outside host)
Eg. Fleas, ticks, lice
Adaptations:
Special hooks, sharp mouths for sucking, biting & hooking.
 Endoparasite (lives inside host)
Eg. Worms, flukes, plasmodium, tapeworm.
Adaptations:
Simple nervous system, sense organs & digestive tracts.
Produce mucus & anti enzyme secretion.

Endoparasites e.g.
tapeworm (Taenia)

TTaappeewwoorrmm ccyyssttss iinn hhuummaann bbrraaiinn

Ectoparasites e.g. dodder (Cuscuta); Malt. Pittma

Mistletoe Rafflesia
 Mistletoe absorbs water from host, not
food.
 Rafflesia absorbs food & water from host.

 is a symbiotic relationship where one partner
benefits (commensal) and the other is
unaffected
Algae that grow on the shells of sea turtles or seals.
How do algae benefit by growing on sea turtles or
seals?

 Epiphyte (plant)
Orchids, mosses, ferns
 Epizoic (animal)
Remora fish & shark
Barnacles on shell of crab
Clown fish & Sea anemone

 epiphytes, e.g.some tropical orchids
 Orchids use trees or branches of trees for
support without harm or benefit to the tree.
 The epiphyte obtains more sunlight and air
in this manner

• The remora, a sucker-fish, lives in close association with sharks or
other larger fish.
• The dorsal fin of the sucker-fish is modified to form a sucker; it uses
this to attach itself to the shark;
• The sucker-fish is small and does not injure (or benefit) the shark, but
envoys the shark's protection and lives on the scraps formed as the
shark devours its prey;

Barnacles that attach to whales
Coronula diadema
bores into whale
skin.
Barnacles-filter feed on water
emerging from the whale’s nostril.

HHoosstt:: Tree
CCoommmmeennssaall::
Lichen

HHoosstt::
Grazing mammals
CCoommmmeennssaall::
Cattle egrets
(birds) feed on
insects flushed
out of the grass
by grazing
animals

 Saprophyte
Mushroom, mucor
 Saprozoit
Paramecium,
earthworm

 Interaction between 2 organisms in which one
will hunt and kill the other for food.
160
120
80
40
0
Snowshoe hare
1850 1875 1900 1925
52.21 Year
9
6
3
0
Lynx population size
(thousands)
Hare population size
(thousands)
Lynx
Predator-the hunter
Prey- the hunted
Dynamic relationship

 control each other’s
population size

DOES NOT MEAN THE SAME AS HABITAT!!

 the way in which an organism utilises its
environment
 may be described in terms of:
– space utilisation
– food consumption
– temperature range
– appropriate conditions for mating
– requirements for moisture and other factors

Gause and the Principle
of Competitive
Exclusion

 between species of Paramecium (in lab)

P. Caudatum: eliminated
P. aurelia: lived
WHY?
P. aurelia grew 6x
faster = high
reproductive rate
better competitor

The Principle of Competitive Exclusion or
Gause’s principle:
Populations ooff ttwwoo ssppeecciieess ccaannnnoott
ooccccuuppyy tthhee ssaammee nniicchhee aatt tthhee ssaammee
ttiimmee aanndd ppllaaccee

The competitive exclusion principle
– Populations of two species cannot coexist in a
community if their niches are nearly identical
High
tide
Chthamalus
Balanus
Low
tide
Ocean

Paramecium
bursaria
Paramecium
caudatum
RReessuulltt::
ccooeexxiisstteedd

Paramecium
bursaria
Paramecium
caudatum
RReeaassoonn::
Occupy a different niche
One of the species fed on suspended bacteria and
the other on settled bacteria.
RReessuulltt::
ccooeexxiisstteedd

Competition between species with identical
niches has two possible outcomes:
The population:
 using resources less efficiently
having a reproductive disadvantage
Natural selection may lead to
resource partitioning
DIE
DIVERSIFY

ssssaaaammmmeeee ssssppppeeeecccciiiieeeessss

ddddiiiiffffffffeeeerrrreeeennnntttt s sssppppeeeecccciiiieeeessss
Camels, goats and
sheep compete for
food.

a) Distinguish between intraspecific and
interspecific competition. (2)
b) Explain why intraspecific competition is
likely to be more intense than interspecific
competition. (1)
Members of a species use the same resources
but different species use different resources.

c. i) List TWO resources that animals compete
for. (2)
space,
food,
water,
mate

ii) List TWO resources that plants compete for.
(2)
Space, light, water, ions in soil, carbon dioxide

d) What is the effect of competition on the
growth of a population? (1)
Reduces the growth rate of a population.

 Storms
 Fires
 Floods
 Droughts
 Overgrazing
 Human activities

 Burning as a means of forest clearance

 Example : An area of rock uncovered (moraine) by a
melting sheet of ice.

 Example : An area might be a new island formed by
the eruption of an undersea volcano

Succession at Mt. St.
Helens.
Ecological Succession
Succession after the
Yellowstone fires.
How long does it take to
recover?
 The large-scale fire in Yellowstone
National Park in 1988
 Demonstrated that communities
can often respond very rapidly to
a massive disturbance

Human activities (e.g. forest clearing, tin
mining and natural phenomena (e.g. forest
fires, tsunamis, earthquakes and volcanic
eruptions) constantly reform our environment,
leaving behind bare rocks, sand, earth, or
ashes with no life.
Colonisation The process whereby
living organisms move
into this newly formed
area which is completely
devoid of life.

Bare
ground
Pioneer
species
Succesor
species
Climax
community
Successio
n
The gradual process where one
community changes its environment
so that it is replaced by another
community.

Bare
ground Lichens
+ Algae Mosses
+ Ferns Grasses
Shrubs
Trees
Starts with a:
Pioneer
community
Ends with a stable
community:
Climax community
(controlled by climate)

 the final stable and self-perpetuating
community
 in equilibrium with its environment
 the most productive which the environment
can sustain

1. Bare rock. 2. Lichens penetrating
the granite with
filaments.
3. Acidified by the
lichens and chemicals
from the soils,
rainwater accelerates
erosion.
5. The whole
succession from lichens
to mature trees.
4. Increased soil depth on the
rock allows shrubs to grow.

Time  is most easily observed
Lake ecosystems
become terrestrial
ecosystems
in:
 Terrestrial
 Freshwater ecosystems

• Mangrove swamps are found in tropical regions
where fresh water meets salt water.
• Unsuitable environment for normal plants.
 soft muddy soil and strong coastal wind
 high concentration of salt
 very low levels of oxygen
 Exposed to high intensity of sunlight

Bad condition of
Mangrove Swamps
Problems faced by
mangroves trees Adaptations
Soft muddy soil,
strong coastal
winds
Support problem
High
concentration of
salt
Hypertonic to root cells,
problem in seeds
germination.
Very low levels of
oxygen
Root breathing problem
in anaerobic condition
Exposed to
intensity of
sunlight
The rate of transpiration
increase caused water
loss

 Avicennia sp – grow facing the sea
 Sonneratia sp – at the mouth of river
which is sheltered.
Avicennia sp
Sonneratia sp

 Root system spread out widely to give support in the
soft muddy soil
 Pneumotophores – grow vertically upwards – spongy,
able to taken in air for respiration
 Having higher osmotic pressure of cell sap than
surrounding sea water
 Excess salt secreted through hydathodes in leaves.
 Thick cuticle and succulent leaves
 Sunken stoma – to reduce transpiration
 Seeds that float

Adaptation of pioneer species:
 Root system spread out widely to give support in the
soft muddy soil

 Pneumotophores – grow vertically upwards – spongy,
able to taken in air for respiration

 Seeds that float

Thick cuticle and
succulent leaves
Long underground
cable roots with
pneumatophore
(breathing root)
Avicennia sp.

Sunken stoma – to reduce transpiration

Excess salt secreted through hydathodes in leaves.

 Having higher osmotic pressure of
cell sap than surrounding sea water

 Root of avicennia and sonneratia trap mud and
soil,
 bank raised and contain less water.
 More suitable for Rhizophora
 Slowly replace the pioneers

RHIZOPHORA SP. (1ST SUCCESSOR)

 Prop roots to support and anchor the trees
 Viviparity in seeds to ensure seedling
survival
 Prop roots traps a lot of soil and mud,
 Died and decomposed adding humus to the
soil
 Soil becomes higher, drier & more fertile

Adaptation in Rhizophora sp:
Prop root of Rhizopora to support and anchor the
trees

Adaptation in Rhizophora sp:
 Viviparity in
seeds to ensure
seedling survival

Viviparous seedlings which able to germinate
while still being attach to the parent tree.

 The banks are rised up higher and drier, the
soil become compact, fertile and less saline.
 Not suitable for Rhizophora, slowly replaced
by Bruguiera sp

 Buttress roots for support
 Knee shape pneumatophores
 More sedimentation of decayed substances
– dried land form
 Replaced by other types of plants;
– Coconut, pandanus, palm trees and others
– Forest formed.

Adaptations in Bruguiera sp :
Viviparous seedlings and succulent leaves

Adaptations in Bruguiera sp :
Buttress root
Knee root

3rd successor : Paya bakau forest
Nypa sp.

CLIMAX COMMUNITY
Tropical Rainforest

Zonation of Mangrove Swamps
Seaward zone middle zone inland zone
The colonisation and succession occur. The condition
becomes more suitable for the successors which are
the dominant species at that time.
Animation

A A A
A A
A A A
A A A
A
A A A
S
S S
A
A
A
A A
A A A
A A A
A
A
S S S S
S S S S
S S
S
S
S
S
S
Distribution of different mangrove species at the mouth of a river.

IMPORTANCE OF THE
MANGROVE SWAMP

 Food, nesting and nursery for animal e.g.
fish, crabs, shrimp and birds.
 Protect coastline by acting as wave
breakers and coastal erosion
 Natural barriers against storms and
tsunamis
 Cleansing system, trap debris, excess
nutrient and toxin brought down by the
rivers

 Poles: shaft of Rhizophora species
 Fuel wood and charcoal: Rhizophora species wood
have a high calorific value (more heat)
 Tannins and dyes: Bark of mangrove trees are
harvested as a source of tannin for the tanning
industry
 Raw materials for industries: lignocellulose for the
manufacture of chipboard, pulpwood (newspaper
and cardboard) or synthetic materials (e.g., rayon).

 industrial ethanol from distillation of the
fermented plant sap – Nypa sp
 Seafood: Oysters, clams, mussels, cockles
and other shellfish may be harvested
directly or cultivated for consumption.
Prawn and crab ponds converted from
mangrove areas

Pioneer stage
(sunken aquatic plants such as Hydrilla, Cabomba)
Succession by
floating plants
Succession by
emergent plants
(sedge, cattails)
Succession by
herbaceous plants
Succession by
woody plants
Climax Community
duckweeds (Lemna sp.), lotus,
water hyacinths (Eichornia sp.)

PIONEER
SPECIES
Phytoplankton
Submerged plants – Elodea, Hydrilla, Cabomba

FLOATING PLANTS
Duckweed/ Lemna sp
1ST SUCESSOR
Lotus / Nelumbium sp

Eichornia sp
Pistia sp
1ST SUCESSOR
FLOATING PLANTS

2ND SUCESSOR
AMPHIBIOUS PLANTS

3RD SUCESSOR
HERBACEOUS PLANTS

CLMAX COMMUNITY
TROPICAL RAINFOREST

When the
species die
decompose
Organic matter converted
into humus
Deposited at the base of
the pond
The pond become shallow
1
2
Eroded soil from
the pond bank
(pond apron)
Animation

Pioneer stage
• When pioneer plants die and
decompose, the organic matter settle
to the bottom of the pond and make
the pond shallower.
• This produce suitable conditions for
aquatic floating plants.
Sucession by aquatic floating plants
• Floating plants cover the surface of
the pond and prevent light from
entering the pond.
• Pioneer plants cannot perform
photosynthesis and die. These
dead plants will sink to the bottom
and increase the organic matter layer
of the bottom

Succession by amphibious plants
• Dead aquatic floating plants and
eroded soil from the pond banks will
raise the pond floor and make the
pond too shallow for aquatic plants
to float.
• The aquatic plants are succeeded by
amphibious plants.
Succession by herbaceous plants
• The continued deposition of organic
matter enables grass to gradually
replace amphibious plants.

Succession by woody plants
• The death of amphibious plants
caused continued deposition of
organic matter and evaporation of
pond water will make the pond very
shallow and eventually dry it up.
• Finally land plants and other woody
plants will replace the amphibious
plants and form a jungle.
Climax community
• The succession will stop when a
level of balance is achieved.

Pioneer stage
Phytoplanktons, zooplanktons & sunken
aquatic plants are the 1st colonizers
Succession by aquatic floating plants
Succession by amphibious plants
The leaves reduce the amount of light
entering the pond.
Succession by grasses (Fimbrostylis sp,
rusiga
Succession by land plants (grass, creepers,
woody plants)
Climax community (tropical rainforest.

Biology Form 4 Chapter 8 :Dynamic Ecosystem Part 2

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Biology Form 4 Chapter 8 :Dynamic Ecosystem Part 2