Transcript 2 Ecosystem Part2 - DAVIS-DAIS

Adaptations
• An adaptation (or
adaptive feature) is an
inherited feature of an
organism that enables it to
survive and reproduce in
its habitat.
Osprey: a diurnal bird of prey
• Adaptations are the end
result of the evolutionary
changes that a species has
gone through over time.
Adaptations may be:
behavioral
physiological
structural (morphological)
Spotted owl: a nocturnal bird of prey
Exploiting a Habitat
• Organisms have adaptations to
exploit, to varying extents, the
resources in their habitat.
• Where resource competition is
intense, adaptations enable
effective niche specialization
and partitioning of resources.
In the African savanna, grazing
and browsing animals exploit
different food resources within
the same area or even within
the same type of vegetation.
Plants and Browsers
•
The large thorns and dense, tangled growth form of the acacias of the African savanna are
adaptations to counter the effects of browsing animals such as antelope.
Acacia forest
African Browsers 1
• Tiny dik diks can only
browse the lowest acacia
branches, less than 1 m
above the ground. Their
small pointed muzzles
avoid the hooks and spines
that defeat clumsier
browsers.
Dik dik
30.5-40.5 cm at shoulder
3-7 kg
• Impalas, with their larger
muzzles and longer necks,
can reach three times
higher than dik diks.
Impala
80-90 cm at shoulder
40-65 kg
African Browsers 2
• The disproportionately
small head of the gerenuk
allows it to browse
between the thorny
branches. Swiveling hip
joints allow it to stand
erect and reach taller
branches.
• Giraffes browse the upper
branches of the acacia.
Its long (45 cm) muscular
tongue is impervious to
thorns and its long neck is
so mobile that its head can
tip vertically.
Gerenuk
90-105 cm at shoulder
28-52 kg
Giraffe
3.3 m at shoulder
6 m to crown
0.6-1.9 tonne
Purposes of Adaptations
• Organisms have adaptations for:
Biorhythms and activity
patterns, e.g. nocturnal behavior
Locomotion (or movement)
Defense of resources
Predator avoidance
Reproduction
Feeding
• These categories are not
mutually exclusive.
Types of Adaptations
‣ Structural adaptations: physical
features of an organism, e.g.
presence of wings for flight.
‣ Behavioral adaptations:
the way an organism acts, e.g.
mantid behavior when seeking,
capturing, and manipulating
prey.
‣ Functional (physiological)
adaptations:
those involving physiological
processes, e.g. the female
mantid produces a frothy liquid
to surround and protect the
groups of eggs she lays.
Praying mantis
Adaptations and Fitness
‣ Fitness is a measure of how
well suited an organism is to
survive in its habitat and its
ability to maximize the
numbers of offspring
surviving to reproductive
age.
The fur of this cat is a striking property...
• Adaptations are distinct
from properties which,
although they may be
striking, cannot be described
as adaptive unless they are
shown to be functional in
the organism’s natural
habitat.
Mothering and play behaviors
are adaptive
Plant
Adaptations
‣ The adaptations found in plants
reflect both the plant’s environment
and the type and extent of
predation to which the plant is
subjected.
Many plant adaptations are
concerned with maintaining water
balance. Terrestrial plant species
show a variety of structural and
physiological adaptations for water
conservation.
Plants evolve defenses, such as
camouflage, spines, thorns, or
poisons, against efficient herbivores.
Water Balance in Plants
• Plants can be categorized according to their adaptations
to particular environments:
Hydrophytes: live partially or fully submerged in water.
Halophytes: salt tolerant species found in coastal and salt marsh environments.
Xerophytes: arid adapted species found in hot and cold deserts.
Hydrophyte: water lily
Halophyte: spinifex
Xerophyte: cactus
Conserving Water
Pinus
Adaptation
for water
conservation
Effect of
adaptation
Example
Thick, waxy
cuticle to stems
and leaves
Reduces water
loss through
the cuticle
Pinus spp.,
ivy, sea holly,
prickly pear
Reduced
number of
stomata
Reduces the
number of pores
for water loss
Prickly pear,
Nerium sp.
Leaves curled,
rolled or folded
when flaccid
Reduces surface
area for
transpiration
Rolled leaf:
marram grass,
Erica spp.
Prickly pear: Opuntia
Marram grass
Adaptations of Hydrophytes
‣ Hydrophytes are plants that have
adapted to living either partially or
fully submerged in water.
• Typical features of submerged
hydrophytes, e.g. the water lily
(Nymphaea alba), include:
Large, thin, floating leaves
Elongated petioles (leaf stalks)
Reduced root system
Aerial flowers
Little or no waxy cuticle
Poorly developed xylem tissue
Little or no lignin in vascular
tissues
Few sclereids or fibers.
Hydrophytic Plants
• The aquatic environment presents different problems to those faced by
terrestrial plants. Water loss is not a problem and, supported by the
water, they require little in the way of structural tissues.
Floating leaves have a
high density of stomata on
the upper surface
Cross section
through the petiole
Submerged leaves are well
spaced, finely divided, and
taper towards the surface
Water milfoil
Myriophyllum spicatum
Water lily
Nymphaea alba
Vascular bundles
Abundant,
large air
spaces
Cortex
Adaptations of
Halophytes
‣
Mangroves are halophytes, adapted to grow in
saline, intertidal environments, where they form
some of the most complex and productive
ecosystems on Earth.
•
Mangrove adaptations include:
Ability to secrete salt or accumulate it in older
leaves.
Specialized tissue that allows water, but not salt, to
enter the roots.
Tissue tolerance for high salt levels.
Extensive root systems give support in soft
substrates; oxygen enters the roots through
pneumatophores.
Mangroves, USA
Dry Desert Plants
• Plants adapted to dry
conditions are called
xerophytes and they
show structural and
physiological adaptations
for water conservation.
Desert plants, e.g.
cacti, cope with low
rainfall and potentially
high transpiration rates.
Leaves modified into
spines or hairs to
reduce water loss
Surface area reduced
by producing a squat,
rounded shape.
Stem becomes
the major
photosynthetic
organ, and a
reservoir for
water storage.
Shallow, but
extensive fibrous
root system
They develop strategies
to reduce water loss,
store water, and tap into
available water supplies.
Water table low
Tropical Forest Plants
‣ Tropical forest plants live in
areas of often high rainfall.
Therefore, they have to cope
with high transpiration rates.
Funnel shaped
leaves channel rain
Shallow
fibrous root
system
Water loss by
transpiration
Water table high
Ocean Margin Plants
‣ Ocean margin plants,
e.g. intertidal seaweeds
and mangroves, must
cope with high salt
content in the water. Seaweeds growing in
the intertidal zone
tolerate exposure to the
drying air every 12 h.
Mangrove pneumatophores
Some mangrove species
take in brackish water and
excrete the salt through
glands in the leaves.
Insectivorous Plants
Sundew
(Drosera)
‣ Insectivorous plants
are plants that obtain
extra nutrients by
capturing and digesting
small invertebrates.
They are commonly
found in marginal
habitats such as acid
bogs or nutrient-poor
soils.
They are often small
because of the marginal
habitats in which they
live.
They make their own
sugars through
photosynthesis, but
obtain nitrogen and
minerals from animal
Pitcher plant
Animal Adaptations
• No animal exists
independently of its
environment, and
different
environments
present animals with
different problems.
• Animals exhibit a
great diversity of
adaptations. These
enable them to live
within the
constraints of their
particular
environment.
Extreme cold
Arid
Forested
Rodents and Lagamorphs
• Lagamorphs (rabbits and hares) and
rodents are two successful and highly
adaptable mammalian orders.
Although different in many respects, they share
similar adaptations, including early maturity,
high reproductive rates, chisel-like teeth, and
dietary flexibility.
• They are found throughout the world
(except in Antarctica) in habitats ranging
from Arctic tundra to desert and semidesert.
Capybara: the world’s largest rodent
Jackrabbit: a lagamorph
Structural Adaptations in Rabbits
• Rabbits are
colonial mammals
that live
underground in
warrens and feed
on a wide range of
vegetation.
• Many of their
more obvious
structural
adaptations are
associated with
detecting
and avoiding
predators.
Structural adaptations
Widely spaced eyes gives a wide field
of vision for surveillance of the habitat
and detection of danger.
Long, mobile ears enable acute
detection of sounds from many angles
for predator detection.
Long, strong hind legs and
large feet enable rapid movement
and are well suited to digging.
Cryptic coloration provides
effective camouflage in
grassland habitat.
Functional Adaptations in Rabbits
• Functional (physiological) adaptations are
associated with physiology.
The functional adaptations of Functional adaptations
rabbits are associated with
detecting and avoiding predation,
High reproductive rate enables rapid
and maintaining populations population increases when food is
available.
despite high losses.
Keen sense of smell allows detection
of potential threats from predators and
from rabbits from other warrens.
Microbial digestion of vegetation in the
hindgut enables more efficient
digestion of cellulose.
High metabolic rate and fast response
times enables rapid response to
dangers.
Hawks are major predators of rabbits
Behavioral Adaptations in Rabbits
• The behavioral
adaptations of rabbits
reflect their functional
position as herbivores
and important prey
items in many food
webs.
Behavioral adaptations
Freeze behavior when startled
reduces the possibility of detection by
wandering predators.
Thumps the ground with hind legs to
warn others in the warren of
impending danger.
Lives in groups with a well organized
social structure that facilitates
cooperative defense.
Burrowing activity provides extensive
underground habitat as refuge from
predators.
Freezing is a typical behavior when
threatened
Monitor Lizards 1
• Goannas or monitor lizards are top predators,
found in a wide range of habitats, from
aquatic to arid semi-desert.
They are strict carnivores and eat a range of
animal species, including carrion.
They are diurnal and active in all seasons. Body
temperatures of up to 38°C are maintained
through basking and other behaviors.
Monitor Lizards 2
•
Adaptations of monitor lizards (Varanus spp.) include:
Skin color is related to the
environment. The skin of
species in arid regions is
highly reflective.
Strong neck and jaw
muscles aid in holding,
shaking, and subduing prey.
The upper jaw can move
independently of the rest of
the skull to facilitate
swallowing of prey whole.
The gular (throat) pouch is
inflated during threat displays.
Rapid movements of the gular
region when the mouth is open
is used as a cooling
mechanism.
Snow Bunting 1
• The snow bunting (Plectrophenax nivalis) is a
small ground feeding bird that lives and
breeds in the Arctic region.
Snow buntings are widespread throughout the
Arctic and sub-Arctic islands. They are active 24
hours a day, resting for only 2-3 hours within that
period.
Snow buntings migrate up
Siberia
to 6000 km but are always
North
Pole
found at high latitudes. North
They have the unique America
Asia
ability to molt very rapidly
Summer
breeding
after breeding, changing
area
color quickly from a brown
summer plumage to the
white winter plumage.
Winter
migratory
destination
Europe
Snow Bunting 2
• Adaptations of the snow bunting
(Plectrophenax nivalis) include:
The internal spaces of the dark
colored feathers are filled with
pigmented cells. More heat is lost
from the dark summer plumage.
Snow buntings, on average, lay 1-2
eggs more eggs than equivalent
species further south. In continuous
daylight, and with an abundance of
insects at high latitudes, they are
able to rear more young.
During snow storms or
periods of high wind, snow
buntings will burrow into
snowdrifts for shelter.
White feathers are hollow and
filled with air, which acts as an
insulator. Less heat is lost from
the white winter plumage.
Trophic Structure 1
• Every ecosystem has a
trophic structure: a
hierarchy of feeding
relationships which
determines the pathways
for energy flow and
nutrient cycling.
• Species are assigned to
trophic levels on the
basis of their nutrition.
• Producers (P) occupy the
first trophic level and
directly or indirectly
support all other levels.
Producers derive their
energy from the sun in
most cases.
Deep sea
hydrothermal vent
Trophic Structure 2
• All organisms other than
producers are consumers
(C).
• Consumers are ranked
according to the trophic
level they occupy. First
order (or primary)
consumers (herbivores),
rely directly on producers
for their energy.
A special class of
consumers, the
detritivores, derive their
energy from the detritus
representing all trophic
levels.
• Photosynthetic
productivity (the amount
Producer
(P)
Consumer
(C1)
Consumer
(C2)
Consumer
(C3)
Organization of Trophic Levels
•
Trophic structure can be described by trophic level or consumer level:
Major Trophic Levels
Trophic Level
Source of Energy
Examples
Producers
Solar energy
Green plants, photosynthetic
protists and bacteria
Herbivores
Producers
Grasshoppers, water fleas,
antelope, termites
Primary
Carnivores
Herbivores
Wolves, spiders,
some snakes, warblers
Secondary
Carnivores
Primary carnivores
Killer whales, tuna, falcons
Omnivores
Several trophic levels
Humans, rats, opossums,
bears, racoons, crabs
Detritivores and
Decomposers
Wastes and dead bodies
of other organisms
Fungi, many bacteria,
earthworms, vultures
Food Chains
• The sequence of organisms, each of which is
a source of food for the next, is called a food
chain.
Food chains commonly have four links but
seldom more than six.
In food chains the arrows go1° from food to feeder.
2°
Producer
(P)
Herbivore
carnivore
carnivore
• Organisms whose food is obtained through
the same number of links belong to the same
trophic
level.cat’s eye
seagull
seaweed
whelk
• Examples of food chains include:
aquatic
macrophyte
freshwater
crayfish
brown
trout
kingfisher
Examples of Food Chains
seaweed
aquatic
macrophyte
abalone
freshwater
crayfish
starfish
seagull
brown
trout
kingfisher
Food Chain Energy Flow
• Energy is lost as heat from each trophic level
via respiration.
• Dead organisms at each level are
decomposed.
• Some secondary consumers feed directly off
decomposer organisms.
Heat
Heat
Heat
Heat
Heat
Food Webs
• Some consumers
(particularly ‘top’
carnivores and
omnivores) may
feed at several
different trophic
levels, and many
herbivores eat
many plant
species.
For example,
moose feed on
grasses, birch,
aspen, firs, and
aquatic plants.
• The different food
chains in an
ecosystem
A Simple Lake Food Web
• This lake food web includes only a limited
number of organisms, and only two
producers. Even with these restrictions, the
web is complex.
Energy in
Ecosystems
Light energy
‣ Energy, unlike,
matter, cannot
be recycled.
Ecosystems
must receive a
constant input
of new energy
from an outside
source which,
in most cases,
is the sun.
Photosynthesis
Carbon
dioxide
and
water
Organic
molecule
s and
oxygen
Cellular respiration
Energy in
Ecosystems
‣
Energy is ultimately lost as heat to
the atmosphere.
Cellular respiration
Static biomass
locks up some
chemical energy
Growth and
repair of
tissues
Muscle contraction
and flagella
movement
Active transport
processes, e.g.
ion pumps
Production of
macromolecules,
e.g. proteins
Heat Energy
Cellular work and accumulated biomass ultimately dissipates as heat energy
Energy Inputs and Outputs
• Living things are
classified according
to the way in which
they obtain their
energy:
Producers (or
autotrophs)
Consumers (or
heterotrophs)
Energy Transformations
• Green plants, algae, and some bacteria
use the sun’s energy to produce glucose
in a process called photosynthesis.
The chemical energy stored in glucose
fuels metabolism.
The photosynthesis that occurs
in the oceans is vital to life on
Earth, providing oxygen and
absorbing carbon dioxide.
Cellular respiration is the
respiration
process by which organisms Cellular
in mitochondria
break down energy rich
molecules (e.g. glucose)
to release the energy in
a useable form (ATP).
Photosynthesis
in chloroplasts
Producers
‣ Producers are able to manufacture their
food from simple inorganic substances
(e.g. CO2). Producers include green plants,
algae and other photosynthetic protists,
and some bacteria.
Respiration
Growth and new offspring
Eaten by consumers
Heat given off in the
process of daily living.
Wastes
Metabolic waste
products are released.
New offspring as well as new
branches and leaves.
Some tissue eaten by
herbivores and omnivores.
Producers
SUN
Solar
radiation
Reflected light
Unused solar radiation
is reflected off the
surface of the organism.
Dead tissue
Death
Some tissue is not
eaten by consumers
and becomes food for
decomposers.
Consumers
‣
Consumers are organisms that feed on autotrophs or on other heterotrophs to
obtain their energy.
•
Includes: animals, heterotrophic protists, and some bacteria.
Respiration
Heat given off in the
process of daily living.
Wastes
Metabolic waste
products are released
(e.g. urine, feces, CO2)
Death
Some tissue not eaten
by consumers becomes
food for detritivores and
decomposers.
Growth and
reproduction
New offspring as well as
growth and weight gain.
Consumers
Dead tissue
Eaten by
consumers
Some tissue eaten by
carnivores and
omnivores.
Food
Consumers obtain their
energy from a variety of
sources: plant tissues
(herbivores), animal
tissues (carnivores),
plant and animal tissues
(omnivores), dead
organic matter or
detritus (detritivores
and decomposers).
‣ DecomposersDecomposers
are consumers that obtain their
nutrients from the breakdown of dead organic
matter. They include fungi and soil bacteria.
Respiration
Heat given off in the
process of daily living.
Wastes
Metabolic waste
products are released.
Producer tissue
Nutrients released from
dead tissues are
absorbed by producers.
Growth and reproduction
New tissue created, mostly in
the form of new offspring.
Decomposers
Death
Decomposers die;
their tissue is broken
down by other
decomposers and
detritivores
Dead tissue
Dead tissue of
producers
Dead tissue of
consumers
Dead tissue of
decomposers
Primary Production
• The energy entering
ecosystems is fixed by
producers in
photosynthesis.
Gross primary
production (GPP) is the
total energy fixed by a
plant through
photosynthesis.
Net primary production
(NPP) is the
GPP minus the energy
required by the plant
for respiration. It
represents the amount
of stored chemical
energy that will be
available to consumers
in an ecosystem.
Grassland: high productivity
Grass biomass available to consumers
Measuring Plant Productivity
‣ The primary
productivity of an
ecosystem
depends on a
number of
interrelated
factors, such as
light
intensity,
temperature,
nutrient
availability,
water, and
mineral supply.
• The most
productive
ecosystems are
systems with high
Ecosystem
Productivity
• The primary
productivity
of oceans is lower
than that of terrestrial ecosystems because
the water reflects (or absorbs) much of the
light energy before it reaches and is utilized
by the plant.kcal m y
Although the open ocean’s
-2 -1
kJ m-2y-1
productivity is low, the ocean
contributes a lot to the Earth’s total
production because of its large size.
Tropical rainforest also contributes a
lot because of its high productivity.
Secondary Production
‣ Secondary
production is
the amount of
biomass at
higher trophic
levels (the
consumer
production).
It represents
the amount of
chemical
energy in
consumers’
food that is
converted to
their own new
biomass.
Energy transfers
between
Herbivores (1° consumers)...
Eaten by 2° consumers