• An adaptation (or adaptive feature) is an inherited feature of an organism that enables it to survive and reproduce in its habitat.

• Adaptations are the end result of the evolutionary changes that a species has gone through over time.

Adaptations may be:

behavioralphysiologicalstructural (morphological)

Adaptations

Osprey: a diurnal bird of prey

Spotted owl: a nocturnal bird of prey

• 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.

Exploiting a Habitat

• 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.

Plants and Browsers

Acacia forest

• 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.

• Impalas, with their larger muzzles and longer necks, can reach three times higher than dik diks.

African Browsers 1

Dik dik30.5-40.5 cm at shoulder3-7 kg

Impala80-90 cm at shoulder40-65 kg

• 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.

African Browsers 2

Gerenuk90-105 cm at shoulder28-52 kg

Giraffe3.3 m at shoulder6 m to crown0.6-1.9 tonne

• Organisms have adaptations for:

Biorhythms and activity patterns, e.g. nocturnal behaviorLocomotion (or movement)Defense of resources Predator avoidanceReproductionFeeding

• These categories are not mutually exclusive.

Purposes 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.

Types of Adaptations

Praying mantis

‣ 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.

• 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.

Adaptations and Fitness

The fur of this cat is a striking property...

Mothering and play behaviors are adaptive

‣ 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.

Plant Adaptations

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.

Halophyte: spinifex Xerophyte: cactusHydrophyte: water lily

Conserving Water

Adaptationfor water

conservation

Effect of adaptation

Example

Thick, waxycuticle to stems

and leaves

Reduces water loss throughthe cuticle

Pinus spp.,ivy, sea holly, prickly pear

Reducednumber ofstomata

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.

Pinus

Prickly pear: Opuntia

Marram grass

‣ Hydrophytes are plants that have adapted to living either partially or fully submerged in water.

• Typical features of submergedhydrophytes, e.g. the water lily (Nymphaea alba), include:

Large, thin, floating leavesElongated petioles (leaf stalks)Reduced root systemAerial flowersLittle or no waxy cuticlePoorly developed xylem tissueLittle or no lignin in vascular tissuesFew sclereids or fibers.

Adaptations of Hydrophytes

• 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.

Hydrophytic Plants

Submerged leaves are well spaced, finely divided, and taper towards the surface

Floating leaves have a high density of stomata

on the upper surface

Water lilyNymphaea alba

Water milfoil Myriophyllum spicatum

Cross section through the petiole

CortexAbundant, large air spaces

Vascular bundles

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

• 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.They develop strategies to reduce water loss, store water, and tap into available water supplies.

Dry Desert Plants

Water table low

Shallow, but extensive fibrous root system

Stem becomes the major photosynthetic organ, and a reservoir for water storage.

Surface area reduced by producing a squat, rounded shape.

Leaves modified into spines or hairs to reduce water loss

‣ Tropical forest plants live in areas of often high rainfall. Therefore, they have to cope with high transpiration rates.

Tropical Forest Plants

Shallow fibrous root system

Funnel shaped leaves channel rain

Water table high

Water loss by transpiration

‣ Ocean margin plants, e.g. intertidal seaweeds and mangroves, must cope with high salt content in the water.

Ocean Margin Plants

Some mangrove species take in brackish water and excrete the salt through glands in the leaves.

Seaweeds growing in the intertidal zone tolerate exposure to the drying air every 12 h.

Mangrove pneumatophores

‣ 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 tissue.Leaf modifications act as traps. Usually the traps contain special glands that secrete digestive enzymes.

Insectivorous PlantsSundew

(Drosera)

Pitcher plant

• 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.

Animal Adaptations

Extreme cold Forested

Arid

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 semi-desert.

Capybara: the world’s largest rodent Jackrabbit: a lagamorph

Structural Adaptations in Rabbits

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 andlarge feet enable rapid movement

and are well suited to digging.

Cryptic coloration provideseffective camouflage in

grassland habitat.

• 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 detectingand avoiding predators.

Functional Adaptations in Rabbits• Functional (physiological) adaptations are

associated with physiology.The functional adaptations of rabbits are associated with detecting and avoiding predation, and maintaining populationsdespite high losses.

Functional adaptations

High reproductive rate enables rapid population increases when food is

available.

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.

Strong neck and jaw

muscles aid in holding,

shaking, and subduing prey.

• Adaptations of monitor lizards (Varanus spp.) include:

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.

The upper jaw can move

independently of the rest of

the skull to facilitate

swallowing of prey whole.

Monitor Lizards 2

Skin color is related to the

environment. The skin of

species in arid regions is

highly reflective.

• 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 upto 6000 km but are alwaysfound at high latitudes.They have the uniqueability to molt very rapidlyafter breeding, changingcolor quickly from a brownsummer plumage to thewhite winter plumage.

Snow Bunting 1

Siberia

Asia

Europe

Summer breeding

area

Winter migratory

destination

NorthAmerica

NorthPole

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.

During snow storms or periods of high wind, snow

buntings will burrow into snowdrifts for shelter.

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.

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.

Hydrothermal vent communities are an exception; the producers are chemosynthetic bacteria that derive energy by oxidizing hydrogen sulfide.

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 of food generated per unit time through photosynthesis) sets the limit for the energy budget of an ecosystem.

Consumer(C3)

Consumer(C2)

Consumer(C1)

Producer(P)

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, photosyntheticprotists and bacteria

Herbivores Producers Grasshoppers, water fleas,antelope, termites

PrimaryCarnivores

Herbivores Wolves, spiders,some snakes, warblers

SecondaryCarnivores

Primary carnivores Killer whales, tuna, falcons

Omnivores Several trophic levels Humans, rats, opossums,bears, racoons, crabs

Detritivores and Decomposers

Wastes and dead bodiesof other organisms

Fungi, many bacteria,earthworms, vultures

• 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 go from food to feeder.

• Organisms whose food is obtained through the same number of links belong to the same trophic level.

• Examples of food chains include:

Food Chains

2° carnivore

1° carnivore

HerbivoreProducer(P)

seaweed

aquatic macrophyte

cat’s eye

freshwater crayfish

whelk

brown trout

seagull

kingfisher

Examples of Food Chains

seagullstarfish

freshwater crayfish

aquatic macrophyte

brown trout kingfisher

seaweed abalone

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

• 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 therefore tend to form complex webs of feeding interactions called a food web.

Food Webs

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, 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.

Energy in Ecosystems

Organic molecule

s andoxygen

Carbon dioxide

andwater

Cellular respiration

Light energy

Photosynthesis

‣ Energy is ultimately lost as heat to the atmosphere.

Cellular respiration

Heat EnergyCellular work and accumulated biomass ultimately dissipates as heat energy

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

Energy in Ecosystems

• Living things are classified according to the way in which they obtain their energy:

Producers (or autotrophs) Consumers (or heterotrophs)

Energy Inputs and Outputs

• 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 occursin the oceans is vital to life onEarth, providing oxygen andabsorbing carbon dioxide.Cellular respiration is theprocess by which organismsbreak down energy richmolecules (e.g. glucose)to release the energy ina useable form (ATP).

Energy Transformations

Cellular respiration in mitochondria

Photosynthesis in chloroplasts

‣ 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.

Producers

DeathSome tissue is not

eaten by consumers and becomes food for

decomposers.

WastesMetabolic waste

products are released.

RespirationHeat given off in the

process of daily living.

Reflected lightUnused solar radiation

is reflected off the surface of the organism.

Dead tissue

Growth and new offspringNew offspring as well as new

branches and leaves.

Eaten by consumersSome tissue eaten by

herbivores and omnivores.

Solar radiation

SUNProducers

‣ Consumers are organisms that feed on autotrophs or on other heterotrophs to obtain their energy.

• Includes: animals, heterotrophic protists, and some bacteria.

Consumers

DeathSome tissue not eaten

by consumers becomes food for detritivores and

decomposers.

WastesMetabolic waste

products are released(e.g. urine, feces, CO2)

RespirationHeat given off in the

process of daily living.

Dead tissue

Growth and reproductionNew offspring as well as growth and weight gain.

Eaten by consumersSome tissue eaten by

carnivores and omnivores.

FoodConsumers 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).

Consumers

Producer tissueNutrients released from

dead tissues are absorbed by producers.

WastesMetabolic waste

products are released.

RespirationHeat given off in the

process of daily living.

Growth and reproductionNew tissue created, mostly in

the form of new offspring.

‣ Decomposers are consumers that obtain their nutrients from the breakdown of dead organic matter. They include fungi and soil bacteria.

Decomposers

Dead tissue

DeathDecomposers die;

their tissue is broken down by other

decomposers and detritivores

Dead tissue of consumers

Dead tissue of producers

Dead tissue of decomposers

Decomposers

• 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 theGPP 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.Productivity is defined as the rate of production. Net primary productivity is the biomass produced per unit areaper unit time, e.g. g m-2y-1

Primary Production

Grassland: high productivity

Grass biomass available to consumers

‣ The primary productivity of an ecosystem depends on a number of interrelatedfactors, such as lightintensity, temperature,nutrient availability,water, andmineral supply.

• The most productive ecosystems aresystems with high temperatures, plenty of water, and non-limiting supplies of soil nitrogen.

Measuring Plant 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.

Ecosystem Productivity

kcal m-2y-1

kJ m-2y-1

Although the open ocean’s

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 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 producers and herbivores, and between herbivores and higher level consumers is inefficient.

Secondary Production

Herbivores (1° consumers)...

Eaten by 2° consumers