Adaptations • 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: • behavioral • physiological • structural (morphological) Osprey: a diurnal bird of prey 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 dikdiks 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 dikdiks. Dikdik 30.5-40.5 cm at shoulder 3-7 kg 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 • Structuraladaptations: 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. • 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. The fur of this cat is a striking property... 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 adaptationsto 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 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 submergedhydrophytes, 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.
Cross section through the petiole Floating leaves have a high density of stomata on the upper surface Submerged leaves are well spaced, finely divided, and taper towards the surface Vascular bundles Cortex Abundant, large air spaces 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. Water milfoil Myriophyllumspicatum Water lily Nymphaea alba
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
Shallow, but extensive fibrous root system 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. 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. • They develop strategies to reduce water loss, store water, and tap into available water supplies. Water table low
Funnel shaped leaves channel rain Shallow fibrous root system Water loss by transpiration Water table high Tropical Forest Plants • Tropical forest plants live in areas of often high rainfall. Therefore, they have to cope with high transpiration rates.
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. Ocean Margin Plants • Ocean margin plants, e.g. intertidal seaweeds and mangroves, must cope with high salt content in the water. Mangrove pneumatophores
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 tissue. • Leaf modifications act as traps. Usually the traps contain special glands that secrete digestive enzymes. Pitcher plant
Animal Adaptations Arid • 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. Forested Extreme cold
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 • 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. 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. Freezing is a typical behavior when threatened
Monitor Lizards 1 • Goannas or monitorlizards 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 Skin color is related to the environment. The skin of species in arid regions is highly reflective. 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. • Adaptations of monitor lizards (Varanus spp.) include: Strong neck and jaw muscles aid in holding, shaking, and subduing prey.
Siberia NorthPole NorthAmerica Asia Summer breeding area Winter migratory destination Europe Snow Bunting 1 • The snow bunting (Plectrophenaxnivalis) 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 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. The internal spaces of the dark colored feathers are filled with pigmented cells. More heat is lost from the dark summer plumage. White feathers are hollow and filled with air, which acts as an insulator. Less heat is lost from the white winter plumage. Snow Bunting 2 • Adaptations of the snow bunting (Plectrophenaxnivalis) include:
Trophic Structure 1 • Every ecosystem has a trophicstructure: 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
Consumer (C1) Producer (P) Consumer (C3) Consumer (C2) 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.
Organization of Trophic Levels • Trophic structure can be described by trophic level or consumer level:
whelk brown trout 2° carnivore 1° carnivore Producer (P) kingfisher Herbivore cat’s eye seagull seaweed aquatic macrophyte freshwater crayfish 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 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:
aquatic macrophyte freshwater crayfish brown trout seaweed abalone seagull starfish kingfisher Examples of Food Chains
Heat Heat Heat Heat Heat 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.
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 therefore tend to form complex webs of feeding interactions called a food web.
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.
Cellular respiration Light energy Carbon dioxideandwater Organic molecules and oxygen Photosynthesis Energy in Ecosystems • 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 Active transport processes, e.g. ion pumps Growth and repair of tissues Static biomass locks up some chemical energy Muscle contraction and flagella movement Production of macromolecules, e.g. proteins Cellular respiration • Energy is ultimately lost as heat to the atmosphere. 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)
Cellular respiration in mitochondria Photosynthesis in chloroplasts 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 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).
Wastes Metabolic waste products are released. Respiration Heat given off in the process of daily living. Growth and new offspring New offspring as well as new branches and leaves. Eaten by consumers Some tissue eaten by herbivores and omnivores. Dead tissue Reflected light Unused solar radiation is reflected off the surface of the organism. SUN Solar radiation 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. Producers Death Some tissue is not eaten by consumers and becomes food for decomposers.
Wastes Metabolic waste products are released (e.g. urine, feces, CO2) Respiration Heat given off in the process of daily living. Growth and reproduction New offspring as well as growth and weight gain. 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). Dead tissue Consumers • Consumers are organisms that feed on autotrophs or on other heterotrophs to obtain their energy. • Includes: animals, heterotrophicprotists, and some bacteria. Consumers Death Some tissue not eaten by consumers becomes food for detritivores and decomposers.
Producer tissue Nutrients released from dead tissues are absorbed by producers. Wastes Metabolic waste products are released. Respiration Heat given off in the process of daily living. Growth and reproduction New tissue created, mostly in the form of new offspring. Dead tissue Death Decomposers die; their tissue is broken down by other decomposers and detritivores Dead tissue of producers Dead tissue of consumers Dead tissue of decomposers Decomposers • Decomposers are consumers that obtain their nutrients from the breakdown of dead organic matter. They include fungi and soil bacteria. 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 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 primaryproductivityis the biomass produced per unit areaper unit time, e.g. g m-2y-1 Grassland: high productivity Grass biomass available to consumers
Measuring Plant Productivity • 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.
kcal m-2y-1 kJ m-2y-1 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. 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 • 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. Herbivores (1° consumers)... Eaten by 2° consumers