B4.1 Adaptation to the environment

habitat

where an organism lives (geographical or physical location within an ecosystem)

adaptations of lyme grass to sand dunes

challenges of water conservation, tolerance of high salt concentrations, lack of organic matter within sand

• thick wax/cuticle on leaves - reduces transpiration

• stomata in indentations (furrows) - humid air remains even in windy conditions

• leaves roll up during droughts - creates humid chamber, reduced surface area exposed to wind

• tough sclerenchyma - prevent wilting during droughts

• rhizomes (underground stems) - grow up as sand accumulates, extends deep into dune to obtain water

• accumulation of fructans (carbohydrates) in root and leaf cells - increased osmotic potential and water uptake

adaptations of mangrove trees to mangrove swamps

challenges of waterlogged anaerobic soils, high salt concentrations accumulated in mud

• salt glands in leaves - secretion of excess salt

• root epidermis coated in suberin (sork) - reduces permeability to salt, prevents excess absorption

• cable roots grow close to soil surface - most oxygen

• pneumatophores (vertical root branches) - grow up into air, absorb oxygen for use in roots

• stilt roots - grow out downward arch from central trunk, buttress tree in soft mud

• large buoyant seeds - carried by ocean to distant muddy shores

• accumulation of mineral ions and carbon compounds - increased osmotic potential of root and leaf cells, allowing water absorption from saline environment

limiting abiotic factors

temperature, salinity, pH, oxygen, carbon dioxide, light, hydrostatic pressure, water current, wind velocity

tolerance

levels of environmental factors in which a population can survive

conditions required for coral reef formation

• depth: <50m of water for enough light penetration

• pH: above 7.8 - allow deposition of calcium carbonate in skeleton

• salinity: between 32-42 parts per thousand of dissolved ions - avoid osmotic problems

• clarity - clear water for better light penetration

• temperature: 23-29 degrees celsius - coral and zooxanthellae remain healthy

principal abiotic determinants of biome distribution on earth

temperature and rainfall

tropical forest

• high temperature

• high precipitation

• high light intensity

• minimal seasonal variation in rainforests

temperate forest

• medium temperature

• high/medium precipitation

• medium light intensity

• warm summers, colder winters

taiga (boreal forest)

• low temperature

• high/medium precipitation

• medium/low light intensity

• short summers; long, cold, winters

hot desert

• high temperature

• very low precipitation

• high light intensity

• minimal seasonal variation

grassland

• high/medium temperature

• medium precipitation

• high/medium light intensity

• seasonal variation with dry season or cold season

tundra

• very low temperature

• medium/low precipitation

• low light intensity

• very short summer, very cold winter

saguaro cactus’s adaptation to hot deserts

• wide-spread root system and deep tap roots - collecting water

• flat stems with storage tissue to conserve water after infrequent desert rains

• pleated stems to allow shrinkage in drought and swelling after rains

• vertical orientation of stems to reduce interception of sunlight at midday and maximize interception at cooler time of day

• thick waxy cuticle on stem epidermis to reduce transpiration

• leaves reduced to spines - reduced surface area for transpiration, prevent getting eaten

• CAM metabolism - allows stomata to open at night, close during day, reduce transpiration

fennec foxes’ adaptations to hot desert

• nocturnal - avoid highest temperatures

• build underground den - stay cool

• long thick hair - heat insulation

• hair covering pads of feet to provide insulation when walking on hot sand

• pale-colored coat - reflects sunlight

• large ears - radiate heat, help keep body temperature down

• variable ventilation rate to cause heat loss by evaporation

meranti trees’ adaptations to tropical rainforests

• can grow up to 100 meters high - avoiding competition for light

• trunk of hard dense wood - provides support, especially against wind stress